Anatomical variability in the quadriceps tendon: structural layering and patellar insertion patterns

The quadriceps tendon is a complex anatomical structure that is crucially involved in knee stability and extension by transmitting forces from the quadriceps muscles to the patella. This study investigated anatomical variability in the quadriceps tendon of elderly Korean cadavers, focusing on the structural layering and muscle contributions at its patellar insertion.

Sixty-three quadriceps tendon specimens from 35 Korean cadavers were dissected to assess the composition and arrangement of the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), and vastus intermedius (VI).

The quadriceps tendon configurations were categorized into four distinct types based on the pattern of muscle layering: Type 1, a trilaminar structure with the RF as the superficial layer, the VM and VL combined as the middle layer, and the VI as the deepest layer (8/20, 40 %); Type 2, a multilayered arrangement with RF insertions merging with the VM and VL (8/20, 40 %); Type 3, comprising the RF, VL, and VI, with no contribution from the VM (3/20, 15 %); and Type 4, consisting solely of the RF and VI (1/20, 5 %). In terms of tendon ratios, the combined vastus muscles (VM + VL) were 1-3 times larger than the RF and VI in 50 of 63 specimens, while 12 specimens displayed ratios as high as 4-6 times.

These data suggest that adjusted approaches that account for individual anatomical differences may improve outcomes in surgical procedures involving the knee.