Implant fracture of the TFNA femoral nail.

ABSTRACT

BACKGROUND: The TFNA (Trochanteric Fixation Nail Advanced) Proximal Femoral Nailing System (DePuy Synthes) is frequently used for intramedullary fixation of proximal femoral fractures. The aim of this study was to evaluate all TFNA implant fractures at a UK trauma unit to ascertain any patient or surgical factors associated with implant failure. METHODS: A retrospective study was carried out identifying all patients that sustained a TFNA implant fracture over a five-year period. Data was collected on demographic information, ASA, co-morbidities, mechanism of injury, fracture pattern according to the AO/OTA classification, procedure details and time to failure. Radiographs were assessed by two independent reviewers to identify tip-apex distance (TAD), calcar TAD, reduction quality and union status at time of implant failure. RESULTS: Six cases were identified, all with implant breakage at the aperture for the proximal screw. All femoral fractures were intertrochanteric reverse obliquity type (OA/OTA 31A3). Two were traumatic fragility fractures and the remainder atraumatic. Mean time from index surgery to revision was 441 days (104-963). Mean TAD was 20.5 mm (15-24) and mean calcar TAD 24 mm (18-32). All six cases displayed radiographic non-union at the time of implant fracture. CONCLUSION: Pathological fractures resulting in reverse obliquity type fracture patterns and subsequent non-union appear to be contributory factors to TFNA breakage at the proximal screw aperture. This may be further exacerbated by alterations to the nail design from previous generations. In these patients, close follow up with clinical and radiographic surveillance should be employed. Further biomechanical and clinical studies are required to compare this finding against other nail designs.