8. Foot and Ankle MCQs

DISCUSSION: Lateral subtalar dislocations, which are less common than medial subtalar dislocations, are high-energy injuries that are frequently associated with small osteochondral fractures. It is generally recommended that large fragments be internally fixed, and small fragments entrapped within the joint be excised. Although arthrosis frequently occurs after this injury and is the most common long-term complication, primary subtalar arthrodesis is not indicated. A talar neck fracture is not evident on the radiographs, and lateral subtalar dislocation usually does not lead to instability. REFERENCE: Saltzman C, Marsh JL: Hindfoot dislocations: When are they not benign? J Am Acad Orthop Surg 1997;5:192-198.

DISCUSSION: Congenital popliteal webbing with contractures of 60 degrees is a difficult deformity to correct. The anatomy of the web is of considerable importance. MRI can delineate the extent of the posterior fibrous band that often stretches from the ischium to the calcaneus. The sciatic nerve, usually shortened, most often runs just anterior to this fibrous band. For mild contractures of less than 20 degrees, nonsurgical management is usually adequate. Hamstring lengthening and postoperative splinting are usually sufficient for contractures of 20 degrees to 40 degrees. Moderate contractures of up to 60 degrees usually require Z-plasties in the popliteal fossa and postoperative serial casting to avoid undue tension on neurovascular structures. Contractures of more than 60 degrees require a femoral shortening osteotomy or gradual correction with an external fixator. However, rapid recurrence following fixator removal is common if formal soft-tissue procedures and postoperative splinting are not performed. REFERENCES: Parikh SN, Crawford AH, Do TT, et al: Popliteal pterygium syndrome: Implications for orthopaedic management. J Pediatr Orthop B 2004;13:197-201. Brunner R, Hefti F, Tgetgel JD: Arthrogrypotic joint contracture at the knee and foot: Correction with a circular frame. J Pediatr Orthop B 1997;6:192-197.

DISCUSSION: The sural nerve lies lateral to the Achilles tendon at the level of the foot but follows an oblique course proximally to lie directly over the tendon as it heads to the popliteal fossa. It is at risk with any proximal dissection from a direct posterior approach and in particular with procedures done at the musculotendinous junction. The nerve crosses over the lateral border of the Achilles tendon at an average of 9.8 cm above its insertion.

DISCUSSION: The most common etiology for plantar ulcers in patients with diabetes is neuropathy; 80% of these patients have adequate vascularity. The pathobiology is increased pressure applied on skin that lacks protective sensation. Once healed, the key to preventing recurrent ulceration is the use of orthopaedic shoes with custom-molded soft inserts that accommodate the contours of the feet. This is particularly true when surgery has removed a portion of the foot; the foot otherwise will shift in a shoe that does not include a custom-molded insert incorporating a filler that occupies the space left by the surgical resection.

DISCUSSION: Additional nonsurgical treatment is not beneficial for peroneal tendon tears. Early repair of longitudinal tears reduces risk for progression to a full-thickness tear that would necessitate peroneus brevis to peroneus longus tenodesis. Platelet-rich plasma has no role in peroneal tendon tears. RECOMMENDED READINGS: Arbab D, Tingart M, Frank D, Abbara-Czardybon M, Waizy H, Wingenfeld C. Treatment of isolated peroneus longus tears and a review of the literature. Foot Ankle Spec. 2014 Apr;7(2):113-8. Coughlin MJ, Schon LC. Disorders of tendons. In: Coughlin MJ, Saltzman CL, Anderson RB, eds. Mann's Surgery of the Foot and Ankle. 9th ed. Philadelphia, PA: Elsevier-Saunders; 2014: 1188-1291.

DISCUSSION: Because the radiograph reveals an intermetatarsal angle of greater than 15 degrees and an incongruent metatarsophalangeal joint, the treatment of choice is a proximal first metatarsal osteotomy with distal soft-tissue realignment. A distal chevron procedure would not correct this degree of deformity. A Keller procedure is reserved for a less active elderly individual. Arthrodesis is appropriate for a patient with advanced arthritis of the metatarsophalangeal joint. The double osteotomy is reserved for the congruent metatarsophalangeal joint with hallux valgus. REFERENCES: Coughlin MJ, Carlson RE: Treatment of hallux valgus with an increased distal metatarsal articular angle: Evaluation of double and triple first ray osteotomies. Foot Ankle Int 1999;20:762-770. Coughlin MJ: Hallux valgus. Instr Course Lect 1997;46:357-391.

DISCUSSION: The Level 2 study by Czisy et al is a review of a randomized trial database that analyzed the prospective clinical outcome of 45 patients who failed closed or open treatment of a displaced intraarticular calcaneal fracture. The cohort underwent a subtalar fusion by distraction bone-block arthrodesis for subtalar arthritis. They found that male worker's compensation patients who participate in heavy labor work with a fracture pattern with Böhler angle less than 0 degrees were the most likely to undergo a subtalar fusion. The meta-analysis by Randle et al reviewed 6 clinical studies comparing the results of operative vs. conservative management of calcaneal fracture studies. They found a trend for nonoperatively treated patients to have a higher risk of experiencing severe foot pain than did operatively treated patients, however they could not draw any definitive conclusions guiding treatment.

DISCUSSION: A Jones fracture occurs at the metaphyseal-diaphyseal junction of the fifth metatarsal. It is often an acute fracture in conjunction with a chronic stress-related injury. It requires either a short leg cast with strict non-weight-bearing or surgical fixation. In the high performance athlete, the need for rapid return to sport activity usually requires surgical intervention, most commonly with an intramedullary screw.

