Abstract
PurposeTo analyze biopsy samples from the subscapularis tendon and from the joint capsule from male patients with subacromial impingement syndrome and compare them with samples from male patients with post-traumatic recurrent shoulder instability, to detect increased inflammatory activity that might be present inside the humeroscapular joint.MethodsTwenty male patients scheduled for surgery for either subacromial decompression or Bankart reconstruction were included. Four biopsies from each patient were obtained during surgery from the capsule and the subscapularis tendon. Each specimen was analyzed for TNF-α, IL-6, CD-3 and CD-72. Multiplex fluorescence immunohistochemistry was performed on histological samples from the capsule and tendon to demonstrate the level of inflammatory markers. Fluorescence microscope images were acquired using an automated scanning system. On each slide, the number of pixels was registered and used in the analyses.ResultsThe subacromial impingement syndrome group comprised eight patients, median age 53 (45–74) years, while the instability group 12, median age 27 (22–48) years (p < 0.00001). The amount of IL-6 and TNF-α was significantly higher in the subscapularis tendon of the patients with subacromial impingement syndrome compared with instability patients (p = 0.0015 and p = 0.0008 respectively). In the capsular samples, significantly higher amount of TNF-α and CD-72 was found in patients with subacromial impingement syndrome compared with instability patients (p < 0.0001 for both). On the other hand, the amount of CD-3 was significantly higher in the instability group (p = 0.0013).ConclusionsThis study provides evidence that an extended inflammatory process is present, not only in the subacromial bursa but also in the glenohumeral joint in patients with subacromial impingement syndrome.Level of evidenceLevel III.Clinical relevanceTo develop a treatment targeted towards intra-articular inflammatory cytokines appears appealing.
Highlights
Subacromial impingement syndrome (SAIS) is described as pain provoked in shoulder movements above the horizontal plane [33]
Each specimen was analyzed for TNF-α, IL-6, CD-3 and CD-72
Increased levels or the expression of TNF-α and IL-6 in the subacromial bursa have been found by Sakai et al [40], Blaine et al [4, 5], and Voloshin et al [47] in patients with rotator cuff tears compared with controls
Summary
Subacromial impingement syndrome (SAIS) is described as pain provoked in shoulder movements above the horizontal plane [33]. It often appears in persons under 25 years of age. In SAIS Stage III, chronic changes, such as partial or complete tears of the rotator cuff, are present The latter appears in patients of more than 40 years of age. Neer proposed that the syndrome results from direct mechanical conflict between the acromion and the adjacent structures and the rotator cuff [34]. This theory is called the extrinsic theory. The syndrome is a result of chronic degenerative and inflammatory changes in the rotator cuff and the subacromial bursa which lead to the thickening of the subacromial soft tissue, which results in friction and mechanical conflict in the subacromial space [8, 9, 12, 15, 19, 29, 43, 45]
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