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The management of flexor tendon injuries in zone II
Current Orthopaedics (2002) 16, 434 ^ 441
c 2003 Elsevier Science Ltd. All rights reserved. doi:10.1054/cuor.2002.0305
TRAUMA
The management of £exor tendon injuries in zone II R. H. Helm Doncaster Royal In¢rmary, Armthorpe Road, Doncaster, DN2 5LT, UK
INTRODUCTION Repair of the lacerated ¢nger £exor tendons has long been regarded as one of the most challenging branches of hand surgery. Historically, the results have been unpredictable and only comparatively recently has repair of ¢nger £exor tendons, especially in zone II, been standard practice.The technical di⁄culty of repair, the complexity of the local anatomy and the large number of things which may potentially go wrong, have all contributed to the reputation of this injury as one in which it is di⁄cult to ensure an excellent outcome. Also, £exor tendon injuries in zone II are relatively uncommon, and an ordinary sized district hospital may only see two or three patients a month, if that. In addition to the surgery, it is an injury demanding skilled and attentive post-operative rehabilitation. After this injury, probably more than any other, compliance of the patient is essential and, unfortunately this is not always the case. Historically, for many centuries physicians were in£uenced by the opinion of Galen1 who regarded tendons and nerves as having the same characteristics and he advised that repair of tendons would result in gangrene and convulsions. Interest in £exor tendon repair was revived in the middle of the19th century after Albrecht Von Haller 1 demonstrated that tendons did not have the same irritability as nerves. However, it was not until the early 20th century that Leo Mayer, in 19162, published his paper on tendon transplantation and emphasised the surgical principles of atraumatic tissue handling and preservation of the tendon sheath. These lessons were carried forward by Bunnel who additionally emphasised the need for a sound knowledge of tendon anatomy, appropriate incisions and a bloodless ¢eld. His book,‘Surgery of the Hand’, published in 19443, is regarded as opening the modern era of hand surgery. He was the ¢rst to use the term ‘no man’s land’ and advised against primary tendon repair in zone II. He advised that the correct treatment for tendon repair in zone II was to excise the injured tendon and perform delayed tendon grafting. Correspondence to: RHH.Tel: +44 1302 366666 ext 3916; Fax: +44 1302 792336
The result of Bunnel’s teaching was that, for many decades, most surgeons would not attempt primary tendon repair in zone II. The concept was supported by several leading hand surgeons who reported good results following tendon grafting. It was not until the 1950s and 1960s that Verdan4 popularised the idea of primary repair rather than tendon grafting. He pointed out that not all surgeons could reproduce the good results reported by the leading hand surgeons after tendon grafting and also that primary repair was a less extensive operation. However, even then, most surgeons would only advise primary repair within 2^ 4 h after injury, although this time period gradually extended until Schneider et al., in 19775, advised that delayed repair up to 21 days did not adversely a¡ect the result. However, they found that better results were obtained when the primary repair was within 10 days of injury, and this is the period which most modern hand surgeons would regard as being appropriate. One’s experience is that after 10 days, tendon retraction and adhesion formation make the surgery technically more di⁄cult.
ANATOMY There are ¢ve distinct zones of the £exor tendons (Fig.1), as outlined ¢rst by Verdan.4 Zone I is from the insertion on the distal phalanx as far proximally as the insertion of £exor digitorum super¢cialis in the middle of the middle phalanx. Zone II is the region of the £exor tendon sheath, from the middle of the middle phalanx as far proximally as the distal palmar crease. Zone III is in the palm of the hand between the distal palmar crease and distal edge of the carpal tunnel. Zone IV is the carpal tunnel and zoneV proximal to the carpal tunnel as far proximally as the musculo-tendinous junction. The ¢nger £exor tendons arise from the £exor digitorum super¢cialis and £exor digitorum profundus muscles in the volar forearm. Flexor digitroum profundus is the deepest layer and is usually a single muscle belly for all four ¢ngers, although the index is often a separate muscle belly. It continues as a single tendon into the distal forearm or even the proximal carpal tunnel when it splits into its separate tendons to each ¢nger. The £exor digitorum super¢cials is the middle layer, and consists of four
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annular pulleys are more £imsy structures, designed to collapse as the annular pulleys approximate each other when the ¢nger £exes (Fig. 2). The £exor tendon sheath is covered internally with a well-vascularized synovium which merges with the epitenon proximally and distally to form a closed system. In addition, the £exor tendons are loosely attached to each other and to the £exor tendon sheath with short and long vinculae which bear blood vessels. From the functional point of view, £exor digitorum profundus is the primary £exor of the ¢nger and £exor digitorum super¢cialis contributes some strength of grip and also, in view of its individual action, balances the grip when handling objects of uneven shape and also, together with the intrinsic muscles, balances individual ¢nger motion. Figure 1 The ¢ve zones of the £exor tendons in the ¢ngers and hand, according toVerdan.
separate muscle bellies, each giving rise to a single tendon to each of the four ¢ngers.The most super¢cial layer comprises pronator teres, £exor carpi radialis, palmaris longus and £exor carpi ulnaris. The eight £exor tendons to the ¢ngers lie in the carpal tunnel with the median nerve. In zone III in the palm of the hand, they are anatomically associated with the deep palmar vascular arcade and the lumbrical muscles. The tendons enter the £exor tendon sheath at the level of the distal palmar crease. Flexor digitorum super¢cialis lies anterior to the profundus tendon initially, but then splits in two and decussates around the profundus tendon to lie posterior, with the ¢bres re-attaching to each other on the deep (posterior) aspect of the profundus tendon in the chiasma of Camper before splitting again at the level of the proximal interphalangeal joint to form two £at slips inserting onto the middle phalanx. The profundus tendon itself passes through the decussation of £exor digitorum super¢cialis to continue past the interphalangeal joints to its insertion on the distal phalanx. The £exor tendon sheath has a quite complex anatomy. Its function is to allow the tendons to glide without friction, whilst maintaining the tendons in close apposition to the bones and joints, thus avoiding bowstringing and at the same time supply adequate nutrition and vascularity. To prevent bowstringing the £exor tendon sheath is arranged in a series of strong ¢brous pulleys. There are ¢ve Annular or ‘A’ pulleys with Cruciate or ‘C’ pulleys between them. The most important pulleys are A2 arising from the periosteum of the proximal phalanx and A4 from the periosteum of the middle phalanx. The smaller A1, A3, and A5 pulleys arise from the palmar plates of the metacarpophalangeal joint, proximal interphalangeal joint and distal interphalangeal joint, respectively. The cruciate pulleys which lie between the
TENDON PHYSIOLOGYAND HEAILNG Tendons were generally thought to be avascular structures until the work of Mayer, in 19162, who performed injection studies with coloured gelatin. He demonstrated that tendon had an internal circulation arising from the periosteum at the tendon insertion, from the muscles and also from the vinculae. Several similar studies have been performed since then including the recent work by Schatzker and Branemark in 19626, who demonstrated the microvascular anatomy of the internal circulation of the tendon, in particular, its segmental nature. There are several ‘watersheds’ where the tendon is relatively avascular, such as the region between the two vinculae, and this may have implications for the prognosis of tendon repair. The physiology of tendon healing can be thought of as being a combination of intrinsic and extrinsic processes.
Figure 2 Lateral view of a ¢nger to depictthe components of the £exor tendon sheath.The sturdy annular pulleys (A1, A2, A3, A4 and A5) have the thinner, more pliable, cruciate pulleys between them to allow them to approximate as the ¢nger £exes.
