AAOS & ABOS Orthopedic MCQs (Set 2): Foot & Ankle Trauma | Board Exam Prep

Cadaver and clinical studies have shown that the sural nerve is at the highest risk for injury with a percutaneous repair of the Achilles tendon.

The primary action of the posterior tibialis tendon is inversion of the foot; secondarily, it plantar flexes the ankle. The anterior tibialis tendon also inverts the foot and only partially antagonizes the posterior tibialis tendon. The primary action of the peroneus longus is plantar flexion of the first ray. It secondarily everts the posterior tibialis tendon. The action of the flexor digitorum longus tendon is synergistic with the posterior tibialis tendon. The primary action of the peroneus brevis tendon is eversion; therefore, it is the primary antagonist of the posterior tibialis tendon. Sarrafian SK: Anatomy of the Foot and Ankle: Descriptive, Topographic, Functional, ed 2. Philadelphia, PA, JB Lippincott, 1993, pp 550-551.

Pseudomonas aeruginosa is the most common infectious organism causing osteochondritis in pediatric puncture wounds of the foot. Eikenella corrodens is found in human bites, and Pasteurella multocida is characteristically seen with animal bites. Serratia marcescens and Proteus mirabilis have been reported but are much less likely. Jacobs RF, Adelman L, Sack CM, et al: Management of pseudomonas osteochondritis complicating puncture wounds of the foot. Pediatrics 1982;69:432-435.

The peroneus brevis and peroneus longus muscles are the main evertors of the hindfoot. As they descend along the posterior fibula, they pass through the retromalleolar sulcus, formed by the concavity of the retromalleolar fibula. This sulcus is deepened by a fibrocartilaginous rim. The superior peroneal retinaculum covers the fibular groove and stabilizes the peroneal tendons within the retromalleolar sulcus. It originates from the posterolateral ridge of the fibula and inserts onto the lateral calcaneus. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2003, pp 81-89.

There is no evidence that early weight bearing enhances ultimate rehabilitation. At the other extreme, weight bearing should not be delayed for a prolonged period of time. In a young, healthy individual, the rigid plaster dressing appears to be the safest method of protecting the wound during the early postoperative period. If the wound appears to be secure, early partial weight bearing can be safely initiated. Burgess EM, Romano RL, Zettl JH: The Management of Lower Extremity Amputations. Washington, DC, US Government Printing Office, 1969, also at: www.prs-research.org.

The most important determining factor for correction of an adult flatfoot without an arthrodesis is the flexibility of the subtalar and transverse tarsal joints. Rigid deformities cannot be corrected with a medial sliding calcaneal osteotomy with FDL transfer or a subtalar arthroereisis. Isolated subtalar or talonavicular arthrodesis does not correct the deformities entirely. If the patient has forefoot supination that can be corrected to less than 7 degrees, an isolated subtalar fusion is a possible alternative.

Cheilectomy has been shown to provide satisfactory pain relief and improved function in long-term studies. It is important to select patients appropriately when choosing a cheilectomy versus an arthrodesis. Pain at the midrange of motion and loss of more than 50% of the metatarsal head cartilage are predictors of a poor outcome following cheilectomy, and these patients should receive an arthrodesis. Coughlin MJ, Shurnas PS: Hallux rigidus: Grading and long-term results of operative treatment. J Bone Joint Surg Am 2003;85:2072-2088.

The deep fascia of the abductor hallucis muscle is released to relieve pressure on the first branch of the lateral plantar nerve. The tibial nerve lies more proximal to this area. The medial plantar nerve has already passed dorsally and medially, while the sural nerve lies on the lateral side of the foot. The flexor hallucis brevis muscle lies deep to the plantar fascia, not the abductor fascia. Baxter DE, Pfeffer GB: Treatment of chronic heel pain by surgical release of the first branch of the lateral plantar nerve. Clin Orthop 1992;279:229-236.

The radiographs do not show significant arthrosis of the hallux metatarsophalangeal joint; therefore, arthrodesis is unnecessary. Orthotics will not correct the deformity. A distally based osteotomy will not achieve sufficient correction of the incongruity of deformity, and a Keller resection is not indicated in the younger population. The treatment of choice is a proximal metatarsal osteotomy with second toe correction.

