Mismatch of long Gamma intramedullary nail with bow of the femur: Does radius of curvature of the nail increase risk of distal femoral complications?

INTRODUCTION

Anterior cortical penetration of the distal nail tip is a recognized complication of intra-medullary nailing of the femur particularly in the geriatric population. This has been attributed to a mismatch between the femoral bow and the radius of curvature (ROC) of the femoral nail. We wanted to see if there was a reduction of this risk comparing cephalomedullary nails with ROC of 200 cm and 150 cm.

METHODS

52 patients were split into 2 groups similar with respect to age, sex and comorbidities. Group A with 25 patients used a nail with a ROC of 200 cm and Group B with 27 patients used a 150 cm ROC nail. Lateral radiographs of the distal femur were evaluated to note the position of the nail tip in relation to the femoral canal. The diameter of the femur at the tip of the nail was divided into 3 equal zones. The anterior one-third was designated as Zone1, the middle one-third as Zone 2 and the posterior one-third as Zone 3.

RESULTS

80% of the cases with a 200 cm ROC nail had the tip of the nail in the anterior one-third of the canal (zone 1). Fracture of the anterior femoral cortex distally by the nail tip was seen in 2 patients.Only 18.5% of cases with a 150 cm ROC nail had the tip of the nail in anterior one-third of the canal (zone 1). There were no incidences of complications such as fractures and anterior cortical perforation.

CONCLUSIONS

A cephalomedullary nail with a ROC of 150 cm had its distal tip more towards the center of the femoral canal when compared to a nail with ROC of 200 cm. No case of anterior femoral penetration was seen when using a nail with an ROC of 150 cm.