Prevalence of labral tears and cartilage loss in patients with mechanical symptoms of the hip: evaluation using MR arthrography.

OBJECTIVE: To determine the prevalence of labral tears and cartilage lesions in patients with mechanical symptoms of the hip using magnetic resonance (MR) arthrography.

METHODS: A total of 100 patients with mechanical symptoms of the hip such as pain, clicking, locking and giving way underwent MR arthrography of the hip to rule out a labral tear. Hip joints were evaluated for labral alterations, bone marrow edema (BME), and other pathology using a novel semi-quantitative scoring system. Cartilage changes were graded separately for the acetabulum and femoral head in the anterior, posterior, central, medial, and lateral hip joint regions (10 locations) on a 6-point scale: 0=normal; 1=signal heterogeneity; 2=fissuring, 3=thinning <50% of the normal thickness; 4=thinning >50% of the normal thickness; 5=full thickness cartilage loss. Labral tears were categorized into normal, intrasubstance degeneration, simple tear or complex tear with two or more tear regions. Statistical methods were contingency tables, Fisher's exact test for discrete outcomes (based on grade scores), Spearman's rank correlation (r) and t tests for continuous outcomes, using pooled and stratified analyses.

RESULTS: On MR arthrography, labral tears were found in 66 patients (66% prevalence) with 13 having more than one location involved. Locations were 19 lateral (13 simple, six complex), 54 anterior (39 simple, 15 complex), eight posterior (six simple, two complex). Cartilage lesions were found in 76 patients (76% prevalence) with 53 demonstrating involvement of more than one compartment. The most common finding was cartilage thinning <50% in 99 regions in 44 patients. Cartilage thinning >50% was shown in 34 patients in 67 areas. When we correlated the grade of cartilage abnormality with the grade of labral tear, we found a statistically significant correlation (r=0.29; P< or =0.01). The size of cartilage abnormality was correlated with the grade of labral tear in the lateral acetabulum (r=0.38; P<0.001), anterior acetabulum (r=0.22; P< or =0.002), and lateral femoral head (r=0.29; P< or =0.004). The grade of cartilage loss was correlated with the grade of BME (r=0.44; P< or =0.001).

CONCLUSION: Labral tears and cartilage loss are common in patients with mechanical symptoms in the hip. Cartilage loss, labral tears and BME appear interrelated and may represent important risk factors that may affect the development and progression of osteoarthritis in the hip joint.