Cephalomedullary nail fixation of subtrochanteric femur fractures in older adults: Is 1 distal locking screw enough?

BACKGROUND: Subtrochanteric (ST) fractures are proximal femur fractures with strong deforming muscular forces, which complicate anatomical reduction and treatment. These fractures are fixed with intramedullary nails with 2 distal locking screws, although the need for both screws has never been researched. PURPOSE: This study's purpose was to investigate the use of 1 versus 2 distal locking screws on clinical and radiographic outcomes and complications. STUDY DESIGN/LEVEL OF EVIDENCE: Retrospective cohort, Level of Evidence III. METHODS: An IRB-approved retrospective review of a consecutive series of ST femoral fractures was performed. Each patient's medical record was reviewed for demographics, injury and treatment information, perioperative details, radiographic parameters, hospital quality measures, and outcomes. Patients were divided into 2 cohorts: 1 distal locking screw (1-screw cohort) and 2 distal locking screws (2-screw cohort). Distal screw number (1 vs. 2 screws) was chosen by surgeon preference. Comparative and multivariable analyses were conducted. RESULTS: Two hundred thirty-two patients met inclusion criteria with a mean age of 71.18 ± 19.05 years and average follow-up of 11 months. All fractures were treated with a long antegrade, reamed cephalomedullary nail. Fifty (21.6%) patients were fixed with one 5 mm distal locking screw, and 182 (78.4%) patients had 2 screws. Patients with 1 screw had a shorter operative time in minutes (156.64 ± 47.06 vs. 176.06 ± 41.32, P = .005), but there were no further perioperative differences. Patients treated with 1 screw were more frequently associated with being fixed in a valgus coronal alignment (20% 1 distal screw vs. 5% 2 distal screws, P = .003) and had higher degree of apex anterior angulation (19.7° ± 8.2° 1-screw vs. 10.6° ± 6.3° 2-screw, P = .011). However, this did not significantly affect healing outcomes because both cohorts experienced similar rates of fracture healing, medical and mechanical complications, mortality, and readmission (all P > .050). CONCLUSION: Clinically, a single distal locking bolt is sufficient for ST femur fractures fixed with a cephalomedullary nail. A second distal locking screw may be reserved for situations in which the first screw may not have achieved adequate fixation.