A Morton's extension limits excursion of the first metatarsophalangeal joint. It also functions as a ground reaction stabilizer during the toe-off phase of gait and thus reduces torque and joint reaction force at the first metatarsophalangeal joint. The metatarsal arch pad and full-length semi-rigid longitudinal arch support may help by dorsiflexing the first metatarsal relative to the phalanx and thus decompress the first metatarsophalangeal joint. However, they are not as biomechanically effective as the Morton's extension. Both medial hindfoot and lateral forefoot posting are contraindicated because they increase ground reaction at the first metatarsophalangeal joint. Coughlin MJ: Arthritides, in Coughlin MJ, Mann RA (eds): Surgery of the Foot and Ankle, ed 7. St Louis, MO, Mosby, 1999, p 611.

Most leaders in orthopaedic surgery support Jacqueline Perry's theory that the postpolio syndrome is an attritional degenerative process that is the result of overuse of muscles and joints that are unable to adequately tolerate overload, and have little functional reserve. For that reason, aerobic conditioning and exercise are important. Overload and exhaustion of involved muscles should be avoided.

Myerson and associates studied the outcomes of 19 patients with tarsometatarsal joint injuries during athletic activity. Injuries were classified as first- or second-degree sprains of the tarsometatarsal joint or a third-degree sprain with diastasis between the metatarsals or cuneiforms. Poor functional results were seen in those with a delay in diagnosis and with inadequate treatment. For patients with third-degree sprains, poor results were obtained with nonsurgical management. These patients required open reduction and internal fixation for optimal return to function. The anatomic reduction is critical to the outcome; therefore, open reduction is preferred. Baxter DE: The Foot and Ankle in Sport, ed 1. St Louis, MO, Mosby, 1995, pp 107-123. Curtis MJ, Myerson M, Szura B: Tarsometatarsal joint injuries in the athlete. Am J Sports Med 1993;21:497-502. Kuo RS, Tejwani NC, DiGiovanni CW, et al: Outcome after open reduction and internal fixation of Lisfranc joint injuries. J Bone Joint Surg Am 2000;82:1609-1618.

History and physical examination are still the gold standard for diagnosis of an interdigital neuroma. Ultrasound and MRI may be helpful adjuncts but are dependent on equipment and operator expertise. Web space injection may be helpful for diagnostic and therapeutic purposes. Electromyography and nerve conduction velocity studies are of little benefit for distal lesions. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 145-147.

Nonsurgical management has failed to provide relief; therefore, the treatment of choice is arthrodesis with an intramedullary nail. Amputation may be indicated if the arthrodesis fails. The patient does have adequate circulation for an attempt at salvage. Total ankle arthroplasty is not indicated in a neuropathic patient. Pinzur MS, Kelikian A: Charcot ankle fusion with a retrograde locked intramedullary nail. Foot Ankle Int 1997;18:699-704.

Parameters for first metatarsal fracture management are different than for shaft fractures of the central second, third, and fourth metatarsals. The first metatarsal carries a greater load and if malunited, can create transfer lesions by virtue of uneven weight distribution; therefore, nonsurgical management is not indicated for this patient. Percutaneous pinning is not as likely to result in an anatomic reduction as open reduction and internal fixation. As his livelihood depends on an expeditious return to function, the choice of open reduction and internal fixation allows for earlier motion and rehabilitation. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 64-65.

The initial stages of posterior tibial tendon insufficiency, where the deformity remains supple, may be treated with bracing or an orthotic for pain relief. The Arizona brace was introduced in 1988, and assists in pain relief and deformity correction by minimizing hindfoot valgus alignment, lateral calcaneal displacement, and medial ankle collapse. It is particularly helpful in those patients with advanced disease that cannot tolerate an ankle-foot orthosis. All other choices are incorrect because of the addition of lateral posting, which is not advantageous in valgus deformities. The addition of medial posting to any of the above choices would render them correct alternatives. A heel lift is applicable in Achilles tendon disorders, not posterior tibial tendon disorders. Chao W, Wapner KL, Lee TH, et al: Nonoperative management of posterior tibial tendon dysfunction. Foot Ankle Int 1996;17:736-741.

