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Crossover toe deformity
CROSSOVER TOE DEFORMITY MICHAEL GOLDBERGER, MD, and JEFFREY KANN, MD
Second metatarsophalangeal joint pathology is a frequent cause of forefoot pain. The final common pathway is loss of the static stabilizers of the joint. Early in the course of the disease, patients will demonstrate provocative instability and lager will display fixed hyperextension, Surgical treatment is initially directed at releasing contracted soft tissues and supplementing the repair with a dynamic flexor to extensor transfer. Once a fixed deformity is present, bony procedures should be added. KEY WORDS: foot, hammer toe, treatment, surgery
Disorders of the second toe metatarsophalangeal (MTP) joint are common causes of pain in patients with metatarsalgia. Pain often iis a manifestation of either altered biomechanics of the foot or, less commonly, idiopathic inflammation of the joint. The chronic mechanical overload or inflammation of the joint leads to progressive elongation of the plantar plate and collateral ligaments with subsequent instability of the joint. When there are other accompanying mechanical abnormalities, such as a large hallux valgus deformity, a crossover toe can develop. To correct the lesser toe deformity, the hallux valgus will also need to be addressed. There have been a number of different treatment modalities used to solve the difficult problem of an unstable second MTP joint. Central to the management of the deformity is understanding the dynamic and static soft tissue stabilizers of the MTP joints. The primary extensor of the MTP joint is the extensor digitorum longus (EDL). The EDL crosses both the MTP and proximal interphalangeal (PIP) joints to insert onto the distal phalanx. It has a fibroaponeurotic sling, which connects to the plantar plate. With longstanding hyperextension at the MTP joint, the extensor hallucis Iongus (EHL) tendon can become contracted and act to resist reduction of the joint. The extrinsic flexor tendons, flexor digitorum longus (FDL), and flexor digitorum brevis (FDB) insert into the distal and middle phalanx, respectivelN and have little influence on MTP stability. It is important surgical anatomy to note that on the plantar aspect of the MTP joint, the FDL is found passing between the two slips of the FDB tendon. The primary dynamic stabilizers of the MTP joint are the intrinsic muscles. There are two dorsal interossei, which take origin from the metatarsal shaft and insert onto the medial and lateral aspect of the proximal phalanx. The lumbricals take origin from the FDL and insert into the extensor hood. Both the interossei and lumbrical tendons course plantar to the axis of rotation of the MTP joint, thus function to flex this joint, in addition to extending the more distal interphalangeal
From Tri-County Orthopedic/Sports Medicine, Mordstown, NJ; and Tristate Orthopaedics, Pittsburgh, PA. Address reprint requests to Jeffrey Kann, MD, Tristate Orthopaedics, 5900 Corporate Drive, Su~ite200, Pittsburgh, PA 15237. Copyright © 1999 by W.B. Saunders Company 1048-6666/99/0901-0003510.00/0
joints. The primary static stabilizers of the MTP joint are the plantar plate, collateral ligaments, and joint capsule? The plantar plate has a stronger attachment to the base of the proximal phalanx than it does to the metatarsal neck. Therefore, it is not uncommon to find attritional tears off of the metatarsal attachment. The dorsal capsule functions as a secondary static stabilizer of the MTP joint. In summary, maintaining dynamic stability of the MTP joint are the intrinsic muscles and statically the plantar plate, collateral ligaments, and dorsal capsule. The etiology of instability of the second MTP joint is thought to be multifactorial. A simplified scheme is to consider either a mechanical or an inflammatory process as the cause of second MTP joint instability. Mechanical causes may include an acute traumatic event injuring the supporting ligaments and joint capsule. These patients present with a painful joint, which displays instability by provocative testing. A long second ray, as well high-heeled footwear, has often been implicated by causing repetitive trauma to the toe as it contacts the end of the toe box in a shoe. This will cause an extension moment to be placed on the MTP joint. Over time there will be stretching of the static stabilizers resulting in instability. Another common cause of mechanical instability can be related to pressure from the great toe deviating into valgus and underlapping the second toe thus forcing the MTP joint into extension. Increased load transmission to the second metatarsal in cases of hallux valgus may also be contributory. Inflammatory conditions have also been described. An isolated synovitis at the second MTP joint has been described to occur idiopathicallN as well as in inflammatory arthritides. The inflammation causes destruction of the joint capsule and subsequent stretching of the ligamentous stabilizers of the joint. Once there is damage to the static stabilizers of the MTP joint, subluxation tends to progress. As the MTP joint dorsally displaces, the dynamic stabilizers sublux dorsal to the midaxis of the MTP joint and act to extend it and flex the PIP joint. There is a continuum of progression from one of only provocative instability to frank dislocation. The pathologic changes associated with a crossover toe occur in a predictable fashion once there is loss of the static stabilizers. The plantar plate attrionally stretches and can rupture from its origin on the plantar metatarsal neck, which allows for subsequent dorsal subluxation. Dorsally,
Operative Techniques in Orthopaedics, Vol 9, No 1 (January), 1999: pp 45-50
