Effect of hydroxyapatite tubes on the lag screw intraoperative insertion torque for the treatment of intertrochanteric femoral fractures.

Abstract Background Hydroxyapatite (HA) augments are frequently used in orthopedic surgery. However, the effectiveness of HA augments on the treatment of intertrochanteric femoral fractures remains unknown. This study aimed to investigate whether the use of HA tubes affects the intraoperative insertion torque of the lag screw during intertrochanteric femoral fracture surgery. Methods From January 2016 to October 2020, 58 patients with intertrochanteric femoral fractures were included and divided into the HA treatment group (HA group, n = 29) and non-HA treatment group (N group, n = 29). Patients with intertrochanteric femoral fractures were treated using the Gamma3 nail system® with or without two HA tubes. HA tubes were inserted into the femoral head through the lag screw hole before the insertion of the lag screw. The mean and maximum intraoperative insertion torques of the lag screw, bone mineral density (BMD) of the uninjured opposite side femoral neck, and tip apex distance (TAD) of the lag screw on postoperative radiographs were assessed. To assess the loss of reduction after the surgery, we investigated the amounts of telescoping of the lag screw and the changes in the neck shaft angle. Results The mean and maximum insertion torques were correlated with BMD in the HA and N groups, respectively. The mean and maximum insertion torques were not correlated with TAD in the HA and N groups, respectively. The mean torque/BMD ratio was significantly higher in the HA group than in the N group (p = 0.03). There were no significant differences in the maximum torque/BMD ratio between HA and N groups (p = 0.06), while the maximum torque/BMD ratio tended to be higher in the HA group than in the N group. The amounts of telescoping of the lag screw in the HA group were significantly lower than that in the N group (p = 0.04), while there were no significant differences in the changes in the neck shaft angle between two groups (p = 0.32). Conclusion Our results strongly suggest that the use of HA tubes increases the intraoperative lag screw insertion torque/BMD ratio and may improve the lag screw fixation by strengthening the bone/metal thread interface in the treatment of intertrochanteric femoral fractures.