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Surgery and the forefoot
8 Surgery and the forefoot J O N A T H A N NOBLE ROBIN PATON
In this chapter the forefoot is defined as the structures distal to the mid-tarsal joints. Conditions of the forefoot can be descriptively subdivided into rheumatoid arthritis, toe conditions and other miscellaneous problems. Generally the large majority of problems arising in the forefoot can and should'be treated by simple conservative measures, often administered by chiropodists. Many of these techniques will be to redistribute stress in its transfer from bone through skin to footwear. The principal indications for surgical involvement are for the relief of pain and to improve deformity, usually after conservative measures have failed.
PRE-OPERATIVE ASSESSMENT A full history and examination is mandatory in every patient with conditions of the feet. If this is not followed, inappropriate surgery may be undertaken with worsening of the underlying condition. It should always be remembered that deformities, especially in rheumatoid arthritis, do not occur in isolation, but various deformities occur together, e.g. the cavus foot and intrinsic muscle shortening which causes hammering of toes.
Specific local problems On examination the presence of deformity, skin condition, gait and neurological status should be carefully noted, as vasculitis, peripheral vascular disease, peripheral neuropathy or, poor skin may militate against surgery.
Systemic problems Severe systemic conditions, such as respiratory or cardiovascular disease, may also influence against surgical treatment and make it inappropriate. Moreover they may restrict the patient's mobility to such a degree as to make foot surgery pointless. Foot problems may be the first indication of systemic neurological disorders, such as the demyelinating diseases or pathology within the spinal canal. Furthermore the stability and integrity of the cervical Baillibre's ClinicalRheumatology--Vol. 1, No. 2, August1987
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spine must be assessed pre-operatively and may require protection with a collar during anaesthesia. Drugs
The commonest drugs to affect the foot are steroids, which can compromise the healing of already atrophic skin. Other drugs may have direct or indirect effects, e.g. anti-coagulation will affect haemostasis and even predispose to haematoma formation post-operatively. SURGICAL TREATMENT OF RHEUMATOID ARTHRITIS OF THE FOREFOOT Clinical
The metatarsophalangeal joints (MTP) of the foot cause more trouble to the rheumatoid sufferer than any other joint in the body (Laurence, 1985). Most small joint disease is treated medically and only disease which has failed to respond to these measures is usually considered for surgical intervention. Foot problems in the rheumatoid patient should not be assessed in isolation and a team approach is required. Thus decisions can be reached as to the order of surgical priorities when upper limbs, hips, knees and feet all command surgical attention. Clearly total replacement of the knees or hips may only be of benefit if painful feet are dealt with first. Moreover the frequency with which forefoot surgery is attended post-operatively by superficial sepsis makes it mandatory to eliminate this problem prior to joint arthroplasty work. The classical history given by the patienf with severe rheumatoid disease of the feet is described as 'walking on marbles', with severe pain, sometimes a feeling of instability and consequently reduced walking distance. Surgical pathology
The small joints of the feet are attacked early and extensively. Both the soft tissues and the joints are affected. The spectrum of this disease varies from a simple synovitis, to the severe classical rheumatoid deformity of hyperextension of the metatarsophalangeal joint (MTP), flexion of the proximal interphalangeal joints (PIP) with pes planus. Splaying of the metatarsal heads occurs early and 60% of patients with rheumatoid develop a hallux valgus of over 20 ~ (Kirkup et al, 1977). The toe deformities are thought to be partly due to intrinsic muscle weakness (Spiegal and Spiegal, 1982). These toe deformities may progress until the proximal phalanges 'piston' the metatarsal heads into the sole of the foot (Fowler, 1959), resulting in their being palpable superficially on the plantar aspect of the forefoot, with the formation of callosities, due to the alteration of the pressure distribution. The most common pressure lesions occur under the 2nd and 3rd metatarsal heads (Collis and Jayson, 1972). Deformities of the toes may draw the
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protective metatarsal fat pad distally, exacerbating these pressure effects. From a surgical point of view, moderate and severe disease require different approaches. The moderate rheumatoid foot is one which has not responded to medical measures, but which lacks severe deformity. This allows methods of surgical treatment which would not be successful in the severe rheumatoid foot, and which it is their principle to prevent. There are two common procedures for moderate disease; the Helal (1975) and Lipscomb (1981) procedures.
The Helal procedure (1975) (Figure la) Technique. Dorsal longitudinal incisions are used over the forefoot. The middle three metatarsal shafts are exposed and are divided at the junction of the middle and distal third of the bone at an angle of 45~ plantarwards and distally (see diagram). Any projecting bone spikes, are trimmed. The bones are divided at the same level, or in a smooth curve on the antero-posterior plane, to prevent pressure inequalities at the metatarsal heads. If the 1st and 5th metatarsal joints are also involved, separate incisions are required and the osteotomy must also be slanted to allow telescoping of the distal fragment towards the adjoining metatarsal, as in the Wilson procedure (see section on hallux valgus).
Post-operative management. If only the middle three metatarsals are osteotomized the patient can bear weight from the onset, in sterile dressings, to protect the wounds. However, if all five metatarsals are operated upon, the foot must be protected with a plaster of Paris for six weeks, until the osteotomies have united.
Rationale. The oblique osteotomy allows some shortening of the skeleton relative to the soft tissues, thereby improving some early toe deformities. (a)
Lateral
Lateral
Figure la. The Helal procedure. [] = bone for excision.
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More importantly these osteotomies allow the metatarsal heads to ride dorsally, reducing the pressure problems in these areas. Helal (personal communication, Tillmann) has claimed that this procedure may improve the synovitis of rheumatoid arthritis, but this claim has yet to be substantiated.
The Lipscomb procedure (Lipscomb, 1981) (Figure lb) Technique. Three dorsal longitudinal incisions are employed. The 1st MTP joint is arthrodesed in a position of 20~valgus and 10-20 ~of dorsiflexion with a lag screw. However, if there is severe interphalangeal joint involvement, a partial proximal phalangectomy is undertaken and a K-wire is used to maintain length in the hallux. In the lesser toes, only a small portion of the (b)
5
Toes
Anteroposterior
Metatarsal bones
f
Anteroposterior
lesser toes
Fusion 1st MTP joint
Figure lb.
The Lipscomb procedure. [] = bone for excision.
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proximal phalanges are excised with only the plantar aspect of the metatarsal heads. K-wires are inserted through the toes and into the metatarsal head in an attempt to maintain forefoot length.
Post-operative management. The feet are elevated post-operatively to allow the inevitable oedema to settle. Mobilization is usually without plaster of Paris support. The K-wires are maintained for 6 weeks.
Rationale. This procedure is only useful in conditions where MTP joint disease and pain are the main problems. It probably has no place in MTP joint deformity, such as subluxation and dislocation. This method attempts to maintain forefoot length. Better balance, stance, and fitting of conventional shoe-wear is possible than after forefoot arthroplasties, by metatarsal head excision.
Advantages and disadvantages of the above procedures in moderate disease. Patient selection is vitally important, if the above procedures are to be useful. The Helal procedure, which does not interfere with the MTP joints, has the advantage of being a quick, easy procedure with swift rehabilitation. Salvage procedures, such as metatarsal head excision, are not compromised by this operation, should they later become necessary. The disadvantages are that although this is an early procedure it must be undertaken meticulously or plantar bone spikes may cause pressure problems. It has no place in severe deformity. The Lipscomb procedure has a more limited role than that of Helal, and again it has no place for the foot with severe deformity. The main advantage is said to be that by maintaining forefoot length, balance and gait are not adversely affected. However by maintaining length this procedure may be inadequate to remove the pressure problems beneath the metatarsal heads, whereupon a secondary forefoot arthroplasty should be undertaken with the potential for problems of wound healing increased.
SURGICAL MANAGEMENT OF SEVERE RHEUMATOID ARTHRITIS OF THE FOREFOOT Severe disease can be defined as pathology that results in severe pain and deformity unrelieved by other methods of treatment and in practice is the classical rheumatoid forefoot deformity, with hallux valgus, splayed anterior arch and dorsally subluxed or dislocated toes. There are four typical surgical procedures: The Hoffmann, The Fowler, The Kates, Kessel and Kay, and the Flint and Sweetnam, although many others have been described.
The Hoffmann operation (Hoffmann, 1912) (Figure 2) This was the first forefoot arthroplasty to have been described. A transverse plantar incision is utilized proximal to the webs of the toes. The metatarsal heads are then exposed, with protection of the neurovascular bundles and
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Anteroposterior
( J
Figure 2.
The Hoffmann operation. [] = bone for excision.
flexor tendons. The metatarsal heads are then excised leaving the metatarsal lengths approximately equal so that a smooth curve is formed on the anteroposterior plane. These metatarsals should be divided smoothly so that no bone spikes are retained.
Post-operative treatment Oedema and wound healing may be a problem. Therefore the foot/feet should be elevated for up to 2 weeks to allow this to settle and the wounds to heal. The foot may then be dressed with a compression bandage or plaster of Paris slipper and mobilization commenced.
Ragonale The toe deformities are secondary to soft tissue shortening with the metatarsal heads prominent in the plantar aspect of the forefoot due to the pistoning effect of the proximal phalanges. The pressure effects due to this can be prevented by reducing bone length, either by removing the metatarsal heads, or by excision of the proximal phalanges.
The Fowler operation (Fowler, 1959) (Figures 3 and 4)
Technique This is a more aggressive surgical procedure than the Hoffmann operation. A dorsal curved transverse incision is used proximal to the webs of the toes. Through this incision, half the proximal phalanges are resected and the longer metatarsal heads trimmed, resulting in the metatarsal outlining a smooth arc in the antero-posterior plane. In the lateral plane the metatarsal
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(a)
3
3
; Anteroposterior
(b) Fashioning metatarsal
~////A
Lateral U/~ " ~ ~ ' ~ " ' ~
Metatarsal fat pad
f P l a n t a r - ~
Excision ellipse of skin
Figure 3. The Fowler operation. [] = bone for excision.
shaft is carefully refashioned to form a curve, so that pressure problems should not occur. A second incision is made on the plantar aspect of the foot, under the metatarsal heads. From this area an ellipse of skin only is excised and the defect primarily closed. The post-operative treatment is basically the same as with the Hoffmann procedure.
Rationale Although the excision of bone is more radical than in the Hoffmann, the principle is the same. The removal of the ellipse of skin removes skin callosities and should pull the toes plantarward to a more anatomical position. It also should resite the displaced metatarsal fat pad from its
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Figure 4. Fowler's arthroplasty rheumatoid (a) pre-op; (b) post-op.
abnormal distal position to a new one beneath the refashioned metatarsal shafts.
