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

OBJECTIVES: 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.

DESIGN: Retrospective.

SETTING: Level I Trauma Center.

PARTICIPANTS: 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.

MAIN OUTCOME MEASURED: The association of axial migration and perforation with the measured TAD.

RESULTS: 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).

CONCLUSIONS: A TAD <20 mm was associated with an increased frequency of axial migration and cutout with the TFN helical blade.

LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.