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there is contracture of the dorsal capsule and EDL tendon, as well as the medial collateral ligament. With medial migration of the toe, the lateral collateral ligament becomes incompetent. Lastly, with attachments to the plantar plate, the fat pad also migrates in a distal direction resulting in the uncovering of the metatarsal head and the predictable callus formation. The physical examination focuses on the forefoot, however, a brief inspection of the hindfoot is required to assess for potential ankle or tendoachilles contracture and midfoot cavus deformities with forefoot equinus. Both of these conditions can lead to mechanical overload at the MTP joints. The forefoot is examined both in the weight-bearing and nonweight-bearing position. The first ray is assessed for hypermobility, as well as a hallux valgus deformity. In both of these first ray conditions, the load borne at the second MTP joint is increased. The second toe is inspected for its length as compared with the other toes, as well as looking for gross swelling and malalignment of the toe (Fig 1). Soft corns between the toes, as well as skin ulceration is noted. The plantar aspect of the foot is examined for either varus or valgus forefoot alignment, as well as isolated plantar callosities. Areas of specific tenderness should be sought. Tenderness lateral to the metatarsal head may be an interdigital neuroma or just irritation of the digital nerve adjacent to the distended capsule of an inflamed MTP joint. This can be difficult to differentiate by physical examination. However, instability at the second MTP joint is much more common than a second web space neuroma. Next, the examiner assesses for range of motion of the MTP, PIP, and distal interphalangeal (DIP) joints. It is important to determine if the contractures at the joints are fixed or flexible. A flexible contracture will change with ankle motion. Next, stability of the joint is checked by the anterior draw test at the MTP joint. The examiner manipulates the proximal phalanx in a plantar to dorsal fashion while stabilizing the metatarsal. The object of this test is to sublux the proximal phalanx on the metatarsal head. A
Fig 1. Preoperative photo showing dorsomedial deviation of the second toe.
46
Fig 2. Anterior draw test. Note the dimple on the skin.
skin dimple may be seen over the MTP joint during the maneuver (Fig 2). Significant instability by this test signifies incompetence of the plantar plate and collateral ligaments. The anterior draw may reproduce the patient's symptoms, as well as produce crepitus. Lastly, the remaining lateral lesser toes are examined. A useful clinical test is to have the patient stand on a step with the edge of the step at the level of the metatarsal heads. The examiner can now assess for true MTP tissue contracture. Weight-bearing radiographs of the foot are obtained to evaluate forefoot alignment. Specifically, the second MTP joint is assessed for arthritis, joint congruencN and to confirm the presence of a long metatarsal. The presence of Freiberg's infraction can also be seen. Thickening of the metatarsal shaft evidences chronic overload at the second ray. Lateral inclination of the joint, which is normally 7°, can also be determined.
MANAGEMENT When either a mechanical abnormality or an inflamed joint is discovered early in its course, the joint can be managed conservatively. The inflamed joint can initially be managed in well-fitting supportive shoe wear. A rigid sole is recommended to decrease flexion of the toe box. Taping of the toe or over the counter toe splints can stabilize the MTP joint while the inflammation is brought under control. A metatarsal pad placed proximal to the metatarsal head may alleviate pain by unloading the joint. Physical therapy is used when significant tendoachilles contracture is present. Nonsteroidal antiinflammatory medication may alleviate pain and inflammation at the joint. Lastly, a steroid injection can be tried to settle the inflammation. We do not recommend repeat injections, as they may further aggravate MTP joint capsular distention. In patients who have a large underlapping hallux and a dorsally dislocated second toe, a depth shoe can be used to accommodate the deformity. If conservative measures fail the joint should be operatively reduced and stabilized. The reduction of the joint involves sequential soft tissue releases. 2 One must also address the distal joints and any associated hallux valgus deformity. With mild subluxation, the collateral ligaments and dorsal capsular are released and the extensor tendon is
GOLDBERGER AND KANN
lengthened. If there is still resistance to reduction of the joint, then the plantar capsule is released. To maintain stability of the joint, a flexor to extensor transfer is added to the procedure. When there is medial or lateral deviation of the joint, the contracted capsule and collateral ligaments are released and the: opposite capsule and collateral ligaments are tightened. In addition, the flexor transfer can be tightened on the weak side. When there is dislocation of the MTP joint, and after soft tissue release as previously mentioned are performed, a bony decompression is indicated if the joint remains unreducable. The bony decompression in this case ,can be a distal metatarsal DuVries arthroplasty. Another approach to the chronically dislocated and arthritic joint is to perform a concomitant proximal phalanx excisional arthroplasty. In all cases, once the toe is realigned, the MTP joint is stabilized with a K-wire. Lastly, in the case of a large deformity and the patient's only complaint is pain on top of the second PIP joint with shoe wear, the elderly patient may opt for a second toe amputation as opposed to a major forefoot reconstruction. However, this will inevitably lead to worsening of any hallux valgus deformity if the entire toe is removed.