Kates, Kessel and Kay (Kates et al, 1967) (Figure 5)
Technique This is basically a modification of the Hoffmann and Fowler procedures. Through a curved plantar incision the metatarsal heads are excised as in the Hoffmann procedure. An ellipse of skin is excised as in the Fowler procedure, to resite the fat pad. The basic difference from these other arthroplasties is that a K-wire is inserted through the great toe and into the first metatarsal, in an attempt to hold the great toe in a good position under some tension and to prevent secondary deformity. It is thought that this K-wire may help to maintain the overall length and therefore prevent secondary
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Anteroposterior
Plantar
~', "4','~"z-.~.~Excision eclipse I /-"----of skin
(a)
(b)
Figure 5. The Kates, Kessel and Kay operation. [] = bone for excision.
deformities of the forefoot. It is also noted that bringing the great toe down into an anatomical position brings the other toes down with it.
Flint and Sweetnam (1960): the 'Pobble' procedure
Technique Through curved transverse incisions all five toes are disarticulated at the metatarsal phalangeal joints. The defect in the skin is primarily sutured.
Post-operative management Elevation and mobilization is the same regimen as in the other forefoot arthroplasties. However since the foot is significantly shortened, a toe block must be incorporated in the patient's shoes or balance and instability may be a problem.
Rationale This operation may also be known as the 'Pobble' procedure' in m e m o r y of Edward Lear's 'Pobble with no Toes'. However it may only have a limited role to play in rheumatoid arthritis. Flint and Sweetnam were of the opinion that in patients with severe fixed deformities of the toes, forefoot excisional arthroplasty gives both a poor functional and cosmetic result. They felt that since these deformed toes can cause footwear or pressure problems amputation is a valid alternative. However, this view is controversial, since
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most surgeons feel that fixed deformities of the toes can be dealt with by other operative procedures and that maintenance of the toes is important for balance. It is also felt that the pressure problems under the metatarsal heads are not altered, so that the 'walking on marbles' symptom may not be improved. Moreover the modern patient just does not like the notion of 'amputation'.
VARIATIONS IN TECHNIQUE: THE GREAT TOE The great toe is usually the key in forefoot arthroplasty. A most controversial aspect is whether MTP joint fusion or excisional arthroplasty is the better procedure to safeguard this cornerstone of the foot. The most important technical aspect, when operating on the great toe, is that its length must be comparable with the lesser metatarsals. Therefore even if the MTP joint is relatively normal it may often have to be operated upon, to make its length compatible with the other metatarsal bones (Tillmann, 1981), to prevent an imbalance of the forefoot with pain and with hallux valgus a probable sequel. If the 1st metatarsal is short, in comparison with the lesser metatarsals, a proximal partial phalangectomy (Keller's procedure) is the best method, If it is long, either excision of the metatarsal head as in the Hoffmann, or an arthrodesis of the MTP joint should be considered. Arthrodesis should only be undertaken if there is no interphalangeal joint disease. The advantage of arthrodesis is that it should preserve 'push off' function at the MTP joint, which is important, particularly in younger patients. Arthrodesis also has the advantage of preventing recurrent hallux valgus and lateral deviation of the lesser toes, which may occur after excisional arthroplasty of the great toe in up to 50% of cases (Vativanen, 1980). Older patients are less demanding on their feet, so that 'push off' function is not so important, therefore arthrodesis has less advantage and excisional arthroplasty, with or without a Kirschner wire, should be preferred.
COMPLICATIONS OF FOREFOOT ARTHROPLASTY Most forefoot arthroplasties suffer similar problems and complications. Initially these are usually related to wound healing and oedema. The Hoffmann and Fowler procedures are particularly prone to this, due to the fact that transverse incisions are used, which disrupt venous and lymphatic drainage. The longitudinal dorsal incisions may therefore result in better skin healing. However the disadvantage of the dorsal longitudinal incisions is that in severe deformity, access may prove difficult, resulting in problems in fashioning the metatarsal shafts correctly. If these are poorly fashioned, secondary pressure problems can occur. Occasionally longitudinal dorsal scars, used to correct severe deformity, undergo contracture. The neuro-
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vascular bundles and flexor tendons are at risk in any transverse plantar incision, since these structures are superficial at that point, the Hoffmann procedure is particularly risky in this respect. All excision arthroplasties result in short floppy toes. These toes usually act as little more than shoe fillers, rather than as functioning units. This in effect shortens the foot and so may exacerbate or worsen pre-existing unsteadiness. This must be explained pre-operatively to the patient. The 'Pobble' procedure is probably the least effective forefoot procedure. The metatarsal head position is not altered by amputation of the toes and the pressure inequalities within the forefoot remain unaltered by this procedure. Amputation is unpopular with patients for cosmetic, as well as emotional, reasons. Unsteadiness may be worse with this than after other procedures. We would therefore not condone its use. SUMMARY OF SURGICAL TREATMENT In moderate disease, the Helal operation is to be recommended since it is a swift operation and it allows early mobilization. Healing is good and the results in the short-term appear to be good. Follow up studies with Helal's procedure have not been long enough to assess tong-term results. In severe disease, forefoot arthroplasty gives very good results; 80-90% of patients' symptoms are relieved, with little or no residual pain (Barton, 1973). The authors, having assessed many of the forefoot procedures, favour the following technique in severe disease. Three dorsal longitudinal incisions, carefully avoiding the skin creases, so that secondary contractures do not occur, are made. These are centred over the 1st MTP joint, the interspaces between the 2nd and 3rd and the 4th and 5th metatarsal shafts. All the lesser metatarsal heads are excised carefully trimming bone ends so there are no bony spikes, creating at the same time a smooth arc on the antero-postero plane. This excision of the metatarsal heads is aggressive and should be through the metatarsal necks. The patient's age and severity of disease in the MTP and IP joints defines what should be done to the great toe. If there is IP joint disease, or if the patient is middle aged and over, either a partial proximal phalangectomy or excision of the metatarsal head is undertaken, dependent upon the length of the 1st metatarsal bone relative to the second. This is supplemented with a K-wire for 6 weeks, through the toe and into the metatarsal bone, in an attempt to maintain length and position of the forefoot. If the patient is young, and there is no interphalangeal joint pain, the MTP joint is fused in a position of 10-15 ~dorsal angulation and 20 ~valgus, using a lag screw. If there is still a severe deformity of the lesser toes after this forefoot arthroplasty and if the neurovascular status of the toes is reasonable, the hammer toes may be corrected by arthrodesis of the PIP joints (see Hammer toe section). However, there are no blanket procedures and we acknowledge that occasionally in severe deformity a plantar incision may have to be used to adequately expose the metatarsal heads, although the senior author seriously doubts if this is ever really necessary.
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N O N - R H E U M A T O I D CONDITIONS OF THE FOREFOOT: SURGICAL TREATMENT
There are two basic problems; those of the toes and those of metatarsalgia. Metatarsalgia is basically a vague term for discomfort around the metatarsal heads, often experienced by overweight, middle-aged ladies, in whom weight loss and symptomatic treatment is to be recommended. Initially there is seldom a place for surgery in these individuals. Occasionally HelM's operation may be offered in a case refractory to conservative care. However there are a few rare conditions, included in this metatarsalgia group, which may be treated differently. These include stress fracture of the metatarsal bones, Freiberg's infraction and Morton's neuroma. The conditions of the toes generally are those of deformity and pain. These include, hammer, claw and mallet toes, hallux valgus and rigidus. Surgical treatment of toe deformities Lesser toe deformities" The h a m m e r toe is a fixed flexion deformity of the proximal interphalangeal joint, with secondary hyperextension of the MTP joint and eventually of the distal interphalangeal (DIP) joint. The claw toe is a flexion deformity of the DIP and PIP joints, passively correctable at first, but later fixed, as secondary joint contractures develop. The mallet toe is a fixed flexion deformity of the DIP joint. Operations are usually undertaken because of pressure symptoms. Aetiology and pathology
Most h a m m e r toes are acquired. Shoewear is thought to be the main cause in that commonly there is an overlong toe, usually the 2nd toe, which is pulled back into alignment with the other lesser toes, resulting in passive deformity, which may eventually become fixed. Claw toes are usually secondary to a cavus foot, and may therefore be secondary to a neurological abnormality or to rheumatoid arthritis. Recently ischaemia has been recognized increasingly in the development of this condition. A mild compartment syndrome may develop after a tibial fracture. This ischaemic episode rarely can end in a Volkmann's contracture with fixed clawing of the toes. The mallet toe is thought to be mainly due to poor footwear, although isolated mallet toes may follow trauma to the DIP joint, with fixed deformity secondary to contracture in the soft tissues and damage to the affected joints surfaces. Callosities develop over flexion deformities secondary to pressure, especially if there is MTP joint hyperextension. This can then proceed to bursitis or skin ulceration.
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Operative technique Hammer toes (Figure 6) Technique. The PIP joint can be exposed by either a longitudinal or elliptical, transverse incision. If there is hyperextension or subluxation of
(a)
~
Proximal interphalangeal joint
K wire
or
(b) Peg and socket proximal interphalangeal joint fusion
or
(c)
K wire
(i) (ii)
Half proximal phalanx excised Excision of proximal interphalangeal joint F i g u r e 6. T h e h a m m e r t o e . [] = b o n e for e x c i s i o n .
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the MTP joint, the longitudinal approach is to be recommended, since tenotomy, MTP joint capsulotomy or a proximal phalangectomy can be undertaken through the same incision. Once the PIP joint is exposed by either dividing or splitting the extensor tendon the joint ends are excised, so that cancellous bone ends can be apposed with a good area of contact in extension. An intermedullary K-wire is then driven across, holding this position. Some surgeons prefer to use two K-wires since they believe bone union will be more assured, since there is better fixation, although this may be technically difficult and it is not a technique we ever use. The extensor tenotomy and capsulotomy at the MTP joint is undertaken subcutaneously with a tenotomy knife. Another satisfactory method of arthrodesing the PIP joints is to use the peg and socket technique, in which the head of the proximal phalanx is fashioned into a peg, leaving one surface with cortical bone for strength and the base of the middle phalanx is fashioned into a round socket with burrs. The toe is then placed into the position for arthrodesis by impacting the peg into the socket. If done well and firmly, this should be immediately stable. If partial proximal phalangectomy is necessary, only the amount of bone required to allow the toe to fall down into a neutral position is excised. The full proximal phalanx is not excised, since this leaves a floppy, pathologically short and useless toe. in early disease, manipulation under anaesthetic may be all that is required at the PIP joint. Sometimes PIP joint arthrodesis is carried out after proximal phalangectomy, if the PIP joint contracture is severe. Amputation of a 2nd hammer toe should be avoided, since this creates an iatrogenic hallux valgus.
