Normal range of femoral version for different measurement methods on CT or MRI-scoping review of normal femoral version.

Abstract

Correct quantification of femoral version (FV) is crucial for femoroacetabular impingement (FAI) patients for diagnosis and for surgical planning. However, different measurement methods for FV and different normal values are confusing. The study aimed to investigate differences in FV measurement methods and to review normal FV. This retrospective comparative study investigated a total of 84 hips for FV measurement: 48 hips (asymptomatic patients) and 36 hips (asymptomatic volunteers) without hip pain. The 48 patients underwent computed tomography (CT) for another reason (mean age 63 ± 11 years) and most (39 hips, 81%) were male patients. The 36 hips reported no hip pain at the time of magnetic resonance imaging (MRI) (mean age 27 ± 7 years, 20 female patients, 56%). FV was measured on CT or MRI included pelvis and knee) and with the Murphy method. Mean FV for 48 hips was 22° (range 5-34°), and for 36 hips, it was 24° (7-44°). No significant differences were found between the two groups. For 39 male patients with CT scans, the mean FV was 21° (6-34°) and was significantly (<i>P</i> = 0.041) decreased compared to female patients (FV of 26°). For the review, 18 studies were compared that evaluated normal FV (total of 2275 hips) in the literature. Increasing values for normal FV were found for measurement methods with a more distal definition of the femoral neck axis: Normal values were reported for the Lee method (most proximal definition; 8-11°), Reikeras method (9-20°), Oblique/Jarrett method (9-15°), Tomczak method (22-24°), and Murphy method (most distal: 18-23°). Reported normal range of FV differs between measurement methods. This is important for patients with FAI/hip dysplasia undergoing hip preservation surgery (hip arthroscopy/femoral derotation osteotomy).