SURGICAL TECHNIQUE Dorsal Capsulotomy At our institution, we prefer regional popliteal block anesthesia, however, ankle block should suffice. A wellpadded tourniquet is used. The leg is then prepped and draped in the usual fashion. The foot is exsanguinated and the tourniquet is elevated. A dorsal incision centered over the joint 2 to 4 cm is length is used. A full thickness flap down to the extensor tendon is created. The extensor tendon is then lengthened in a standard Z-fashion. By flexing and extending the toe, an attempt is made to relocate the MTP. Next, the dorsal capsule is perforated and circumferentialy released. With the base of the proximal phalanx in view subperiosteally, the medial and collateral ligaments are released along with the origin of the lumbricals. When there is still resistance to reduction, the plantar plate is released off of the metatarsal neck. This is accomplished by plantar flexing the proximal phalanx to expose the metatarsal head, and the plantar plate adhesions are sharply released off the neck of the material.
Flexor to Extensor Transfer The purpose of this procedure is to stabilize the proximal phalanx. In theorN the FDL tendon transfer dynamically stabilizes the MTP joint by replacing the function of the intrinsics. The incision is begun just proximal to the MTP joint and carried distally to the level of the midproximal phalanx (Fig3). Soft tissue releases are performed as required to achieve reduction of the joint (Fig 4). Attention is then turned to the plantar aspect of the toe. A transverse incision is made at the level of the proximal flexion crease (Fig 5). The soft tissues are bluntly spread to the level of the flexor tendon sheath and pulley. Careful attention is paid to protect the neurovascular structures, which lie just medial and lateral to the sheath. The sheath is then sharply split longitudinallN so not to injure the tendons below. Care now is taken to identify the FDL tendon. At this level, the FDL runs centrally between the two slips of the FDB tendon. A curved mosquito clamp is passed beneath the FDL tendon. The DIP joint is flexed and extended to confirm that the correct tendon is chosen. Next, the FDL is released percutaneously from its insertion on the distal phalanx (Fig 6). The mosquito clamp pulls the FDL tendon out of the wound. Using a small mosquito clamp on either side of the FDL tendon, the tendon is split down the center, inline with the central raphe to create two tails (Fig 7). Attention is now directed to the dorsal aspect of second toe. At the level of the middiaphysis of the proximal phalanx, a curved mosquito is passed deep to the extensor mechanism along the sides of the proximal phalanx to exit on the plantar aspect of the wound (Fig 8). Each tail is then pulled dorsal to the midportion of the proximal phalanx (Fig 9). With the MTP joint held reduced the transfer is tensioned with the ankle joint neutral and the proximal phalanx is plantarflexed 10 ° and the two ends are crossed and sutured to the EDL and themselves with nonabsorbable suture (Fig 10). A K-wire is the passed in a retrograde fashion to protect the repair (Fig 11).
Metatarsophalangeal Joint Arthroplasty Metatarsophalangeal joint arthroplasty is indicated when there is chronic dislocation of the joint or when the joint is arthritic. Metatarsal head sculpting is favored over partial
Capsular Reefing
Reefing of the redundant capsule is indicated when the toe has significant medial or lateral deviation. The soft tissue release is performed as described above with special attention to release the contracted capsular side. Next, attention is turned to the attenuated side. The capsule on this side is opened vertically. An ellipse of tissue is removed in line with the capsulotomy. With the toe held in an overcorrected position, a figure of eight suture is passed in a proximoplantar to a distodorsal fashion. This effectively tightens the collateral ligament.
CROSSOVERTOE DEFORMITY
Fig 3. Dorsal incision medial to long extensor tendon.
47
Fig 6. FDL tendon has been identified and now percutaneously released, Fig 4. Dorsomedial capsule and medial collateral ligament of the MTP joint has been released.
proximal phalangectomy when the second metatarsal is exceedingly long. The approach to the joint is as described above with appropriate soft tissue releases. Because the dislocation is long-standing, the medial and lateral capsular releases should be complete. The distal metatarsal head is exposed and the amount of bony resection is based on the amount of overlap of the proximal phalanx on the metatarsal head. Usually 3 to 4 m m of distal metatarsal head is resected. Once the osteotomy is completed, the metatarsal head is sculpted on the dorsal and plantar condyles. A cannulated cup shaped reamer can be used to accomplish the sculpting, as well. After bony decompression, the joint should be reducible with about 3 m m between the sculpted metatarsal head and proximal phalanx. For added stability, a flexor to extensor transfer can be added.