Rationale. The flexion deformity at the PIP joint must be corrected, usually by arthrodesis. The secondary contracture at the MTP joint is usually treated by extensor tenotomy and MTP joint capsulotomy. However if the MTP joint is subluxed dorsally, this may not be enough to correct deformity, and partial proximal phalangectomy may be the only method of reducing the subluxation. Claw toe Technique. In t h e mobile deformity, the Girdlestone flexor to extensor technique is utilized. A longitudinal incision is made over the toe. The long flexor tendon is exposed and divided as distally as possible. This is then brought dorsally, threaded through the extensor expansion, over the proximal phalanx, and sutured tightly to itself, as slackening can occur with time. If the lesion is fixed, arthrodesis of both the DIP and PIP joints has to be undertaken. Initial extensive soft tissue release may have to be undertaken around the joints. Usually the K-wire technique of arthrodesis is employed for both joints. An extensor tenotomy and capsulotomy usually has to be undertaken subcutaneously. A previous technique used less now than in the past, is that of Lambrinudi, in which the joint surfaces of both DIP and PIP joints were excised and arthrodesis was achieved by keeping the bones apposed with the toes straight,
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by tying previously placed subcutaneous loops of suture material around the proximal phalanges and on to a special foot frame. If the great toe is involved, the Robert Jones" operation should be used. In this extensor hatlucis longus is detached distally, threaded through the head of the first metatarsal and sutured to itself. The interphalangeal joint of the hallux is then arthrodesed, usually to the above K-wire technique. Claw toes secondary to rheumatoid arthritis should be treated as recommended in the previous section, that is by forefoot arthroplasty.
Rationale. If this deformity is mobile, a muscle balancing procedure may improve the deformity. However if deformity is fixed, arthrodesis has to be employed. It is doubtful if the Lambrinudi procedure has any great advantage over other methods.
Mallet toes
This is a comparatively rare condition, which usually causes fewer problems than either claw or hammer toe. The simplest surgical procedure is amputation of the distal phalanx, usually undertaken through an L-shaped incision, removing the nail and nail bed dorsally. The distal bone is filleted out and the procedure is finished by closing this dorsal defect by simple sutures. However, amputation of even a part of the toe is increasingly unacceptable to many patients these days, thus arthrodesis by the K-wire technique is now more commonly employed.
Complications of toe operations The main complications at the arthrodesis site are of non-union or fibrous union. If these are not strong, recurrence of the deformity may occur, although firm fibrous union itself may not be a problem. The K-wire which is usually in situ for 6 weeks may be a portal for infection and require early removal, which of course can predispose to recurrence. If the end of the K-wire is not bent into an L shape, this wire can migrate proximally under the skin due to recurrent banging of the wire end while walking. This can make removal very difficult. At operation, the neurovascular bundles can be damaged if the surgical adage of 'get to bone and stay there' is not kept, resulting in loss of sensation or even loss of the toe due to circulatory problems. These structures are more at risk with a transverse incision. In arthrodesing the DIP joint, inadvertent damage can occur to the germinal nail bed and this can result in secondary nail deformity. The patient should also be warned that most of these procedures shorten the toes and that arthrodesis is for improvement of deformity, not improvement of function and that deformities may recur, due to skin contracture.
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Ingrowing toe nail
Aetiology and pathology Ingrowing toe nail occurs frequently in the great toe, and most commonly between the ages of 15 and 40, with males affected more commonly than females. The main cause is usually incorrect nail trimming and tight shoe wear. The nail, especially at its sides is cut too short and this results in the edge of this nail being embedded in the soft tissues, which may overgrow. Because of sweating and poor hygiene secondary infection is likely to occur. This condition usually only presents to the orthopaedic surgeon after infection has occurred. However, it often presents earlier to the chiropodist and at that stage treatment is to ensure correct trimming and good hygiene of the nails.
Surgical treatments (Sykes, 1986) Once infection has occurred numerous operative procedures have been advocated.
Simple nail avulsion is still commonly practised. However, the recurrence rate is 60-70%. It therefore should only be used if there is marked sepsis. The best procedure is probably that of lateral wedge resection. In this technique, one third of the affected nail edge is resected. The germinal nail bed at the base of this resected nail is exposed and surgically ablated or chemically destroyed with topical phenol, which is left for three minutes and then washed off with alcohol. This method results in a good cosmetic result with lower recurrence rates. It is therefore often the most acceptable operative procedure for younger, partioularly female, patients, and is probably the procedure of choice. The Zadikprocedure (Zadik, 1950) is a more aggressive surgical procedure, in which the nail is avulsed, the germinal nail bed layer exposed and destroyed either by surgical excision, or by excision and topical phenolization. If the nail bed is only partially destroyed an ugly deformed nail may grow. This procedure is not necessary in most cases, since lateral resection and phenolization are usually adequate.
The great toe
The two common conditions requiring surgical treatment are hallux rigidus and hallux valgus.
Hallux rigidus (Figure 7) Clinical. Basically this is osteoarthritis of the MTP joint of the great toe, which results in painful limitation of dorsiflexion of this joint, especially on walking or running, both of which may become restricted. Night pain may also be a feature.
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Figure 7. Hallux rigidus.
Pathology and aetiology. The pathology is that of osteo-arthritis, with dorsal osteophyte formation, joint space narrowing, periarticular cyst formation, cartilage erosion and eventually subchondral bone erosion. The cause in many cases is thought to be recurrent trauma to the joint. If there has been an intra-articular fracture, through the MTP joint, the risk of osteoarthritis is increased. Secondary osteoarthritis may also occur due to systemic disease, such as rheumatoid arthritis or gout. In some cases the aetiology is thought to be osteochondritis of the metatarsal head.
Surgical management. The type of surgery is dependent on the age of the patient and whether the interphalangeal joint is involved. In the elderly and middle-aged patient, the treatment of choice is excisional arthroplasty at the MTP joint (Keller's procedure). If the patient is younger, and especially if he or she is very active, silastic spacers may be useful in preserving some 'push off' function. In the even younger adult excisional arthroplasty is too
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functionally disabling and arthrodesis of the MTP joint should be the method of treatment. Silastic implants should be avoided if possible in the young since they can fragment with possibly adverse effects. In the adolescent, surgical treatment should be avoided as long as possible, and if surgical treatment is unavoidable, arthrodesis is preferred. In the unusual case of a young adult in whom there is also interphalangeal joint involvement, arthrodesis at the MTP joint, will probably fail, since pain will worsen from the interphalangeal joint. This would be a rare indication in a young patient for an excisional arthroplasty, with a silastic spacer, associated with arthrodesis of the interphalangeal joint.
1. Keller's procedure (1904) (Figure 8). A longitudinal dorso-medial incision is centred over the metatarsophalangeal joint. The joint capsule is opened and the proximal phalanx is exposed. There is controversy about the percentage of proximal phalanx to be excised; most would remove about a third of the bone, although some advocate a half. It is important to leave no bone spikes, and to protect the flexor hallucis longus tendon from damage. The prominent 'bunion' on the metatarsal head is excised with an osteotome. Any prominent osteophytes, especially in the dorsal position of the joint, are excised. The medial joint capsule is reefed to tighten this side and improve the deformity, if present. If the extensor hallucis longus tendon is tight, it is lengthened by a Z-plasty. An attempt can be made to hold the original toe length and in a neutral position, by inserting a K-wire into the toe and through the metatarsal head, for 3 or 4 weeks. This may also help to prevent secondary deformity especially that due to skin contracture. The rationale of this method is that half the diseased joint is excised and left rather floppy and therefore pain should be reduced. After this procedure complications c~n arise; the toe will of necessity be short and floppy. If physiotherapy is not instituted early, utilizing the flexor hallucis longus, the dorsal structures may become tight and this can eventually result in a 'cocked up' toe! In young active people the loss of push off function from this method of treatment may be quite disabling. Patient selection is therefore very important. The advantage of this procedure is that it is quick and mobility is swiftly obtained; clearly a great benefit, when dealing with more elderly patients, particularly as pain relief is usually good. 2. Arthrodesis of the MTP joint. A dorso-medial, longitudinal incision is used, centred over the MTP joint. It is important to protect the neurovascular bundle with this incision. The MTP joint is opened. Using an oscillating saw the joint surfaces are excised, until good flat surfaces of cancellous bone are exposed. All surrounding osteophytes are trimmed away and if there is a 'bunion' this is also removed. It is important to protect the long flexor and extensor tendons, The surfaces of the bone of this joint must have good apposition, in a position of 15~ of both dorsiflexion and valgus, in which they are then fixed with a lag screw technique, which gives good compression, with a high rate of bony union. This position of dorsiflexion is important for push off function. This arthrodesis is protected in plaster for an average of 6 weeks. Many other techniques of arthrodesis are
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described, using wire loops, external fixation or staples. However we prefer this lag screw technique; it is both simple, accurate and reliable. After this procedure, the most important complications are those of non-union or mal-union, either of which may require surgical revision, which can be difficult technically and which may require bone grafting. If too
iiiiiiis,on us
Z-lengthening of xtensor hallucis Iongus
Figure 8. The Keller's procedure. [] = bone for excision.
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much bone is removed in achieving this arthrodesis, an overlong second toe will result which can cause the development of a secondary, second hammer toe. Digital nerves may be damaged in any toe procedure and this can result in partial anaesthesia, and/or painful neuroma formation.
Hallux valgus Definition. This is basically a deformity of the great toe, with lateral deviation occurring at the MTP joint. Rotation of the toe and subluxation at the MTP joint occur later.
Clinical. More females than males seek surgical attention. A male presenting with hallux valgus should alert the clinician to the possibility of this being a harbinger of rheumatoid arthritis. The major problems are of secondary pain associated with bursitis or skin problems over this prominent bunion. Difficulty in obtaining good shoewear is a frequent reason for seeking advice, especially from younger females with broad feet. Later pain develops in the MTP joint, due to the development of secondary osteoarthritis. Pathology and aetiology. Many theories have been expounded on this problem, which is a common entity whose aetiology is usually multifactorial. Conditions associated with its presence are: rheumatoid arthritis, amputation of the second toe and long-term use of poor tight shoe and sock wear. There is often a hereditary factor, with the first metatarsal bone in a varus position (metatarsus primus varus). There is some controversy as to whether this is a primary or secondary phenomenon. Whatever the cause, an imbalance occurs between the muscles attached to the great toe. The adductor muscle becomes relatively short and develops a mechanical advantage over its antagonistic muscle group; the abductor, flexor hallucis longus and extensor hallucis longus, which usually bowstrings, to worsen the deformity. This is the basis of the McBride procedure, which negates this adductor imbalance. The pathology is basically that of a valgus toe, which will eventually sublux and then rotate at the MTP joint. The 'bunion' is the medial side of the metatarsal head, although secondary osteophytes can later occur. Because of the broadening of the foot and local irritation, secondary skin thickening, bursa formation and skin ulceration can occur over this 'bunion'. In the long-term, secondary osteo-arthritic changes can occur in the MTP joint. The valgus deformity of the great toe can cause the lesser toes to become crowded and secondary hammering or clawing can develop, sometimes associated with metatarsalgia.
Rationale of surgical treatment. If the deformity is purely due to adductor muscle imbalance a soft tissue procedure can be undertaken. However a pure soft tissue problem is rare and the varus deformity of the metatarsal must be corrected by some bony re-alignment procedure. When osteoarthritis occurs in the MTP joint either a Keller's procedure or arthrodesis of the MTP joint should be considered.
