Relationship Between Osteoarthritic Changes and Rotator Cuff Tear Analyzed by MRI in Various Shoulder Disorders

Abstract

The osteoarthritis of glenohumeral joint is relatively rare and the pathomechanism is not well understood. Using MRI, we analyzed the incidence and the location of the cartilage injury which are not detected by plain x-rays and try to elucidate the relationship between rotator cuff tear and osteoarthritis. The materials were patients who came to our clinic with various shoulder problems and were examined by MRI during 2009, which included 98 patients (67 men and 31 women), 100shoulders. The mean age was 61.9 years (37-90). MRI and plain x-rays were reviewed in all cases. OA changes were assessed by obvious osteophyte, cartilage defect, narrowing of the width of the cartilage and the abnormal signal of subchondral bone. Decentering of humeral head is defined by the relationship of the humeral head and the glenoid. The diagnosis were 39 rotator cuff tears which included 30 complete-tear and 9 incomplete/small-tear, and 61 non-tears. The decentering of humeral head was found in 16 of 39 complete-tear shoulders, 10 of which were displaced superior and 6 were inferior. Six of 61 non-tear shoulders showed decentering, all of them displaced inferiorly. OA changes were seen in superior portion of 18 humeral head, inferior portion of 48 heads, and 41 glenoids. The pattern of locations of these findings was significantly different between complete-tear and non-tear shoulders. OA changes of upper portion were significantly more often found in complete-tear shoulders. Cartilage lesions indicating osteoarthritic findings are found in the inferior portion of the humeral head more than in the superior portion of the head and the glenoid. The pattern of combination of the position of the decentering humeral head and the location of the OA changes is significantly different between complete-tear and non-tear shoulders, but it is similar with incomplete/small-tear and non-tear shoulders.