Predicting Severe Cartilage Damage in the Hip: A Model Using Patient-Specific Data From 2,396 Hip Arthroscopies

Abstract

Purpose: To determine patient-specific factors that can be used to predict the presence of severe articular cartilage damage in the hip in patients without osteoarthritis.

Methods: The prevalence of severe (Outerbridge grade III or IV) cartilage damage to the acetabulum and femoral head was prospectively recorded at hip arthroscopy. Patients who underwent primary hip arthroscopic surgery between 2006 and 2016 performed by a single surgeon were included. Patients were excluded if they underwent previous hip surgery, had poor-quality radiographs, were younger than 16 years at the time of surgery, or had a minimal joint space of 2 mm or less. The relation between severe cartilage damage and preoperative patient characteristics was examined using multivariable logistic regression analysis with restricted cubic splines.

Results: Of the 2,396 hips presenting for hip arthroscopy, 995 (41%) had severe cartilage damage to the acetabulum and 257 (11%) had severe cartilage damage to the femoral head. Older age was a significant risk factor for severe cartilage damage both to the acetabulum (χ² = 69.5, P < .001) and to the femoral head (χ² = 53.9, P < .001). An age of 45 years was associated with a 1.96 (95% confidence interval, 1.54-2.49) increase in the odds of severe acetabular cartilage damage and a 3.94 (95% confidence interval, 2.61-5.94) increase in the odds of severe femoral head cartilage damage relative to an age of 20 years. Male sex was associated with severe cartilage damage to the acetabulum (χ² = 66.7, P < .001), and a lower center-edge angle was a significant risk factor for severe cartilage damage to the femoral head (χ² = 78.5, P < .001). Predictive nomograms were established for severe cartilage lesions.

Conclusions: The primary risk factors for severe hip cartilage damage were older age for both the femoral head and acetabulum; a lower center-edge angle and larger Tönnis angle for the femoral head; and male sex, body mass index, alpha angle, and joint space for the acetabulum. The likelihood of cartilage damage to the hip can be estimated clinically using a prediction nomogram.

Level of evidence: Level III, cross-sectional study.