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Surgical management. The two important factors which influence the choice of surgical procedure are age and whether or not there are osteoarthritic changes in the MTP joint. In the adolescent a soft tissue procedure may be sufficient if secondary bony changes have not occurred and if so can be influenced by balancing of the excessive adductor muscle pull. In the young adult, with no MTP joint involvement an osteotomy of the metatarsal shaft is the procedure of choice. With patients over the age of 40, there are probably osteoarthritic changes in the MTP joint and an excisional arthroplasty, with a temporary K-wire or silastic spacer is usually required. The difficult age group to manage is that between 25 and 45 years old, in whom the presence or absence of osteoarthritis in the MTP joint is crucial. For if it is present an MTP joint arthrodesis is probably the procedure of choice, providing there is no interphalangeal joint arthritis. If the MTP joint is in good condition, a conventional metatarsal osteotomy can be employed. Some may ask why if the symptoms arise from the medial bunion, should its simple excision not suffice. Often in practice simple bunionectomy usually only gives relief for 2-3 years, the symptoms returning, because the underlying cause of the deformity has not been altered.
1. The McBride soft tissue procedure (modified) (McBride, 1928). This soft tissue procedure has only a limited place, possibly in the treatment of young adolescents. Some surgeons feel that it should never be used alone and that it should be combined with a metatarsal osteotomy. The modification of this operation occasionally used in our unit uses a dorsal longitudinal incision, through which the adductor muscle insertions to the proximal phalanx and lateral MTP joint capsule are divided. The medial capsule is reefed, using a Y to V plasty and if the soft tissues are still tight the extensor hallucis longus is lengthened by Z-plasty. The original McBride procedure transferred the adductor insertion to the neck of the first metatarsal bone, which is a technically difficult procedure, of dubious function. If this soft tissue operation does not improve the deformity a bony procedure on the metatarsal should be undertaken. 2. Re-alignment osteotomy. The principle is to cancel the hallux valgus, by countering the metatarsal varus, with an osteotomy towards a more neutral position. These osteotomies, which may be proximal or distal, also tend to shorten the metatarsal slightly which may improve the soft tissue tension at the MTP joint. (i) Distal osteotomy. In the Mitchell Osteotomy (Mitchell et al, 1958) (Figures 9 and 10a) a dorsal longitudinal skin incision is undertaken over the MTP joint. The joint is not opened. The medial capsule is incised in a Y shaped manner and the bone of the distal metatarsal is exposed. A medially based cube of bone is removed, leaving a lateral tongue or peg. The osteotomy is completed and the distal fragment can be displaced laterally, the peg helping to keep the displacement. This may be stabilized with a heavy suture passed through drill holes in proximal and distal fragments. Alternatively, staples, screws or K-wires can be used. Any projection of
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J. NOBLE AND R. PATON
Figure 9. Hallux valgus (a) prior to Mitchell's osteotomy; (b) post Mitchell's osteotomy.
bone is excised. Care must be taken that the distal fragment does not ride up. The Y flap of the medial capsule is sutured as a V, therefore tightening the medial tissues. Post-operatively the foot is protected in plaster for 6-8 weeks. There are numerous modifications of this distal type of osteotomy. A popular and simple procedure is the Wilson Osteotomy (Wilson, 1963) (Figure 10b). This is an oblique osteotomy allowing the bone to slide towards the neighbouring metatarsal. The osteotomy is also angled backwards to prevent the distal fragment riding up. (ii) Proximal osteotomy. The varus deformity of the metatarsal can be corrected at the base of the metatarsal shaft, through a dorsal, longitudinal skin incision, positioned more proximally than in the Mitchell procedure, although it can be extended distally so as to combine it with a McBride soft tissue release. The osteotomy may use the opening or closing wedge principle. In the latter, a wedge with its apex at the medial cortex is removed from the metatarsal base and the bone surfaces are apposed to correct the
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varus deformity. In the opening procedure a transverse osteotomy leaving the lateral cortex intact is made and a bone wedge, easily taken from the bunion at the metatarsal head is then inserted from the medial side. Despite the use of K-wires with these procedures the foot must be protected in plaster for 6-8 weeks post-operatively. With all types of osteotomy there is a risk of delayed union, non-union or real-union. It is particularly important to prevent the distal fragment riding up, relative to the proximal shaft, because such a mal-union may result in subsequent metatarsalgia, with imbalance of the forefoot. This can also occur if the first metatarsal is shortened too much. The proximal osteotomy procedures may result in a longer scar and since its fixation may be poorer than with distal osteotomies, the non-union rate may be higher. Advice about shoe wear post-operatively is all important, since wearing pointed shoes may quickly result in the deformity recurring. The main problem with most active young people is that the enforced use of bilateral walking plasters usually for 6-8 weeks, causes not only discomfort, but great inconvenience. For this reason some surgeons recommend only operating
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(al
Figure lOa.
The Mitchell osteotomy.
upon one foot at once, a practice with obvious disadvantages of its own, with doubled time in hospital and two anaesthetics.
3. Keller's Procedure and metatarsal phalangeal arthrodesis. Both arthroplasty and arthrodesis have been described earlier in the section on hallux rigidus. The Keller's procedure works since it releases the soft tissue tension, as the adductor insertion is excised. It is effective in relieving pain, as is arthrodesis. Miscellaneous forefoot conditions
Morton's neuroma This is a relatively rare condition and there is some doubt in our minds as to whether it exists at all. Whereas it probably does, we suspect that not only is it excessively diagnosed, but consequently overtreated. It was first described by M o r t o n in 1876, with a clinical picture of pain in the forefoot radiating into the toes, especially in the 3rd/4th interspace, although it also occurs in the 2nd/3rd interspace. Sensation in the interspace may be altered and the pain can be worsened by walking on hard shoes. If lateral pressure is applied across the forefoot there may be pain and an audible click. The condition is said to occur most commonly in middle-aged females. The causative pathology is thought to be ischaemia of the nerve, before it bifurcates. The nerve becomes fusiform and degenerate and is therefore strictly not a true neuroma. A similar clinical picture can occur in rheumatoid arthritis due to pressure on the nerve secondary to synovitis. H o w e v e r this is a pressure effect and not a M o r t o n ' s neuroma.
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(b)
Anteroposterior
\
> Dsteotomy
1
Lateral
Figure lOb. The Wilson osteotomy.
Operative technique. A dorsal or plantar skin incision can be used. The disadvantage of the dorsal incision is that access may be limited and the nerve difficult to expose and resect. The plantar skin incision may be transverse or longitudinal. The main advantage of this approach is that the nerve can be easily located and resected and that any other pathology can be excluded. If the transverse incision is proximal to the weight bearing area, no secondary pain from the scar should occur. We therefore recommend this approach. The nerve should be divided cleanly and handled carefully or a secondary traumatic neuroma may form, causing pain and discomfort on weight bearing. It is also important to divide the nerve sufficiently proximal, so that the end of the transected nerve is not under the weight bearing area. Post-operatively there will be a loss of sensation in the nerve's sensory area. However, the pain should be relieved. Freiberg's infraction (Figure 11) Clinical. This is a rare, but fascinating disease which occurs typically in the
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Figure 11. Freibcrg's infraction.
10218 year old group, and in females more than males. The commonest area affected is the 2nd metatarsal head, although it can also occur in the 3rd and 4th metatarsal heads. It usually presents with pain and thickening in the forefoot, specifically over the affected area of bone. The aetiology is unknown, but it is thought to be secondary to repeated trauma to this metatarsal head. There maybe a predisposition caused by an over-long second metatarsal. The pathology is of avascular necrosis of the metatarsal head. Although this area should eventually revascularize, whilst it is avascular the bone is soft and can deform, resulting in secondary osteoarthritis. The diagnosis is usually confirmed by seeing the increased density, pathognomonic of avascular necrosis, on X-ray. Treatment. The rationale is to prevent the deformity of the metatarsal head from occurring and therefore hopefully to prevent secondary osteoarthritis. Unfortunately this condition often presents late, once deformity of the metatarsal head has occurred, which makes successful management difficult.
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Conservative treatment consists of metatarsal insoles or metatarsal supports, with a below the knee plaster of Paris, in an effort to reduce pressure over the metatarsal head, and therefore to prevent deformity. However, most patients will find plaster unacceptable since revascularization may take up to two years. For early disease, two procedures have been advocated; these are of Smillie and of Helal. Smillie's operation consists of gutting the metatarsal head of the avascular bone, using a window in the metatarsal neck. The head is then packed with cancellous bone graft. Helal'sprocedure is identical to that described in the section on rheumatoid arthritis. The middle three metatarsal shafts are osteotomied, including the affected one, since if only one was realigned this would cause imbalance of the metatarsal compared with its nighbours, causing subsequent problems, especially metatarsalgia. Unfortunately there have been few long-term reports on the results of treating this rare condition by either of the above procedures. Therefore it must be concluded that their efficacy is not proven. Late disease when osteoarthritis has occurred is even more difficult to treat with p o o r results from surgical treatment. Excision of the metatarsal head has been advocated. This may give short-term relief by removing the affected segment, but in the long-term, this will result in forefoot pain due to metatarsal imbalance as a result of the shortening effect. In our view metatarsal head excision in the treatment of Freiberg's disease is to be deprecated. Numerous other procedures have been advocated; these include, excision of the metatarsal head with syndactyly of the adjacent toes, wedge osteotomy of the metatarsal head so that unaffected cartilage may be rotated around, silastic hinge joints and spacers have also been utilized. The problems with any of these procedures are that the numbers are low in each series and usually no controls are used. It is therefore difficult to decide if any of these various procedures is successful or not. However the procedure of osteotomy and rotation is difficult technically and there may be no normal articular cartilage to rotate. This disease occurs in young people therefore the use of silastic joints and spacers may be unwise, since the long-term effects of this material to the bone and soft tissues is as yet unknown. If relief cannot be gained by other methods palliation may only be found by excision of the whole ray.
REFERENCES Barton NJ (1973) Arthroplasty of the forefoot in rheumatoid arthritis. Journal of Bone and Joint Surgery 55B: 126. Collis WJMF & Jayson MIV (1972) Measurement of pedal pressures. Annals of Rheumatic Disease 31: 215. Flint M & Sweetnam R (1960) Amputation of all toes. Journal of Bone and Joint Surgery 42B: 90. Fowler AW (1959) A method of forefoot reconstruction. Journal of' Bone and Joint Surgery 41B: 507. Helm B (1975) Metatarsal osteotomy for metatarsalgia. Journal of Bone and Joint Surgery 57B: 187.
