Femoral offset loss and internal arch restoration defect are correlated with intramedullary nail cut-out complications after pertrochanteric fractures: a case–control study

Abstract

Background and purposeIn a previous study, we investigated the link between the femoral offset (FO) loss by trochanteric impaction (TI) and cut-out complication occurrence after pertrochanteric fractures. Three major factors are likely to drive to failure after intramedullary nailing (IN): fracture stability, reduction quality and osteosynthesis quality. We wanted to investigate the quality of the fracture reduction through the TI and the neck-shaft angle (NSA) measurement and correlate these parameters with the risk of mechanical failure occurrence.Materials and methodsIt was a retrospective multicentric one case–one control match design study with age and gender randomization. The cases presented a mechanical failure of nailing: $${\\text{TI}} = 1 - \\frac{{{\\text{FO}}_{\\text{fractured}} }}{{{\\text{FO}}_{\\text{healthy}} }}$$TI=1-FOfracturedFOhealthy in percentage. Femoral rotation was taken into account, and all TI were rotation-corrected (TIcorrected). Rotation-corrected neck-shaft angles (NSAcorrected) were calculated. The neck-shaft angle gap between the fractured and the healthy sides (NSAgap) was a ratio: $${\\text{NSA}}_{\\text{gap}} = 1 - \\frac{{{\\text{NSA}}_{\\text{corrected}} }}{{{\\text{NSA}}_{\\text{healthy}} }}$$NSAgap=1-NSAcorrectedNSAhealthy in percentage. The tip–apex distance (TAD) was measured. Absolute values of TIcorrected and NSAgap were analyzed.ResultsTwenty-one cases and 21 controls were examined. The average TIcorrected rate was 30% for the cases and 11% for the controls (p\u2009=\u20090.007). A 13% TIcorrected threshold had maximum specificity and sensitivity, equal to 71%. The average TAD was 27\xa0mm for cases and 19\xa0mm for controls (p\u2009=\u20090.004). The average NSAgap rate was 7% for the case group and 4% for the control group (p\u2009=\u20090.009). The areas under the ROC curves for TIcorrected, TAD and NSAgap were 0.73, 0.73 and 0.66, respectively.InterpretationClosed reduction and exclusive implantation of IN do not seem optimal in case of FO or NSA restoration failure after pertrochanteric fractures.Level of evidenceLevel III, case–control study.