Does Femoral Rotation More Closely Mirror the Contralateral Side or a Population Mean of 15 Degrees of Anteversion? A Radiologic Study of 219 Healthy Patients.

Abstract

Objectives: To compare whether femoral version more closely mirrors the contralateral femur or a population norm estimate of 15° of anteversion.

Design: Radiologic observational study.

Setting: Level I Trauma Center.

Patient selection criteria: Patients with no history of anatomy-altering femoral injury who underwent bilateral lower extremity CT scans.Outcome Measures and Comparisons: CTs were analyzed to measure femoral version on each side. The asymmetry in femoral version between left and right in each patient (interfemoral rotational variance [IRV]) was recorded. The difference of each femur's version from a proposed population mean of 15° of anteversion was also recorded.

Results: 219 patients with a mean femoral version of 14.9° ± 10.5° of anteversion were included. Mean IRV was 5.3°, compared to 8.2° of mean variation from the population norm of 15° of anteversion (p<0.001). Five percent of patients had IRV >15° compared to 15% that had femoral rotation > 15° from the population mean of 15° (p<0.001).

Conclusions: In the setting of a comminuted diaphyseal femur fracture, knowledge of the appropriate target for restoration of rotational alignment is critical. This radiologic cohort study found that on average, femoral version more closely mirrors an individual patient's contralateral femur as opposed to a population norm of 15° of anteversion.

Level of evidence: III.