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Hoffmann P (1912) An operation for severe grades of contracted or clawed toes. American Journal of Orthopedic Surgery 9: 441. Kates A, Kessel L & Kay A (1967) Arthroplasty of the forefoot. Journal of Bone and Joint Surgery 49B: 552. Kirkup JR, Vidigal E & Jacoby RK (1977) The hallux and rheumatoid arthritis. Acta Orthopaedica Scandinavica 48: 527. Keller WL (1904) The surgical treatment of bunions and hallux valgus. New York Medical Journal 80: 74. Laurence M (1985) The surgery of rheumatic conditions. Surgery 1: No. 25,599. Lipscomb PR (1981) Surgery of the rheumatoid foot: preferable procedures. Revue de Chirurgie Orthopedique 67: 375. McBride ED (1928) Conservative operation for bunions. Journal of Bone and Joint Surgery 10: 735-739. Mitchell CL, Fleming JL, Allen R, Glenney R & Sandford G A (1958) Osteotomy bunionectomy for hallux valgus. Journal of Bone and Joint Surgery 40A: 41. Spiegal TM & Spiegal JS (1982) Rheumatoid arthritis in the foot and ankle: diagnosis, pathology and treatment. Foot and Ankle 2: No. 6,318. Sykes PA (1986) Ingrowing toe nails: Time for critical appraisal? Journal of the Royal College of Surgery of Edinburgh 31: 300. Tillmann K (1981) Surgical treatment o f the foot in rheumatoid arthritis. Reconstruction Surgery and Traumatology 18: 195. Vahvanen V, Piirainen H & Kettunen P (1980) Resection arthroplasty of the metatarsophalangeal joints in rheumatoid arthritis. Scandinavian Journal of Rheumatology 9: 257-265. Wilson JN (1963) Oblique displacement osteotomy for hallux valgus. Journal of Bone and Joint Surgery 45B: 552-556. Zadik ER (1950) Obliteration of the nail bed of the great toe without shortening the terminal phalanx. Journal of Bone and Joint Surgery 32B: 66.
In this chapter the forefoot is defined as the structures distal to the mid-tarsal joints. Conditions of the forefoot can be descriptively subdivided into rheumatoid arthritis, toe conditions and other miscellaneous problems. Generally the large majority of problems arising in the forefoot can and should'be treated by simple conservative measures, often administered by chiropodists. Many of these techniques will be to redistribute stress in its transfer from bone through skin to footwear. The principal indications for surgical involvement are for the relief of pain and to improve deformity, usually after conservative measures have failed.
PRE-OPERATIVE ASSESSMENT A full history and examination is mandatory in every patient with conditions of the feet. If this is not followed, inappropriate surgery may be undertaken with worsening of the underlying condition. It should always be remembered that deformities, especially in rheumatoid arthritis, do not occur in isolation, but various deformities occur together, e.g. the cavus foot and intrinsic muscle shortening which causes hammering of toes.
Specific local problems On examination the presence of deformity, skin condition, gait and neurological status should be carefully noted, as vasculitis, peripheral vascular disease, peripheral neuropathy or, poor skin may militate against surgery.
Systemic problems Severe systemic conditions, such as respiratory or cardiovascular disease, may also influence against surgical treatment and make it inappropriate. Moreover they may restrict the patient's mobility to such a degree as to make foot surgery pointless. Foot problems may be the first indication of systemic neurological disorders, such as the demyelinating diseases or pathology within the spinal canal. Furthermore the stability and integrity of the cervical Baillibre's ClinicalRheumatology--Vol. 1, No. 2, August1987
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spine must be assessed pre-operatively and may require protection with a collar during anaesthesia. Drugs
The commonest drugs to affect the foot are steroids, which can compromise the healing of already atrophic skin. Other drugs may have direct or indirect effects, e.g. anti-coagulation will affect haemostasis and even predispose to haematoma formation post-operatively. SURGICAL TREATMENT OF RHEUMATOID ARTHRITIS OF THE FOREFOOT Clinical
The metatarsophalangeal joints (MTP) of the foot cause more trouble to the rheumatoid sufferer than any other joint in the body (Laurence, 1985). Most small joint disease is treated medically and only disease which has failed to respond to these measures is usually considered for surgical intervention. Foot problems in the rheumatoid patient should not be assessed in isolation and a team approach is required. Thus decisions can be reached as to the order of surgical priorities when upper limbs, hips, knees and feet all command surgical attention. Clearly total replacement of the knees or hips may only be of benefit if painful feet are dealt with first. Moreover the frequency with which forefoot surgery is attended post-operatively by superficial sepsis makes it mandatory to eliminate this problem prior to joint arthroplasty work. The classical history given by the patienf with severe rheumatoid disease of the feet is described as 'walking on marbles', with severe pain, sometimes a feeling of instability and consequently reduced walking distance. Surgical pathology
The small joints of the feet are attacked early and extensively. Both the soft tissues and the joints are affected. The spectrum of this disease varies from a simple synovitis, to the severe classical rheumatoid deformity of hyperextension of the metatarsophalangeal joint (MTP), flexion of the proximal interphalangeal joints (PIP) with pes planus. Splaying of the metatarsal heads occurs early and 60% of patients with rheumatoid develop a hallux valgus of over 20 ~ (Kirkup et al, 1977). The toe deformities are thought to be partly due to intrinsic muscle weakness (Spiegal and Spiegal, 1982). These toe deformities may progress until the proximal phalanges 'piston' the metatarsal heads into the sole of the foot (Fowler, 1959), resulting in their being palpable superficially on the plantar aspect of the forefoot, with the formation of callosities, due to the alteration of the pressure distribution. The most common pressure lesions occur under the 2nd and 3rd metatarsal heads (Collis and Jayson, 1972). Deformities of the toes may draw the
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protective metatarsal fat pad distally, exacerbating these pressure effects. From a surgical point of view, moderate and severe disease require different approaches. The moderate rheumatoid foot is one which has not responded to medical measures, but which lacks severe deformity. This allows methods of surgical treatment which would not be successful in the severe rheumatoid foot, and which it is their principle to prevent. There are two common procedures for moderate disease; the Helal (1975) and Lipscomb (1981) procedures.
The Helal procedure (1975) (Figure la) Technique. Dorsal longitudinal incisions are used over the forefoot. The middle three metatarsal shafts are exposed and are divided at the junction of the middle and distal third of the bone at an angle of 45~ plantarwards and distally (see diagram). Any projecting bone spikes, are trimmed. The bones are divided at the same level, or in a smooth curve on the antero-posterior plane, to prevent pressure inequalities at the metatarsal heads. If the 1st and 5th metatarsal joints are also involved, separate incisions are required and the osteotomy must also be slanted to allow telescoping of the distal fragment towards the adjoining metatarsal, as in the Wilson procedure (see section on hallux valgus).
Post-operative management. If only the middle three metatarsals are osteotomized the patient can bear weight from the onset, in sterile dressings, to protect the wounds. However, if all five metatarsals are operated upon, the foot must be protected with a plaster of Paris for six weeks, until the osteotomies have united.
Rationale. The oblique osteotomy allows some shortening of the skeleton relative to the soft tissues, thereby improving some early toe deformities. (a)
Lateral
Lateral
Figure la. The Helal procedure. [] = bone for excision.
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J. NOBLE AND R. PATON
More importantly these osteotomies allow the metatarsal heads to ride dorsally, reducing the pressure problems in these areas. Helal (personal communication, Tillmann) has claimed that this procedure may improve the synovitis of rheumatoid arthritis, but this claim has yet to be substantiated.
The Lipscomb procedure (Lipscomb, 1981) (Figure lb) Technique. Three dorsal longitudinal incisions are employed. The 1st MTP joint is arthrodesed in a position of 20~valgus and 10-20 ~of dorsiflexion with a lag screw. However, if there is severe interphalangeal joint involvement, a partial proximal phalangectomy is undertaken and a K-wire is used to maintain length in the hallux. In the lesser toes, only a small portion of the (b)
5
Toes
Anteroposterior
Metatarsal bones
f
Anteroposterior
lesser toes
Fusion 1st MTP joint
Figure lb.
The Lipscomb procedure. [] = bone for excision.
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proximal phalanges are excised with only the plantar aspect of the metatarsal heads. K-wires are inserted through the toes and into the metatarsal head in an attempt to maintain forefoot length.
Post-operative management. The feet are elevated post-operatively to allow the inevitable oedema to settle. Mobilization is usually without plaster of Paris support. The K-wires are maintained for 6 weeks.
Rationale. This procedure is only useful in conditions where MTP joint disease and pain are the main problems. It probably has no place in MTP joint deformity, such as subluxation and dislocation. This method attempts to maintain forefoot length. Better balance, stance, and fitting of conventional shoe-wear is possible than after forefoot arthroplasties, by metatarsal head excision.
Advantages and disadvantages of the above procedures in moderate disease. Patient selection is vitally important, if the above procedures are to be useful. The Helal procedure, which does not interfere with the MTP joints, has the advantage of being a quick, easy procedure with swift rehabilitation. Salvage procedures, such as metatarsal head excision, are not compromised by this operation, should they later become necessary. The disadvantages are that although this is an early procedure it must be undertaken meticulously or plantar bone spikes may cause pressure problems. It has no place in severe deformity. The Lipscomb procedure has a more limited role than that of Helal, and again it has no place for the foot with severe deformity. The main advantage is said to be that by maintaining forefoot length, balance and gait are not adversely affected. However by maintaining length this procedure may be inadequate to remove the pressure problems beneath the metatarsal heads, whereupon a secondary forefoot arthroplasty should be undertaken with the potential for problems of wound healing increased.
SURGICAL MANAGEMENT OF SEVERE RHEUMATOID ARTHRITIS OF THE FOREFOOT Severe disease can be defined as pathology that results in severe pain and deformity unrelieved by other methods of treatment and in practice is the classical rheumatoid forefoot deformity, with hallux valgus, splayed anterior arch and dorsally subluxed or dislocated toes. There are four typical surgical procedures: The Hoffmann, The Fowler, The Kates, Kessel and Kay, and the Flint and Sweetnam, although many others have been described.
The Hoffmann operation (Hoffmann, 1912) (Figure 2) This was the first forefoot arthroplasty to have been described. A transverse plantar incision is utilized proximal to the webs of the toes. The metatarsal heads are then exposed, with protection of the neurovascular bundles and
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Anteroposterior
( J
Figure 2.
The Hoffmann operation. [] = bone for excision.
flexor tendons. The metatarsal heads are then excised leaving the metatarsal lengths approximately equal so that a smooth curve is formed on the anteroposterior plane. These metatarsals should be divided smoothly so that no bone spikes are retained.
Post-operative treatment Oedema and wound healing may be a problem. Therefore the foot/feet should be elevated for up to 2 weeks to allow this to settle and the wounds to heal. The foot may then be dressed with a compression bandage or plaster of Paris slipper and mobilization commenced.
Ragonale The toe deformities are secondary to soft tissue shortening with the metatarsal heads prominent in the plantar aspect of the forefoot due to the pistoning effect of the proximal phalanges. The pressure effects due to this can be prevented by reducing bone length, either by removing the metatarsal heads, or by excision of the proximal phalanges.
