Central head perforation, or "cut through," caused by the helical blade of the proximal femoral nail antirotation.

Abstract

This study was designed to investigate the specific type and incidence of implant failure in patients with a proximal femur fracture treated with a proximal femoral nail antirotation. This device has a helical-shaped blade as a neck-head holding device, instead of the lag screw used in other intramedullary nails. The advantage of the blade is believed to originate from bone impaction and a larger bone-implant interface in comparison with the lag screw design, with consequential greater mechanical resistance to torsion in the cancellous bone. This is a retrospective cohort study conducted at the state hospital of Winterthur, Switzerland. From December 2006 until November 2008, 210 consecutive patients were treated with a pertrochanteric femur fracture (OTA type 31-A1, 31-A2, and 31-A3) using a proximal femoral nail antirotation. One hundred and twelve patients were followed up clinically for a minimum of 12 months after discharge. Clinical and radiologic assessment of fracture healing and/or implant failure was investigated. We report 7 cases of implant failure with a "Cut Through," defined as a postoperative central perforation of the spiral blade into the hip joint, without any displacement of the neck-head fragment. Cut through needs to be distinguished from the well-known anterocranial perforation combined with a varus displacement of the neck-head fragment, known as "Cut Out," seen with intramedullary nails utilizing lag screws. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.