Partial Proximal Phalangectomy The indications for this procedure are similar to the metatarsal head arthroplasty. The surgical technique is identical except (1) 3 to 4 m m of the base of the proximal phalanx is excised and (2) in a long-standing dislocation, additional bone from the base of the proximal phalanx may be removed to achieve reduction of the joint.
Fig 5. Plantar incisions.
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The difference between decompressing the MTP joint at the metatarsal head or base of the proximal phalanx should be considered. Excising the distal metatarsal head will decompress the joint and shorten the metatarsal, which is helpful in patients who feel pressure during push-off. This procedure also will not clinically shorten the length of the toe itself. The disadvantage, however, is that it can often lead to stiffness at the MTP joint, making extension of the toe painful.
K-Wire Technique We recommend retrograde placement of a K-wire to stabilize the MTP joint while the soft tissue reconstruction heals. It is important to realize that the wire is not meant to correct deformity. After bony resection or before suturing the tendon transfer, the proximal phalanx is plantarflexed and a 0.45 K-wire is placed in the center of the base of the proximal phalanx. It is the driven through the phalanges to exit 2 to 3 m m plantar to the nail bed centrally in the toe. Next, the MTP joint is held reduced and the K-wire is drilled into the proximal metatarsal shaft. The wire usually is left out the skin and removed at the 4-week visit.
Fig 7. FDL tendon is split.
GOLDBERGERAND KANN
Fig 8. A hemostat is passed from the dorsal wound to retrieve the split tendon in the plantar wound.
Fig 10. With toe held 10 ° to 20 ° of plantarflexion, the two ends of the FDL tendon are crossed and sutured to themselves and the extensor mechanism.
Soft Tissue Considerations If the toe has been contracted for a long period of time, one must be concerned with straightening of the digit, as it may induce vascular compromise. When the procedure is completed, the tourniquet should be deflated and the toe vascularity is assessed. If any question exists, the K-wire should be removed and allow shortening of the toe. In the extreme case and during revision surgery, z-plasty of skin should be considered.
DISCUSSION Thompson and Deland s reported on 13 patients with second toe MTP instability. Eleven of the patients had a hallux valgus deformity, and six of these patients presented with a crossover toe. The patients were surgically treated with soft tissue procedures including a flexor to extensor transfer. They noted that the joint stability is a result of stiffness as opposed to a functioning dynamic transfer. Gazdag and Cracchiolo4 reported on 20 feet, which they treated with a flexor to extensor transfer. They noted that
13 of the feet had an excellent result. Seven patients had a fair result, but only reported mild discomfort at the joint. This points to the inconsistent results, which may be achieved with flexor to extensor transfers. Counseling of patients is necessary to achieve satisfactory results. When the joint is arthritic, soft tissue releases should be combined with bony decompression. Stability of the joint in these cases is maintained by scar tissue. The patients should have a painless joint that passively extends during push-off. Second toe instability can result from several different mechanical or inflammatory etiologies. The end result is loss of competence of the static stabilizers of the joint. The plantar plate is felt to be the primary static stabilizer to prevent dorsal translation of the joint. Functional loss of the plantar plate will result in a positive draw sign at the MTP joint. Thus, the diagnosis is made based on clinical exam. When there is longstanding biplanar ligamentous
iii
Fig 9. The tendon is delivered to the dorsal wound.
CROSSOVER TOE DEFORMITY
Fig 11. Final result.
4,9
incompetence, in addition to pressure on the second toe from a large hallux valgus deformity, a crossover toe deformity results. The treatment principles are to achieve a painless reduced joint, which is stable. This can be accomplished by soft tissue procedures if the joint is not arthritic. Arthritic joints, or those with a longstanding joint dislocation, require a bony procedure for symptomatic relief. Hallux valgus deformity must always be addressed to allow for proper alignment of the forefoot.
