Why and how does lateral epicondylitis occur to give rise to elbow pain? This study examined the anatomy of the lateral aspect of the elbow under static and dynamic conditions in order to identify bone-to-tendon and tendon-to-tendon contact or rubbing that might cause abrasion of the tissues.
Eighty-five cadaveric elbows were examined to determine details related to the bone structure and musculotendinous origins. We identified the relative positions of the musculotendinous units and the underlying bone when the elbow was in different degrees of flexion.
It was found that the average site of origin of the extensor carpi radialis brevis on the humerus lay slightly medial and superior to the outer edge of the capitellum. As the elbow was extended, the undersurface of the extensor carpi radialis brevis rubbed against the lateral edge of the capitellum while the extensor carpi radialis longus compressed the brevis against the underlying bone. The extensor carpi radialis brevis tendon has a unique anatomic location that makes its undersurface vulnerable to contact and abrasion against the lateral edge of the capitellum during elbow motion. (Bunata RE, Brown DS, Capelo R: Anatomic factors related to the cause of tennis elbow. Journal of Bone & Joint Surgery - American Volume. 89(9):1955-63, 2007 Sep.
Maximal muscle strain on the ECRL and ECRB was obtained with elbow extension, forearm pronation, and wrist flexion-ulnar deviation. Muscle stretching of the wrist extensors for lateral epicondylitis should be performed in this position. (Takasaki H, Aoki M, Muraki T, Uchiyama E, Murakami G, Yamashita T: Muscle strain on the radial wrist extensors during motion-simulating stretching exercises for lateral epicondylitis: a cadaveric study. Journal of Shoulder & Elbow Surgery. 16(6):854-8, 2007).