THE SHORT TERM OUTCOME OF SUBTROCHANTERIC FRACTURES TREATED WITH THE NEW SYNTHES PROXIMAL FEMORAL NAIL ANTIROTATION (PFNA)

Abstract

Introduction: The PFNA device was developed to address problems of rotational instability in proximal femoral fractures whilst simultaneously employing a single femoral neck element. The PFNA makes use of a helical blade that compresses rather than destroys osteopaenic cancellous bone. It is hammered into place over the guide wire and then locked laterally to prevent rotation.

Study Design: Prospective cohort.

Methods: All subtrochanteric fractures (AO 31A3) admitted to the department were treated with the PFNA. Demographic and clinical data during admission was recorded and formal post-operative X-Rays performed.

Outcome Measures: 4 month follow-up appointment with clinical and radiological assessments, VAS, SF36, Jensen Social Function Score and Parker Mobility Score.

Results: From April 2006 to June 2007, 62 patients were included in the study. 4 month follow up has been completed in 30 patients (77% of those available). 11 are awaiting follow up, 12 died and 9 were unable to attend follow up for various reasons. The mean age was 79.9 years. 13 short and 17 long nails were inserted. 6 patients required open reduction and internal fixation. There were no significant intra-operative or immediate postoperative complications. 1 patient with a short PFNA nail sustained a fracture of the femur through the site of the distal locking bolt during the follow up period and required revision. At follow up, 9 patients had tenderness over the greater trochanter and 1 had leg length discrepancy. None had malrotation. Only 7 patients regained their pre-operative mobility status. The mobility and social function scores were significantly reduced at follow up compared to preoperative status (p=0.001). All domains of SF36 were low compared to normative data. The mean VAS was 3/10. All 30 fractures united and there was no migration, lysis around or cut out of the helical blade. In total, 46 distal locking bolts were utilised. 4 of these had migrated or become loose.

Conclusions: Subtrochanteric fractures in the elderly are a devastating injury. Patients do not return to pre-fracture function at 4 months post injury. Early results suggest that the PFNA appears to work well as evident by the fact that all of the fractures united. We recommend adding 4 to 6mm to the measured length of the distal locking bolts to prevent migration.