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REFERENCES 1. Myerson MS, Shereff MJ: The pathologic anatomy of claw and hammer toes. J Bone Joint Surg 71-A:45-49, 1991 2. Coughlin MJ: Subluxation and dislocation of the second metatarsophalangeal joint. Orth Clin North Am 20:535-551, 1989 3. Thompson FM, Deland JT: Flexor tendon transfer for metatarsophalangeal instability of the second toe. Foot Ankle 14:385-388, 1993 4. Gazdag A, Cracchiolo A: Surgical treatment of patients with painful instability of the second metatarsophalangeal joint. Foot Ankle 19:137143, 1998
GOLDBERGER AND KANN
Second metatarsophalangeal joint pathology is a frequent cause of forefoot pain. The final common pathway is loss of the static stabilizers of the joint. Early in the course of the disease, patients will demonstrate provocative instability and lager will display fixed hyperextension, Surgical treatment is initially directed at releasing contracted soft tissues and supplementing the repair with a dynamic flexor to extensor transfer. Once a fixed deformity is present, bony procedures should be added. KEY WORDS: foot, hammer toe, treatment, surgery
Disorders of the second toe metatarsophalangeal (MTP) joint are common causes of pain in patients with metatarsalgia. Pain often iis a manifestation of either altered biomechanics of the foot or, less commonly, idiopathic inflammation of the joint. The chronic mechanical overload or inflammation of the joint leads to progressive elongation of the plantar plate and collateral ligaments with subsequent instability of the joint. When there are other accompanying mechanical abnormalities, such as a large hallux valgus deformity, a crossover toe can develop. To correct the lesser toe deformity, the hallux valgus will also need to be addressed. There have been a number of different treatment modalities used to solve the difficult problem of an unstable second MTP joint. Central to the management of the deformity is understanding the dynamic and static soft tissue stabilizers of the MTP joints. The primary extensor of the MTP joint is the extensor digitorum longus (EDL). The EDL crosses both the MTP and proximal interphalangeal (PIP) joints to insert onto the distal phalanx. It has a fibroaponeurotic sling, which connects to the plantar plate. With longstanding hyperextension at the MTP joint, the extensor hallucis Iongus (EHL) tendon can become contracted and act to resist reduction of the joint. The extrinsic flexor tendons, flexor digitorum longus (FDL), and flexor digitorum brevis (FDB) insert into the distal and middle phalanx, respectivelN and have little influence on MTP stability. It is important surgical anatomy to note that on the plantar aspect of the MTP joint, the FDL is found passing between the two slips of the FDB tendon. The primary dynamic stabilizers of the MTP joint are the intrinsic muscles. There are two dorsal interossei, which take origin from the metatarsal shaft and insert onto the medial and lateral aspect of the proximal phalanx. The lumbricals take origin from the FDL and insert into the extensor hood. Both the interossei and lumbrical tendons course plantar to the axis of rotation of the MTP joint, thus function to flex this joint, in addition to extending the more distal interphalangeal
From Tri-County Orthopedic/Sports Medicine, Mordstown, NJ; and Tristate Orthopaedics, Pittsburgh, PA. Address reprint requests to Jeffrey Kann, MD, Tristate Orthopaedics, 5900 Corporate Drive, Su~ite200, Pittsburgh, PA 15237. Copyright © 1999 by W.B. Saunders Company 1048-6666/99/0901-0003510.00/0
joints. The primary static stabilizers of the MTP joint are the plantar plate, collateral ligaments, and joint capsule? The plantar plate has a stronger attachment to the base of the proximal phalanx than it does to the metatarsal neck. Therefore, it is not uncommon to find attritional tears off of the metatarsal attachment. The dorsal capsule functions as a secondary static stabilizer of the MTP joint. In summary, maintaining dynamic stability of the MTP joint are the intrinsic muscles and statically the plantar plate, collateral ligaments, and dorsal capsule. The etiology of instability of the second MTP joint is thought to be multifactorial. A simplified scheme is to consider either a mechanical or an inflammatory process as the cause of second MTP joint instability. Mechanical causes may include an acute traumatic event injuring the supporting ligaments and joint capsule. These patients present with a painful joint, which displays instability by provocative testing. A long second ray, as well high-heeled footwear, has often been implicated by causing repetitive trauma to the toe as it contacts the end of the toe box in a shoe. This will cause an extension moment to be placed on the MTP joint. Over time there will be stretching of the static stabilizers resulting in instability. Another common cause of mechanical instability can be related to pressure from the great toe deviating into valgus and underlapping the second toe thus forcing the MTP joint into extension. Increased load transmission to the second metatarsal in cases of hallux valgus may also be contributory. Inflammatory conditions have also been described. An isolated synovitis at the second MTP joint has been described to occur idiopathicallN as well as in inflammatory arthritides. The inflammation causes destruction of the joint capsule and subsequent stretching of the ligamentous stabilizers of the joint. Once there is damage to the static stabilizers of the MTP joint, subluxation tends to progress. As the MTP joint dorsally displaces, the dynamic stabilizers sublux dorsal to the midaxis of the MTP joint and act to extend it and flex the PIP joint. There is a continuum of progression from one of only provocative instability to frank dislocation. The pathologic changes associated with a crossover toe occur in a predictable fashion once there is loss of the static stabilizers. The plantar plate attrionally stretches and can rupture from its origin on the plantar metatarsal neck, which allows for subsequent dorsal subluxation. Dorsally,