The radiograph shows advanced changes in the medial tibial growth plates. The metaphyseal-diaphyseal angle is more than 20 degrees. With these advanced changes, an osteotomy is indicated. Waiting will allow the problem to increase. Bracing (KAFO or night bar) has not been shown effective in advanced Blount disease.

DISCUSSION: When a lateral condylectomy alone is performed for all bunionette deformities, a high recurrence rate is expected. Lateral condylectomy should be used alone when the primary deformity is an enlarged lateral condyle of the fifth metatarsal head. In cases with significant divergence of the fifth metatarsal shaft in relationship to the fourth metatarsal shaft or with lateral bowing of the distal fifth metatarsal shaft, the lateral fifth metatarsal prominence will not be effectively reduced and recurrent symptoms and deformity are expected.

DISCUSSION: 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.

DISCUSSION: The lateral calcaneal nerve is a branch of the sural nerve that runs along the lateral border of the Achilles tendon to innervate the lateral heel pad. Ankle arthroscopy involves posterior portals that hug the Achilles tendon to avoid the main trunks of the sural nerve and tibial nerve; however, the lateral calcaneal branch remains potentially vulnerable. The first branch of the lateral plantar nerve is actually a medial structure that partially innervates the plantar fascia and the abductor digiti quinti. The deep peroneal nerve is anterior to the ankle.

DISCUSSION: While other surgeries have provided some success, first metatarsophalangeal joint arthrodesis has the highest overall success rate compared to other surgeries in ambulatory and nonambulatory children with cerebral palsy. The recurrence rate is unacceptably high with the other procedures listed above. In contrast, neurologically normal children are amenable to osteotomies and soft-tissue procedures.

DISCUSSION: The structure labeled “A” is a peroneus quartus, a supernumerary muscle arising most commonly from the peroneus brevis. The presence of peroneus quartus is not uncommon, with an incidence of up to 21%, and is associated with lateral ankle pain and peroneal tendon symptoms, theoretically as a result of mass effect within the peroneal tendon sheath.

DISCUSSION: The girl shows clinical features of hereditary motor sensory neuropathy type 1, Charcot-Marie-Tooth disease. The most common type of this autosomal-dominant disease is due to an underlying defect in the gene coding for peripheral myelin protein-22 on chromosome 17. Many other less common mutations have been identified in this family of neuropathies. Dystrophin is a protein that is abnormal in Duchenne’s muscular dystrophy, which affects males and is diagnosed earlier. Type I collagen is defective in osteogenesis imperfecta. Alpha-L-iduronidase is defective in mucopolysaccharidosis type I, Hurler’s syndrome. Defective cartilage oligomeric matrix protein is associated with some forms of multiple epiphyseal dysplasia.

DISCUSSION: The TcPO2 measures the O2 delivering capacity of the local vasculature. Values above 40 mm Hg have been shown to correlate with positive healing potential. The hemoglobin A1c is a good indicator of long-term glucose levels; however, it has no direct correlation with wound healing potential. Serum albumin is an indirect measure of nutritional status, and deficiencies in nutrition must be addressed before any surgery. Adequate hemoglobin levels are also necessary to promote adequate oxygenation to the amputation site. The ankle-brachial index may be falsely elevated as a result of calcified vessels in patients with diabetes mellitus. REFERENCES: Wyss CR, Harrington RM, Burgess EM, et al: Transcutaneous oxygen tension as a predictor of success after amputation. J Bone Joint Surg Am 1988;70:203-207. Dwars BJ, van den Broek TA, Rauwerda JA, et al: Criteria for reliable selection of the lowest level of amputation in peripheral vascular disease. J Vasc Surg 1992;15:536-542.

DISCUSSION: Based on the radiographic findings, the patient has a metallic foreign body in her foot that is consistent with a needle. She has local infection secondary to the continued presence of the foreign body. CT is not necessary to localize the foreign body as it is adequately visualized on the plain radiographs. The infection cannot be adequately treated until the foreign body is removed. Attempted removal of foreign bodies without proper anesthesia and fluoroscopy frequently results in frustration because of the inability to localize the foreign body. Removal in a surgical suite with proper anesthesia and fluoroscopy is the preferred option. Once the foreign body is removed, the local infection will resolve rapidly. REFERENCES: Combs AH, Kernek CB, Heck DA: Orthopedic grand rounds: Retained wooden foreign body in the foot detected by computed tomography. Orthopedics 1986;9:1434-1435. Markiewitz AD, Karns DJ, Brooks PJ: Late infections of the foot due to incomplete removal of foreign bodies: A report of two cases. Foot Ankle Int 1994;15:52-55.

Arthrodesis of any of the ankle or hindfoot joints should be reserved for fixed deformities or end-stage degenerative arthritis. Achilles tendon lengthening is necessary to correct the equinus and to improve dorsiflexion-plantar flexion balance. Similarly, transfer of the posterior tibialis tendon reduces both plantar flexion and inversion torque.

DISCUSSION: The patient will continue to have pain secondary to the ankle arthrosis with both the UCBL and the molded articulated ankle-foot orthosis. The total contact orthotic does not provide enough hindfoot control to support the progressive collapse of the ankle into valgus positioning. A molded leather gauntlet will not only control tibiotalar motion but also control hindfoot motion and allow support of the longitudinal arch. REFERENCE: Augustin JF, Lin SS, Berberian WS, et al: Nonoperative treatment of adult acquired flat foot with the Arizona brace. Foot Ankle Clin 2003;8:491-502.

The dorsomedial cutaneous nerve of the hallux, which is a distal branch of the superficial peroneal nerve, supplies sensation to the skin on the dorsal and medial half of the hallux and may be injured during a chevron bunionectomy.