Factors Associated With Severity of Intra-articular Lesions in Patients With Severe Hip Dysplasia

Purpose: To identify demographic and morphologic factors associated with the severity of intra-articular lesions in patients with severe hip dysplasia.

Methods: One hundred twenty-one patients (134 hips) with symptomatic hip dysplasia were retrospectively reviewed. The cartilage and labral lesions were scored according to the Outerbridge and the original classification systems, respectively. The association of the cartilage and labrum scores with patient demographics (age, gender, body mass index, bilateral hip dysplasia, and treatment history for developmental hip dislocation) and morphologic factors (the lateral center-edge angle, Sharp angle, acetabular index, acetabular head index, acetabular depth ratio, Shenton line disruption, roundness index of the femoral head, and femoral neck shaft angle) were determined using a multiple linear regression analysis.

Results: The cartilage and labral scores were significantly associated with radiographic osteoarthritis; however, these scores showed wide distribution among hips with equivalent degrees of radiographic osteoarthritis. Age (38.4 ± 12.8 years) (P < .001), lateral center-edge angle (0.2 ± 9.0°) (P = .014), acetabular head index (54.4 ± 9.1%) (P = .001), and the roundness index of the femoral head (55.6 ± 4.6%) (P = .022) were identified as independent factors associated with the cartilage score. Age (P < .001), having a medical history of developmental hip dislocation (P = .002), acetabular index (27.8 ± 6.8°) (P = .011), and the roundness index of the femoral head (P = .022) were identified as independent factors associated with the labral score.

Conclusions: Our findings suggest that the morphologic factors responsible for severe intra-articular lesions differ for cartilage degeneration and labral tears in patients with severe hip dysplasia. Decreased acetabular coverage of the femoral head was responsible for cartilage degeneration severity, whereas an increased acetabular index was responsible for labral tear severity.

Level Of Evidence: Level III, diagnostic study.