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Intrinsic repair is that derived from the internal biology of the tendon itself whereas extrinsic involves ingress of in£ammatory cells and ¢broblasts from the outside, via adhesions. Early experiments on tendon healing from the1930s to the1950s seem to indicate that the most important aspect of tendon healing was extrinsic. In, 1954, Skoog and Persson7 found no evidence of intrinsic tendon repair and noted that isolating the repair area from the outside greatly impaired tendon healing. However, more recent studies in animals by several authors have demonstrated signi¢cant intrinsic healing potential, with proliferation of epitenon and transformation of resulting tenocytes into tenoblasts which subsequently proliferate and produce collagen. Important work by Potenza8 showed the signi¢cant contribution of tendon handling to the subsequent formation of adhesions, and it is now thought that the technique of tendon repair and handling, etc., in the early studies, may have been the main cause of adhesions, thereby over-emphasizing the importance of extrinsic tendon repair. It is now thought that tendons do have a signi¢cant capacity for intrinsic repair, supported by synovial £uid and the intrinsic vascularity of the tendon. It is therefore of obvious great importance to maximize the intrinsic process whilst at the same time minimizing adhesion formation. There is no signi¢cant experimental evidence that non-steroidal or other drugs a¡ect the process of tendon repair. It is also important to consider the strength of the repair when planning post-operative rehabilitation. Important research by Strickland in 19939 showed that the strength of a £exor tendon repair would range from 1800g for a two-strand repair to 5400g for a sixstrand repair (vide infra) and this could be also increased by peripheral epitenon sutures. He further showed that the strength of repair would fall by 50% 1 week after surgery and this would gradually increase over the next 6 weeks. This has to be compared with the tensile forces generated at the site of tendon repair, which can be 500g for passive movement up to 9000g for tip pinch of the index ¢nger. As mentioned previously, the ¢bro-osseous pulleys are vital for normal tendon function. A recent paper by Rispler et al.,10 dealt with the e¡ect of sectioning the various pulleys sequentially.They found that the minor (A1, A3 and A5) pulleys could be sectioned without loss of function. The A2 pulley alone could be sectioned, reducing the excursion e⁄ciency to 94%, but complete loss of the A2 pulley, or the A2 and A4 pulley combined, would reduce excursion e⁄ciency to 82%. All these experimental studies, however, have to be taken in context.The in vivo human situation may be quite di¡erent. The tensile forces generated in a tendon may vary with the degree of post-operative swelling and in£ammation. Also unpredictable degrees of force may be generated at times, for instance when a patient is asleep or when patient compliance is poor.
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CLINICAL ASSESSMENTAND MANANGEMENT As with any other injured patient, assessment and management should be along established protocols. However, in practice, £exor tendon lacerations are nearly always isolated injuries. A full medical history should be obtained from the patient, including smoking status, drug history and allergies, etc. A detailed history of the mechanism of injury should also be taken, paying particular attention to possible contamination of the wound, especially with soil or similar material, the lacerating instrument and whether it was sharp, blunt or ragged, and the position of the ¢nger at the time of impact, as lacerations sustained with the ¢nger £exed will result in the distal cut end being at a more distal level than the skin injury. The diagnosis of a lacerated £exor tendon is not usually di⁄cult and in most patients can be made from the abnormal posture of the ¢nger, i.e. the ¢nger with a divide will adopt a straighter position. The ¢nger should be carefully examined to determine the nature of the wound and whether it is a clean incised wound or a contaminated or ragged wound, and whether or not there is evidence of soft tissue crushing or bursting. The distal neurovascular status should also be assessed. Vascular impairment could be suspected if there is distal pallor or duskiness, and slowness of capillary re¢ll. Sensation distally should be assessed by simply ascertaining whether light touch sensation is normal or abnormal. More sophisticated sensory examination including twopoint discrimination would not be appropriate or reliable in the emergency setting. It should also be borne in mind that sensation after nerve injury can often be surprisingly normal, at least on the ¢rst day or two after injury. In cases of penetrating wounds and apparently normal tendon function, one should bear in mind the possibility of a partial laceration of the tendon. Assessment should be made by performing the tendon tests against resistance, and if resistance causes pain, then a partial tendon injury should be suspected. Flexor digitorum profundus is examined by active £exion of the distal interphalangeal joint and £exor digitorum super¢cialis is tested by immobilizing the other digits in full extension to prevent profundus function and seeing if the digit will £ex at the proximal interphalangeal joint level yet leaving the terminal joint lax.This latter test needs to be done carefully in the index, which may have an independent profundus muscle belly. When the diagnosis is made, a decision is required about primary repair of the £exor tendon. As mentioned above, there is no reason to perform this as an emergency, but the operation should be performed in daylight hours, preferably on an established trauma list, by a surgeon experienced in the technique. This can be done safely at any time up to a week or even 10 days after injury. Contra-indications to primary £exor tendon repair
THE MANAGEMENT OF FLEXOR TENDON INJURIES IN ZONE II
include contamination of the wound, when the wound cannot be converted into a safe clean wound, signi¢cant skin loss and severe multiple soft tissue injuries. Concomitant fractures of the ¢nger are not necessarily a contra-indication provided that the fractures can be suf¢ciently stabilised to allow some early movement of the ¢nger and neurovascular injuries also are not a contraindication, but it should be appreciated that the results may not be as good. The patient should be thoroughly counselled before surgery about the nature of the injury and the fact that surgery can be di⁄cult and the results sometimes unpredictable. They should be particularly counselled about the prolonged post-operative rehabilitation and the importance of strict compliance with post-operative therapy. This is particularly important in cases where only the £exor digitorum profundus is injured, as a patient may decide to accept the disability caused by loss of active distal interpharangeal joint £exion rather than undergo a programme of surgery and rehabilitation which may involve 3 months or more o¡ work.
SURGICALTECHNIQUE The goals of surgery are to make a strong, reliable repair of the tendon causing minimal tissue trauma by avoiding as far as possible handling of the surface of the tendon. The operation should result in a tendon repair which is smooth and neat and not too bulky to interfere with tendon gliding. It is essential to preserve the A2 and A4 pulleys. There are various suture techniques (Fig. 3) but the commonest in use is probably the modi¢ed Kessler suture with a circumferential continuous epitenon repair. In general terms, multi-strand repair techniques give increased strength but can increase the bulk of the tendon repair and also caused increased intra-tendinous disruption of tendon architecture and blood supply compared with two-strand repair techniques. The suture material should be non-absorbable and braided. I would advise against using Prolene because it runs too easily through the tissues and can allow gap formation to occur.The epitenon circular circumferential repair should normally be done with a ¢ne Prolene or nylon.When the distal slips of £exor digitorum super¢cialis are to be repaired, then a simple horizontal mattress suture usually su⁄ces. Considerable research has been undertaken looking into the mechanical strength of the di¡erent repair techniques. Momose et al.,11 found that double Kessler, doubleTsuge cruciate and Becker repairs were stronger than modi¢ed Kessler and Tsuge repairs. Trail et al.12 tested ¢ve techniques and found that the modi¢ed Kessler with circumferential suture required the greatest load to produce gapping but the Becker and Savage repairs withstood the highest load before failure.
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Figure 3 Schematic drawings of di¡erent suture techniques: (A) modi¢ed Kessler, (B) Tsuge, (C) double modi¢ed Kessler, (D) double modi¢ed Tsuge, (E) Savage, (F) Becker.
