Occult periarthrosis of the shoulder: a possible progenitor of tennis elbow.

Nineteen outpatients, nine women and ten men, all right-handed, ranging in age from 33 to 87 yrs, with an average age of 53.5 yrs, presented with complaints of lateral epicondylitis (i.e., tennis elbow). Each was subsequently identified as having a heretofore unrecognized loss of ipsilateral shoulder internal rotation. The authors suggest that in this scenario the occult shoulder periarthrosis is interlinked in a pathokinetic chain potentially predisposing to the presenting symptoms of tennis elbow. During a tennis serve, excessive wrist flexion may be substituted as to compensate for a restricted arc of shoulder internal rotation. The extensor carpi radialis longus and brevis cross both the elbow and wrist. Functionally, they have the capacity of reversing their osseous attachments, both at their origin and insertion, as these muscles cycle under load from a concentric/shortening to an eccentric/elongating contraction. Aging muscle, with its increased viscoelastic stiffness, may be "too slow" to accommodate this transition recoil, especially when repetitive. Instead, it is pathomechanically absorbed at the proximal elbow extensor tendon insertion.