Intravenous antibiotics alone will not adequately treat this infection. At 8 weeks after surgery, the hardware must be removed because Staphylococcus aureus is a virulent microbe. VAC therapy alone is not adequate without debridement and hardware removal, but it may play a role in postoperative wound care. Calcanectomy is a salvage procedure for calcaneal osteomyelitis or recalcitrant heel ulceration. Benirschke SK, Kramer PA: Wound healing complications in closed and open calcaneal fractures. J Orthop Trauma 2004;18:1-6. Lim EV, Leung JP: Complications of intra-articular calcaneal fractures. Clin Orthop 2001;391:7-16.

The MRI scans reveal an enlarged posterior tibial tendon, with degenerative signal within the tendon and an excessive amount of fluid in its sheath. This is a type II tear, as noted by Conti and associates, which is the most commonly seen tear. Slovenkai MP: Clinical and radiographic evaluation (Adult flatfoot: Posterior tibial tendon dysfunction). Foot Ankle Clin 1997;2:241-260.

Following a calcaneal fracture, the patient has severe subtalar arthritis with loss of talar declination and shortening of the heel; therefore, the treatment of choice is subtalar distraction arthrodesis. Orthotics will not provide significant relief as bracing has failed. Ankle arthrodesis will not be beneficial because the arthritis is in the subtalar joint. Subtalar arthroscopy would only be helpful for a small area of arthrosis, and calcaneal osteotomy would not be beneficial given the extent of the arthritis of the subtalar joint.

With a gap of less than 4 cm, a V-Y repair would be appropriate without a tendon transfer. For gaps greater than 5 cm, a lengthening with augmentation is the most appropriate treatment. Therefore, the treatment of choice is an Achilles tendon turndown with flexor hallucis longus tendon transfer. The plantaris tendon is not a strong enough repair, and direct repair is not possible given the large defect in the Achilles tendon. Continued use of the ankle-foot orthosis will not provide adequate relief for this patient.

Painful incisional neuromas after bunion surgery frequently involve the dorsomedial cutaneous branch of the superficial peroneal nerve. This is the medial branch of the superficial peroneal nerve that terminates as the dorsomedial cutaneous nerve to the hallux. Branches of the deep peroneal nerve to this area are rare, and no branches to this area exist from the sural nerve. The saphenous nerve branches are generally more proximal, and the medial plantar nerve lies plantarly. Kenzora JE: Sensory nerve neuromas: Leading to failed foot surgery. Foot Ankle 1986;7:110-117.

The patient has not undergone a trial of foot-specific patient education and accommodative/therapeutic shoe wear. He must use therapeutic shoe wear at all times, as even the occasional use of pressure-concentrating shoe wear has a high likelihood of leading to the development of a diabetic foot ulcer. Pinzur MS, Kernan-Schroeder D, Emmanuele NV, et al: Development of a nurse-provided health system strategy for diabetic foot care. Foot Ank Int 2001;22:744-746. Pinzur MS, Shields N, Goelitz B, et al: American Orthopaedic Foot & Ankle Society shoe survey of diabetic patients. Foot & Ankle Int 1999;20:703-707.

Initial management of a young patient with a cavovarus deformity of the foot and a family history of Charcot-Marie-Tooth disease should focus on mobilization and strengthening of the weakening muscular units and an accommodative insert. Surgical intervention should be delayed until progression of the deformity begins to cause symptoms and/or weakness of the muscular units, resulting in contractures of the antagonistic muscle units. Pinzur MS: Charcot's foot. Foot Ankle Clin 2000;5:897-912. Holmes JR, Hansen ST Jr: Foot and ankle manifestations of Charcot-Marie-Tooth disease. Foot Ankle 1993;14:476-486.

The diagnosis of an interdigital neuroma is best made by a thorough history and careful physical examination. Radiographs are helpful in excluding other pathologic processes such as a metatarsal stress fracture. MRI and ultrasound have both been reported to aid in the diagnosis of an interdigital neuroma. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2003, pp 145-151.

The radiograph reveals either a fractured or bipartite sesamoid. The bone scan shows asymmetrically increased uptake over the medial sesamoid. Given the history and physical examination, a stress fracture is the most likely diagnosis. Medial sesamoidectomy reliably improves pain, and athletes return to sports on an average of 7 weeks after excision. Immobilization typically requires more than 4 to 8 weeks and is not always successful; however, it would be appropriate management for a patient who is not an elite athlete. Sanders R: Fractures of the midfoot and forefoot, in Coughlin MJ, Mann RA (eds): Surgery of the Foot and Ankle, ed 7. St Louis, MO, Mosby, 1999, pp 1601-1603.