FRAX score predicts vertebral compression fractures impairing spinal alignment and hip function after total hip arthroplasty: a retrospective cohort study

Background Vertebral compression fractures (VCFs) can impair posture, gait, and daily activities in patients undergoing total hip arthroplasty (THA). However, limited data are available regarding the incidence, risk factors, and impact of VCFs on sagittal spinal alignment following THA. Therefore, the purpose of this study was to investigate the incidence and risk factors of VCFs after THA, and to evaluate their impact on sagittal spinal alignment and clinical outcomes. Methods This retrospective cohort study included 220 patients (243 hips) who underwent primary THA, with a mean follow-up period of 6.1 years. Data collected included patient demographics, Fracture Risk Assessment Tool (FRAX) scores, lumbar bone mineral density measured before THA, sagittal spinal alignment parameters, Harris Hip Score (HHS), and the occurrence of new VCFs. We analyzed changes in spinal alignment and identified risk factors associated with incident VCFs. Results VCFs occurred in 20% of hips during the follow-up period. Patients who developed VCFs demonstrated a significantly increased sagittal vertical axis, reduced lumbar lordosis angle, and lower postoperative HHS compared to those without VCFs. Preexisting VCF and higher preoperative FRAX scores were significantly associated with the development of new VCFs. Multivariate logistic regression analysis identified the FRAX score as an independent predictor of incident VCFs. Conclusions In this 6.1-year retrospective cohort study, 20% of hips developed new VCFs after THA, which were associated with worsened spinal alignment and hip function. The higher FRAX score, calculated prior to THA surgery, is a useful predictor of VCF risk and may help identify individuals who require closer monitoring or preventive interventions during follow-up after surgery.