PREDICTING FAILURE OF FIXATION DUE TO CUT OUT IN EXTRACAPSULAR FRACTURE OF THE HIP TREATED BY FIXED ANGLE DEVICES: EFFECT OF THE SURGEON’S EXPERIENCE

Abstract

Introduction: Previous studies have demonstrated the value of the tip-apex distance (TAD) and the location of the screw in the femoral head in predicting cut-out. Similarly surgeons’ volume has been shown to affect mortality and morbidity in various surgical specialties, including in trauma and orthopaedics.

Aim: To determine whether re-operation due to cut out at six month can be predicted using TAD, location of the screw and fracture type; and whether the experience of the surgeon is important.

Methods: Logistic regression was used to analyse data collected retrospectively from 241 patients with extracapsular fractures (Jensen’s modification of Evans’ classification: Class I – 90, Class II – 93 and Class III – 58), treated with a dynamic hip screw, classic hip screw or intramedullary hip screw from April 2005 to October 2007.

Results: There were 7 cut outs (2.5%) requiring re-operation within 6 months – 1 in the consultant group and 6 in the trainee group,. The model used was statistically significant (X2=23.6 [13df], p< 0.05). The tip-apex distance was a strong predictor (p< 0.05) of cut-out requiring re-operation at six months. The odds of the patient requiring re-operation due to cut out increases by a factor of 1.2 for each millimetre increase in the TAD. Location of the hip screw and fracture type were however not significant predictors. The first surgeon was a consultant in 54 cases and trainee in 187 cases. There was no statistically significant difference in re-operation rate due to cut out between patients operated on by consultants compared to trainees.

Conclusion: The TAD is a strong predictor of cut out requiring re-operation at 6 months. No difference was found in our series in re-operation rate due to cut out among cases performed by consultants compared to trainees.