COMPUTED-TOMOGRAPHY IN PRIMARY GLENOHUMERAL OSTEOARTHRITIS WITHOUT HUMERAL HEAD ELEVATION

Few studies have evaluated computed tomography in glenohumeral osteoar thritis without humeral head elevation. Two recent studies included on ly ten and 11 patients, respectively. We evaluated computed tomography findings in 113 cases of primary glenohumeral osteoarthritis without humeral head elevation. Glenoid retroversion was substantially increas ed, with a mean of 16 degrees versus 8 degrees in a control group. The method used to measure this parameter was reproducible, with a mean i nterobserver variability of 4 degrees for a 95% confidence interval (P less than or equal to 0.05). Humeral retrotorsion was apparently decr eased (8 degrees), but osteoarthritis-related changes in the humeral h ead resulted in substantial measurement errors (interobserver variabil ity, 11 degrees for a 95% confidence interval; P less than or equal to 0.05). Humeral head subluxation was found in 35% of cases and measure ment of this parameter was reproducible (interobserver variability, 4 degrees for a 95% confidence interval). Changes in the glenoid over ti me were dependent on the position of the humeral head in the glenoid f ossa, which classified the shape of the glenoid with satisfactory repr oducibility (intra-and interobserver Kappa, 0.68). The subscapularis a nd infraspinatus muscles were normal (stage 0 or 1) in 98% and 91% of cases, respectively and the method of Goutallier and Bernageau used fo r muscle evaluation proved highly reproducible (Kappa, 0.85). Computed tomography is invaluable for planning surgical treatment for primary glenohumeral osteoarthritis without humeral head elevation.