Background: Prolonged lateral instability of the ankle after ligament injury has been believed to be a major cause of osteoarthritis of the ankle, yet the rate of development of osteoarthritis of the ankle is relatively low. Clarifying the relationship between patient factors and chondral damage of the ankle with prolonged instability is essential to identify the important risk factors underlying osteoarthritis of the ankle.

Methods: Arthroscopic examination was performed to assess the condition of the articular cartilage in a series of patients with prolonged lateral instability of the ankle. There were ninety-three patients with ninety-nine involved ankles. Their mean age was 28.7 years (range, fifteen to fifty-nine years). The relationships between the severity of the chondral damage and patient factors, the number and combination of torn ligaments, and mechanical instability and alignment of the ankle mortise were studied.

Results: Twenty-three ankles were classified as grade 0 (normal cartilage); thirty-five, as grade 1 (superficial softening, fibrillation, or fissuring of the cartilage); twenty-four, as grade 2 (a cartilage defect without exposure of the subchondral bone); and seventeen, as grade 3 (exposure of the subchondral bone). Patient age, the talar tilt angle, and varus inclination of the ankle plafond were significantly associated with more severe chondral changes.

Conclusions: Patient age, the talar tilt angle, and varus inclination of the ankle are risk factors for severe chondral damage of the ankle in patients with a prolonged history of lateral ankle instability.

Level of Evidence: Prognostic Level IV. See Instructions to Authors for a complete description of levels of evidence.