The Fowler operation (Fowler, 1959) (Figures 3 and 4)
Technique This is a more aggressive surgical procedure than the Hoffmann operation. A dorsal curved transverse incision is used proximal to the webs of the toes. Through this incision, half the proximal phalanges are resected and the longer metatarsal heads trimmed, resulting in the metatarsal outlining a smooth arc in the antero-posterior plane. In the lateral plane the metatarsal
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(a)
3
3
; Anteroposterior
(b) Fashioning metatarsal
~////A
Lateral U/~ " ~ ~ ' ~ " ' ~
Metatarsal fat pad
f P l a n t a r - ~
Excision ellipse of skin
Figure 3. The Fowler operation. [] = bone for excision.
shaft is carefully refashioned to form a curve, so that pressure problems should not occur. A second incision is made on the plantar aspect of the foot, under the metatarsal heads. From this area an ellipse of skin only is excised and the defect primarily closed. The post-operative treatment is basically the same as with the Hoffmann procedure.
Rationale Although the excision of bone is more radical than in the Hoffmann, the principle is the same. The removal of the ellipse of skin removes skin callosities and should pull the toes plantarward to a more anatomical position. It also should resite the displaced metatarsal fat pad from its
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Figure 4. Fowler's arthroplasty rheumatoid (a) pre-op; (b) post-op.
abnormal distal position to a new one beneath the refashioned metatarsal shafts.
Kates, Kessel and Kay (Kates et al, 1967) (Figure 5)
Technique This is basically a modification of the Hoffmann and Fowler procedures. Through a curved plantar incision the metatarsal heads are excised as in the Hoffmann procedure. An ellipse of skin is excised as in the Fowler procedure, to resite the fat pad. The basic difference from these other arthroplasties is that a K-wire is inserted through the great toe and into the first metatarsal, in an attempt to hold the great toe in a good position under some tension and to prevent secondary deformity. It is thought that this K-wire may help to maintain the overall length and therefore prevent secondary
363
SURGERY AND THE FOREFOOT
Anteroposterior
Plantar
~', "4','~"z-.~.~Excision eclipse I /-"----of skin
(a)
(b)
Figure 5. The Kates, Kessel and Kay operation. [] = bone for excision.
deformities of the forefoot. It is also noted that bringing the great toe down into an anatomical position brings the other toes down with it.
Flint and Sweetnam (1960): the 'Pobble' procedure
Technique Through curved transverse incisions all five toes are disarticulated at the metatarsal phalangeal joints. The defect in the skin is primarily sutured.
Post-operative management Elevation and mobilization is the same regimen as in the other forefoot arthroplasties. However since the foot is significantly shortened, a toe block must be incorporated in the patient's shoes or balance and instability may be a problem.
Rationale This operation may also be known as the 'Pobble' procedure' in m e m o r y of Edward Lear's 'Pobble with no Toes'. However it may only have a limited role to play in rheumatoid arthritis. Flint and Sweetnam were of the opinion that in patients with severe fixed deformities of the toes, forefoot excisional arthroplasty gives both a poor functional and cosmetic result. They felt that since these deformed toes can cause footwear or pressure problems amputation is a valid alternative. However, this view is controversial, since
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most surgeons feel that fixed deformities of the toes can be dealt with by other operative procedures and that maintenance of the toes is important for balance. It is also felt that the pressure problems under the metatarsal heads are not altered, so that the 'walking on marbles' symptom may not be improved. Moreover the modern patient just does not like the notion of 'amputation'.
VARIATIONS IN TECHNIQUE: THE GREAT TOE The great toe is usually the key in forefoot arthroplasty. A most controversial aspect is whether MTP joint fusion or excisional arthroplasty is the better procedure to safeguard this cornerstone of the foot. The most important technical aspect, when operating on the great toe, is that its length must be comparable with the lesser metatarsals. Therefore even if the MTP joint is relatively normal it may often have to be operated upon, to make its length compatible with the other metatarsal bones (Tillmann, 1981), to prevent an imbalance of the forefoot with pain and with hallux valgus a probable sequel. If the 1st metatarsal is short, in comparison with the lesser metatarsals, a proximal partial phalangectomy (Keller's procedure) is the best method, If it is long, either excision of the metatarsal head as in the Hoffmann, or an arthrodesis of the MTP joint should be considered. Arthrodesis should only be undertaken if there is no interphalangeal joint disease. The advantage of arthrodesis is that it should preserve 'push off' function at the MTP joint, which is important, particularly in younger patients. Arthrodesis also has the advantage of preventing recurrent hallux valgus and lateral deviation of the lesser toes, which may occur after excisional arthroplasty of the great toe in up to 50% of cases (Vativanen, 1980). Older patients are less demanding on their feet, so that 'push off' function is not so important, therefore arthrodesis has less advantage and excisional arthroplasty, with or without a Kirschner wire, should be preferred.
COMPLICATIONS OF FOREFOOT ARTHROPLASTY Most forefoot arthroplasties suffer similar problems and complications. Initially these are usually related to wound healing and oedema. The Hoffmann and Fowler procedures are particularly prone to this, due to the fact that transverse incisions are used, which disrupt venous and lymphatic drainage. The longitudinal dorsal incisions may therefore result in better skin healing. However the disadvantage of the dorsal longitudinal incisions is that in severe deformity, access may prove difficult, resulting in problems in fashioning the metatarsal shafts correctly. If these are poorly fashioned, secondary pressure problems can occur. Occasionally longitudinal dorsal scars, used to correct severe deformity, undergo contracture. The neuro-
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vascular bundles and flexor tendons are at risk in any transverse plantar incision, since these structures are superficial at that point, the Hoffmann procedure is particularly risky in this respect. All excision arthroplasties result in short floppy toes. These toes usually act as little more than shoe fillers, rather than as functioning units. This in effect shortens the foot and so may exacerbate or worsen pre-existing unsteadiness. This must be explained pre-operatively to the patient. The 'Pobble' procedure is probably the least effective forefoot procedure. The metatarsal head position is not altered by amputation of the toes and the pressure inequalities within the forefoot remain unaltered by this procedure. Amputation is unpopular with patients for cosmetic, as well as emotional, reasons. Unsteadiness may be worse with this than after other procedures. We would therefore not condone its use. SUMMARY OF SURGICAL TREATMENT In moderate disease, the Helal operation is to be recommended since it is a swift operation and it allows early mobilization. Healing is good and the results in the short-term appear to be good. Follow up studies with Helal's procedure have not been long enough to assess tong-term results. In severe disease, forefoot arthroplasty gives very good results; 80-90% of patients' symptoms are relieved, with little or no residual pain (Barton, 1973). The authors, having assessed many of the forefoot procedures, favour the following technique in severe disease. Three dorsal longitudinal incisions, carefully avoiding the skin creases, so that secondary contractures do not occur, are made. These are centred over the 1st MTP joint, the interspaces between the 2nd and 3rd and the 4th and 5th metatarsal shafts. All the lesser metatarsal heads are excised carefully trimming bone ends so there are no bony spikes, creating at the same time a smooth arc on the antero-postero plane. This excision of the metatarsal heads is aggressive and should be through the metatarsal necks. The patient's age and severity of disease in the MTP and IP joints defines what should be done to the great toe. If there is IP joint disease, or if the patient is middle aged and over, either a partial proximal phalangectomy or excision of the metatarsal head is undertaken, dependent upon the length of the 1st metatarsal bone relative to the second. This is supplemented with a K-wire for 6 weeks, through the toe and into the metatarsal bone, in an attempt to maintain length and position of the forefoot. If the patient is young, and there is no interphalangeal joint pain, the MTP joint is fused in a position of 10-15 ~dorsal angulation and 20 ~valgus, using a lag screw. If there is still a severe deformity of the lesser toes after this forefoot arthroplasty and if the neurovascular status of the toes is reasonable, the hammer toes may be corrected by arthrodesis of the PIP joints (see Hammer toe section). However, there are no blanket procedures and we acknowledge that occasionally in severe deformity a plantar incision may have to be used to adequately expose the metatarsal heads, although the senior author seriously doubts if this is ever really necessary.
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N O N - R H E U M A T O I D CONDITIONS OF THE FOREFOOT: SURGICAL TREATMENT
There are two basic problems; those of the toes and those of metatarsalgia. Metatarsalgia is basically a vague term for discomfort around the metatarsal heads, often experienced by overweight, middle-aged ladies, in whom weight loss and symptomatic treatment is to be recommended. Initially there is seldom a place for surgery in these individuals. Occasionally HelM's operation may be offered in a case refractory to conservative care. However there are a few rare conditions, included in this metatarsalgia group, which may be treated differently. These include stress fracture of the metatarsal bones, Freiberg's infraction and Morton's neuroma. The conditions of the toes generally are those of deformity and pain. These include, hammer, claw and mallet toes, hallux valgus and rigidus. Surgical treatment of toe deformities Lesser toe deformities" The h a m m e r toe is a fixed flexion deformity of the proximal interphalangeal joint, with secondary hyperextension of the MTP joint and eventually of the distal interphalangeal (DIP) joint. The claw toe is a flexion deformity of the DIP and PIP joints, passively correctable at first, but later fixed, as secondary joint contractures develop. The mallet toe is a fixed flexion deformity of the DIP joint. Operations are usually undertaken because of pressure symptoms. Aetiology and pathology
Most h a m m e r toes are acquired. Shoewear is thought to be the main cause in that commonly there is an overlong toe, usually the 2nd toe, which is pulled back into alignment with the other lesser toes, resulting in passive deformity, which may eventually become fixed. Claw toes are usually secondary to a cavus foot, and may therefore be secondary to a neurological abnormality or to rheumatoid arthritis. Recently ischaemia has been recognized increasingly in the development of this condition. A mild compartment syndrome may develop after a tibial fracture. This ischaemic episode rarely can end in a Volkmann's contracture with fixed clawing of the toes. The mallet toe is thought to be mainly due to poor footwear, although isolated mallet toes may follow trauma to the DIP joint, with fixed deformity secondary to contracture in the soft tissues and damage to the affected joints surfaces. Callosities develop over flexion deformities secondary to pressure, especially if there is MTP joint hyperextension. This can then proceed to bursitis or skin ulceration.
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Operative technique Hammer toes (Figure 6) Technique. The PIP joint can be exposed by either a longitudinal or elliptical, transverse incision. If there is hyperextension or subluxation of
(a)
~
Proximal interphalangeal joint
K wire
or
(b) Peg and socket proximal interphalangeal joint fusion
or
(c)
K wire
(i) (ii)
Half proximal phalanx excised Excision of proximal interphalangeal joint F i g u r e 6. T h e h a m m e r t o e . [] = b o n e for e x c i s i o n .
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the MTP joint, the longitudinal approach is to be recommended, since tenotomy, MTP joint capsulotomy or a proximal phalangectomy can be undertaken through the same incision. Once the PIP joint is exposed by either dividing or splitting the extensor tendon the joint ends are excised, so that cancellous bone ends can be apposed with a good area of contact in extension. An intermedullary K-wire is then driven across, holding this position. Some surgeons prefer to use two K-wires since they believe bone union will be more assured, since there is better fixation, although this may be technically difficult and it is not a technique we ever use. The extensor tenotomy and capsulotomy at the MTP joint is undertaken subcutaneously with a tenotomy knife. Another satisfactory method of arthrodesing the PIP joints is to use the peg and socket technique, in which the head of the proximal phalanx is fashioned into a peg, leaving one surface with cortical bone for strength and the base of the middle phalanx is fashioned into a round socket with burrs. The toe is then placed into the position for arthrodesis by impacting the peg into the socket. If done well and firmly, this should be immediately stable. If partial proximal phalangectomy is necessary, only the amount of bone required to allow the toe to fall down into a neutral position is excised. The full proximal phalanx is not excised, since this leaves a floppy, pathologically short and useless toe. in early disease, manipulation under anaesthetic may be all that is required at the PIP joint. Sometimes PIP joint arthrodesis is carried out after proximal phalangectomy, if the PIP joint contracture is severe. Amputation of a 2nd hammer toe should be avoided, since this creates an iatrogenic hallux valgus.