At the time of surgery, the wound is extended to produce a zig ^zag incision. After identifying and protecting the neurovascular structures the tendon sheath is inspected. The proximal tendons, especially £exor digitorum profundus, will have retracted proximally and will need to be retrieved. It is important not to blindly grasp with forceps as this may cause tendon damage. Sometimes the tendon can be retrieved by inserting a skin hook, rotating through 90o degree etc and gently pulling distally. Often the tendon has retracted into the palm and I can recommend the technique described by Sourmelis and McGrouther13. This involves making a small incision at the level of the distal palmar crease to identify the tendons, passing a very ¢ne plastic catheter from proximal to distal adjacent to the tendons until it emerges into the distal wound, suturing the catheter to the tendon proximally, pulling distally on the catheter to deliver the tendon into the wound, inserting a core suture, pulling the catheter backwards and freeing it from the tendon to remove it, then ¢nally pulling on the core suture to deliver the tendon back into the wound.When the tendon is delivered into the wound it can be secured using a trans¢xing hypodermic needle proximal to the site of repair. When repairing the tendon, it is essential, as mentioned above, to preserve the A2 and A4 pulleys. All surgeons performing this procedure should be familiar with the de¢nitive article by Graham Lister who, in198514, described his technique of L-shaped windows and combined window repair. When opening windows between the annular pulley, these should be L-shaped to facilitate passing the tendon under the strong non-elastic annular pulley, otherwise the bulky tendon can get snagged on the edge of the annular pulley (Fig. 4). An L-shaped window is made proximal to the annular pulley to be preserved, commonly the A4 pulley. The
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Advocates of tendon sheath repair claim that repairing the tendon increases the synovial £uid nutrition of the tendon repair as well as facilitating gliding and avoiding the problem of triggering of the repair on the pulley. However, it has not been demonstrated clinically that tendon sheath repair improves the results of surgery. Also, I ¢nd repair of the L-shaped windows can be technically di⁄cult at times, so my practice is to leave them unrepaired. Figure 4 Diagram to illustrate the L-shaped windows made and below the £exor tendon pulley to be preserved. In a combined distal window repair the sutures will be passed through the A4 pulley and then placed in the distal tendon.
¢nger is then £exed to see how much distal tendon emerges into the window (it is always possible to deliver su⁄cient proximal tendon into the window). It is necessary to have access to 10 mm of tendon to insert a core suture and 5 mm to apply the epitendinous circumferential suture. If 10 mm of distal tendon will deliver into the wound by £exion of the distal interphalangeal joint then a window repair proximal to A4 can be made. If only 5^10 mm can be delivered, this is insu⁄cient tendon length to insert a core suture, so the distal end has to be delivered distal to the A4 pulley through a separate L-shaped window, the core suture inserted into the distal end, the suture ends and needle passed through the A4 pulley to the proximal window, the suture pulled through whilst £exing the distal interphalangeal joint to deliver the tendon into the proximal window where the core suture can be tied and there will then be enough room for the circumferential suture. This is called a proximal combined repair because two windows are combined for the core suture and the circumferential suture is inserted in the proximal window. If less than 5 mm of distal tendon can be delivered into the wound, then this is not even enough for a circumferential suture, so it is then necessary to insert the core suture into the proximal tendon in the proximal window, pass the suture material and needle through A4 pulley, deliver the proximal end into the distal window by £exing both proximal and distal interphalangeal joints, and then completing the core suture and circumferential suture. This can be technically quite awkward with the ¢nger £exed.This is known as a distal combined repair. Sometimes it is found that there is a partial laceration to the tendon. It has been shown that, when the laceration is less than 60%, then the results of leaving it alone are better than the results of repair15. If, however, the laceration is nearly complete, then the tendon should be repaired in the usual way as a late rupture of the tendon is more di⁄cult to deal with than a primary repair.There is a debate about whether or not the £exor tendon sheath should be repaired over the £exor tendon repair.
POST-OPERATIVE MANAGEMENT The quality of post-operative management and rehabilitation and the co-operation of the patient are probably more important after £exor tendon repair in the ¢nger than in almost any other branch of surgery. The aim of post-operative treatment is to allow controlled gliding of the tendons relative to each other and to the tendon sheath in order to avoid adhesion formation but at the same time to also avoid tendon rupture. It is also important to maintain the passive range of motion in the joints to avoid the development of a ¢xed £exion deformity in the interphalangeal joints. The three commonest rehabilitation programmes in common use today are those described by Kleinert and colleagues16, Duran and Houser17 and the Belfast group18. Kleinert’s method involves the use of rubber bands attached from the ends of the ¢ngers to the bandage on the volar side of the forearm. This produces £exion of the ¢nger by contraction of the elastic band rather than by muscle contraction, which may produce tension at the tendon repair site. Extension against the pull of the elastic allows the £exor muscle to relax. It is hoped that the reduced tension in the £exor muscle will reduce the rate of post-operative rupture. There have been several modi¢cations of the technique published, including different types of splints and also pulleys at the level of the palm to increase mechanical advantage of the elastic. This is a very popular and successful method but a common mistake is to use elastic which is too strong, and this can, in my experience, be associated with the development of £exion contractures. The method described by Duran in197617 concentrates on passive £exion and extension movements of the ¢ngers only and avoids £exion. He reported a rupture rate of 13% in 30 patients. In 1989, Small et al. of Belfast18 reported their experience of controlled early active motion in the rehabilitation of these injuries. All of these programmes involve detailed recommendations about exactly what exercises the patient should be doing at a particular time, and how frequently. My own experience is that the Kleinert and the Belfast methods produce similar results and therefore I favour the Belfast method in view of its simplicity. Peck et al.,19 reported a prospective trial with patients treated either with the Kleinert
THE MANAGEMENT OF FLEXOR TENDON INJURIES IN ZONE II
method or the Belfast method, with 26 patients in each group, and found similar outcomes with the exception of a signi¢cantly lower rate of rupture (7.7%) in the Kleinert group than in the active motion group (46%). However, the report does not say that the patients were randomised. Whichever method of rehabilitation is used, it is essential to review the patient frequently in a dedicated clinic in association with the responsible hand therapist. Review should be at least weekly in the ¢rst few weeks. The rate of progress of the patient should be correlated with the progress of therapy. For instance, a patient who rapidly regains a normal active and passive range of motion is at high risk of rupture and should be protected in a splint for longer, whereas a patient with signi¢cant swelling and sti¡ness of the ¢nger is at a higher risk of hand sti¡ness, and should be allowed out of the splint sooner.
Complications There are several complications which can ensue. The three commonest complications are ¢nger sti¡ness because of adhesion formation, ¢xed £exion contracture of the interphalangeal joints and tendon rupture.Tendon adherence can be diagnosed when the passive range of motion is greater than the active range, and the tendon is still intact.This is managed by active and passive range of motion exercises as well as massage and wound management. In the longer term, if a tendon is not functioning, then surgery can be considered, but not for at least 6 months, or preferably longer, to allow the tendon to regain mechanical strength. Brie£y, tenolysis may be possible to improve tendon gliding, but more commonly the tendon is hopelessly stuck with a mass of adhesions and the only surgical option is to excise the tendon and perform two-stage £exor tendon grafting. Fixed £exion contracture of the joints can be a common problem as the ¢nger £exors are stronger than the ¢nger extensors and the natural posture of the ¢nger is £exion of the interphalangeal joints. For these reasons, £exion contractures can swiftly occur and should be prevented by daily exercises to passively extend the interphalangeal joints, while keeping the metacarpophalangeal joints £exed. Once established, £exion contractures of the interphalangeal joints are extremely di⁄cult to treat and great care should be taken to prevent their occurrence. Rupture of the tendon repair can be a sudden event and a patient can complain that something went in the ¢nger, followed by lack of active £exion, but sometimes can be a gradual process as the gap formation at the repair site develops. Diagnosis can sometimes be di⁄cult in a swollen ¢nger and, if available, ultrasound or MRI scanning can be very useful.The usual course of action is to recommend immediate exploration
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of the ¢nger with a view to revision of the repair, but if a profundus tendon only is a¡ected with intact super¢cialis, it may be preferable in some circumstances to accept the situation.With all this, prevention is better than cure and patients need to be constantly reminded that they should not do any more than the recommended exercise. For this reason I routinely add an ‘anti-grab’ bar to the protective splint (Fig. 5). An important study by Harris et al.,20 reported a rupture rate of 4% in 397 ¢ngers with zone II injuries and of these 50% were due to acts of stupidity on the part of the patient, including 11 who ruptured whilst using the hand for a variety of tasks, including one patient who was lifting a wardrobe. Other complications include wound infection, skin £ap necrosis and regional pain syndromes.
