Purpose: The goal of the study was to analyze the impact of the pre-operative bone mineral density on the patients' reported outcomes at two year minimum follow-up of cementless THA using a proximally fixed anatomic stem.
Methods: A prospective study included all patients who underwent a cementless THA using a specific proximally fixed anatomic stem and a 3D preoperative CT scan-based planning. The bone mineral density (BMD) of the metaphyseal cancellous bone was computed in a volume (of 1 mm thick and of 1 cm2 surface) at the level of the calcar 10 mm above the top of the lesser trochanter. Patients were assessed at two year follow-up using self-administered auto-questionnaires corresponding to the modified Harris (mHHS), the Oxford (OHS), and the Forgotten Hip (FHS) scores. A multiple linear regression statistical analysis was performed to assess the link between the mHHS, the age, body mass index (BMI), BMD, gender, and ASA grade.
Results: Fifty patients were included (29 men, 21 women), with an average age of 62 ± 12 years and an average BMI of 27 ± 5 kg/m2. At two year follow-up, on multivariate analysis, excellent mHHS (≥ 90%) was significantly associated with only two parameters: a BMI ≤ 25 kg /m2 with an odd ratio OR = 10 (CI95% [2.1-48.3], p = 0.004) and a BMD ≥ 72 mg/cm3 with an odd ratio OR = 4.87 (CI95% [1.2-18.6], p = 0.02).
Conclusion: The short-term PROMs after cementless THA are impacted by pre-operative cancellous bone density. However, the BMI remains the most influential parameter on the clinical outcomes.
Keywords: Anatomic stem; Bone mineral density; Hip arthroplasty; Patient-reported outcomes; Proximal fixation.