Risk factors for progressive cartilage loss in the knee

Objective. To evaluate the rate of progression of cartilage loss in the knee joint using magnetic resonance imaging (MRI) and to evaluate potential risk factors for more rapid cartilage loss. Methods. We evaluated baseline and followup MRIs of the knees in 43 patients (minimum time interval of 1 year, mean 1.8 years, range 52-285 weeks). Cartilage loss was graded in the anterior, central, and posterior regions of the medial and lateral knee compartments. Knee joints were also evaluated for other pathology. Data were analyzed using analysis of variance models. Results. Patients who had sustained meniscal tears showed a higher average rate of progression of cartilage loss (22%) than that seen in those who had intact menisci (14.9%) (P less than or equal to 0.018). Anterior cruciate ligament (ACL) tears had a borderline significant influence (P less than or equal to 0.06) on the progression of cartilage pathology. Lesions located in the central region of the medial compartment were more likely to progress to more advanced cartilage pathology (progression rate 28%; P less than or equal to 0.003) than lesions in the anterior (19%; P less than or equal to 0.564) and posterior (17%; P less than or equal to 0.957) regions or lesions located in the lateral compartment (average progression rate 15%; P less than or equal to 0.707). Lesions located in the anterior region of the lateral compartment showed less progression of cartilage degradation (6%; P less than or equal to 0.001). No specific grade of lesion identified at baseline had a predilection for more rapid cartilage loss (P less than or equal to 0.93). Conclusion. MRI can detect interval cartilage loss in patients over a short period (<2 years). The presence of meniscal and ACL tears was associated with more rapid cartilage loss. Cartilage lesions located in the central region of the medial compartment showed more rapid progression of cartilage loss than cartilage lesions in the anterior and posterior portions of the medial compartment. The findings in this study suggest that patients entering clinical trials investigating antiarthritis regimens may need to be randomized based on location of the lesion.