The objective of this study was to determine whether the tear size of a supraspinatus tendon correlated with synovial inflammation and tendon degeneration in patients that underwent shoulder arthroscopy for rotator cuff repair. We hypothesized that increased synovial inflammation would correlate with greater tear size of the supraspinatus tendon at the time of surgery.
Materials and Methods
Tissue from the synovium, bursa, torn supraspinatus tendon and subscapularis tendon were obtained from patients during shoulder arthroscopy in order to evaluate the mRNA expression of pro-inflammatory cytokines, tissue remodeling and angiogenesis factors in the tendon, bursa, and synovium. Additional tissue was fixed to determine histological changes including inflammation, vascular ingrowths, and collagen organization.
Increased expression of IL-1β, IL-6, COX-2, MMP-9, and VEGF was found in the synovium of patients with full-thickness tears versus partial-thickness tears (p<0.05). In the supraspinatus tendon, increased expression of MMP-1, -9, and -13 and VEGF was found in the full-thickness group. The upregulation of these genes in the full-thickness group was consistent with enhanced synovium inflammation, greater vascular ingrowth and the loss of collagen organization in both supraspinatus and subscapularis tendons as determined by histology.
Increased synovium inflammation and tissue degeneration correlates with the tear size of the supraspinatus tendon. A better understanding of the relationship between synovial inflammation and the progression of tendon degeneration can help design novel and effective treatments to limit the advance of rotator cuff diseases and to improve their clinical outcomes.
Level of evidence
Basic Science, Molecular and Cell Biology Study