# Effect of Hydroxyapatite Augmentation on Femoral Lag Screw Insertion in Intertrochanteric Femoral Fractures in the Elderly: A Biomechanical Study

## TL;DR

This study found that hydroxyapatite augmentation improves lag screw fixation in elderly patients with femoral fractures.

## Contribution

The study demonstrates that hydroxyapatite improves screw fixation in osteoporotic bone, offering a novel augmentation technique.

## Key findings

- HA augmentation significantly increased the TMax/f-BMD ratio compared to the non-HA group.
- No significant differences in bone mineral density or maximum torque were found between groups.
- The correlation between bone density and torque remained strong in both groups.

## Abstract

Background: This study aimed to investigate the effect of hydroxyapatite (HA) augmentation on the maximum lag screw insertion torque (TMax) using extracted human femoral heads.

Materials and methods: Hemispherical femoral heads extracted from patients who underwent bipolar hip arthroplasty were used. These samples were divided into the HA treatment group (HA group) and the non-HA treatment group (N group). After drilling, HA was inserted into the femoral heads in the HA group. A lag screw was inserted into the femoral head using a dedicated jig in both groups. The bone mineral density of the uninjured contralateral femoral neck (f-BMD), TMax, and the TMax/f-BMD ratio were evaluated.

Results: Twenty-seven samples were analyzed in this study: 14 samples in the HA group and 13 samples in the N group. No significant differences were observed in f-BMD and TMax between the two groups (HA: 0.49 ± 0.11 vs. N: 0.48 ± 0.092 g/cm2, p = 0.90; HA: 5.6 ± 1.9 vs. N: 4.3 ± 1.9 N･m, p = 0.78). Considering bone mineral density, the HA group showed a significantly higher TMax/f-BMD ratio than the N group (11.7 ± 3.3 vs. 8.9 ± 3.2 N･m･cm2/g, p = 0.036). Correlation coefficients between f-BMD and TMaxin both groups were moderately strong (r = 0.50 vs. 0.50).

Conclusion: Our results suggest that HA augmentation improves lag screw fixation strength in the treatment of osteoporotic intertrochanteric femoral fractures.