Outcomes of Angular Stable Locking System in Femoral Diaphyseal Fractures of Elderly Patients: A Multicenter Comparative Study

Background: The angular stable locking system (ASLS) was developed to provide additional stability to the distal interlocking screw of the intramedullary (IM) nail. Effects of ASLS on the treatment of femoral diaphyseal fractures in the elderly remain un-known. The aim of this study was to compare radiological outcomes of IM nailing using ASLS screws to IM nails with conventional interlocking screws in elderly patients with femoral shaft fractures. Methods: A multicenter retrospective review of 129 patients (average age, 73.5 years; 98 women and 31 men) aged 65 years or older who underwent IM nail fixation for femoral diaphyseal fractures (AO/Orthopaedic Trauma Association [OTA] classification 32) was conducted. Demographic information of patients, fracture site (subtrochanteric or shaft), fracture type (traumatic or atypical), and AO/OTA fracture classification were investigated. Reduction status was evaluated by postoperative plain radiography. Pres-ence of union and time to union were evaluated through serial plain radiograph follow-up. Reoperation due to nonunion or implant failure was also evaluated. Results: ASLS was used in 65 patients (50.3%). A total of 118 patients (91.5%) achieved union without additional surgery and the mean union time was 31.8 +/- 13.0 weeks. In terms of reduction status, angulation was greater in the group using ASLS. There were no statistically significant differences of union rate, time to union, and reoperation rate according to the use of ASLS (p > 0.05). There was no difference in the outcomes according to the use of ASLS even when the analysis was divided in terms of fracture site or fracture type (p > 0.05). In further subgroup analysis, only the traumatic subtrochanteric area group showed statistically sig-nificantly shorter time to union when ASLS was used (p = 0.038). Conclusions: In geriatric patients with femoral diaphyseal fractures, the use of ASLS was not considered to have a significant effect on fracture healing. Fracture healing seemed to be more affected by surgical techniques such as minimizing the gap and fracture characteristics such as atypical femoral fractures, rather than implants.