Risk factors for cut-out of double lag screw fixation in proximal femoral fractures

Abstract

Objective: We assessed factors associated with cut-out after internal fixation of proximal femoral fractures using double lag screw nails.

Design: Retrospective cohort study.

Setting: A university hospital.

Patients and methods: Patients with non-pathological intertrochanteric femur fractures and a minumum 90days follow-up who underwent internal fixation with dual lag screw nails were included. Potential risk factors for lag screw cut-out investigated by our study were: age, gender, body mass index, comorbidities (American Society of Anesthesiologists [ASA] classification), type of fracture (AO/OTA classification), fracture stability, side, operation time, implant length, reduction quality, tip-apex distance (TAD), and lag screw configuration. Logistic regression was used to investigate potential predictors of screw cut-out.

Results: Eighty-five of the 118 patients with hip fractures treated between February 2010 and November 2013 at our institution met the inclusion criteria for the study. Fifty-eight patients were female (68.2%), mean age was 77.4 (range: 50-95 years), mean follow up was 380days (range: 150days-2.5 years), and cut of was observed in 9 patients (10.5%). The following variables identified through univariate analysis with p<0.2 were included in multivariant logistic regression model: age, side, reduction quality, implant length, TAD and ASA score. Only TAD (p=0.003) was found to be significant in the multivariant model.

Conclusions: Our study confirmed that risk factors for cut-out with single-lag screw devices are also applicable to dual-lag screw implants. We found that TAD was a significant factor for cut-out in dual-lag screw implants. Thus, screw cut-out can be minimized by optimizing screw position.

Keywords: Cut-out; Intertrochanteric fractures; Logistic regression; Prognostic level II; Risk factors; Tip-apex distance.