Sex differences in passive lateral and medial patellar mobility in healthy young adults

Sex differences in passive patellar mobility have not been quantitatively evaluated.

The present study aimed to: 1) investigate sex differences in absolute and normalized patellar mobility, and 2) verify the relationship between patellar mobility and knee joint laxity.

Two hundred and five pain-free individuals (205 knees, 103 men, 102 women) participated. Passive lateral and medial patellar displacement was measured using a modified patellofemoral arthrometer and manual pushing method at 0∘ and 30∘ knee flexion angles. The absolute values of lateral and medial patellar displacement (LPD and MPD, respectively), and values normalized to patellar width (PW) and body height (HT) were used in the final analysis.

At a 30∘ knee flexion angle, LPD/PW and LPD/HT were greater in women than in men (LPD/PW: 27.0 ± 6.7% vs. 22.6 ± 6.7%, LPD/HT: 0.81 ± 0.19% vs. 0.70 ± 0.15%, respectively, P< 0.001, effect size > 0.50). Absolute and normalized lateral and medial patellar mobility correlated positively with the range of the knee extension angle.

Sex differences in LPD/PW and LPD/HT at a 30∘ knee flexion were detected in healthy subjects. Although the knee extension angle related to both the lateral and medial direction of the patellar mobility, the relations were only fairly correlated in asymptomatic young subjects.