RESULTS OF SURGERY The percentage of good results of £exor tendon repair in zone II have gradually increased as the years have gone by and presently most series report the percentage of good or excellence results as being in the range of 70 ^90%. The di⁄culty with comparing results is that there is no universally accepted assessment system. Many of the early papers have little in the way of objective measurements. Recently, however, the two main scoring or assessment systems are those described by Lister and Strickland. Lister’s14 method involves the assessment of £exion and extension de¢cits. Flexion de¢cit is the pulp to palm distance and extension de¢cit is the sum of the extension loss at the metacarpophalangeal and interphalangeal joints. An excellent result is a ¢nger which £exes to within 1 cm of the distal palmar crease and has less than 151 combined extension de¢cit and a poor result is a ¢nger which cannot £ex to within 3 cm from the distal palmar crease or has an extension de¢cit of over 501.The assessment method described by Stickland21, which in my opinion is more di⁄cult to use, involves calculating the percentage of normal active PIP and DIP joint movement by summing the active PIPJ and DIPJ £exion, substracting the extension lag and expressing this as a percentage of 1751. Thus an excellent result has a ¢nger with 75^100% of normal active movement and a poor result has a 0 ^24% of normal active movement. There have been several papers in the last decade reporting the results of £exor tendon repair in zone II, usually after introducing some modi¢cation of technique or rehabilitation. Peck et al., in 1998, compared the results of 26 matched pairs of injuries assessed 12 weeks posteriorly, one group having had the Kleinert regime of rehabilitation and one the Belfast19. Overall 76% of patients had a good or excellent result and there was no di¡erence between the two groups. Kitsis et al., in 1998, reported on 87 patients with zone II injuries of whom 88% had a good or excellent result and the rupture rate
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Figure 5 To show the protective splint applied after £exor tendon repair, the wrist should be in slight £exion, the metacarpophalangeal joints in moderate 45^601 of £exion and the portion behind the ¢ngers should be straight. There should be nothing on the volar side of the ¢ngers distal to the distal palmar crease that may block £exion of the ¢ngers. An anti-grab bar prevents inadvertent use of the hand.
CURRENT ORTHOPAEDICS
operative period. In our unit, all zone II £exor tendon repairs should be performed by a small number of designated surgeons using a standard technique (modi¢ed Kessler suture of 4/0 Ethibond with circumferential 6/0 Prolene) and all patients should be referred immediately to our hand therapists and followed up in our weekly hand clinic. I assessed the results in 53 patients treated over a 4 -year period in our unit and found a 79% incidence of good and excellent results when the above conditions had been met, but this dropped to 9% when the treatment had not followed this standard. The most common cause of a poor result was when a patient had had inadequate rehabilitation. One patient was onearmed and another had psychosis, about which we could do little, but four patients had delayed referral to the hand therapists and 11 patients repeatedly failed to keep appointments in physiotherapy or in the hand clinic and complied poorly with their instructed exercises. It seems, therefore, that at least 70% of patients should achieve a good or excellent result but that this requires very close attention to detail in terms of operative technique, a reliable organization of trauma services in respect of hand injuries and painstaking attention to detail in the post-operative period with frequent follow-up and chasing up of poor attenders. In view of the above-mentioned problems, there has been a tendency recently for patients with these injuries to be referred to the nearest tertiary centre, but this is in itself not without problems as patients may be unwilling or unable to travel long distances regularly for follow-up and treatment. Our experience has been that it should be possible to obtain satisfactory results of treatment of this di⁄cult injury in most large district hospitals.
REFERENCES was 6%22. Karlander et al., in 1993, reported on 85 ¢ngers using a modi¢cation of the Kleinert technique of rehabilitation and found a 70% incidence of good and excellent results23. Overall there was a 6% rupture rate. Elliott et al., in1994, when using the Belfast rehabilitation programme, found 79% of 63 patients having a good or excellent result and a rupture rate of 6%.24 Small et al., in 1989, using the Belfast technique, found 77% of 98 patients had a good or excellent result18. Of the repairs, 9.4% ruptured.Baktir et al., in1996, assessed 88 ¢ngers.25 Thirty-three had the Kleinert method and of these 78% had a good or excellent result.Thirty-eight had the early active mobilization programme and of these 85% had a good or excellent result. Mean grip strength was 84% and 90%, respectively, of normal with two early ruptures in each group. My own experience of following up all patients in our unit with this injury is that the result depends mainly on patient compliance in the post-
1. Kleinert H E, Spokevicius S, Papas N. History of flexor tendon repair. J Hand Surg 1995; 20A: S46–S52. 2. Mayer L. The physiological method of tendon transplantation. Surg Gynaecol Obstet 1916; 22: 182–192. 3. Bunnell S. Surgery of the Hand. Philadelphia: J B Lippincott, 1944. 4. Verdan C E. Primary repair of flexor tendons. J Bone Joint Surg 1960; 42A: 647–656. 5. Schneider L H, Hunter J M, Norris, T R, Nadeau P O. Delayed flexor tendon repair in no man’s land. J Hand Surg 1977; 2: 452–455. 6. Schatzker J, Branemark P. Introvital observation on the microvascular and microcirculation of the tendon. Acta Orthop Scand 1969; 126: (Suppl) 3–23. 7. Skoog T, Persson B. An experimental study of the early healing of tendons. Scand J Plast Reconstr Surg 1954; 13: 384–399. 8. Potenza A D. Effect of associated trauma of healing of divided flexor tendons. Surg Clin North Am 1962; 2: 175–184. 9. Strickland J W. Flexor tendon repair: Indiana method. Indiana Hand Centre Newslett 1993; 1: 1–12. 10. Risper D, Greenwald D, Shumway S, Allan C, Mass D. Efficiency of the flexor tendon pulley system in human cadaver hands. J Hand Surg 1996; 21A: 444–450.
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11. Momose T, Amadio B, Chunfeng Zhao, Zobitz M, Couvreur P, Kai-Nan An. Suture techniques with high breaking strength and low gliding resistance. Acta Orthop Scand 2001; 72: 635–641. 12. Trail I A, Powell E S, Noble J. The mechanical strength of various suture techniques. J Hand Surg 1992; 17B: 89–91. 13. Soumelis S G, McGrouther D A. Retrieval of the retracted flexor tendon. J Hand Surg 1987; 12B: 109–111. 14. Lister G. Indications and techniques for repair of the flexor tendon sheath. Hand Clin 1985; 1: 85–95. 15. McGeorge D D, Stilwell J H. Partial flexor tendon injuries: to repair or not. J Hand Surg 1992; 17B: 176–177. 16. Kleinert H E, Kutz J E, Atasoy E, Stormo A. Primary repair of flexor tendons. Orthop Clin North Am 1973; 4: 865–876. 17. Duran R J, Houser R G, Coleman C R, Postlewaite D S. A preliminary report in the use of controlled passive motion following flexor tendon repair in zones II and III (abstract). J Hand Surg 1976; 1: 79. 18. Small J O, Brennen M D, Colville, J. Early active mobilisation following flexor tendon repair in zone II. J Hand Surg 1989; 14B: 383–391. 19. Peck F H, Bu¨cher C A, Watson J S, Roe A. A comparative study of two methods of controlled mobilisation of flexor tendon repairs in zone II. J Hand Surg 1998; 23B: 41–45.
