Background: Osteoporosis and hip osteoarthritis (HipOA)/ hip replacement (THR) often coexist. Hip DEXA provides an opportunity to screen patients for HipOA. In The Busselton Healthy Ageing Study, baseline May 2010 and December 2015), 5107 participants (80% of those eligible) were recruited. Baseline bone density (BMD) of both hips was measured. This study aims to identify factors associated with hip replacement.
Methods: Total 145 patients had THR. This cohort was matched with 445 (no THR). Kellgren-Lawrence (KL) HipOA grading was performed (grades 0 to 4). Groups were compared at baseline (means and SD). Correlations between combined KL grades, BMD, and hip replacement status were assessed using Pearson's correlation coefficient and multivariate logistic regression analysis.
Results: Of 590 patients (59.15% male; mean age 59.95±5.16 years, range 47.1-68.9) patients with THR had significantly higher baseline Neck of Femur BMD (1.005 vs 0.941 g/cm2, p<0.001) and higher baseline OA grades (Higher Grade: 1.63 vs 0.93, p<0.001; Composite score: 2.79 vs 1.54, p<0.001). Males had higher OA grades compared to females (Composite score: 1.99 vs 1.65; Higher Grade: 1.17 vs 1.00). The correlation between OA grade and BMD was stronger in females (right hip: r=0.175) than males (r=0.078). The combination of high KL grade (≥2) and low neck of femur BMD (≤0.8 g/cm2) was associated with a 4.5-fold increased risk of hip replacement (OR 4.50, 95% CI 2.61-7.75, p<0.001).
Conclusions: This study identifies combined KL grade and BMD as significant risk factors for hip replacement in middle-aged Australians. Predictive models incorporating both scores on DEXA could help identify high-risk patients, enabling targeted interventions to delay or prevent the need for hip replacement. Future research should focus on developing and validating such models, as well as evaluating the effectiveness of early intervention strategies in reducing hip replacement risk based on baseline DEXA scans.