Patellar tendon orientation and patellar tracking in male and female knees.

Knowledge of patellofemoral joint biomechanics is important for understanding sex-related dimorphism in patellofemoral pathologies and advancement of related treatments. We evaluated the hypotheses that sex differences exist in patellar tendon (PT) orientation and patellar tracking during weight-bearing knee flexion and that they relate to differences in tibiofemoral rotation. The PT orientation and patellar tracking were measured in healthy subjects (18 male, 13 female) during weight-bearing knee flexion, using magnetic resonance and dual fluoroscopic imaging. These data were analyzed for sex differences and correlation with previously reported tibiofemoral rotation data. The results indicated a significant effect of sex on PT orientation, particularly at low flexion angles. In females, the PT was oriented more anteriorly in the sagittal plane, more medially in the coronal plane, and showed greater external tilt in the transverse plane of the tibia (p < 0.05). Significant correlations between tibiofemoral rotation and PT orientation (p < 0.01) indicated that sex differences in coronal and transverse plane orientation of the PT relate to differences in tibiofemoral rotation. Patellar tracking did not show significant sex differences or correlation to tibiofemoral rotation. Further studies are warranted to determine implications for patellofemoral pathologies and treatments like total knee arthroplasty.