Humeral rotation osteotomy is not associated with glenohumeral and scapulohumeral decentering at long-term follow-up.

BACKGROUND

Weber rotational osteotomy that increases humeral retrotorsion in patients with anterior shoulder instability has become unpopular because of recurrence of instability and high rates of early-onset osteoarthritis (OA). However, the wear pattern in patients after rotational osteotomy remains unknown. The aim of this study was to determine the influence of surgically increased humerus retrotorsion on glenohumeral and scapulohumeral centering in a long-term follow-up.

METHODS

The data of 18 shoulders in 18 patients diagnosed with a unilateral chronic recurrent anterior shoulder instability treated with an internal rotation subcapital humerus osteotomy between 1984 and 1990 were drawn from a previously published cohort and enrolled in the study. All patients had available bilateral computed tomography (CT) scans performed after a mean follow-up of 14 (12-18) years. On these CT scans a comparison of the operated and the contralateral healthy side with regard to humerus torsion, glenoid version, glenoid offset, glenohumeral and scapulohumeral subluxation indices, rotator cuff action lines, and osteoarthritic changes was performed.

RESULTS

The analysis of follow-up CT scans revealed a significantly higher mean humeral retrotorsion in the operated side compared with the healthy side (41.6° ± 14.0° vs. 20.7° ± 8.2°, P < .001). No differences were found in terms of glenohumeral subluxation index (0.50 ± 0.08 vs. 0.51 ± 0.03, P = .259), scapulohumeral subluxation index (0.53 ± 0.09 vs. 0.54 ± 0.03, P = .283), glenoid version (-3.9° ± 4.6° vs. -4.1° ± 3.7°, P = .424), glenoid offset (4.0 ± 2.8 mm vs. 4.0 ± 1.3 mm, P = .484), infraspinatus action lines (102.5° ± 4.7° vs. 101.2° ± 2.1°, P = .116), subscapularis action lines (74.0° ± 6.0° vs. 73.1° ± 2.3°, P = .260), and resultant rotator cuff action lines (87.8° ± 4.9° vs. 87.0° ± 1.8°, P = .231) between operated and healthy shoulders. Osteoarthritic changes were observed in all operated shoulders and in 13 of 18 healthy shoulders. The OA grade was mild in 5 patients, moderate in 11, and severe in 2 cases for operated shoulders and mild in 13 healthy shoulders at the last follow-up.

CONCLUSION

The surgical increase of humeral retrotorsion by 20°-30° did not affect glenohumeral and scapulohumeral centering in patients with a Weber rotational osteotomy after a long-term follow-up compared to the healthy side. Although a high degree of early-onset OA was observed it remains unclear whether the cause is the surgical interventions performed or the joint instability itself.