Objectives . The effects of disease progression and common tendinopathy treatments on the tissue characteristics of human rotator cuff tendons have not previously been evaluated in detail owing to a lack of suitable sampling techniques. This study evaluated the structural characteristics of torn human supraspinatus tendons across the full disease spectrum, and the short-term effects of subacromial corticosteroid injections (SCIs) and subacromial decompression (SAD) surgery on these structural characteristics. . Methods . Samples were collected inter-operatively from supraspinatus tendons containing small, medium, large and massive full thickness tears (n = 33). Using a novel minimally invasive biopsy technique, paired samples were also collected from supraspinatus tendons containing partial thickness tears either before and seven weeks after subacromial SCI (n = 11), or before and seven weeks after SAD surgery (n = 14). Macroscopically normal subscapularis tendons of older patients (n = 5, mean age = 74.6 years) and supraspinatus tendons of younger patients (n = 16, mean age = 23.3) served as controls. Ultra- and micro-structural characteristics were assessed using atomic force microscopy and polarised light microscopy respectively. . Results. Significant structural differences existed between torn and control groups. Differences were identifiable early in the disease spectrum, and increased with increasing tear size. Neither SCI nor SAD surgery altered the structural properties of partially torn tendons seven weeks after treatment. . Conclusions . These findings may suggest the need for early clinical intervention strategies for torn rotator cuff tendons in order to prevent further degeneration of the tissue as tear size increases. Further work is required to establish the long-term abilities of SCI and SAD to prevent, and even reverse, such degeneration. Cite this article: Bone Joint Res 2014;3:252–61

The aim of this study was to investigate the occurrence of tissue hypoxia and apoptosis at different stages of tendinopathy and tears of the rotator cuff.

We studied tissue from 24 patients with eight graded stages of either impingement (mild, moderate and severe) or tears of the rotator cuff (partial, small, medium, large and massive) and three controls. Biopsies were analysed using three immunohistochemical techniques, namely antibodies against HIF-1α (a transcription factor produced in a hypoxic environment), BNip3 (a HIF-1α regulated pro-apoptotic protein) and TUNEL (detecting DNA fragmentation in apoptosis).

The HIF-1α expression was greatest in mild impingement and in partial, small, medium and large tears. BNip3 expression increased significantly in partial, small, medium and large tears but was reduced in massive tears. Apoptosis was increased in small, medium, large and massive tears but not in partial tears.

These findings reveal evidence of hypoxic damage throughout the spectrum of pathology of the rotator cuff which may contribute to loss of cells by apoptosis. This provides a novel insight into the causes of degeneration of the rotator cuff and highlights possible options for treatment.

We assessed the predictive value of the macroscopic and detailed microscopic appearance of the coracoacromial ligament, subacromial bursa and rotator-cuff tendon in 20 patients undergoing subacromial decompression for impingement in the absence of full-thickness tears of the rotator cuff. Histologically, all specimens had features of degenerative change and oedema in the extracellular matrix. Inflammatory cells were seen, but there was no evidence of chronic inflammation. However, the outcome was not related to cell counts. At three months the mean Oxford shoulder score had improved from 29.2 (20 to 40) to 39.4 (28 to 48) (p < 0.0001) and at six months to 45.5 (36 to 48) (p < 0.0001). At six months, although all patients had improved, the seven patients with a hooked acromion had done so to a less extent than those with a flat or curved acromion judged by their mean Oxford shoulder scores of 43.5 and 46.5 respectively (p = 0.046). All five patients with partial-thickness tears were within this group and demonstrated less improvement than the patients with no tear (mean Oxford shoulder scores 43.2 and 46.4, respectively, p = 0.04). These findings imply that in the presence of a partial-thickness tear subacromial decompression may require additional specific treatment to the rotator cuff if the outcome is to be improved further