Operative Techniques in Orthopaedics, Vol 9, No 1 (January), 1999: pp 45-50
45
there is contracture of the dorsal capsule and EDL tendon, as well as the medial collateral ligament. With medial migration of the toe, the lateral collateral ligament becomes incompetent. Lastly, with attachments to the plantar plate, the fat pad also migrates in a distal direction resulting in the uncovering of the metatarsal head and the predictable callus formation. The physical examination focuses on the forefoot, however, a brief inspection of the hindfoot is required to assess for potential ankle or tendoachilles contracture and midfoot cavus deformities with forefoot equinus. Both of these conditions can lead to mechanical overload at the MTP joints. The forefoot is examined both in the weight-bearing and nonweight-bearing position. The first ray is assessed for hypermobility, as well as a hallux valgus deformity. In both of these first ray conditions, the load borne at the second MTP joint is increased. The second toe is inspected for its length as compared with the other toes, as well as looking for gross swelling and malalignment of the toe (Fig 1). Soft corns between the toes, as well as skin ulceration is noted. The plantar aspect of the foot is examined for either varus or valgus forefoot alignment, as well as isolated plantar callosities. Areas of specific tenderness should be sought. Tenderness lateral to the metatarsal head may be an interdigital neuroma or just irritation of the digital nerve adjacent to the distended capsule of an inflamed MTP joint. This can be difficult to differentiate by physical examination. However, instability at the second MTP joint is much more common than a second web space neuroma. Next, the examiner assesses for range of motion of the MTP, PIP, and distal interphalangeal (DIP) joints. It is important to determine if the contractures at the joints are fixed or flexible. A flexible contracture will change with ankle motion. Next, stability of the joint is checked by the anterior draw test at the MTP joint. The examiner manipulates the proximal phalanx in a plantar to dorsal fashion while stabilizing the metatarsal. The object of this test is to sublux the proximal phalanx on the metatarsal head. A
Fig 1. Preoperative photo showing dorsomedial deviation of the second toe.
46
Fig 2. Anterior draw test. Note the dimple on the skin.
skin dimple may be seen over the MTP joint during the maneuver (Fig 2). Significant instability by this test signifies incompetence of the plantar plate and collateral ligaments. The anterior draw may reproduce the patient's symptoms, as well as produce crepitus. Lastly, the remaining lateral lesser toes are examined. A useful clinical test is to have the patient stand on a step with the edge of the step at the level of the metatarsal heads. The examiner can now assess for true MTP tissue contracture. Weight-bearing radiographs of the foot are obtained to evaluate forefoot alignment. Specifically, the second MTP joint is assessed for arthritis, joint congruencN and to confirm the presence of a long metatarsal. The presence of Freiberg's infraction can also be seen. Thickening of the metatarsal shaft evidences chronic overload at the second ray. Lateral inclination of the joint, which is normally 7°, can also be determined.
MANAGEMENT When either a mechanical abnormality or an inflamed joint is discovered early in its course, the joint can be managed conservatively. The inflamed joint can initially be managed in well-fitting supportive shoe wear. A rigid sole is recommended to decrease flexion of the toe box. Taping of the toe or over the counter toe splints can stabilize the MTP joint while the inflammation is brought under control. A metatarsal pad placed proximal to the metatarsal head may alleviate pain by unloading the joint. Physical therapy is used when significant tendoachilles contracture is present. Nonsteroidal antiinflammatory medication may alleviate pain and inflammation at the joint. Lastly, a steroid injection can be tried to settle the inflammation. We do not recommend repeat injections, as they may further aggravate MTP joint capsular distention. In patients who have a large underlapping hallux and a dorsally dislocated second toe, a depth shoe can be used to accommodate the deformity. If conservative measures fail the joint should be operatively reduced and stabilized. The reduction of the joint involves sequential soft tissue releases. 2 One must also address the distal joints and any associated hallux valgus deformity. With mild subluxation, the collateral ligaments and dorsal capsular are released and the extensor tendon is
GOLDBERGER AND KANN
lengthened. If there is still resistance to reduction of the joint, then the plantar capsule is released. To maintain stability of the joint, a flexor to extensor transfer is added to the procedure. When there is medial or lateral deviation of the joint, the contracted capsule and collateral ligaments are released and the: opposite capsule and collateral ligaments are tightened. In addition, the flexor transfer can be tightened on the weak side. When there is dislocation of the MTP joint, and after soft tissue release as previously mentioned are performed, a bony decompression is indicated if the joint remains unreducable. The bony decompression in this case ,can be a distal metatarsal DuVries arthroplasty. Another approach to the chronically dislocated and arthritic joint is to perform a concomitant proximal phalanx excisional arthroplasty. In all cases, once the toe is realigned, the MTP joint is stabilized with a K-wire. Lastly, in the case of a large deformity and the patient's only complaint is pain on top of the second PIP joint with shoe wear, the elderly patient may opt for a second toe amputation as opposed to a major forefoot reconstruction. However, this will inevitably lead to worsening of any hallux valgus deformity if the entire toe is removed.
