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Glucocorticoid injection (GCI) and surgical rotator cuff repair are two widely used treatments for rotator cuff tendinopathy. Little is known about the way in which medical and surgical treatments affect the human rotator cuff tendon in vivo. We assessed the histological and immunohistochemical effects of these common treatments on the rotator cuff tendon.Controlled laboratory study.Supraspinatus tendon biopsies were taken before and after treatment from 12 patients undergoing GCI and 8 patients undergoing surgical rotator cuff repair. All patients were symptomatic and none of the patients undergoing local GCI had full thickness tears of the rotator cuff. The tendon tissue was then analysed using histological techniques and immunohistochemistry.There was a significant increase in nuclei count and vascularity after rotator cuff repair and not after GCI (both p=0.008). Hypoxia inducible factor 1α (HIF-1α) and cell proliferation were only increased after rotator cuff repair (both p=0.03) and not GCI. The ionotropic N-methyl-d-aspartate receptor 1 (NMDAR1) glutamate receptor was only increased after GCI and not rotator cuff repair (p=0.016). An increase in glutamate was seen in both groups following treatment (both p=0.04), while an increase in the receptor metabotropic glutamate receptor 7 (mGluR7) was only seen after rotator cuff repair (p=0.016).The increases in cell proliferation, vascularity and HIF-1α after surgical rotator cuff repair appear consistent with a proliferative healing response, and these features are not seen after GCI. The increase in the glutamate receptor NMDAR1 after GCI raises concerns about the potential excitotoxic tendon damage that may result from this common treatment.

Original publication




Journal article


British journal of sports medicine

Publication Date





1620 - 1626


Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), Botnar Research Centre, Institute of Musculoskeletal Sciences, Nuffield Orthopaedic Centre, Oxford, UK.


Rotator Cuff, Humans, Shoulder Pain, Athletic Injuries, Tendon Injuries, Methylprednisolone, Glutamic Acid, Receptors, N-Methyl-D-Aspartate, Nerve Tissue Proteins, Anti-Inflammatory Agents, Glucocorticoids, Observer Variation, Ultrasonography, Interventional, Immunohistochemistry, Injections, Intra-Articular, Case-Control Studies, Wound Healing, Cell Proliferation, Adult, Aged, Middle Aged, Female, Male, Hypoxia-Inducible Factor 1, alpha Subunit, Tendinopathy, Image-Guided Biopsy, Rotator Cuff Injuries