Femoral Antetorsion: Comparing Asymptomatic Volunteers and Patients with Femoroacetabular Impingement
Abstract
Patients with pincer-type femoroacetabular impingement (FAI) had a significantly larger femoral antetorsion than patients with cam-type FAI, although there was a wide range of values in both volunteers and patients with FAI.
Purpose
To assess the range of femoral antetorsion with magnetic resonance (MR) imaging in asymptomatic volunteers and patients with different subtypes of femoroacetabular impingement (FAI) because abnormal femoral antetorsion might be a contributing factor in the development of FAI.
Materials and Methods
This study was institutional review board approved; all individuals provided signed informed consent. Sixty-three asymptomatic volunteers and 63 patients with symptomatic FAI between age 20 and 50 years were matched for age and sex. They underwent standard MR imaging with two additional rapid transverse sequences over the proximal and distal femur for antetorsion measurement. Twenty volunteers underwent a second MR imaging examination in the same leg. Two readers independently measured femoral antetorsion. The time for the additional sequences was tabulated. Interobserver agreement was calculated; differences in antetorsion were assessed by using analysis of variance and the unpaired t test.
Results
Femoral antetorsion can be assessed with MR imaging in about 80 seconds, with high interobserver agreement (intraclass correlation coefficient [ICC] = 0.967) and high agreement between different MR examinations (ICC = 0.966). Women had a significantly larger antetorsion than men (P < .001 for both readers), and antetorsion of the left femur was significantly larger than that of the right femur (P = .01 for reader 1, P = .02 for reader 2). Overall, antetorsion was similar in volunteers and in patients for reader 1 (12.7° ± 10.0 [standard deviation] vs 12.6° ± 9.8, respectively; P = .9) and reader 2 (12.8° ± 10.1 vs 13.5° ± 9.8, respectively; P = .7). Femoral antetorsion was significantly higher in patients with pincer-type FAI than in those with cam-type FAI for reader 1 (18.3° ± 9.8 vs 10.0° ± 9.1, P = .02) and reader 2 (18.7° ± 10.5 vs 11.6° ± 8.8, P = .04).
Conclusion
Femoral antetorsion can be measured rapidly and with good reproducibility with MR imaging. Patients with pincer-type FAI had a significantly larger femoral antetorsion than patients with cam-type FAI.
© RSNA, 2012
References
- 1 . Early osteoarthritic changes of human femoral head cartilage subsequent to femoro-acetabular impingement. Osteoarthritis Cartilage 2003;11(7):508–518.
- 2 . Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res 2003;(417):112–120.
- 3 . Cam and pincer femoroacetabular impingement: characteristic MR arthrographic findings in 50 patients. Radiology 2006;240(3):778–785.
- 4 . Prevalence of associated deformities and hip pain in patients with cam-type femoroacetabular impingement. J Bone Joint Surg Br 2009;91(5):589–594.
- 5 . Radiographic markers of acetabular retroversion: correlation of the cross-over sign, ischial spine sign and posterior wall sign. Acta Orthop Belg 2010;76(2):166–173.
- 6 . Anteroposterior pelvic radiographs to assess acetabular retroversion: high validity of the “cross-over-sign”. J Orthop Res 2007;25(6):758–765.
- 7 . Diminished femoral antetorsion syndrome: a cause of pain and osteoarthritis. J Pediatr Orthop 1991;11(4):419–431.
- 8 . Acetabular and femoral anteversion: relationship with osteoarthritis of the hip. J Bone Joint Surg Am 1999;81(12):1747–1770.
- 9 . Treatment of reduced femoral antetorsion by subtrochanteric rotational osteotomy. Acta Orthop Belg 2009;75(4):490–496.
- 10 . Measurement of femoral antetorsion and tibial torsion by magnetic resonance imaging. Br J Radiol 1997;70(834):575–579.
- 11 . MR imaging measurement of the femoral antetorsional angle as a new technique: comparison with CT in children and adults. AJR Am J Roentgenol 1997;168(3):791–794.
