Effect of Supraspinatus Tendon Injury on Supraspinatus and Infraspinatus Muscle Passive Tension and Associated Biochemistry

Abstract

Muscle stiffness after rotator cuff tendon injury is more severe with large tears. This finding supports the concept of early intervention, when tendon tears are smaller, and interventions targeting the extracellular matrix.

Shear Wave Ultrasound Elastographic Evaluation of the Rotator Cuff Tendon

“…Significantly lower deltoid muscle SWV values were unexpectedly found in studies with higher morphologic grades and in symptomatic studies, suggesting that softening may occur in the setting of rotator cuff disease. Stiffening is known to occur in the rotator cuff musculature after rotator cuff tendon injury as a result of increased collagen deposition in the extracellular matrix . We surmise that an indirect mechanism must lead to isolated softening in the deltoid, perhaps as a result of the deltoid–rotator cuff coronal plane force couple .…”

The role of mechanobiology in progression of rotator cuff muscle atrophy and degeneration

“…A second consequence of chronic muscle retraction is increased muscle fiber‐bundle stiffness . Because single fiber passive mechanics are not altered with RC tear, this stiffening is likely attributable to increased fibrosis, that is, collagen content in the muscle (Fig. , ECM Stiffening ).…”

“…, ECM Stiffening ). While fibrosis predicts stiffness to a degree, the existing data suggests that muscle stiffness is dictated by additional variables. One possible contributor is reduced sarcomere number following tear, which would lead to higher average sarcomere strains for a given change in muscle length .…”

“…Indeed, one prevailing hypothesis is that accumulation of adipose tissue serves as a necessary mechanical buffer to counter changes in muscle volume and pennation angle, in order to preserve a maximum possible amount of muscle force producing capacity . As RC disease progresses and stiff muscle is replaced by more extensible fat, overall organ extensibility increases, even though there is no evidence suggesting that remaining muscle tissue becomes more extensible itself. The resulting tissue is a complex and compartmentalized biomechanical system, which can in turn give rise to significant but localized changes in the micromechanical environment that impact both individual muscle fibers and resident stem cells.…”

Analgesic treatment, by using a systemic algorithm

“…Роль болезненного напряжения мышц в патогенезе МСБ также может обсуждаться и при ревматической пато-логии околосуставных мягких тканей -в первую очередь при хронической боли в области плеча, связанной с тенди-нитом мышц вращающей манжеты [28,29].…”