The Utility of the Tip-Apex Distance in Predicting Axial Migration and Cutout With the Trochanteric Fixation Nail System Helical Blade.

To determine whether a tip-apex distance (TAD) <20 mm is associated with a higher rate of axial migration and perforation with the Trochanteric Fixation Nail (TFN) System helical blade implant.Retrospective.Level I Trauma Center.Four hundred forty-three patients surgically treated for proximal femur fractures were identified through a query of Current Procedural Terminology code 27245 from January 2009 to February 2013. A total of 258 patients treated with the TFN helical blade system were included in the study.The association of axial migration and perforation with the measured TAD.The overall rate of mechanical complications was 10.1%. The average TAD was 20.4 mm. Axial perforation occurred in 8 patients (3.4%). Axial migration up to subchondral bone without perforation occurred in 3 patients (1.1%). Only 1 fracture failed in varus (0.38%). There was a significant difference in the rates of combined axial migration and perforation with a TAD <20 mm (P = 0.03). Logistic regression model demonstrated increased odds for combined axial cutout and migration with TAD less than 20 (odds ratio = 1.15, P = 0.01).A TAD <20 mm was associated with an increased frequency of axial migration and cutout with the TFN helical blade.Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.