An Anatomic Study on Whether Femoral Version Originates in the Neck or the Shaft

BACKGROUND: Femoral anteversion is generally asymptomatic but can result in lower extremity issues like patellofemoral instability and pain. Surgical correction of anteversion can be performed proximal, mid shaft or distal. A better understanding of the specific location of the rotational deformity can help guide the optimal location of the osteotomy. In this study we examine the contribution of the femoral neck and shaft to total femoral version. METHODS: We studied 590 pairs of well-preserved cadaveric femurs. Total femoral version was defined as the axial plane angle between the femoral neck and posterior femoral condyles. Femoral shaft torsion was defined as the axial plane angle between the lesser trochanter and posterior femoral condyles. Neck version was the mathematical difference between total femoral version and shaft version. RESULTS: Neck version (right femur R=0.582; left femur R=0.632) contributed slightly more than shaft version (right femur R=0.505; left femur R=0.480) to overall femoral version, but both were substantial and neither completely predicted overall femoral version. Age was not found to contribute to femoral version, and sex and race had statistically significant but small contributions. CONCLUSIONS: Our data show that both the femoral neck and femoral shaft substantially contribute to femoral version, and to our knowledge is the first to statistically demonstrate that neither level can be used to predict total femoral version. This suggests that one cannot generalize a single optimal site for correction or prediction of femoral version from an osteological perspective, and that individualized assessment may be beneficial. CLINICAL RELEVANCE: This study suggests that methodologies for determining the level of femoral version might be important as the level in any given patient can vary.