8. Foot and Ankle MCQs

DISCUSSION: Osteochondral fractures involving the talar dome have been classified based on radiographic and MRI findings. A nondisplaced and incomplete fracture may be treated effectively with a short leg cast and no weight bearing for 6 weeks. This patient has a complete, separated, and displaced osteochondral fragment involving the midlateral talar dome that will most likely cause pain, mechanical symptoms, and effusion if treated nonsurgically. In addition, there is very little bone remaining on the fragment, making the likelihood of healing with open reduction and internal fixation problematic. The treatment of choice includes arthroscopy, removal of the loose fragment, curettage or drilling of the base, and a rehabilitation program that emphasizes peroneal strengthening, range of motion, and proprioceptive training. REFERENCES: Lutter LD, Mizel MS, Pfeffer GB (eds): Orthopaedic Knowledge Update: Foot and Ankle. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 205-226. Baker CL, Morales RW: Arthroscopic treatment of tranchondral talar dome fractures: A long-term follow-up study. Arthroscopy 1999;15:197-202.

DISCUSSION: Isolated Lauge-Hansen supination-external rotation-type ankle fractures comprise 20% to 40% of ankle fractures and nonsurgical management is effective for managing SER-2 ankle fractures. Tornetta and associates recently showed that medial ankle tenderness, ecchymosis, and swelling are not reliable findings when trying to determine deltoid competence. Stress radiographs showing a medial clear space of greater than 4 mm or one that is also 1 mm greater than the superior joint space, or any lateral talar subluxation are indicative of deltoid incompetence and indicative of a SER-4 ankle fracture.

DISCUSSION: Brachymetatarsia is a congenital hypoplasia of one or more metatarsals. Shortening of the fourth metatarsal is the most common form of brachymetatarsia and is often bilateral. Taping and manipulative reduction attempts are ineffective, and extensor tenotomy and capsulotomy are not likely to sufficiently correct the deformity. Fusion or metatarsal lengthening result in complications and generally are not indicated. Shoe modifications, such as extra-depth or extra-wide shoes, generally will improve symptoms. If pressure and trauma persist in the older child, metatarsal lengthening or amputation may be indicated.

All of the portals listed pose risk for some structures. Because they have been shown to be the safest, the most common anterior portals are the anteromedial and the anterolateral. The safest posterior portal is the posterolateral portal. Because of the location of the posterior medial tendons and the neurovascular bundle, the posteromedial portal is at highest risk for serious complications.

The child has Kohler’s disease. This is a self-limiting osteochondritis of the navicular. It is treated symptomatically with initial cast immobilization for 6 to 12 weeks, followed possibly by orthotic management. Findings shown in the radiograph usually will normalize within 1 year, and there are no long-term sequelae.

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.

DISCUSSION: Necrotizing fasciitis is an aggressive and rapidly spreading soft-tissue infection, usually caused by group A beta-hemolytic Streptococcus pyogenes. Presentation is typical of a rapidly ascending cellulitis, recalcitrant to antibiotic treatment. Differentiation between cellulitis and impetigo is difficult, and success depends on a high level of suspicion. The skin and subcutaneous tissues are affected, with sparing of the muscles. Septic shock and multi-organ system failure can be fatal. Treatment is aggressive surgical debridement with broad-spectrum antibiotics. Repeat irrigation and debridement may be necessary. Hyperbaric oxygen studies have shown inconsistent results.

Patients with painful progressive hallux valgus are surgical candidates. Presurgical evaluation includes radiographic examination. The IMA between the first and second metatarsals as well as the HVA must be measured. If the IMA is smaller than 15 degrees and the HVA is smaller than 35 degrees, a distal osteotomy is preferred. Distal soft-tissue reconstruction is only useful for IMAs smaller than 11 degrees and HVAs smaller than 25 degrees. Proximal osteotomies and the Lapidus bunionectomy are reserved for larger hallux valgus deformities with IMAs exceeding 15 degrees and HVAs exceeding 35 degrees.

The longitudinal arch is stabilized by heavy ligamentous structures surrounding the tarsal joints with passive assistance from the plantar aponeurosis. EMG studies have shown little or no intrinsic muscle activity during quiet standing.