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20. Harris S B, Harris D, Foster A J, Elliot D. The aetiology of acute rupture of flexor tendon repairs in zone I and II of the fingers during early mobilisation. J Hand Surg 1999; 24B: 275–280. 21. Strickland J W, Glogovac S V. Digital function following flexor tendon repair in zone II: a comparison of immobilization and controlled passive motion techniques. J Hand Surg 1980; 5: 537–543. 22. Kitsis C K, Wade P J F, Krikler S J, Parson, N K, Nichools L K. Controlled active motion following primary flexor tendon repair: a prospective study over nine years. J Hand Surg 1998; 23B: 344–349. 23. Karlander L E, Berggren M, Larrsson M, So¨derberg G, Nylander G. Improved results in zone II flexor tendon injuries with a modified technique of immediate controlled mobilisation. J Hand Surg 1993; 18B: 26–32. 24. Elliot D, Moiemen N S, Flemming A F S, Harris S B, Foster A J. The rupture rate of acute flexor tendon repairs mobilised by the controlled active motion regimen. J Hand Surg. 1994; 19B: 607–612. 25. Baktir A, Tu¨rk C Y, Kabak S, Sahin V, Kardas Y, Flexor tendon repair in zone II followed by early active mobilisation. J Hand Surg 1996; 21B: 624–628.
c 2003 Elsevier Science Ltd. All rights reserved. doi:10.1054/cuor.2002.0305
TRAUMA
The management of £exor tendon injuries in zone II R. H. Helm Doncaster Royal In¢rmary, Armthorpe Road, Doncaster, DN2 5LT, UK
INTRODUCTION Repair of the lacerated ¢nger £exor tendons has long been regarded as one of the most challenging branches of hand surgery. Historically, the results have been unpredictable and only comparatively recently has repair of ¢nger £exor tendons, especially in zone II, been standard practice.The technical di⁄culty of repair, the complexity of the local anatomy and the large number of things which may potentially go wrong, have all contributed to the reputation of this injury as one in which it is di⁄cult to ensure an excellent outcome. Also, £exor tendon injuries in zone II are relatively uncommon, and an ordinary sized district hospital may only see two or three patients a month, if that. In addition to the surgery, it is an injury demanding skilled and attentive post-operative rehabilitation. After this injury, probably more than any other, compliance of the patient is essential and, unfortunately this is not always the case. Historically, for many centuries physicians were in£uenced by the opinion of Galen1 who regarded tendons and nerves as having the same characteristics and he advised that repair of tendons would result in gangrene and convulsions. Interest in £exor tendon repair was revived in the middle of the19th century after Albrecht Von Haller 1 demonstrated that tendons did not have the same irritability as nerves. However, it was not until the early 20th century that Leo Mayer, in 19162, published his paper on tendon transplantation and emphasised the surgical principles of atraumatic tissue handling and preservation of the tendon sheath. These lessons were carried forward by Bunnel who additionally emphasised the need for a sound knowledge of tendon anatomy, appropriate incisions and a bloodless ¢eld. His book,‘Surgery of the Hand’, published in 19443, is regarded as opening the modern era of hand surgery. He was the ¢rst to use the term ‘no man’s land’ and advised against primary tendon repair in zone II. He advised that the correct treatment for tendon repair in zone II was to excise the injured tendon and perform delayed tendon grafting. Correspondence to: RHH.Tel: +44 1302 366666 ext 3916; Fax: +44 1302 792336
The result of Bunnel’s teaching was that, for many decades, most surgeons would not attempt primary tendon repair in zone II. The concept was supported by several leading hand surgeons who reported good results following tendon grafting. It was not until the 1950s and 1960s that Verdan4 popularised the idea of primary repair rather than tendon grafting. He pointed out that not all surgeons could reproduce the good results reported by the leading hand surgeons after tendon grafting and also that primary repair was a less extensive operation. However, even then, most surgeons would only advise primary repair within 2^ 4 h after injury, although this time period gradually extended until Schneider et al., in 19775, advised that delayed repair up to 21 days did not adversely a¡ect the result. However, they found that better results were obtained when the primary repair was within 10 days of injury, and this is the period which most modern hand surgeons would regard as being appropriate. One’s experience is that after 10 days, tendon retraction and adhesion formation make the surgery technically more di⁄cult.
ANATOMY There are ¢ve distinct zones of the £exor tendons (Fig.1), as outlined ¢rst by Verdan.4 Zone I is from the insertion on the distal phalanx as far proximally as the insertion of £exor digitorum super¢cialis in the middle of the middle phalanx. Zone II is the region of the £exor tendon sheath, from the middle of the middle phalanx as far proximally as the distal palmar crease. Zone III is in the palm of the hand between the distal palmar crease and distal edge of the carpal tunnel. Zone IV is the carpal tunnel and zoneV proximal to the carpal tunnel as far proximally as the musculo-tendinous junction. The ¢nger £exor tendons arise from the £exor digitorum super¢cialis and £exor digitorum profundus muscles in the volar forearm. Flexor digitroum profundus is the deepest layer and is usually a single muscle belly for all four ¢ngers, although the index is often a separate muscle belly. It continues as a single tendon into the distal forearm or even the proximal carpal tunnel when it splits into its separate tendons to each ¢nger. The £exor digitorum super¢cials is the middle layer, and consists of four
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annular pulleys are more £imsy structures, designed to collapse as the annular pulleys approximate each other when the ¢nger £exes (Fig. 2). The £exor tendon sheath is covered internally with a well-vascularized synovium which merges with the epitenon proximally and distally to form a closed system. In addition, the £exor tendons are loosely attached to each other and to the £exor tendon sheath with short and long vinculae which bear blood vessels. From the functional point of view, £exor digitorum profundus is the primary £exor of the ¢nger and £exor digitorum super¢cialis contributes some strength of grip and also, in view of its individual action, balances the grip when handling objects of uneven shape and also, together with the intrinsic muscles, balances individual ¢nger motion. Figure 1 The ¢ve zones of the £exor tendons in the ¢ngers and hand, according toVerdan.
separate muscle bellies, each giving rise to a single tendon to each of the four ¢ngers.The most super¢cial layer comprises pronator teres, £exor carpi radialis, palmaris longus and £exor carpi ulnaris. The eight £exor tendons to the ¢ngers lie in the carpal tunnel with the median nerve. In zone III in the palm of the hand, they are anatomically associated with the deep palmar vascular arcade and the lumbrical muscles. The tendons enter the £exor tendon sheath at the level of the distal palmar crease. Flexor digitorum super¢cialis lies anterior to the profundus tendon initially, but then splits in two and decussates around the profundus tendon to lie posterior, with the ¢bres re-attaching to each other on the deep (posterior) aspect of the profundus tendon in the chiasma of Camper before splitting again at the level of the proximal interphalangeal joint to form two £at slips inserting onto the middle phalanx. The profundus tendon itself passes through the decussation of £exor digitorum super¢cialis to continue past the interphalangeal joints to its insertion on the distal phalanx. The £exor tendon sheath has a quite complex anatomy. Its function is to allow the tendons to glide without friction, whilst maintaining the tendons in close apposition to the bones and joints, thus avoiding bowstringing and at the same time supply adequate nutrition and vascularity. To prevent bowstringing the £exor tendon sheath is arranged in a series of strong ¢brous pulleys. There are ¢ve Annular or ‘A’ pulleys with Cruciate or ‘C’ pulleys between them. The most important pulleys are A2 arising from the periosteum of the proximal phalanx and A4 from the periosteum of the middle phalanx. The smaller A1, A3, and A5 pulleys arise from the palmar plates of the metacarpophalangeal joint, proximal interphalangeal joint and distal interphalangeal joint, respectively. The cruciate pulleys which lie between the
TENDON PHYSIOLOGYAND HEAILNG Tendons were generally thought to be avascular structures until the work of Mayer, in 19162, who performed injection studies with coloured gelatin. He demonstrated that tendon had an internal circulation arising from the periosteum at the tendon insertion, from the muscles and also from the vinculae. Several similar studies have been performed since then including the recent work by Schatzker and Branemark in 19626, who demonstrated the microvascular anatomy of the internal circulation of the tendon, in particular, its segmental nature. There are several ‘watersheds’ where the tendon is relatively avascular, such as the region between the two vinculae, and this may have implications for the prognosis of tendon repair. The physiology of tendon healing can be thought of as being a combination of intrinsic and extrinsic processes.
