Subtrochanteric femoral fractures are a subset of hip fractures generally treated with cephalomedullary nail fixation\[1\]. Single lag screw devices are most commonly-used, but integrated dual screw constructs have become increasingly popular\[2,3\]. The aim of this study was to compare outcomes of fixation of subtrochanteric femoral fractures using a single lag screw (Gamma3 nail, GN) with a dual screw device (InterTAN nail, IN). The primary outcome was mechanical failure, defined as lag screw cut-out, back-out, nail breakage or peri-implant fracture. Consecutive adult patients (18yrs) with subtrochanteric femoral fracture treated in a single centre were retrospectively identified using electronic records. Patients that underwent surgical fixation using either a long GN (2010–2017) or IN (2017–2022) were included. Medical records and radiographs were reviewed to identify complications of fixation. Cox regression analysis was used to determine the risk of mechanical failure and secondary outcomes by implant design. Multivariable regression models were used to identify predictors of mechanical failure. The study included 622 patients, 354 in the GN group (median age 82yrs, 72% female) and 268 in the IN group (median age 82yrs, 69% female). The risk of any mechanical failure was increased two-fold in the GN group (HR 2.44 \[95%CI 1.13 to 5.26\]; _p=0.024_). Mechanical failure comprising screw cut-out (_p=0.032_), back-out (_p=0.032_) and nail breakage (_p=0.26_) was only observed in the GN group. Technical predictors of failure included varus >5° for cut-out (OR 19.98 \[2.06 to 193.88\]; _p=0.01_), TAD;25mm for back-out (8.96 \[1.36 to 58.86\]; p=0.022) and shortening 1cm for peri-implant fracture (7.81 \[2.92 to 20.91\]; _p=<0.001_). Our results demonstrate that an intercalated screw construct is associated with a lower risk of mechanical failure compared with the a single lag screw device. Intercalated screw designs may reduce the risk of mechanical complications for patients with subtrochanteric femoral fractures.
This study compares outcomes of fixation of subtrochanteric femoral fractures using a single lag screw (Gamma3 nail, GN) with a dual lag screw device (InterTAN nail, IN). The primary outcome was mechanical failure, defined as lag screw cut-out, back-out, nail breakage or peri-implant fracture. Technical factors associated with mechanical failure were also identified. All adult patients (>18yrs) with a subtrochanteric femoral fracture treated in a single centre were retrospectively identified using electronic records. Included patients underwent surgical fixation using either a long GN (2010–2017) or IN (2017–2022). Cox regression analysis was used to determine the risk of mechanical failure and technical predictors of failure. The study included 587 patients, 336 in the GN group (median age 82yrs, 73% female) and 251 in the IN group (median age 82yrs, 71% female). The IN group exhibited a higher prevalence of osteoporosis (p=0.002) and CKD□3 (p=0.007). There were no other baseline differences between groups. The risk of any mechanical failure was increased two-fold in the GN group (HR 2.51, p=0.020). Mechanical failure comprising screw cut-out (p=0.040), back-out (p=0.040) and nail breakage (p=0.51) was only observed in the GN group. The risk of peri-implant fracture was similar between the groups (HR 1.10, p=0.84). Technical predictors of mechanical included varus >5° for cut-out (HR 15.61, p=0.016), TAD>25mm for back-out (HR 9.41, p=0.020) and shortening >1cm for peri-implant fracture (HR 6.50, p=<0.001). Dual lag screw designs may reduce the risk of mechanical complications for patients with subtrochanteric femoral fractures.
