8. Foot and Ankle MCQs

DISCUSSION: The history is most consistent with a plantar fibroma. The nodules typically are located within the substance of the plantar aponeurosis. The clinical appearance is usually diagnostic without the need for advanced imaging studies. While the lesion may be prominent and painful to direct palpation, the anatomic location is usually off of the weight-bearing surface. Observation with or without an accommodative orthotic is the treatment of choice. Recurrence is common following attempted excision.

DISCUSSION: A flexor digitorum longus transfer, while not as strong as the peroneals, improves the tendon balance and maintains hindfoot mobility. Subtalar fusion is a salvage procedure. Posterior tibial tendon transfer compromises inversion strength and arch height. Functional absence of the peroneals results in an imbalance that could lead to forefoot varus.

Figure 14 depicts an X-ray of a child with a Ball-and-Socket ankle. This is a rare deformity associated with such pre-existing conditions as congenital shortening of the lower limb, coalition of tarsal bones, absent digital rays and aplasia or hypoplasia of the fibula. Ball-and-socket joint is not congenital, but is an acquired deformity formed in compensation for the loss of inversion and eversion caused by tarsal coalition or various other pre-existing congenital conditions.

The patient has a zone 1 base of the fifth metatarsal fracture (Pseudojones) that represents a less serious injury compared to zone 2 and 3 fractures with regard to healing potential. Treatment is symptomatic and casting is not necessary. These fractures are well treated with a hard-soled shoe for comfort and weight bearing as tolerated. Surgical intervention is not warranted.

DISCUSSION: The patient has the typical end stage residuals from long-standing Charcot-Marie-Tooth disease. Initial management consisting of shoe wear modifications and orthotic devices is preferred, but these are not successful when the disease process has progressed. Surgical correction with calcaneal osteotomy or Achilles tendon lengthening and Steindler stripping is not indicated in the presence of significant hindfoot arthritis. Because this patient has findings consistent with hindfoot arthritis, a triple arthrodesis with correction of the cavus deformity is the preferred treatment. REFERENCES: Roper BA, Tibrewal SB: Soft tissue surgery in Charcot-Marie-Tooth disease. J Bone Joint Surg Br 1989;71:17-20. Wetmore RS, Drennan JC: Long-term results of triple arthrodesis in Charcot-Marie-Tooth disease. J Bone Joint Surg Am 1989;71:417-422.

DISCUSSION: Atraumatic Achilles tendon disease can be differentiated into Achilles tendinosis and peritendinitis. Thickening and tenderness of the Achilles tendon are present in both, but thickening and tenderness of the tendon sheath indicates peritendinitis. Histologic examination of Achilles tendinosis reveals an absence of acute and chronic inflammatory cells. Radiologists often diagnose partial tendon rupture by MRI and there may be microscopic longitudinal tears present, but there is no mechanical compromise as would be implied by a partial rupture. The thickening typically occurs in the portion of the tendon with the poorest blood supply, and biochemical analysis detects high levels of lactate and other products of anaerobic glycolysis. REFERENCES: Astrom M, Rausing A: Chronic Achilles tendinopathy: A survey of surgical and histopathologic findings. Clin Orthop 1995;316:151-164. Ohberg L, Lorentzon R, Alfredson H: Neovascularisation in Achilles tendons with painful tendinosis but not in normal tendons: An ultrasonographic investigation. Knee Surg Sports Traumatol Arthrosc 2001;9:233-238. Alfredson H, Bjur D, Thorsen K, et al: High intratendinous lactate levels in painful chronic Achilles tendinosis: An investigation using microdialysis technique. J Orthop Res 2002;20:934-938.

DISCUSSION: The patient has the dystrophic type of scoliosis seen in patients with neurofibromatosis type I (NF-1). The NF-1 gene is located on chromosome 17 and codes for neurofibromin, believed to be a tumor-suppressor gene. Abnormalities in the dystrophin gene are seen in Duchenne muscular dystrophy and Becker muscular dystrophy. A mutation in the frataxin gene is responsible for Friedreich ataxia. The most common type of hereditary motor and sensory neuropathy (Charcot-Marie-Tooth), HMSN type IA is caused by a complete duplication of the peripheral myelin protein gene. A defect in the cellular sulfate transport protein results in undersulfation of proteoglycans seen in diastrophic dysplasia.

The CT scans show large cystic lesions in the talus and calcaneus with complete subluxation of the subtalar joint, allowing the calcaneus to slide laterally until it becomes blocked by the fibula. The cause of this subluxation is severe posterior tibial tendon dysfunction. Although no fibular fracture has yet appeared, it can occur with continued stress from the calcaneus. There is, however, a pathologic fracture in the medial calcaneus through a medial degenerative cyst.

DISCUSSION: Osteochondrosis of the tarsal navicular (Kohler disease) is an infrequent cause of midfoot pain in children, and the etiology is unknown. The typical radiographic findings include flattening and irregular ossification of the tarsal navicular. The medial cuneiform and talus maintain their normal articular contours. The acute process is best treated with rest and immobilization. A short leg walking cast results in relief of pain and a quicker return to activity compared with orthotics, although long-term success is similar with either method of treatment. Children may return to activities when the symptoms subside. The radiographic appearance of the talus begins to normalize by about 8 to 10 months following the onset of symptoms. REFERENCE: Lutter LD: Sports-related injuries, in Drennan JC (ed): The Child’s Foot and Ankle. New York, NY, Raven Press, 1992.