Figure 2 Lateral view of a ¢nger to depictthe components of the £exor tendon sheath.The sturdy annular pulleys (A1, A2, A3, A4 and A5) have the thinner, more pliable, cruciate pulleys between them to allow them to approximate as the ¢nger £exes.
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Intrinsic repair is that derived from the internal biology of the tendon itself whereas extrinsic involves ingress of in£ammatory cells and ¢broblasts from the outside, via adhesions. Early experiments on tendon healing from the1930s to the1950s seem to indicate that the most important aspect of tendon healing was extrinsic. In, 1954, Skoog and Persson7 found no evidence of intrinsic tendon repair and noted that isolating the repair area from the outside greatly impaired tendon healing. However, more recent studies in animals by several authors have demonstrated signi¢cant intrinsic healing potential, with proliferation of epitenon and transformation of resulting tenocytes into tenoblasts which subsequently proliferate and produce collagen. Important work by Potenza8 showed the signi¢cant contribution of tendon handling to the subsequent formation of adhesions, and it is now thought that the technique of tendon repair and handling, etc., in the early studies, may have been the main cause of adhesions, thereby over-emphasizing the importance of extrinsic tendon repair. It is now thought that tendons do have a signi¢cant capacity for intrinsic repair, supported by synovial £uid and the intrinsic vascularity of the tendon. It is therefore of obvious great importance to maximize the intrinsic process whilst at the same time minimizing adhesion formation. There is no signi¢cant experimental evidence that non-steroidal or other drugs a¡ect the process of tendon repair. It is also important to consider the strength of the repair when planning post-operative rehabilitation. Important research by Strickland in 19939 showed that the strength of a £exor tendon repair would range from 1800g for a two-strand repair to 5400g for a sixstrand repair (vide infra) and this could be also increased by peripheral epitenon sutures. He further showed that the strength of repair would fall by 50% 1 week after surgery and this would gradually increase over the next 6 weeks. This has to be compared with the tensile forces generated at the site of tendon repair, which can be 500g for passive movement up to 9000g for tip pinch of the index ¢nger. As mentioned previously, the ¢bro-osseous pulleys are vital for normal tendon function. A recent paper by Rispler et al.,10 dealt with the e¡ect of sectioning the various pulleys sequentially.They found that the minor (A1, A3 and A5) pulleys could be sectioned without loss of function. The A2 pulley alone could be sectioned, reducing the excursion e⁄ciency to 94%, but complete loss of the A2 pulley, or the A2 and A4 pulley combined, would reduce excursion e⁄ciency to 82%. All these experimental studies, however, have to be taken in context.The in vivo human situation may be quite di¡erent. The tensile forces generated in a tendon may vary with the degree of post-operative swelling and in£ammation. Also unpredictable degrees of force may be generated at times, for instance when a patient is asleep or when patient compliance is poor.
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CLINICAL ASSESSMENTAND MANANGEMENT As with any other injured patient, assessment and management should be along established protocols. However, in practice, £exor tendon lacerations are nearly always isolated injuries. A full medical history should be obtained from the patient, including smoking status, drug history and allergies, etc. A detailed history of the mechanism of injury should also be taken, paying particular attention to possible contamination of the wound, especially with soil or similar material, the lacerating instrument and whether it was sharp, blunt or ragged, and the position of the ¢nger at the time of impact, as lacerations sustained with the ¢nger £exed will result in the distal cut end being at a more distal level than the skin injury. The diagnosis of a lacerated £exor tendon is not usually di⁄cult and in most patients can be made from the abnormal posture of the ¢nger, i.e. the ¢nger with a divide will adopt a straighter position. The ¢nger should be carefully examined to determine the nature of the wound and whether it is a clean incised wound or a contaminated or ragged wound, and whether or not there is evidence of soft tissue crushing or bursting. The distal neurovascular status should also be assessed. Vascular impairment could be suspected if there is distal pallor or duskiness, and slowness of capillary re¢ll. Sensation distally should be assessed by simply ascertaining whether light touch sensation is normal or abnormal. More sophisticated sensory examination including twopoint discrimination would not be appropriate or reliable in the emergency setting. It should also be borne in mind that sensation after nerve injury can often be surprisingly normal, at least on the ¢rst day or two after injury. In cases of penetrating wounds and apparently normal tendon function, one should bear in mind the possibility of a partial laceration of the tendon. Assessment should be made by performing the tendon tests against resistance, and if resistance causes pain, then a partial tendon injury should be suspected. Flexor digitorum profundus is examined by active £exion of the distal interphalangeal joint and £exor digitorum super¢cialis is tested by immobilizing the other digits in full extension to prevent profundus function and seeing if the digit will £ex at the proximal interphalangeal joint level yet leaving the terminal joint lax.This latter test needs to be done carefully in the index, which may have an independent profundus muscle belly. When the diagnosis is made, a decision is required about primary repair of the £exor tendon. As mentioned above, there is no reason to perform this as an emergency, but the operation should be performed in daylight hours, preferably on an established trauma list, by a surgeon experienced in the technique. This can be done safely at any time up to a week or even 10 days after injury. Contra-indications to primary £exor tendon repair
THE MANAGEMENT OF FLEXOR TENDON INJURIES IN ZONE II
include contamination of the wound, when the wound cannot be converted into a safe clean wound, signi¢cant skin loss and severe multiple soft tissue injuries. Concomitant fractures of the ¢nger are not necessarily a contra-indication provided that the fractures can be suf¢ciently stabilised to allow some early movement of the ¢nger and neurovascular injuries also are not a contraindication, but it should be appreciated that the results may not be as good. The patient should be thoroughly counselled before surgery about the nature of the injury and the fact that surgery can be di⁄cult and the results sometimes unpredictable. They should be particularly counselled about the prolonged post-operative rehabilitation and the importance of strict compliance with post-operative therapy. This is particularly important in cases where only the £exor digitorum profundus is injured, as a patient may decide to accept the disability caused by loss of active distal interpharangeal joint £exion rather than undergo a programme of surgery and rehabilitation which may involve 3 months or more o¡ work.
SURGICALTECHNIQUE The goals of surgery are to make a strong, reliable repair of the tendon causing minimal tissue trauma by avoiding as far as possible handling of the surface of the tendon. The operation should result in a tendon repair which is smooth and neat and not too bulky to interfere with tendon gliding. It is essential to preserve the A2 and A4 pulleys. There are various suture techniques (Fig. 3) but the commonest in use is probably the modi¢ed Kessler suture with a circumferential continuous epitenon repair. In general terms, multi-strand repair techniques give increased strength but can increase the bulk of the tendon repair and also caused increased intra-tendinous disruption of tendon architecture and blood supply compared with two-strand repair techniques. The suture material should be non-absorbable and braided. I would advise against using Prolene because it runs too easily through the tissues and can allow gap formation to occur.The epitenon circular circumferential repair should normally be done with a ¢ne Prolene or nylon.When the distal slips of £exor digitorum super¢cialis are to be repaired, then a simple horizontal mattress suture usually su⁄ces. Considerable research has been undertaken looking into the mechanical strength of the di¡erent repair techniques. Momose et al.,11 found that double Kessler, doubleTsuge cruciate and Becker repairs were stronger than modi¢ed Kessler and Tsuge repairs. Trail et al.12 tested ¢ve techniques and found that the modi¢ed Kessler with circumferential suture required the greatest load to produce gapping but the Becker and Savage repairs withstood the highest load before failure.
