The aim of the study was to investigate the levels of matrixmetalloproteinases and their inhibitors in blood samples from patients with rotator cuff tears and compare with blood samples from healthy matched controls.

Background: Extracellular matrix remodeling is altered in rotator cuff tears, partly due to altered expression of matrix metalloproteinases (MMPs) and their inhibitors. It is unclear if this altered expression can be traced as changes in plasma protein levels. We measured the plasma level of MMPs and their tissue inhibitors (TIMPs) in patients with rotator cuff tears.

Material and methods: Blood samples were collected from 17 patients, median 61 (range 39-77) years, with sonographically verified rotator cuff tears (partial- or full-thickness). These were compared with 16 gender and age matched control persons with sonographically intact rotator cuffs. Plasma levels of MMPs and TIMPs were measured simultaneously using Luminex technology.

Inclusion Criteria:

- degenerative rotator cuff tear verified by ultrasound

Exclusion Criteria:

• systemic joint disease such as rheumatoid arthritis
• a fracture non-union
• dupuytrens disease
• frozen shoulder
• tendinosis or rupture of any other tendons than in the rotator cuff
• disorders of the spine such as disc disease,idiopathic scoliosis, spondylitis
• cerebral or cardiovascular disease during the past year
• abdominal or bowel disease
• surgery or trauma during the past year
• any infection during the last month
• malignancy
• treatment for the last month with medications that may affect MMPs or TIMPs (tetracycline, bisphosphonates, anti-inflammatory drugs, statins)
• vigorous physical activity during the last 24 hours
• inability to understand written and spoken Swedish

Patients with ultrasound verified rotator cuff tears and healthy age and gender matched controls