The history of patients with chronic ankle pain should be thoroughly investigated. The patient may report (1) isolated or recurrent ankle sprains; (2) pain during normal or sustained activities; (3) giving way of the ankle; and (4) locking or catching. Associated swelling, stiffness, and weakness about the ankle are also common. Symptoms are typically exacerbated by prolonged weight-bearing or high-impact activities such as running or jumping sports.

Physical examination to evaluate medial and lateral instability should include (1) inversion stress test; (2) eversion stress test; and (3) the anteroposterior stress test (anterior drawer sign). Special tests for the evaluation of syndesmosis injuries include (1) the squeeze test; (2) the external rotation stress test; (3) the fibula translation test; (4) the Cotton test; (5) the crossedleg test; and (6) the stabilization test. The stabilization test is performed by tightly applying several layers of 5 cm athletic tape just above the ankle joint to stabilize the distal syndesmosis. The patient is then asked to stand, walk, and perform a toe raise and jump. The test result is positive if these maneuvers are less painful after taping. This test is particularly useful to confirm diagnosis during the subacute or chronic phase of injury, once acute swelling and pain have subsided. All of the stress tests cited must clearly demonstrate a significant difference between the affected and normal ankles before they can be considered diagnostic.

The flexion-extension range of motion must be evaluated as well, in order to exclude anterior or posterior impingement. Joint effusion and localized tenderness over the joint line may indicate intrarticular disorders (ossicles, loose bodies, osteochondral lesions [OCLs], arthritis, etc.). The foot alignment evaluation is mandatory and some deformities (i.e., hindfoot varus, first ray plantar flexion, and midfoot cavus) may predispose to recurrent sprains.

A correct work-up must include plain radiographs with weight-bearing anteroposterior, lateral, and mortise views of both ankles. Stress radiographs may be useful to confirm the diagnosis, but are not mandatory. MRI evaluation is essential in demonstrating ligament injury signs (ligament swelling, discontinuity, a lax or wavy ligament, and nonvisualization) and associated causes of ankle pain (chondral injury, bone bruising, radiographically occult fractures, sinus tarsi injury, periarticular tendon tears, and impingement syndrome) (Fig. 92.1).

Intra-articular pathology is a common finding in chronic ankle instability (Table 92.1), and the main role of arthroscopy is found here in diagnosing and treating these conditions.

The accuracy of arthroscopy in diagnosing ankle pathologies associated with lateral instability has been reported by many authors. A recent investigation by Hintermann et al. (6) demonstrated the sensitivity of arthroscopy in diagnosing abnormalities in the chronically unstable ankle. In their study, 148 patients with chronic ankle instability (>6 months) underwent arthroscopic evaluation. All structural changes were noted and compared with the original diagnosis as assessed by standardized physical exam and imaging. Arthroscopy demonstrated that over 50% of the cases had cartilage lesions of the talus, whereas the preoperative diagnosis was made in only 4% of the patients. Arthroscopic examination also revealed cartilage lesions of the tibial pilon (8%), medial malleolus (11%), and lateral malleolus (2.5%) that were not identified preoperatively. Furthermore, arthroscopic examination provided a more sensitive means to diagnose medial and rotational instability as well as visualize synovitis. Similar findings were seen in Kibler’s (10) study of 44 patients (46 ankles) who underwent a modified Broström procedure to repair the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) in chronically symptomatic ankles. Arthroscopy identified intra-articular pathology in 38 (83%) of the 46 ankles. Preoperative diagnosis of intra-articular pathologies based on physical exam was made in only 28 (60%) cases.