Osteochondral lesions are associated with a dull ankle pain deep in a location with a prior ankle injury; in some cases, the pain will become chronic.31 Physical exam findings typically include ankle joint effusion with localized tenderness around the joint.31
Ankle radiographs are insensitive for identifying osteochondral lesions, and MRI is recommended for evaluating suspected lesions.29,31 Treatment varies, depending on symptoms and severity. Patients with minimal symptoms may be treated conservatively; however, high failure rates have been reported.32 Surgical treatment depends on the size and site of the lesion and the degree of cartilage injury, and surgical consultation is recommended.31
Fractures of the talar dome (FIGURE 2) may be either medial or lateral and are often the result of inversion ankle injuries.14 History and clinical findings vary depending on the type of fracture.
FIGURE 2
Talar dome injuries often result from inversion ankle injuries
As with osteochondral lesions, ankle radiographs may fail to identify talus fractures. Computed tomography (CT) should be used to evaluate acute fractures of the talus, as CT scan is better able to define displacement, size, and intra-articular involvement.33 Talar fractures may be managed conservatively with immobilization and nonweight-bearing for 4 to 6 weeks, but specialty consultation should be considered.14,33
A tarsal coalition—an incomplete, congenital separation of the bones, occasionally involving the talus and the calcaneus—can also be a cause of persistent pain after a sprain.28 Physical exam typically demonstrates decreased range of motion in the subtalar or transverse tarsal joint. Radiographs may identify the coalition, but MRI or CT scan provides optimal visualization. Immobilization for 6 weeks is the recommended initial treatment, but if that fails, surgical excision or fusion may be necessary.
Peroneal tendon injuries may cause ankle instability
Peroneal tendon injuries, which include strains, subluxation, dislocation, and tears of one or both of the peroneal tendons, are often caused by ankle inversion similar to that of an uncomplicated sprain. Subsequent ankle instability may result from untreated peroneal tendon injuries.34 Peroneal tendon subluxation accounts for a very small number (0.3%-0.5%) of traumatic ankle injuries.35
Peroneal tendon injuries often occur during sports that involve frequent lateral movement or cutting—eg, football, basketball, and soccer—and are often caused by sudden dorsiflexion of the inverted foot, with coincident contraction of the peroneal muscles.36,37 This mechanism can disrupt the superior peroneal retinaculum, leading to recurrent subluxation or dislocation and subsequent ankle instability.36,38 Chronic subluxation can also result in longitudinal tears of the peroneal tendons, especially of the peroneus brevis.36,38,39
Patients with peroneal tendon injuries may report a “pop” at the time of injury. Pain is typically located posterior to the lateral malleolus, and recurrent subluxation is often described as a “snapping” around the lateral ankle during athletic activities.37,38 Instability is common in patients with subacute or chronic peroneal tendon injuries, especially on uneven surfaces.38
Acute peroneal tendon injuries cause posterolateral ankle pain, swelling, and weakness; exam findings include tenderness along the course of the peroneal tendons with associated edema.37 Subluxation or dislocation of the peroneal brevis tendon may be confirmed by placing the foot in plantar flexion and inversion and asking the patient to forcibly dorsiflex and evert the injured ankle.
Plain radiographs are usually normal in an isolated injury to the peroneal tendons. A fracture of the posterolateral margin of the fibula is a rare finding but indicates disruption of the peroneal retinaculum.36 MRI provides the best imaging for peroneal tendons and the stabilizing retinaculum, although a CT scan can provide detailed bony anatomy when subtle fractures are suspected or additional evaluation is needed.
Subluxation or dislocation indicate a need for surgery
Conservative management is recommended for peroneal tendon strains, but surgical treatment is increasingly recommended for subluxation or dislocation, especially if the problem is recurrent.36,37 Conservative treatment consists of short-term immobilization with a walking boot or brace, followed by physical therapy to improve strength and motion. Surgical treatment of subluxation and dislocation by stabilizing the peroneal tendons within the peroneal groove has been shown to provide lasting stability and improvement.37,38,40,41
CORRESPONDENCE Scott Hall, MD, University of Nevada-Reno, Brigham Building 316, Reno, NV 89557; shallmd@specialtyhealth.com