Correlation of Trochanter-Shaft Angle in Selection of Entry Site in Antegrade Intramedullary Femoral Nail

Background. Selection of entry point for nail insertion is controversial and lack firm anatomical basis. The study is done to analyze the proximal anthropometry of femur and measure the Trochanter-Shaft Angle to find its relation and significance in selection of entry point for antegrade uniplanar femoral nail. Materials and Methods. Study involves the measurement of trochanter-shaft angle and other anthropometric measurements on 50 dry femora and on digital radiogram. Results. Trochanter-Shaft angle ranges between 5–17 degrees in anthropometric study and 4–14 degrees in radiological study. Over all in 27 cases (54%), exit points of reamur fall in the middle quadrant in sagittal and coronal plane, which corresponds to the T-S angle of 6–12 degrees. Discussion and Conclusion. Proximal femoral Anthropometry and Trochanter-shaft angle is variable; hence it is difficult to fix any anatomical point as a universal entry point for antegrade femoral nail insertion. Trochanter shaft angle (TSA) can be well accessed radiologically and serve as a guide for selection of proper entry point.for safe nail insertion. Clinical Relevance. Individual variations in the proximal femur anatomy for safe nail insertion can be correlated with Trochanter shaft angle to serve safe entry site. 1. Introduction Selection of entry point for antegrade femoral interlocking nail is controversial, and there still is debate as to the most appropriate starting point [1–4]. Piriformis fossa [5–7] has been advocated as traditional entry point. However, complications [7–9] have been reported with traditional Piriformis fossa as a starting point. This has led to interest in the off-axis entry point, but to some extent, this off-axis entry used is not clear as this results in high femoral strain during insertion. Moreover proximal femoral anthropometry and anatomy of greater trochanter has different dimension [4, 10, 11]; hence it is difficult to define the universal entry point piriformis fossa, greater trochanter, or any other site for antegrade intramedullary nailing. The least starining and anatomical point for safe nail insertion should be in the line of medullary canal of femur, which can be determined proximally on trochanteric area by measuring Trochanter-shaft angle (TSA). Therefore, the present study is undertaken to measure the trochanter shaft angle and develop the anatomical and radiological basis for it. 2. Materials and Methods The Study involves the 50 dry adult cadaveric femora in anatomy museum and biomechanical laboratory. Adult femoral bones that were nonfractured having no