The procedure shown is subtalar arthroereisis. It is used as an adjunct spacer/distractor following tarsal coalition excision if hindfoot valgus remains following resection.In the pediatric population, arthroereisis is one option to restore the alignment of the hindfoot after talocalcaneal coalition. Hindfoot deformity correction is required because resection of the coalition alone will often increase the hindfoot valgusdeformity. The arthroereisis implant prevents this valgus collapse. Another alternative to correct the hindfoot valgus deformity is a calcaneal lateral column lengthening osteotomy.Khoshbin et al. reviewed the long-term outcomes of coalition resection in 24 patients (32 coalitions). Resected talocalcaneal (TC) coalitions had less inversion/eversion postoperatively than resected calcaneonavicular (CN) coalitions but there was no difference in outcome scores. They obtained favorable results when even resecting talocalcaneal coalition with >50% involvement of the middle facet and hindfoot valgus angles >16 °, which were considered historical contraindications to resection.Zaw et al. reviewed tarsal coalitions. Radiographic signs of CN coalition include the anteater sign (elongated anterior calcaneal process), decreased CN gap, reverse anteater sign (elongated lateral navicular) and hypoplastic lateral talar head. Radiographic signs of TC coalition include obliterated middle facet on a Harris view (osseous coalition), irregular cortices/dysplastic sustentaculum tali on a Harris view (nonosseous), C-sign on a lateral view, talar beaking, short talar neck with concave inferior surface, narrow posterior facet, and non-visibility of the middle facet.Giannini et al. reviewed subtalar arthroereisis with coalition resection in 14 feet in patients aged 9-18 years. They achieved 57% excellent, 21% good and 21% fair results. Regarding pain, 86% had improvement and 14% had no change. Regarding ROM, 93% had improvement, and 7% had no change. Better scores were seen in patients <14 years.Figure A shows the implantation of an arthroereisis implant in the sinus tarsi. Illustration A comprises coronal CT images of talocalcaneal coalition.Incorrect Answers:

DISCUSSION: The patient has a malunion of an attempted open reduction of a Lisfranc dislocation. The pain occurs during the terminal stance phase of gait as load is being transferred from the hindfoot to the forefoot. The bending moment can be best neutralized with shoe modification with a cushioned heel and rocker sole, which best unloads the tarsal-metatarsal junction.

DISCUSSION: 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. REFERENCES: Chao W, Wapner KL, Lee TH, et al: Nonoperative management of posterior tibial tendon dysfunction. Foot Ankle Int 1996;17:736-741. Imhauser CW, Abidi NA, Frankel DZ, et al: Biomechanical evaluation of the efficacy of external stabilizers in conservative treatment of acquired flat foot deformity. Foot Ankle Int 2002;23:727-737.

SMA is caused by a deficiency in SMN protein. Deficiency of SMN protein leads to progressive loss of anterior horn cells and progressive muscle weakness. The severity of disease is directly related to the amount of reduction in circulating levels of SMN proteins, which are encoded by 2 alleles of the SMN1 gene and multiple copies of the SMN2 genes on chromosome 5. Affected patients with all types of SMA will have functional loss of both SMN1 genes, so this does not differentiate disease severity. Disease severity depends on the number of functional copies of SMN2 that remain. Patients with SMA1 have only 1 functioning SMN2 gene, whereas the milder forms, SMA types 2 and 3, have multiple copies that produce higher levels of SMN protein. The other choices are not associated with spinal muscular atrophy. Defects in PMP22 are the cause of 70% to 80% of cases of Charcot-Marie-Tooth disease. Mutations in the dystrophin gene cause Duchenne muscular dystrophy.

DISCUSSION: Ankle sprains most commonly involve injury to the lateral collateral ligaments of the ankle (anterior talofibular, posterior talofibular, and calcaneofibular) from an inversion mechanism of injury. A different entity has been more recently described that involves an external rotation mechanism of injury that widens the ankle mortise and disrupts the anterior inferior tibiofibular ligament. Deltoid ligament and extensor retinaculum injuries do occur, although infrequently, and involve eversion and extreme plantar flexion mechanisms, respectively.

DISCUSSION: The MRI scan shows a rupture of the Achilles tendon. The substantiated advantages of repair are less risk of re-rupture and greater plantar flexion strength. Dorsiflexion strength is not influenced. Motion, pain, and period of recovery are not specifically improved as a consequence of surgery.

The radiograph shows a displaced calcaneal beak fracture, a tongue-type fracture variant. The fracture fragment typically includes the insertion point of the Achilles tendon, which places marked tension on the thin overlying soft-tissue envelope and can lead to full-thickness necrosis if not acutely addressed. Cast immobilization does not adequately address the increased soft-tissue tension, as the fragment will be difficult to control. Arthroscopic-assisted techniques or primary arthrodesis are not indicated because calcaneal beak fractures are typically extra-articular.

A 38-year-old woman underwent left knee anterior cruciate ligament (ACL) reconstruction with patellar tendon autograft and medial meniscus repair 11 years ago. She has no complaints of instability since surgery. She presents with left knee pain, swelling and the inability to extend her knee after getting up from a kneeling position one week prior. She reports feeling a pop in her knee at the time of injury. On examination she lacks 5° of extension and has a symmetric Lachman test. Figure 1 is the radiograph of her knee. Figures 2 through 4 show the findings at the time of arthroscopy. What is the most appropriate treatment?

This deformity is early in the disease process. The foot is still flexible, as evidenced by correction with the Coleman block test. A simple dorsiflexion osteotomy of the first metatarsal should provide a plantigrade foot. More complex osteotomies are required later in the disease process when the foot is not flexible and the deformity does not correct with the Coleman block test. The patient may also require a tibialis anterior transfer later in the disease process but not at the present time.

Nonsurgical care for hallux rigidus involves limiting the motion of the first metatarsophalangeal joint during toe-off and ensuring that there is a deep enough toe box to accommodate dorsal osteophytes. A rigid shank or forefoot rocker both help to reduce the forces of extension during toe-off.