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Primary osteoarthritis of the hip, often referred to as idiopathic, may be secondary to mechanical causes. There have been numerous studies on the measurement of torsion of the bones of the lower extremity1,3,8,13,14,31,34,39,44,45,47,48,54,63,79,80,84. Some studies have supported the hypothesis that a persistent increase in femoral anteversion predisposes to osteoarthritis of the hip29,53,54,62, whereas others have not35,40,61. Menke et al.45 found an association between decreased acetabular anteversion and osteoarthritis of the hip, and Eckhoff23 found a similar association between femoral anteversion and osteoarthritis of the knee. Increased femoral torsion also has been documented in patients who have pain or osteoarthritis of the knee and patellar instability5,22.
There have been few reports on the potential problems that are associated with decreased femoral anteversion15,21,36,37,51,69. In 1959, Crane15 noted that decreased femoral anteversion or retroversion was associated with a toeing-out gait whereas increased femoral anteversion was associated with a toeing-in gait. Decreased femoral anteversion has been consistently observed in patients who have a slipped capital femoral epiphysis25,28,38,52,58,59 as well as in those who have congenital hypoplasia of the femur60,73.
Etiology of Altered Acetabular and Femoral Anteversion
There is some evidence to suggest a congenital etiology for increased or decreased anteversion of the femur and acetabulum19. Watanabe77 examined 144 embryos and stillborn fetuses between six and twenty-four weeks of gestation. At the completion of the first half of the prenatal stage (that is, by twenty weeks of gestation), the fetus is completely formed and resembles the newborn infant. Femoral anteversion was measured in specimens that were between eleven and twenty-four weeks of gestation; it was not possible to measure anteversion in younger specimens because the hip joint space had not yet formed. The femur and the tibia were dissected out, and the knee was flexed to 90 degrees and held in a vertical plane on a small platform. The angle between the upper surface of the platform and the femoral neck was then measured. Watanabe reported that, at twenty to twenty-four weeks, femoral anteversion ranged from -10 to 30 degrees. In addition, he found that marked internal rotation of the lower extremity was associated with increased femoral anteversion whereas external rotation was associated with femoral retroversion. External rotation of the lower limbs was more common in males and internal rotation...