Factors influencing mechanical failure following intramedullary nailing of proximal femur fractures: a retrospective cohort study.

BACKGROUND

Proximal femur fractures are a common injury in elderly patients and are associated with high morbidity and mortality worldwide. Recent data indicate that the age-standardized incidence of hip fractures in adults over 55 years has increased significantly. We aimed to identify radiographic stability parameters and patient- or procedure-related factors associated with clinical fixation success following intramedullary nailing of proximal femur fractures.

METHODS

In this retrospective study, we evaluated 373 patients aged ≥35 years who underwent proximal femoral nail (PFN) implantation for intertrochanteric, pertrochanteric, subtrochanteric, or reverse-oblique femur fractures at our tertiary center between 2012 and 2024. Fractures were classified preoperatively using the Evans classification system, and the quality of reduction was graded as good, fair, or poor according to the standard radiographic Modified Baumgaertner criteria. Radiographic variables, including proximal lag screw tip-head distance (ApLAG1), distal lag screw tip-head distance (ApLAG2), ApLAG2-calcar distance, lesser trochanter-calcar distance, lateral lag screw tip-apex distance (LatTAD), and normal-side lesser trochanter-calcar distance, were measured postoperatively. Clinical outcomes were categorized into two groups: success or failure.

RESULTS

The cohort (mean age: 78.06±12.79 years; 66.5% female) included 262 (70.2%) standard PFNs, 79 (21.2%) integrated intertrochanteric antegrade nails (InterTAN) PFNs, and 32 (8.6%) single-screw PFNs. Overall, 359 patients (96.2%) had successful fixation and 14 (3.8%) experienced failure. No significant differences were found in radiographic parameters between the success and failure groups. PFN type did not influence radiographic measurements except for ApLAG2-related variables, in which InterTAN and single-screw nails differed from standard PFNs (p<0.001). Univariate analysis revealed that only poor reduction quality was significantly associated with failure (χ²=36.298; p<0.001).

CONCLUSION

Quality of fracture reduction emerged as the sole independent predictor of PFN fixation success, whereas patient demographics, Evans classification, and implant design did not significantly affect outcomes. Surgeons should prioritize achieving nearanatomic alignment and stable implant positioning to minimize mechanical failure.