Multivariate analysis of biochemical markers in synovial fluid from the shoulder joint for diagnosis of rotator cuff tears.

Multivariate discriminant analysis allowed definition of cytokine, matrix metalloproteinases (MMP), and tissue inhibitors of metalloproteinases (TIMP) levels in synovial fluid (SF) of patients with rotator cuff tears and other shoulder lesions. We analyzed SF aspirated from the glenohumeral joints of 17 patients with rotator cuff tears; SF from nine patients with other shoulder lesions was used to characterize a non-rotator-cuff-tear (NRCT) group. Discriminant analysis demonstrated statistically significant differences in (1) the determination of whether rotator cuff tear patients are separable from the NRCT group using the influential functions, the most influential of which were interleukin 1-beta, MMP-2, and MMP-13, and (2) the assessment of whether full-thickness rotator cuff tears are distinguishable from partial tears using identical influential functions. The most influential function in the latter analysis was MMP-13. Both interleukin 1-beta and MMP-13 might be biochemical markers of impending rotator cuff tears.