DISCUSSION: Once degenerative changes have occurred, soft-tissue procedures are not indicated. Triple arthrodesis is the treatment of choice for adult-acquired flatfoot. Isolated fusion of the subtalar or talonavicular joint will not be sufficient to correct the problem. REFERENCES: Lutter LD, Mizel MS, Pfeffer GB (eds): Orthopaedic Knowledge Update: Foot and Ankle. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 269-282. Graves SC, Stephenson K: The use of subtalar and triple arthrodesis in the treatment of posterior tibial tendon dysfunction. Foot Ankle Clin 1997;2:319.

The CT scan is an important test to help determine the extent of involvement of the talocalcaneal facet in a talocalcaneal coalition. In a young patient with no arthritis and joint involvement of less than 50%, resection of the coalition and fat pad interposition has been shown to be successful. A calcaneal osteotomy does not address the coalition. Subtalar arthroereisis has been used for treatment of a flexible flatfoot; tarsal coalition patients have a rigid-type flatfoot deformity.

Multiple biomechanical studies have investigated the contribution of the Gould modification with the Broström anatomic repair for chronic ankle instability. No studies to date have demonstrated a statistically significant difference in initial ankle stability with inclusion of the Gould modification or augmentation of the repair with a mobilized lateral portion of the extensor retinaculum. No clear association exists between the Broström-Gould repair technique and risk for nerve injury, postsurgical range of motion, or incidence of osteoarthritis on long-term follow-up.

The radiographs reveal a malunited distal fibular fracture with shortening. Because there appears to be an adequate cartilage space within the ankle joint, the role of reconstruction would be to prevent arthrosis and the need for ankle arthrodesis, as well as to decrease symptoms. The treatment of choice is restoration of fibular length, alignment, and rotation with osteotomy plating, and bone grafting as needed. There is no indication for ligament reconstruction of a mechanically stable ankle, and tibial shortening osteotomy will not assist in correcting the deformity. Cast immobilization may assist with improvement of symptoms but will not correct the overall process. Determination of fibular length is best done by comparing the talocrural angle of the injured side with the uninjured side. The goal is to perfectly reduce the talus in the ankle mortise.

DISCUSSION: Interdigital neuromas represent perineural fibrosis of the intermetatarsal nerve most commonly seen in the second and third web spaces. The most popular theory on the etiology of interdigital neuromas is compression neuropathy by the intermetatarsal ligament. Infection and allergic reactions such as hives are rare after steroid injection. CRPS is not known to occur in this setting. Hammertoe formation can occur, especially after multiple steroid injections into an interdigital neuroma.

DISCUSSION: The patient has a ligamentous Lisfranc injury. Diastasis seen between the bases of the second metatarsal and medial cuneiform is pathognomonic for a rupture of the Lisfranc ligament. This injury is best treated surgically with either open reduction and internal fixation or possibly closed manipulation and percutaneous screw fixation if anatomic alignment can be achieved closed. Pin fixation has been shown to be inferior to screw fixation due to the length of time that fixation is required for adequate ligament healing.

The flexor hallucis longus tendon provides the best, most direct route of transfer for filling Achilles tendon gaps. The tendon lies lateral to the neurovascular structures, making it safe for harvest and providing a direct route for transfer into the calcaneus without crossing these important structures. The flexor hallucis longus tendon also has a muscle belly that extends distal on the tendon itself, often beyond the actual tibiotalar joint. When the tendon is transferred, this muscle belly brings excellent blood supply to the anterior portion of the reconstruction.

The patient has a supple plantigrade foot that would benefit from a drop foot brace to prevent catching of the toes. Tendon transfer should not be considered until the patient has undergone bracing. Achilles tendon lengthening is not necessary because the foot is plantigrade and flexible. Nerve grafting is not indicated because of the length of time the peroneal nerve palsy has been present.

The complex pathology in this scenario includes: incongruous subtalar joint, loss of calcaneal body height, and likely decreased lateral talocalcaneal angle. Complications of this injury include pain, shoe wear difficulties, and foot deformity. Foot deformity (collapse of the talus into the posterior facet) can result in tibiotalar neck impingement. Carr et al described a subtalar fusion technique for late complications of calcaneus fractures that were treated conservatively. The subtalar fusion technique involves distraction of the subtalar joint, insertion of a bone block, and rigid screw fixation. The distraction allows correction of the talocalcaneal relationship and regains lost hindfoot height. Chandler et al states that distraction arthrodesis should be considered only if findings of anterior ankle impingement are present, as is true in this case.

The indications for surgery in a Charcot joint are an unbraceable deformity or recurrent ulceration despite use of adequate bracing. Any significant varus/valgus deformity of the ankle or hindfoot (as in this patient) is unbraceable, whereas midfoot Charcot deformities usually can be treated nonsurgically. The goal of surgery is to provide a stable aligned foot and ankle to permit activities and reduce risk for recurrent ulceration. This does not mean that there has to be a radiographic fusion because many patients with diabetes achieve a stable nonunion without pain. The only surgical construct that will provide long-term inherent stability and alignment in this situation is use of a hindfoot fusion rod. It provides better stability and purchase than screw fixation and can be left in indefinitely (unlike an external fixator).

DISCUSSION: This patient jumped on his forefoot and landed with pain in his great toe. His radiograph shows possible increased space between the sesamoids and the base of the phalanx. A comparison radiograph on the other side will reveal if this position is normal for this patient. If findings are asymmetric, turf toe injury is a possibility based on this patient's symptoms and mechanism of injury.