The geometry of patella and patellar tendon measured on knee MRI.

This study provides the geometry of patella and patellar tendon measured on sagittal and axial magnetic resonance images of 172 knees (142 males, 30 females) of 163 subjects (135 males, 28 females) whose mean age was 26.7. The gender difference and the relationship with anthropometry were also given. As for patella, the longitudinal lengths of the whole and articulating surface were 44.6, 32.9 mm, and the thickness was 22.3 mm. The mediolateral width was 45.8 mm, and the central ridge was located 19.9 mm or 43% lateral from the medial border. As for patellar tendon, the longitudinal length was 40.2 mm. The widths of proximal and distal part were 30.3, and 24.0 mm. The thicknesses of proximal and distal part were 3.2, and 5.0 mm. The geometry of the patella and patellar tendon was larger in male than in female (P < 0.001). Anthropometry including weight, height, body mass index corresponds well with the thickness of patella but poorly with the length of patellar tendon. These data can provide useful information in the field of knee surgery and sports medicine.