Rationale. The flexion deformity at the PIP joint must be corrected, usually by arthrodesis. The secondary contracture at the MTP joint is usually treated by extensor tenotomy and MTP joint capsulotomy. However if the MTP joint is subluxed dorsally, this may not be enough to correct deformity, and partial proximal phalangectomy may be the only method of reducing the subluxation. Claw toe Technique. In t h e mobile deformity, the Girdlestone flexor to extensor technique is utilized. A longitudinal incision is made over the toe. The long flexor tendon is exposed and divided as distally as possible. This is then brought dorsally, threaded through the extensor expansion, over the proximal phalanx, and sutured tightly to itself, as slackening can occur with time. If the lesion is fixed, arthrodesis of both the DIP and PIP joints has to be undertaken. Initial extensive soft tissue release may have to be undertaken around the joints. Usually the K-wire technique of arthrodesis is employed for both joints. An extensor tenotomy and capsulotomy usually has to be undertaken subcutaneously. A previous technique used less now than in the past, is that of Lambrinudi, in which the joint surfaces of both DIP and PIP joints were excised and arthrodesis was achieved by keeping the bones apposed with the toes straight,
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by tying previously placed subcutaneous loops of suture material around the proximal phalanges and on to a special foot frame. If the great toe is involved, the Robert Jones" operation should be used. In this extensor hatlucis longus is detached distally, threaded through the head of the first metatarsal and sutured to itself. The interphalangeal joint of the hallux is then arthrodesed, usually to the above K-wire technique. Claw toes secondary to rheumatoid arthritis should be treated as recommended in the previous section, that is by forefoot arthroplasty.
Rationale. If this deformity is mobile, a muscle balancing procedure may improve the deformity. However if deformity is fixed, arthrodesis has to be employed. It is doubtful if the Lambrinudi procedure has any great advantage over other methods.
Mallet toes
This is a comparatively rare condition, which usually causes fewer problems than either claw or hammer toe. The simplest surgical procedure is amputation of the distal phalanx, usually undertaken through an L-shaped incision, removing the nail and nail bed dorsally. The distal bone is filleted out and the procedure is finished by closing this dorsal defect by simple sutures. However, amputation of even a part of the toe is increasingly unacceptable to many patients these days, thus arthrodesis by the K-wire technique is now more commonly employed.
Complications of toe operations The main complications at the arthrodesis site are of non-union or fibrous union. If these are not strong, recurrence of the deformity may occur, although firm fibrous union itself may not be a problem. The K-wire which is usually in situ for 6 weeks may be a portal for infection and require early removal, which of course can predispose to recurrence. If the end of the K-wire is not bent into an L shape, this wire can migrate proximally under the skin due to recurrent banging of the wire end while walking. This can make removal very difficult. At operation, the neurovascular bundles can be damaged if the surgical adage of 'get to bone and stay there' is not kept, resulting in loss of sensation or even loss of the toe due to circulatory problems. These structures are more at risk with a transverse incision. In arthrodesing the DIP joint, inadvertent damage can occur to the germinal nail bed and this can result in secondary nail deformity. The patient should also be warned that most of these procedures shorten the toes and that arthrodesis is for improvement of deformity, not improvement of function and that deformities may recur, due to skin contracture.
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Ingrowing toe nail
Aetiology and pathology Ingrowing toe nail occurs frequently in the great toe, and most commonly between the ages of 15 and 40, with males affected more commonly than females. The main cause is usually incorrect nail trimming and tight shoe wear. The nail, especially at its sides is cut too short and this results in the edge of this nail being embedded in the soft tissues, which may overgrow. Because of sweating and poor hygiene secondary infection is likely to occur. This condition usually only presents to the orthopaedic surgeon after infection has occurred. However, it often presents earlier to the chiropodist and at that stage treatment is to ensure correct trimming and good hygiene of the nails.
Surgical treatments (Sykes, 1986) Once infection has occurred numerous operative procedures have been advocated.
Simple nail avulsion is still commonly practised. However, the recurrence rate is 60-70%. It therefore should only be used if there is marked sepsis. The best procedure is probably that of lateral wedge resection. In this technique, one third of the affected nail edge is resected. The germinal nail bed at the base of this resected nail is exposed and surgically ablated or chemically destroyed with topical phenol, which is left for three minutes and then washed off with alcohol. This method results in a good cosmetic result with lower recurrence rates. It is therefore often the most acceptable operative procedure for younger, partioularly female, patients, and is probably the procedure of choice. The Zadikprocedure (Zadik, 1950) is a more aggressive surgical procedure, in which the nail is avulsed, the germinal nail bed layer exposed and destroyed either by surgical excision, or by excision and topical phenolization. If the nail bed is only partially destroyed an ugly deformed nail may grow. This procedure is not necessary in most cases, since lateral resection and phenolization are usually adequate.
The great toe
The two common conditions requiring surgical treatment are hallux rigidus and hallux valgus.
Hallux rigidus (Figure 7) Clinical. Basically this is osteoarthritis of the MTP joint of the great toe, which results in painful limitation of dorsiflexion of this joint, especially on walking or running, both of which may become restricted. Night pain may also be a feature.
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Figure 7. Hallux rigidus.
Pathology and aetiology. The pathology is that of osteo-arthritis, with dorsal osteophyte formation, joint space narrowing, periarticular cyst formation, cartilage erosion and eventually subchondral bone erosion. The cause in many cases is thought to be recurrent trauma to the joint. If there has been an intra-articular fracture, through the MTP joint, the risk of osteoarthritis is increased. Secondary osteoarthritis may also occur due to systemic disease, such as rheumatoid arthritis or gout. In some cases the aetiology is thought to be osteochondritis of the metatarsal head.
Surgical management. The type of surgery is dependent on the age of the patient and whether the interphalangeal joint is involved. In the elderly and middle-aged patient, the treatment of choice is excisional arthroplasty at the MTP joint (Keller's procedure). If the patient is younger, and especially if he or she is very active, silastic spacers may be useful in preserving some 'push off' function. In the even younger adult excisional arthroplasty is too
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functionally disabling and arthrodesis of the MTP joint should be the method of treatment. Silastic implants should be avoided if possible in the young since they can fragment with possibly adverse effects. In the adolescent, surgical treatment should be avoided as long as possible, and if surgical treatment is unavoidable, arthrodesis is preferred. In the unusual case of a young adult in whom there is also interphalangeal joint involvement, arthrodesis at the MTP joint, will probably fail, since pain will worsen from the interphalangeal joint. This would be a rare indication in a young patient for an excisional arthroplasty, with a silastic spacer, associated with arthrodesis of the interphalangeal joint.
1. Keller's procedure (1904) (Figure 8). A longitudinal dorso-medial incision is centred over the metatarsophalangeal joint. The joint capsule is opened and the proximal phalanx is exposed. There is controversy about the percentage of proximal phalanx to be excised; most would remove about a third of the bone, although some advocate a half. It is important to leave no bone spikes, and to protect the flexor hallucis longus tendon from damage. The prominent 'bunion' on the metatarsal head is excised with an osteotome. Any prominent osteophytes, especially in the dorsal position of the joint, are excised. The medial joint capsule is reefed to tighten this side and improve the deformity, if present. If the extensor hallucis longus tendon is tight, it is lengthened by a Z-plasty. An attempt can be made to hold the original toe length and in a neutral position, by inserting a K-wire into the toe and through the metatarsal head, for 3 or 4 weeks. This may also help to prevent secondary deformity especially that due to skin contracture. The rationale of this method is that half the diseased joint is excised and left rather floppy and therefore pain should be reduced. After this procedure complications c~n arise; the toe will of necessity be short and floppy. If physiotherapy is not instituted early, utilizing the flexor hallucis longus, the dorsal structures may become tight and this can eventually result in a 'cocked up' toe! In young active people the loss of push off function from this method of treatment may be quite disabling. Patient selection is therefore very important. The advantage of this procedure is that it is quick and mobility is swiftly obtained; clearly a great benefit, when dealing with more elderly patients, particularly as pain relief is usually good. 2. Arthrodesis of the MTP joint. A dorso-medial, longitudinal incision is used, centred over the MTP joint. It is important to protect the neurovascular bundle with this incision. The MTP joint is opened. Using an oscillating saw the joint surfaces are excised, until good flat surfaces of cancellous bone are exposed. All surrounding osteophytes are trimmed away and if there is a 'bunion' this is also removed. It is important to protect the long flexor and extensor tendons, The surfaces of the bone of this joint must have good apposition, in a position of 15~ of both dorsiflexion and valgus, in which they are then fixed with a lag screw technique, which gives good compression, with a high rate of bony union. This position of dorsiflexion is important for push off function. This arthrodesis is protected in plaster for an average of 6 weeks. Many other techniques of arthrodesis are
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described, using wire loops, external fixation or staples. However we prefer this lag screw technique; it is both simple, accurate and reliable. After this procedure, the most important complications are those of non-union or mal-union, either of which may require surgical revision, which can be difficult technically and which may require bone grafting. If too
iiiiiiis,on us
Z-lengthening of xtensor hallucis Iongus
Figure 8. The Keller's procedure. [] = bone for excision.
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much bone is removed in achieving this arthrodesis, an overlong second toe will result which can cause the development of a secondary, second hammer toe. Digital nerves may be damaged in any toe procedure and this can result in partial anaesthesia, and/or painful neuroma formation.
Hallux valgus Definition. This is basically a deformity of the great toe, with lateral deviation occurring at the MTP joint. Rotation of the toe and subluxation at the MTP joint occur later.
Clinical. More females than males seek surgical attention. A male presenting with hallux valgus should alert the clinician to the possibility of this being a harbinger of rheumatoid arthritis. The major problems are of secondary pain associated with bursitis or skin problems over this prominent bunion. Difficulty in obtaining good shoewear is a frequent reason for seeking advice, especially from younger females with broad feet. Later pain develops in the MTP joint, due to the development of secondary osteoarthritis. Pathology and aetiology. Many theories have been expounded on this problem, which is a common entity whose aetiology is usually multifactorial. Conditions associated with its presence are: rheumatoid arthritis, amputation of the second toe and long-term use of poor tight shoe and sock wear. There is often a hereditary factor, with the first metatarsal bone in a varus position (metatarsus primus varus). There is some controversy as to whether this is a primary or secondary phenomenon. Whatever the cause, an imbalance occurs between the muscles attached to the great toe. The adductor muscle becomes relatively short and develops a mechanical advantage over its antagonistic muscle group; the abductor, flexor hallucis longus and extensor hallucis longus, which usually bowstrings, to worsen the deformity. This is the basis of the McBride procedure, which negates this adductor imbalance. The pathology is basically that of a valgus toe, which will eventually sublux and then rotate at the MTP joint. The 'bunion' is the medial side of the metatarsal head, although secondary osteophytes can later occur. Because of the broadening of the foot and local irritation, secondary skin thickening, bursa formation and skin ulceration can occur over this 'bunion'. In the long-term, secondary osteo-arthritic changes can occur in the MTP joint. The valgus deformity of the great toe can cause the lesser toes to become crowded and secondary hammering or clawing can develop, sometimes associated with metatarsalgia.