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Figure 3 Schematic drawings of di¡erent suture techniques: (A) modi¢ed Kessler, (B) Tsuge, (C) double modi¢ed Kessler, (D) double modi¢ed Tsuge, (E) Savage, (F) Becker.
At the time of surgery, the wound is extended to produce a zig ^zag incision. After identifying and protecting the neurovascular structures the tendon sheath is inspected. The proximal tendons, especially £exor digitorum profundus, will have retracted proximally and will need to be retrieved. It is important not to blindly grasp with forceps as this may cause tendon damage. Sometimes the tendon can be retrieved by inserting a skin hook, rotating through 90o degree etc and gently pulling distally. Often the tendon has retracted into the palm and I can recommend the technique described by Sourmelis and McGrouther13. This involves making a small incision at the level of the distal palmar crease to identify the tendons, passing a very ¢ne plastic catheter from proximal to distal adjacent to the tendons until it emerges into the distal wound, suturing the catheter to the tendon proximally, pulling distally on the catheter to deliver the tendon into the wound, inserting a core suture, pulling the catheter backwards and freeing it from the tendon to remove it, then ¢nally pulling on the core suture to deliver the tendon back into the wound.When the tendon is delivered into the wound it can be secured using a trans¢xing hypodermic needle proximal to the site of repair. When repairing the tendon, it is essential, as mentioned above, to preserve the A2 and A4 pulleys. All surgeons performing this procedure should be familiar with the de¢nitive article by Graham Lister who, in198514, described his technique of L-shaped windows and combined window repair. When opening windows between the annular pulley, these should be L-shaped to facilitate passing the tendon under the strong non-elastic annular pulley, otherwise the bulky tendon can get snagged on the edge of the annular pulley (Fig. 4). An L-shaped window is made proximal to the annular pulley to be preserved, commonly the A4 pulley. The
438
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Advocates of tendon sheath repair claim that repairing the tendon increases the synovial £uid nutrition of the tendon repair as well as facilitating gliding and avoiding the problem of triggering of the repair on the pulley. However, it has not been demonstrated clinically that tendon sheath repair improves the results of surgery. Also, I ¢nd repair of the L-shaped windows can be technically di⁄cult at times, so my practice is to leave them unrepaired. Figure 4 Diagram to illustrate the L-shaped windows made and below the £exor tendon pulley to be preserved. In a combined distal window repair the sutures will be passed through the A4 pulley and then placed in the distal tendon.
¢nger is then £exed to see how much distal tendon emerges into the window (it is always possible to deliver su⁄cient proximal tendon into the window). It is necessary to have access to 10 mm of tendon to insert a core suture and 5 mm to apply the epitendinous circumferential suture. If 10 mm of distal tendon will deliver into the wound by £exion of the distal interphalangeal joint then a window repair proximal to A4 can be made. If only 5^10 mm can be delivered, this is insu⁄cient tendon length to insert a core suture, so the distal end has to be delivered distal to the A4 pulley through a separate L-shaped window, the core suture inserted into the distal end, the suture ends and needle passed through the A4 pulley to the proximal window, the suture pulled through whilst £exing the distal interphalangeal joint to deliver the tendon into the proximal window where the core suture can be tied and there will then be enough room for the circumferential suture. This is called a proximal combined repair because two windows are combined for the core suture and the circumferential suture is inserted in the proximal window. If less than 5 mm of distal tendon can be delivered into the wound, then this is not even enough for a circumferential suture, so it is then necessary to insert the core suture into the proximal tendon in the proximal window, pass the suture material and needle through A4 pulley, deliver the proximal end into the distal window by £exing both proximal and distal interphalangeal joints, and then completing the core suture and circumferential suture. This can be technically quite awkward with the ¢nger £exed.This is known as a distal combined repair. Sometimes it is found that there is a partial laceration to the tendon. It has been shown that, when the laceration is less than 60%, then the results of leaving it alone are better than the results of repair15. If, however, the laceration is nearly complete, then the tendon should be repaired in the usual way as a late rupture of the tendon is more di⁄cult to deal with than a primary repair.There is a debate about whether or not the £exor tendon sheath should be repaired over the £exor tendon repair.
POST-OPERATIVE MANAGEMENT The quality of post-operative management and rehabilitation and the co-operation of the patient are probably more important after £exor tendon repair in the ¢nger than in almost any other branch of surgery. The aim of post-operative treatment is to allow controlled gliding of the tendons relative to each other and to the tendon sheath in order to avoid adhesion formation but at the same time to also avoid tendon rupture. It is also important to maintain the passive range of motion in the joints to avoid the development of a ¢xed £exion deformity in the interphalangeal joints. The three commonest rehabilitation programmes in common use today are those described by Kleinert and colleagues16, Duran and Houser17 and the Belfast group18. Kleinert’s method involves the use of rubber bands attached from the ends of the ¢ngers to the bandage on the volar side of the forearm. This produces £exion of the ¢nger by contraction of the elastic band rather than by muscle contraction, which may produce tension at the tendon repair site. Extension against the pull of the elastic allows the £exor muscle to relax. It is hoped that the reduced tension in the £exor muscle will reduce the rate of post-operative rupture. There have been several modi¢cations of the technique published, including different types of splints and also pulleys at the level of the palm to increase mechanical advantage of the elastic. This is a very popular and successful method but a common mistake is to use elastic which is too strong, and this can, in my experience, be associated with the development of £exion contractures. The method described by Duran in197617 concentrates on passive £exion and extension movements of the ¢ngers only and avoids £exion. He reported a rupture rate of 13% in 30 patients. In 1989, Small et al. of Belfast18 reported their experience of controlled early active motion in the rehabilitation of these injuries. All of these programmes involve detailed recommendations about exactly what exercises the patient should be doing at a particular time, and how frequently. My own experience is that the Kleinert and the Belfast methods produce similar results and therefore I favour the Belfast method in view of its simplicity. Peck et al.,19 reported a prospective trial with patients treated either with the Kleinert
THE MANAGEMENT OF FLEXOR TENDON INJURIES IN ZONE II
method or the Belfast method, with 26 patients in each group, and found similar outcomes with the exception of a signi¢cantly lower rate of rupture (7.7%) in the Kleinert group than in the active motion group (46%). However, the report does not say that the patients were randomised. Whichever method of rehabilitation is used, it is essential to review the patient frequently in a dedicated clinic in association with the responsible hand therapist. Review should be at least weekly in the ¢rst few weeks. The rate of progress of the patient should be correlated with the progress of therapy. For instance, a patient who rapidly regains a normal active and passive range of motion is at high risk of rupture and should be protected in a splint for longer, whereas a patient with signi¢cant swelling and sti¡ness of the ¢nger is at a higher risk of hand sti¡ness, and should be allowed out of the splint sooner.