- 12 . Femoroacetabular cam-type impingement: diagnostic sensitivity and specificity of radiographic views compared to radial MRI. Eur J Radiol 2011;80(3):805–810.
- 13 . Retroversion of the acetabulum: a cause of hip pain. J Bone Joint Surg Br 1999;81(2):281–288.
- 14 . Ischial spine projection into the pelvis: a new sign for acetabular retroversion. Clin Orthop Relat Res 2008;466(3):677–683.
- 15 . The protrusive malformation and its arthrosic complication. I. Radiological and clinical symptoms: etiopathogenesis [in French]. Rev Rhum Mal Osteoartic 1962;29:476–489.
- 16 . Pathomorphologic alterations predict presence or absence of hip osteoarthrosis. Clin Orthop Relat Res 2007;465:46–52.
- 17 . The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement. J Bone Joint Surg Br 2002;84(4):556–560.
- 18 . Debridement of the adult hip for femoroacetabular impingement: indications and preliminary clinical results. Clin Orthop Relat Res 2004;(429):178–181.
- 19 . Osseous abnormalities and early osteoarthritis: the role of hip impingement. Clin Orthop Relat Res 2004;(429):170–177.
- 20 . Femoroacetabular impingement: caution is warranted in making imaging-based assumptions and diagnoses. Radiology 2010;257(1):4–7.
- 21 . Femoroacetabular impingement: evidence of an established hip abnormality. Radiology 2010;257(1):8–13.
- 22 . Cams and pincer impingement are distinct, not mixed: the acetabular pathomorphology of femoroacetabular impingement. Clin Orthop Relat Res 2010;468(8):2143–2151.
- 23 . The role of acetabular and femoral osteotomies in reconstructive surgery of the hip: 2005 and beyond. Clin Orthop Relat Res 2005;441:188–199.
- 24 . Intertrochanteric osteotomy combined with acetabular shelfplasty in young patients with severe deformity of the femoral head and secondary osteoarthritis: a long-term follow-up study. J Bone Joint Surg Br 2005;87(1):25–31.
- 25 . Rationale of osteotomy and related procedures for hip preservation: a review. Clin Orthop Relat Res 2002;(405):108–121.
- 26 . The effect of varus and valgus osteotomies on femoral version. J Pediatr Orthop 2009;29(7):666–675.
- 27 . A simple biplanar method of measuring femoral anteversion and neck-shaft angle. J Bone Joint Surg Am 1979;61(6A):846–851.
- 28 . Measurement of femoral anteversion by biplane radiography and computed tomography imaging: comparison with an anatomic reference. Invest Radiol 2003;38(4):221–229.
- 29 . Femoral anteversion. J Bone Joint Surg Am 1987;69(8):1169–1176.
- 30 . A new method for determination of torsion of the femur. J Bone Joint Surg Am 1953;35-A(2):289–311.
- 31 . Torsion of the femur: a follow-up study in normal and abnormal conditions. J Bone Joint Surg Am 1973;55(8):1726–1738.
- 32 . Angle of torsion of the femur and its correlates. Clin Anat 1996;9(2):109–117.
- 33 . Proximal femoral anatomy in the normal human population. Clin Orthop Relat Res 2009;467(4):876–885.
- 34 . NMR tomographic measurement of femoral ante-torsion and tibial torsion [in German]. Rofo 1995;162(3):229–231.
- 35 . Morphometric study of the fetal development of the human hip joint: significance for congenital hip disease. Yale J Biol Med 1981;54(6):411–437.
- 36 . Femoroacetabular impingement and the cam-effect: a MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br 2001;83(2):171–176.
- 37 . Does femoral anteversion play a role in the pathomechanics and subsequent surgical treatment of femoroacetabular impingement? Arthroscopy 2011;27(5 suppl):e53.
Article History
Received September 5, 2011; revision requested October 27; revision received November 7; accepted November 22; final version accepted December 8.Published online: May 2012
Published in print: May 2012