Sex differences in clinical measures of lower extremity alignment.

STUDY
DESIGN: Descriptive, cohort design.
OBJECTIVES: To comprehensively examine sex differences in clinical measures of static lower extremity alignment (LEA).
BACKGROUND: Sex differences in LEA have been included among a myriad of risk factors as a potential cause for the increased prevalence of knee injury in females. While clinical observations suggest that sex differences in LEA exist, little empirical data are available to support these sex differences or the normal values that should be expected in a healthy population. METHODS AND MEASURES: The right and left static LEA of 100 healthy college-age participants (50 males [mean +/- SD age, 23.3 +/- 3.6 years; height, 177.8 +/- 8.0 cm, body mass, 80.4 +/- 11.6 kg] and 50 females [mean +/- SD age, 21.8 +/- 2.5 years; height, 164.3 +/- 6.9 cm; body mass, 67.4 +/- 15.2 kg]) was measured. Each alignment characteristic was analyzed via separate repeated-measures analyses of variance, with 1 between-subject factor (sex) and 1 within-subject factor (side).
RESULTS: There were no significant sex-by-side interactions and no differences between sides. Females had greater mean anterior pelvic tilt, hip anteversion, quadriceps angles, tibiofemoral angles, and genu recurvatum than males (P < .0001). No sex differences were observed in tibial torsion (P = .131), navicular drop (P = .130), and rearfoot angle (P = .590).
CONCLUSION: Sex differences in LEA indicate that females, on average, have greater anterior pelvic tilt, thigh internal rotation, knee valgus, and genu recurvatum. These sex differences were not accompanied by differences in the lower leg, ankle, and foot. Understanding these collective sex differences in LEA may help us to better examine the influence of LEA on dynamic lower extremity function and clarify their role as a potential injury risk factor.