Abstract
Tendonosis is characterized by an increase in collagen type III relative to collagen type I, but the precise ratio of collagen type I to collagen type III in pathologic shoulder tendons has not been reported. A tendon continuously bathed in an OA synovial environment may exhibit histomorphologic differences as compared to those from shoulders with a preserved articular surface. The purpose of this study was to evaluate the biochemical and histological differences in the proximal portion of the long head of the biceps tendon (LHBT) from a non-arthritic versus an arthritic glenohumeral joint. Sixteen patients undergoing shoulder surgery were prospectively enrolled in the study. Group-1 consisted of patients with glenohumeral OA and Group-2 consisted of patients without OA. The LHBT was tenodesed and excised tendon was fixed, embedded, sectioned (5 µm), deparaffinized, and used for histology (H&E and Masson trichrome staining) and immunofluorescence analysis to determine levels of collagen III, MMP-1, MMP-9, TIMP-1, and TIMP-2. Compared to the patients without arthritis, group-1 exhibited significant inflammation with extracellular matrix disorganization and significantly higher (P < 0.05) collagen III, MMP-2, and MMP-9 levels. No considerable difference in collagen I was observed between the two groups. TIMP-1 and TIMP-2 were completely absent in both the groups. The level of collagen subtypes varied markedly between LHBT tendons from patients with and without OA. Increased collagen III in the LHBT is associated with glenohumeral arthritis. Measuring collagen type in the LHBT may serve as a useful metric in the diagnosis and treatment of musculoskeletal pathology.