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

Abstract

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.

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

Outcome assessment consisted of a 4 month follow-up appointment with clinical and radiological assessments, VAS, SF36, Jensen Social Function Score and Parker Mobility Score.

From April to December 2006, 46 patients were included in the study. 4 month follow up has been completed in 17 of 23 patients. The average age was 78. 11 short and 7 long nails were inserted. Four patients required open reduction and internal fixation. There were no significant intra-operative or immediate postoperative complications. 1 short nail fractured through the site of the distal locking bolt during the follow up period and required revision.

At follow up, 5 patients had tenderness over the greater trochanter and 2 had leg length discrepancy. None had malrotation. Only 2 patients regained their pre-operative mobility status. The mobility and social function scores were significantly reduced at follow up compared to pre-operative status (p=0.003 and p=0.001 respectively). All domains of SF36 were low compared to normative data. The mean VAS was 3/10.

All fractures united and there was no migration, lysis around or cut out of the helical blade. In total, 25 distal locking bolts were utilised. Four of these had migrated or become loose.

Patients with subtrochanteric fractures do not return to pre-fracture function at 4 months post injury. The PFNA appears to work well although there may be concern about bone hold of the distal locking bolts.

Correspondence should be addressed to Major M Butler RAMC, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter Hospital, Exeter, Devon.