Meniscal subluxation: association with osteoarthritis and joint space narrowing

Objective: Since complete meniscectomy leads to knee OA, we investigated th e potential links among meniscal subluxation, joint space narrowing and sym ptomatic OA. Materials and methods. 233 cases with symptomatic knee OA and 58 asymptomat ic controls underwent radiography and MR imaging of the knee. Joint space n arrowing was measured on weight-bearing PA fluoroscopy-positioned radiograp hs. The amount of medial or lateral meniscal subluxation was measured on co ronal MR images. The prevalence and severity of meniscal subluxation was co mpared in cases and controls. We evaluated the correlation of the degree of meniscal subluxation with joint space narrowing, Kellgren and Lawrence gra de, and two major risk factors for the development of OA, age and weight. Results: Cases had more medial and lateral subluxation than controls. Mean medial meniscal subluxation was 5.1 mm in cases and 2.8 mm in controls (P=0 .001). Modest degrees of meniscal subluxation were common in both cases and controls: 81% of cases and 64% of controls had greater than or equal to 3 mm of subluxation; age and gender adjusted (P=0.006). Severe degrees of sub luxation were almost unique to OA cases (e.g. prevalence of greater than or equal to 7 mm, 35% cases vs. 7% controls, P<0.001). Among controls, severe degrees of subluxation were present only in those with radiographic joint space narrowing (defined as greater than or equal to grade 1 narrowing on a 0-3 scale). In cases, there was a strong correlation between the degree of medial meniscal subluxation and the severity of medial joint space narrowi ng (r=0.56, P=0.0001). Similar results were present in the lateral compartm ent. Meniscal subluxation did not correlate with age or weight. Conclusion: Meniscal subluxation is highly associated with symptomatic knee OA. In subjects with osteoarthritis, increasing meniscal subluxation on MR correlates with the severity of joint space narrowing. (C) 1999 OsteoArthr itis Research Society International.