Complications There are several complications which can ensue. The three commonest complications are ¢nger sti¡ness because of adhesion formation, ¢xed £exion contracture of the interphalangeal joints and tendon rupture.Tendon adherence can be diagnosed when the passive range of motion is greater than the active range, and the tendon is still intact.This is managed by active and passive range of motion exercises as well as massage and wound management. In the longer term, if a tendon is not functioning, then surgery can be considered, but not for at least 6 months, or preferably longer, to allow the tendon to regain mechanical strength. Brie£y, tenolysis may be possible to improve tendon gliding, but more commonly the tendon is hopelessly stuck with a mass of adhesions and the only surgical option is to excise the tendon and perform two-stage £exor tendon grafting. Fixed £exion contracture of the joints can be a common problem as the ¢nger £exors are stronger than the ¢nger extensors and the natural posture of the ¢nger is £exion of the interphalangeal joints. For these reasons, £exion contractures can swiftly occur and should be prevented by daily exercises to passively extend the interphalangeal joints, while keeping the metacarpophalangeal joints £exed. Once established, £exion contractures of the interphalangeal joints are extremely di⁄cult to treat and great care should be taken to prevent their occurrence. Rupture of the tendon repair can be a sudden event and a patient can complain that something went in the ¢nger, followed by lack of active £exion, but sometimes can be a gradual process as the gap formation at the repair site develops. Diagnosis can sometimes be di⁄cult in a swollen ¢nger and, if available, ultrasound or MRI scanning can be very useful.The usual course of action is to recommend immediate exploration
439
of the ¢nger with a view to revision of the repair, but if a profundus tendon only is a¡ected with intact super¢cialis, it may be preferable in some circumstances to accept the situation.With all this, prevention is better than cure and patients need to be constantly reminded that they should not do any more than the recommended exercise. For this reason I routinely add an ‘anti-grab’ bar to the protective splint (Fig. 5). An important study by Harris et al.,20 reported a rupture rate of 4% in 397 ¢ngers with zone II injuries and of these 50% were due to acts of stupidity on the part of the patient, including 11 who ruptured whilst using the hand for a variety of tasks, including one patient who was lifting a wardrobe. Other complications include wound infection, skin £ap necrosis and regional pain syndromes.
RESULTS OF SURGERY The percentage of good results of £exor tendon repair in zone II have gradually increased as the years have gone by and presently most series report the percentage of good or excellence results as being in the range of 70 ^90%. The di⁄culty with comparing results is that there is no universally accepted assessment system. Many of the early papers have little in the way of objective measurements. Recently, however, the two main scoring or assessment systems are those described by Lister and Strickland. Lister’s14 method involves the assessment of £exion and extension de¢cits. Flexion de¢cit is the pulp to palm distance and extension de¢cit is the sum of the extension loss at the metacarpophalangeal and interphalangeal joints. An excellent result is a ¢nger which £exes to within 1 cm of the distal palmar crease and has less than 151 combined extension de¢cit and a poor result is a ¢nger which cannot £ex to within 3 cm from the distal palmar crease or has an extension de¢cit of over 501.The assessment method described by Stickland21, which in my opinion is more di⁄cult to use, involves calculating the percentage of normal active PIP and DIP joint movement by summing the active PIPJ and DIPJ £exion, substracting the extension lag and expressing this as a percentage of 1751. Thus an excellent result has a ¢nger with 75^100% of normal active movement and a poor result has a 0 ^24% of normal active movement. There have been several papers in the last decade reporting the results of £exor tendon repair in zone II, usually after introducing some modi¢cation of technique or rehabilitation. Peck et al., in 1998, compared the results of 26 matched pairs of injuries assessed 12 weeks posteriorly, one group having had the Kleinert regime of rehabilitation and one the Belfast19. Overall 76% of patients had a good or excellent result and there was no di¡erence between the two groups. Kitsis et al., in 1998, reported on 87 patients with zone II injuries of whom 88% had a good or excellent result and the rupture rate
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Figure 5 To show the protective splint applied after £exor tendon repair, the wrist should be in slight £exion, the metacarpophalangeal joints in moderate 45^601 of £exion and the portion behind the ¢ngers should be straight. There should be nothing on the volar side of the ¢ngers distal to the distal palmar crease that may block £exion of the ¢ngers. An anti-grab bar prevents inadvertent use of the hand.
CURRENT ORTHOPAEDICS
operative period. In our unit, all zone II £exor tendon repairs should be performed by a small number of designated surgeons using a standard technique (modi¢ed Kessler suture of 4/0 Ethibond with circumferential 6/0 Prolene) and all patients should be referred immediately to our hand therapists and followed up in our weekly hand clinic. I assessed the results in 53 patients treated over a 4 -year period in our unit and found a 79% incidence of good and excellent results when the above conditions had been met, but this dropped to 9% when the treatment had not followed this standard. The most common cause of a poor result was when a patient had had inadequate rehabilitation. One patient was onearmed and another had psychosis, about which we could do little, but four patients had delayed referral to the hand therapists and 11 patients repeatedly failed to keep appointments in physiotherapy or in the hand clinic and complied poorly with their instructed exercises. It seems, therefore, that at least 70% of patients should achieve a good or excellent result but that this requires very close attention to detail in terms of operative technique, a reliable organization of trauma services in respect of hand injuries and painstaking attention to detail in the post-operative period with frequent follow-up and chasing up of poor attenders. In view of the above-mentioned problems, there has been a tendency recently for patients with these injuries to be referred to the nearest tertiary centre, but this is in itself not without problems as patients may be unwilling or unable to travel long distances regularly for follow-up and treatment. Our experience has been that it should be possible to obtain satisfactory results of treatment of this di⁄cult injury in most large district hospitals.
REFERENCES was 6%22. Karlander et al., in 1993, reported on 85 ¢ngers using a modi¢cation of the Kleinert technique of rehabilitation and found a 70% incidence of good and excellent results23. Overall there was a 6% rupture rate. Elliott et al., in1994, when using the Belfast rehabilitation programme, found 79% of 63 patients having a good or excellent result and a rupture rate of 6%.24 Small et al., in 1989, using the Belfast technique, found 77% of 98 patients had a good or excellent result18. Of the repairs, 9.4% ruptured.Baktir et al., in1996, assessed 88 ¢ngers.25 Thirty-three had the Kleinert method and of these 78% had a good or excellent result.Thirty-eight had the early active mobilization programme and of these 85% had a good or excellent result. Mean grip strength was 84% and 90%, respectively, of normal with two early ruptures in each group. My own experience of following up all patients in our unit with this injury is that the result depends mainly on patient compliance in the post-
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THE MANAGEMENT OF FLEXOR TENDON INJURIES IN ZONE II
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20. Harris S B, Harris D, Foster A J, Elliot D. The aetiology of acute rupture of flexor tendon repairs in zone I and II of the fingers during early mobilisation. J Hand Surg 1999; 24B: 275–280. 21. Strickland J W, Glogovac S V. Digital function following flexor tendon repair in zone II: a comparison of immobilization and controlled passive motion techniques. J Hand Surg 1980; 5: 537–543. 22. Kitsis C K, Wade P J F, Krikler S J, Parson, N K, Nichools L K. Controlled active motion following primary flexor tendon repair: a prospective study over nine years. J Hand Surg 1998; 23B: 344–349. 23. Karlander L E, Berggren M, Larrsson M, So¨derberg G, Nylander G. Improved results in zone II flexor tendon injuries with a modified technique of immediate controlled mobilisation. J Hand Surg 1993; 18B: 26–32. 24. Elliot D, Moiemen N S, Flemming A F S, Harris S B, Foster A J. The rupture rate of acute flexor tendon repairs mobilised by the controlled active motion regimen. J Hand Surg. 1994; 19B: 607–612. 25. Baktir A, Tu¨rk C Y, Kabak S, Sahin V, Kardas Y, Flexor tendon repair in zone II followed by early active mobilisation. J Hand Surg 1996; 21B: 624–628.