Sunday, February 5, 2017

Rotator cuff tears - muscle degeneration to the point of no return

Histological Evidence of Muscle Degeneration in Advanced Human Rotator Cuff Disease

To study the effects of chronic cuff tears on the cuff musculature, these authors took biopsy samples were taken from the scapular fossae from 23 consecutive patients undergoing reverse total shoulder arthroplasty.

The samples primarily consisted of dense, organized connective tissue and disorganized, loose connective tissue, with substantially smaller fractions of muscle and fat. Only one quarter of the biopsy pool contained any muscle fibers at all. Increased inflammatory cell counts and increased vascularization were observed across biopsies.

Muscle fiber degeneration was observed in most of the observable muscle fascicles, and the percentage of centrally nucleated muscle fibers was pathologically elevated. Fat accumulation was noted in both perifascicular and intrafascicular spaces, with evidence that lipid may replace contractile elements without altering muscle organization.

They concluded that dramatic degeneration and inflammation of the rotator cuff muscles are characteristics of the mostchronic and severe rotator cuff disease states, suggesting that muscle loss is more complicated than, and distinct from the simple atrophy found in less severe cases.
In a large majority of the samples, muscle tissue was completely replaced by a disorganized, vascular connective-tissue network with high macrophage density. It is possible that such tissue appears similar to muscle in clinical imaging, leading to gross underestimation of muscle degeneration.

Comment: While there is enthusiasm in some parts for attempting repair of chronic massive cuff tears, these results indicate that severe forms of degeneration may not respond well to muscle reloading.