Insertion orientation of terminal vastus lateralis obliquus and vastus medialis obliquus muscle fibers in human knees

Abstract

Abstract The quadriceps mechanism consists of the patellar ligament distally and the quadriceps tendon proximally. The quadriceps tendon is the confluence of the tendinous portions of the vastus medialis, vastus lateralis, vastus intermedius, and rectus femoris. Lieb and Perry (J. Bone Joint Surg. 50A:1535–1547, 1968) have described the vastus medialis obliquus (VMO) and Hallisey et al. (J. Bone Joint Surg. 69A:545–549, 1987) have described the vastus lateralis obliquus (VLO). These muscles are the terminal medial and lateral insertions of the vastus medialis and vastus lateralis. This study delineates and quantifies anatomic sex differences for the medial and lateral angular terminal insertions of the vastus lateralis obliquus and vastus medialis obliquus in relationship to the longitudinal axis of the patella in 40 embalmed cadaver knees. A mathematical model is developed and discussed using least steps regression equations y = Ax + B, where y = the VLO insertion angle, x = the VMO insertion angle, A = the coefficients, and B = the y intercept. These equations are different in males and females, with males having more horizontally oriented VLO fibers than females. The vastus lateralis obliquus (VLO) insertion angle can be predicted based upon measurement of the vastus medialis obliquus insertion angle and sex: Log VLO = 1.36 + .00531 VNIO − 0.000166 (S × VMO), where S = 1 for females and S = 0 for males. In embalmed cadaver knees, the angular terminal insertion of the vastus lateralis obliquus related to the longitudinal axis of the patella is more horizontally oriented in males than in females. The angular terminal insertion of the vastus medialis obliquus of males and females does not increase equally with increases in the angular terminal insertion of the vastus lateralis obliquus. © 1993 Wiley‐Liss, Inc.