SURGICAL TECHNIQUE Dorsal Capsulotomy At our institution, we prefer regional popliteal block anesthesia, however, ankle block should suffice. A wellpadded tourniquet is used. The leg is then prepped and draped in the usual fashion. The foot is exsanguinated and the tourniquet is elevated. A dorsal incision centered over the joint 2 to 4 cm is length is used. A full thickness flap down to the extensor tendon is created. The extensor tendon is then lengthened in a standard Z-fashion. By flexing and extending the toe, an attempt is made to relocate the MTP. Next, the dorsal capsule is perforated and circumferentialy released. With the base of the proximal phalanx in view subperiosteally, the medial and collateral ligaments are released along with the origin of the lumbricals. When there is still resistance to reduction, the plantar plate is released off of the metatarsal neck. This is accomplished by plantar flexing the proximal phalanx to expose the metatarsal head, and the plantar plate adhesions are sharply released off the neck of the material.
Flexor to Extensor Transfer The purpose of this procedure is to stabilize the proximal phalanx. In theorN the FDL tendon transfer dynamically stabilizes the MTP joint by replacing the function of the intrinsics. The incision is begun just proximal to the MTP joint and carried distally to the level of the midproximal phalanx (Fig3). Soft tissue releases are performed as required to achieve reduction of the joint (Fig 4). Attention is then turned to the plantar aspect of the toe. A transverse incision is made at the level of the proximal flexion crease (Fig 5). The soft tissues are bluntly spread to the level of the flexor tendon sheath and pulley. Careful attention is paid to protect the neurovascular structures, which lie just medial and lateral to the sheath. The sheath is then sharply split longitudinallN so not to injure the tendons below. Care now is taken to identify the FDL tendon. At this level, the FDL runs centrally between the two slips of the FDB tendon. A curved mosquito clamp is passed beneath the FDL tendon. The DIP joint is flexed and extended to confirm that the correct tendon is chosen. Next, the FDL is released percutaneously from its insertion on the distal phalanx (Fig 6). The mosquito clamp pulls the FDL tendon out of the wound. Using a small mosquito clamp on either side of the FDL tendon, the tendon is split down the center, inline with the central raphe to create two tails (Fig 7). Attention is now directed to the dorsal aspect of second toe. At the level of the middiaphysis of the proximal phalanx, a curved mosquito is passed deep to the extensor mechanism along the sides of the proximal phalanx to exit on the plantar aspect of the wound (Fig 8). Each tail is then pulled dorsal to the midportion of the proximal phalanx (Fig 9). With the MTP joint held reduced the transfer is tensioned with the ankle joint neutral and the proximal phalanx is plantarflexed 10 ° and the two ends are crossed and sutured to the EDL and themselves with nonabsorbable suture (Fig 10). A K-wire is the passed in a retrograde fashion to protect the repair (Fig 11).
Metatarsophalangeal Joint Arthroplasty Metatarsophalangeal joint arthroplasty is indicated when there is chronic dislocation of the joint or when the joint is arthritic. Metatarsal head sculpting is favored over partial
Capsular Reefing
Reefing of the redundant capsule is indicated when the toe has significant medial or lateral deviation. The soft tissue release is performed as described above with special attention to release the contracted capsular side. Next, attention is turned to the attenuated side. The capsule on this side is opened vertically. An ellipse of tissue is removed in line with the capsulotomy. With the toe held in an overcorrected position, a figure of eight suture is passed in a proximoplantar to a distodorsal fashion. This effectively tightens the collateral ligament.
CROSSOVERTOE DEFORMITY
Fig 3. Dorsal incision medial to long extensor tendon.
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Fig 6. FDL tendon has been identified and now percutaneously released, Fig 4. Dorsomedial capsule and medial collateral ligament of the MTP joint has been released.
proximal phalangectomy when the second metatarsal is exceedingly long. The approach to the joint is as described above with appropriate soft tissue releases. Because the dislocation is long-standing, the medial and lateral capsular releases should be complete. The distal metatarsal head is exposed and the amount of bony resection is based on the amount of overlap of the proximal phalanx on the metatarsal head. Usually 3 to 4 m m of distal metatarsal head is resected. Once the osteotomy is completed, the metatarsal head is sculpted on the dorsal and plantar condyles. A cannulated cup shaped reamer can be used to accomplish the sculpting, as well. After bony decompression, the joint should be reducible with about 3 m m between the sculpted metatarsal head and proximal phalanx. For added stability, a flexor to extensor transfer can be added.