Rationale of surgical treatment. If the deformity is purely due to adductor muscle imbalance a soft tissue procedure can be undertaken. However a pure soft tissue problem is rare and the varus deformity of the metatarsal must be corrected by some bony re-alignment procedure. When osteoarthritis occurs in the MTP joint either a Keller's procedure or arthrodesis of the MTP joint should be considered.
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Surgical management. The two important factors which influence the choice of surgical procedure are age and whether or not there are osteoarthritic changes in the MTP joint. In the adolescent a soft tissue procedure may be sufficient if secondary bony changes have not occurred and if so can be influenced by balancing of the excessive adductor muscle pull. In the young adult, with no MTP joint involvement an osteotomy of the metatarsal shaft is the procedure of choice. With patients over the age of 40, there are probably osteoarthritic changes in the MTP joint and an excisional arthroplasty, with a temporary K-wire or silastic spacer is usually required. The difficult age group to manage is that between 25 and 45 years old, in whom the presence or absence of osteoarthritis in the MTP joint is crucial. For if it is present an MTP joint arthrodesis is probably the procedure of choice, providing there is no interphalangeal joint arthritis. If the MTP joint is in good condition, a conventional metatarsal osteotomy can be employed. Some may ask why if the symptoms arise from the medial bunion, should its simple excision not suffice. Often in practice simple bunionectomy usually only gives relief for 2-3 years, the symptoms returning, because the underlying cause of the deformity has not been altered.
1. The McBride soft tissue procedure (modified) (McBride, 1928). This soft tissue procedure has only a limited place, possibly in the treatment of young adolescents. Some surgeons feel that it should never be used alone and that it should be combined with a metatarsal osteotomy. The modification of this operation occasionally used in our unit uses a dorsal longitudinal incision, through which the adductor muscle insertions to the proximal phalanx and lateral MTP joint capsule are divided. The medial capsule is reefed, using a Y to V plasty and if the soft tissues are still tight the extensor hallucis longus is lengthened by Z-plasty. The original McBride procedure transferred the adductor insertion to the neck of the first metatarsal bone, which is a technically difficult procedure, of dubious function. If this soft tissue operation does not improve the deformity a bony procedure on the metatarsal should be undertaken. 2. Re-alignment osteotomy. The principle is to cancel the hallux valgus, by countering the metatarsal varus, with an osteotomy towards a more neutral position. These osteotomies, which may be proximal or distal, also tend to shorten the metatarsal slightly which may improve the soft tissue tension at the MTP joint. (i) Distal osteotomy. In the Mitchell Osteotomy (Mitchell et al, 1958) (Figures 9 and 10a) a dorsal longitudinal skin incision is undertaken over the MTP joint. The joint is not opened. The medial capsule is incised in a Y shaped manner and the bone of the distal metatarsal is exposed. A medially based cube of bone is removed, leaving a lateral tongue or peg. The osteotomy is completed and the distal fragment can be displaced laterally, the peg helping to keep the displacement. This may be stabilized with a heavy suture passed through drill holes in proximal and distal fragments. Alternatively, staples, screws or K-wires can be used. Any projection of
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Figure 9. Hallux valgus (a) prior to Mitchell's osteotomy; (b) post Mitchell's osteotomy.
bone is excised. Care must be taken that the distal fragment does not ride up. The Y flap of the medial capsule is sutured as a V, therefore tightening the medial tissues. Post-operatively the foot is protected in plaster for 6-8 weeks. There are numerous modifications of this distal type of osteotomy. A popular and simple procedure is the Wilson Osteotomy (Wilson, 1963) (Figure 10b). This is an oblique osteotomy allowing the bone to slide towards the neighbouring metatarsal. The osteotomy is also angled backwards to prevent the distal fragment riding up. (ii) Proximal osteotomy. The varus deformity of the metatarsal can be corrected at the base of the metatarsal shaft, through a dorsal, longitudinal skin incision, positioned more proximally than in the Mitchell procedure, although it can be extended distally so as to combine it with a McBride soft tissue release. The osteotomy may use the opening or closing wedge principle. In the latter, a wedge with its apex at the medial cortex is removed from the metatarsal base and the bone surfaces are apposed to correct the
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varus deformity. In the opening procedure a transverse osteotomy leaving the lateral cortex intact is made and a bone wedge, easily taken from the bunion at the metatarsal head is then inserted from the medial side. Despite the use of K-wires with these procedures the foot must be protected in plaster for 6-8 weeks post-operatively. With all types of osteotomy there is a risk of delayed union, non-union or real-union. It is particularly important to prevent the distal fragment riding up, relative to the proximal shaft, because such a mal-union may result in subsequent metatarsalgia, with imbalance of the forefoot. This can also occur if the first metatarsal is shortened too much. The proximal osteotomy procedures may result in a longer scar and since its fixation may be poorer than with distal osteotomies, the non-union rate may be higher. Advice about shoe wear post-operatively is all important, since wearing pointed shoes may quickly result in the deformity recurring. The main problem with most active young people is that the enforced use of bilateral walking plasters usually for 6-8 weeks, causes not only discomfort, but great inconvenience. For this reason some surgeons recommend only operating
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(al
Figure lOa.
The Mitchell osteotomy.
upon one foot at once, a practice with obvious disadvantages of its own, with doubled time in hospital and two anaesthetics.
3. Keller's Procedure and metatarsal phalangeal arthrodesis. Both arthroplasty and arthrodesis have been described earlier in the section on hallux rigidus. The Keller's procedure works since it releases the soft tissue tension, as the adductor insertion is excised. It is effective in relieving pain, as is arthrodesis. Miscellaneous forefoot conditions
Morton's neuroma This is a relatively rare condition and there is some doubt in our minds as to whether it exists at all. Whereas it probably does, we suspect that not only is it excessively diagnosed, but consequently overtreated. It was first described by M o r t o n in 1876, with a clinical picture of pain in the forefoot radiating into the toes, especially in the 3rd/4th interspace, although it also occurs in the 2nd/3rd interspace. Sensation in the interspace may be altered and the pain can be worsened by walking on hard shoes. If lateral pressure is applied across the forefoot there may be pain and an audible click. The condition is said to occur most commonly in middle-aged females. The causative pathology is thought to be ischaemia of the nerve, before it bifurcates. The nerve becomes fusiform and degenerate and is therefore strictly not a true neuroma. A similar clinical picture can occur in rheumatoid arthritis due to pressure on the nerve secondary to synovitis. H o w e v e r this is a pressure effect and not a M o r t o n ' s neuroma.
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(b)
Anteroposterior
\
> Dsteotomy
1
Lateral
Figure lOb. The Wilson osteotomy.
Operative technique. A dorsal or plantar skin incision can be used. The disadvantage of the dorsal incision is that access may be limited and the nerve difficult to expose and resect. The plantar skin incision may be transverse or longitudinal. The main advantage of this approach is that the nerve can be easily located and resected and that any other pathology can be excluded. If the transverse incision is proximal to the weight bearing area, no secondary pain from the scar should occur. We therefore recommend this approach. The nerve should be divided cleanly and handled carefully or a secondary traumatic neuroma may form, causing pain and discomfort on weight bearing. It is also important to divide the nerve sufficiently proximal, so that the end of the transected nerve is not under the weight bearing area. Post-operatively there will be a loss of sensation in the nerve's sensory area. However, the pain should be relieved. Freiberg's infraction (Figure 11) Clinical. This is a rare, but fascinating disease which occurs typically in the
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Figure 11. Freibcrg's infraction.
10218 year old group, and in females more than males. The commonest area affected is the 2nd metatarsal head, although it can also occur in the 3rd and 4th metatarsal heads. It usually presents with pain and thickening in the forefoot, specifically over the affected area of bone. The aetiology is unknown, but it is thought to be secondary to repeated trauma to this metatarsal head. There maybe a predisposition caused by an over-long second metatarsal. The pathology is of avascular necrosis of the metatarsal head. Although this area should eventually revascularize, whilst it is avascular the bone is soft and can deform, resulting in secondary osteoarthritis. The diagnosis is usually confirmed by seeing the increased density, pathognomonic of avascular necrosis, on X-ray. Treatment. The rationale is to prevent the deformity of the metatarsal head from occurring and therefore hopefully to prevent secondary osteoarthritis. Unfortunately this condition often presents late, once deformity of the metatarsal head has occurred, which makes successful management difficult.
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Conservative treatment consists of metatarsal insoles or metatarsal supports, with a below the knee plaster of Paris, in an effort to reduce pressure over the metatarsal head, and therefore to prevent deformity. However, most patients will find plaster unacceptable since revascularization may take up to two years. For early disease, two procedures have been advocated; these are of Smillie and of Helal. Smillie's operation consists of gutting the metatarsal head of the avascular bone, using a window in the metatarsal neck. The head is then packed with cancellous bone graft. Helal'sprocedure is identical to that described in the section on rheumatoid arthritis. The middle three metatarsal shafts are osteotomied, including the affected one, since if only one was realigned this would cause imbalance of the metatarsal compared with its nighbours, causing subsequent problems, especially metatarsalgia. Unfortunately there have been few long-term reports on the results of treating this rare condition by either of the above procedures. Therefore it must be concluded that their efficacy is not proven. Late disease when osteoarthritis has occurred is even more difficult to treat with p o o r results from surgical treatment. Excision of the metatarsal head has been advocated. This may give short-term relief by removing the affected segment, but in the long-term, this will result in forefoot pain due to metatarsal imbalance as a result of the shortening effect. In our view metatarsal head excision in the treatment of Freiberg's disease is to be deprecated. Numerous other procedures have been advocated; these include, excision of the metatarsal head with syndactyly of the adjacent toes, wedge osteotomy of the metatarsal head so that unaffected cartilage may be rotated around, silastic hinge joints and spacers have also been utilized. The problems with any of these procedures are that the numbers are low in each series and usually no controls are used. It is therefore difficult to decide if any of these various procedures is successful or not. However the procedure of osteotomy and rotation is difficult technically and there may be no normal articular cartilage to rotate. This disease occurs in young people therefore the use of silastic joints and spacers may be unwise, since the long-term effects of this material to the bone and soft tissues is as yet unknown. If relief cannot be gained by other methods palliation may only be found by excision of the whole ray.
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