Glenohumeral motion in patients with rotator cuff tears: A comparison of asymptomatic and symptomatic shoulders

The purpose of this study was to determine whether there was a relationship between altered scapular plane glenohumeral kinematics end shoulder pain. Subjects were divided into 3 groups: normal volunteers (n = 10), patients w ith symptomatic rotator cuff fears severe enough to warrant surgery in = 10 ), and subjects with no symptoms who had tears documented on magnetic reson ance imaging and normal examination (n = 10). Humeral kinematics were obser ved with a computer-enhanced modification of the Poppen and Walker techniqu e. Scapular plane x-ray films were obtained at 0 degrees 30 degrees 60 degr ees 90 degrees 120 degrees and 150 degrees of elevation. Measurements were made by 3 independent observers blinded to the diagnosis, and data interpre tation was performed based on mean values for independent observers. Result s showed a high degree of interobserver and intraobserver reliability (coef ficients = 0.96 and 0.95, respectively). The symptomatic and asymptomatic g roups showed progressive superior translation of the humeral head on the gl enoid with increasing arm elevation. The normal group, in contrast, maintai ned a constant center of rotation along the geometric center of the glenoid . Symptomatic and asymptomatic rotator cuff tear groups showed superior hea d migration from 30 degrees to 150 degrees which was significantly differen t from those seen in the normal group. No significant difference between th e symptomatic and asymptomatic groups was demonstrated with the small numbe rs used in this study. The presence of a rotator cuff tear was associated i n a disruption of normal glenohumeral kinematics in the scapular plane. Bec ause significant superior migration of the humeral head was seen in both th e asymptomatic and symptomatic rotator cuff groups, painless and normal sho ulder motion is possible in the presence of abnormal glenohumeral kinematic s. Abnormal glenohumeral kinematics alone was not an independent factor, wh ich could explain the occurrence of symptoms.