No difference between lag screw and helical blade for cephalomedullary nail cut-out a systematic review and meta-analysis.

introductionCephalomedullary nail (CMN) cut-out is a severe complication of treatment of intertrochanteric femur fractures. This study aimed to identify modifiable risk factors predictive of implant cut-out including: CMN proximal fixation type (lag screw vs. helical blade), tip-apex distance (TAD), reduction quality, nail length, screw location, and surgeon fellowship training.

methodsA systematic review of the published literature was conducted on Pubmed/MEDLINE and Cochrane Library databases for English language papers (January 1st, 1985-May 10th, 2020), with 21 studies meeting inclusion/exclusion criteria. Studies providing quantitative data comparing factors affecting CMN nail cut-out were included, including fixation type (lag screw vs. helical blade), tip-apex distance (TAD), reduction quality, nail length, and screw location. Twelve studies were included and graded by MINOR and Newcastle-Ottawa Scale to identify potential biases. Meta-analysis and pooled analysis were conducted when possible with forest plots to summarize odds ratios (OR) and associated 95% confidence interval (CI).

resultsThere was no difference in implant cut-out rate between lag screws (n = 745) versus helical blade (n = 371) (OR: 1.03; 95% CI: 0.25-4.23). Pooled data analysis revealed TAD > 25 mm (n = 310) was associated with higher odds of increased cut-out rate relative to TAD < 25 mm (n = 730) (OR: 3.72; 95% CI: 2.06-6.72).

conclusionOur review suggests that cephalomedullary implant type (lag screw vs. helical blade) is not a risk factor for implant cut-out. Consistent with the previous literature, increased tip-apex distance > 25 mm is a reliable predictor of implant cut-out risk. Suboptimal screw location and poor reduction quality are associated with increased risk of screw cut-out. LEVEL OF EVIDENCE: Level III.