Partial Proximal Phalangectomy The indications for this procedure are similar to the metatarsal head arthroplasty. The surgical technique is identical except (1) 3 to 4 m m of the base of the proximal phalanx is excised and (2) in a long-standing dislocation, additional bone from the base of the proximal phalanx may be removed to achieve reduction of the joint.
Fig 5. Plantar incisions.
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The difference between decompressing the MTP joint at the metatarsal head or base of the proximal phalanx should be considered. Excising the distal metatarsal head will decompress the joint and shorten the metatarsal, which is helpful in patients who feel pressure during push-off. This procedure also will not clinically shorten the length of the toe itself. The disadvantage, however, is that it can often lead to stiffness at the MTP joint, making extension of the toe painful.
K-Wire Technique We recommend retrograde placement of a K-wire to stabilize the MTP joint while the soft tissue reconstruction heals. It is important to realize that the wire is not meant to correct deformity. After bony resection or before suturing the tendon transfer, the proximal phalanx is plantarflexed and a 0.45 K-wire is placed in the center of the base of the proximal phalanx. It is the driven through the phalanges to exit 2 to 3 m m plantar to the nail bed centrally in the toe. Next, the MTP joint is held reduced and the K-wire is drilled into the proximal metatarsal shaft. The wire usually is left out the skin and removed at the 4-week visit.
Fig 7. FDL tendon is split.
GOLDBERGERAND KANN
Fig 8. A hemostat is passed from the dorsal wound to retrieve the split tendon in the plantar wound.
Fig 10. With toe held 10 ° to 20 ° of plantarflexion, the two ends of the FDL tendon are crossed and sutured to themselves and the extensor mechanism.
Soft Tissue Considerations If the toe has been contracted for a long period of time, one must be concerned with straightening of the digit, as it may induce vascular compromise. When the procedure is completed, the tourniquet should be deflated and the toe vascularity is assessed. If any question exists, the K-wire should be removed and allow shortening of the toe. In the extreme case and during revision surgery, z-plasty of skin should be considered.
DISCUSSION Thompson and Deland s reported on 13 patients with second toe MTP instability. Eleven of the patients had a hallux valgus deformity, and six of these patients presented with a crossover toe. The patients were surgically treated with soft tissue procedures including a flexor to extensor transfer. They noted that the joint stability is a result of stiffness as opposed to a functioning dynamic transfer. Gazdag and Cracchiolo4 reported on 20 feet, which they treated with a flexor to extensor transfer. They noted that
13 of the feet had an excellent result. Seven patients had a fair result, but only reported mild discomfort at the joint. This points to the inconsistent results, which may be achieved with flexor to extensor transfers. Counseling of patients is necessary to achieve satisfactory results. When the joint is arthritic, soft tissue releases should be combined with bony decompression. Stability of the joint in these cases is maintained by scar tissue. The patients should have a painless joint that passively extends during push-off. Second toe instability can result from several different mechanical or inflammatory etiologies. The end result is loss of competence of the static stabilizers of the joint. The plantar plate is felt to be the primary static stabilizer to prevent dorsal translation of the joint. Functional loss of the plantar plate will result in a positive draw sign at the MTP joint. Thus, the diagnosis is made based on clinical exam. When there is longstanding biplanar ligamentous
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Fig 9. The tendon is delivered to the dorsal wound.
CROSSOVER TOE DEFORMITY
Fig 11. Final result.
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incompetence, in addition to pressure on the second toe from a large hallux valgus deformity, a crossover toe deformity results. The treatment principles are to achieve a painless reduced joint, which is stable. This can be accomplished by soft tissue procedures if the joint is not arthritic. Arthritic joints, or those with a longstanding joint dislocation, require a bony procedure for symptomatic relief. Hallux valgus deformity must always be addressed to allow for proper alignment of the forefoot.
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REFERENCES 1. Myerson MS, Shereff MJ: The pathologic anatomy of claw and hammer toes. J Bone Joint Surg 71-A:45-49, 1991 2. Coughlin MJ: Subluxation and dislocation of the second metatarsophalangeal joint. Orth Clin North Am 20:535-551, 1989 3. Thompson FM, Deland JT: Flexor tendon transfer for metatarsophalangeal instability of the second toe. Foot Ankle 14:385-388, 1993 4. Gazdag A, Cracchiolo A: Surgical treatment of patients with painful instability of the second metatarsophalangeal joint. Foot Ankle 19:137143, 1998
GOLDBERGER AND KANN