Long-term Prognosis of Early-stage Medial Osteoarthritis with Chronic Lateral Ankle Instability

Purpose: Despite the consensus regarding the correlation between chronic ankle instability and osteoarthritis, there is a lack of information on the pattern and frequency of degenerative changes, and the treatment options for preventing progressive osteoarthritis.This study evaluated the long-term prognosis after operative and conservative treatments for early-stage medial osteoarthritis accompanied by chronic lateral ankle instability.Materials and Methods: Among the patients with chronic ankle instability and osteoarthritis of Takakura grade 2, 44 patients who underwent the modified Broström procedure and 62 patients with conservative treatment were analyzed with follow-up ≥8 years.The clinical outcomes were evaluated using the Foot and Ankle Ability Measure (FAAM) and visual analog scale for ankle pain during walking.The progression of osteoarthritis was evaluated with periodic weightbearing radiographs.The correlation between the clinical outcome measures and the presence of progressive osteoarthritis was analyzed.Results: The FAAM score improved from an average of 48.5 preoperatively to 83.8 points at the final follow-up in the surgical group (p<0.001),while the conservative group showed a trend toward clinical improvement with no significant difference (p=0.245).No significant difference in daily living ability of FAAM was observed between the two groups, but the surgical group (79.1 points) showed a better score than the conservative group (67.2 points) in sports ability (p<0.001).The Takakura grade of osteoarthritis progressed in six patients (13.6%) in the surgical group and 10 patients (16.1%) in the conservative group (p=0.753).Significant correlations were observed between the FAAM score and Takakura grade in both groups (r=-0.78,-0.61; p<0.001).Conclusion: Patients who received lateral stabilizing surgery and conservative treatment for early-stage medial osteoarthritis accompanied by chronic ankle instability showed comparable long-term clinical outcomes, but the surgical group showed better sports ability than the conservative group.Both groups showed a similar frequency of progression of osteoarthritis over a mean follow-up of 10.5 years.