Muscle activity during shoulder dislocation.
EMG activity from eight shoulder muscles in parallel was recorded from 4 patients with generalized joint laxity. During external rotation of the humerus in 45 degrees abduction, humeroscapular dislocation occurred in 2 patients and subluxation in the 2 others. The activity level in the subscapularis was low, and the activation speed was slow. The low muscle activity and delay in activation of the subscapularis muscle may contribute to the instability.
Broström
L A
LA
Department of Orthopedics, Karolinska Hospital, Stockholm, Sweden.
Kronberg
M
M
Nemeth
G
G
D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D009132:Muscles / Q000503:physiopathology*; D012399:Rotation; D012783:Shoulder Dislocation / Q000503:physiopathology*; D012785:Shoulder Joint / Q000503:physiopathology*