Influence of broach surface design of a fully hydroxyapatite coated, double tapered stem on periprosthetic bone mineral density after total hip arthroplasty: a study based on the morphology of the proximal femur.

Introduction: This study aimed to compare the impact of different broach surface designs on post-operative clinical outcomes, bone reactions and changes in bone mineral density (BMD) in patients who underwent total hip arthroplasty (THA) using a fully hydroxyapatite coated and double tapered stem with either compaction shape (COM) or hybrid shape (HYB) broaches.

Materials And Methods: A retrospective analysis was conducted on 76 patients (100 hips) who underwent primary THA using the Avenir complete stem®. Patients were divided into two groups: the COM broach group (50 hips) and HYB broach group (50 hips). We evaluated clinical outcomes using the Japanese Orthopaedic Association hip scores one month before the surgery, and 12 and 24 months after the surgery. Radiographic findings, including stem alignment angles, radiolucent lines, spot welds, and cortical hypertrophy, were assessed. BMD around the stem in Gruen zones 1-7 was evaluated using dual-energy X-ray absorptiometry (DEXA) at 7 days, 12, and 24 months post-operatively. The Dorr classification was used to assess femoral morphology.

Results: There were no significant differences in clinical outcomes, radiographic findings, or BMD changes between the COM and HYB broach groups in the overall patient cohort. However, in Dorr type A femurs, the COM broach group demonstrated superior BMD superior preservation in zones 1 and 7 after 12 months and in zones 1, 6 and 7 after 24 months. Additionally, in Dorr type B femurs, significant BMD preservation was observed in zone 3 at 24 months in the COM broach group.

Conclusions: This study suggests that the broach surface design of fully hydroxyapatite coated stems may influence periprosthetic BMD changes, especially in Dorr type A and B femurs. Surgeons should consider broach selection based on patient-specific femoral morphology to optimize BMD preservation in THA procedures using fully hydroxyapatite coated stems.