Anatomical and biomechanical parameters relating to migration of the helical blade in proximal femoral fractures fixed by proximal femoral nail anti-rotation

Abstract

Introduction: Proximal femoral fractures fixation pose dilemma on fixation device to use. Western designed copied proximal femoral nail anti rotation is being used in South-East Asian population extensively. The study aims to study of migration in our population representative of the developing nations. Methods: 92 patients enrolled in prospective cross-sectional study for 9 months; 89 were evaluated for final migration studies as 3 major complications occurred. The effects of age, fracture, tip-apex distance, quadrant position in femoral head, blade size and length and Neck Shaft angle on migration were analyzed. Results: There were 42 males and 50 females with the mean age was 68.14 years. At the time of fixation mean Tip Apex Distance was 12.2 mm (7.0mm – 25mm). At 6 months follow-ups, migration occurred in 78.65%. On univariate analysis, there was no effect of fracture pattern on migration (p=0.524). Femoral-Neck shaft angles were fixed in varus in 7, 5 in valgus and 77 within normal range. Relatively higher migration did occur with varus fixation but was not statistically significant (p=0.306). Multivariate analyses were done for nail diameter, nail length, old age and fracture patterns with no statistically significant interactions. The position of helical blade in the quadrant of the femoral head with center-center having minimum migration (p= 0.000). Major complications occurred in 3 patients. Conclusions: All helical blades do migrate but within acceptable range provided fixation in acceptable Tip Apex Distance. Bone Mineral Density should be kept as co-variable in further studies.