Ankle arthroscopy is a highly effective technique for managing an assortment of intraarticular disorders of the ankle, including ankle osteophytes, and talar osteochondral lesions (1, 2 and 3). The joint is constrained, related to the shape of the articular surfaces and ligaments. In general, ankle arthroscopy is more challenging technically compared to larger joints such as the knee. In the past two decades, advances have been made to the extent that ankle arthroscopy is now a standard operative technique. It is now possible to visualize the entire ankle joint with the use of noninvasive distraction. This also lessens the potential for inadvertent damage to the articular cartilage during the operations and avoids problems associated with the more invasive external fixator distraction using pins in the calcaneus and tibia. The surgical instruments have improved markedly, with small diameter and shorter arthroscopes of higher resolution, designed for smaller joints.

Osteophytes occur most commonly at the anterior margin of the tibia and may cause mechanical joint impingement in ankle dorsiflexion with painful limitation of range of motion. The etiology of anterior tibial osteophytes is not definitively known with some investigators postulating a mechanism of direct trauma to the area, for example, during kicking in soccer, and some suggesting a traction mechanism of injury from forced plantarflexion of the ankle joint (4, 5 and 6). The osteophyte appears on plain radiographs as a beak-like prominence on the anterior tibia and may be accompanied by a talar neck lesion, known as a kissing lesion, which may appear to physically impinge on the anterior tibial osteophyte in ankle dorsiflexion. However, some researchers have suggested that the tibial lesions tend to be more medial in location, sometimes extending down the medial malleolus, and the talar lesions tend to be more laterally located. Therefore, the lateral radiograph may suggest mechanical impingement that may not actually be present. Less commonly, osteophytes may form at the medial malleolus or lateral malleolus. Posterior tibial osteophytes are least common and tend to cause greatest symptoms in the plantarflexed ankle.

The main indication for osteophyte excision is ankle pain attributable to the presence of this lesion, in the absence of other causes of pain such as severe degenerative arthritis, osteochondral lesions of the talus, loose bodies, or soft tissue impingement lesions. Patients may complain of limitation of range of motion of the ankle joint, which is particularly noticeable during stair climbing or squatting, and surgical excision of the osteophyte may allow improved ankle dorsiflexion. However, recovery of motion is not as predictable as diminution of pain after osteophyte excision. A contraindication to performing surgical excision of the osteophyte is significant ankle degenerative arthritis causing diffuse narrowing of the joint or asymmetric bone on bone appearance on plain radiographs. In this case, osteophyte excision will predictably fail because the symptoms are actually due to the arthritic changes rather than the osteophyte.

A comprehensive history and physical examination must be performed for any patient with ankle pain, and the presence of an osteophyte to determine whether the osteophyte itself is responsible for the symptoms or if other abnormalities of the joint must be addressed. Careful evaluation must be performed to differentiate anterior ankle pain arising from a primary ankle joint problem from a subtalar joint condition. A diagnostic injection of local anesthetic into the ankle and subtalar joints at separate times may assist in differentiating pain due to one or both of these joints. Patients with a symptomatic osteophyte complain of pain localized over the osteophyte that usually worsens during activities such as stair or hill climbing, squatting, or running. Occasionally, patients complain of instability or giving way of the joint but do not have objective evidence of ligament laxity. Physical examination must include evaluation of range of motion, alignment, stability, localized swelling, and tenderness over the area of the osteophyte. Passive forced dorsiflexion usually causes increased discomfort in patients with symptomatic anterior tibial osteophytes. Patients may have limited ankle dorsiflexion compared with the normal contralateral ankle. There should be no clinical evidence of joint laxity.

Radiographic evaluation should include routine anteroposterior, lateral, and mortise views (Fig. 33.1). Van Dijk et al. (7) observed that most anterior tibial osteophytes occur asymmetrically on the anterior aspect of the tibia, more on the medial compared with the lateral side. They found that routine lateral radiographs tend to underestimate the size of the osteophyte and suggested a modified radiographic technique to better visualize these lesions (Fig. 33.2). Lateral dorsiflexion stress radiographs may demonstrate impingement of the anterior tibial and talar neck osteophytes.

Scranton and McDermott (8) developed a classification of anterior tibiotalar spurs based on the size of the tibial spur, the presence or absence of a talar spur, and the presence of generalized
degenerative changes within the ankle joint. In type 1, there is synovial impingement, the tibial spur measures less than 3 mm, and there is no talar spur. In type 2, there are osteochondral reaction exostoses, a tibial spur larger than 3 mm, and no associated talar spur. In type 3, there is significant exostosis with tibial and talar spurs. In type 4, there is pantalocrural impingement, and degenerative changes in the ankle joint are present.

The lateral radiograph may be used as a guide to the amount of osteophyte that should be resected surgically. The lateral radiograph is taken with the ankle in neutral position and the angle between the anterior edge of the tibia and the talar neck is determined. This angle should be at least 60° in the normal ankle (Fig. 33.3). The angle decreases to less than 60° with anterior tibial and talar neck osteophytes. Any bony osteophyte projecting anterior to the 60° angle on the lateral radiograph should be resected surgically. Although this method provides a guideline for appropriate resection, arthroscopic visualization of the amount of resection is a better guide.

A computed tomography (CT) scan is usually unnecessary to evaluate these lesions but can be useful for precise localization of a spur if required preoperatively or if there is a concern about other pathology. If used, the CT scan should include thin-section axial images with sagittal and coronal
reconstructions. A bone scan may be helpful in excluding other potential causes of ankle pain, such as an osteochondral lesion of the talus or tibial, and usually shows increased uptake over the area of a symptomatic osteophyte. However, the bone scan has largely been replaced by magnetic resonance imaging (MRI) because it is able to visualize abnormalities both of the bone and soft tissue, which may be contributing to a patient’s pain.

Although anterior tibial osteophytes may be removed using open techniques, arthroscopic surgery has largely supplanted open surgery because it may be performed on an outpatient basis with minimal morbidity while affording a more complete view of the joint than with open surgery.