The Influence of Partial and Full Thickness Tears on Infraspinatus Tendon Strain Patterns

Abstract

Tears on the bursal and articular sides of the rotator cuff tendons are known to behave differently and strain is thought to play a role in this difference. This study investigates the effect of tear location on the changes in three strain measurements (grip-to-grip, insertion, and mid-substance tissue) in a sheep infraspinatus tendon model during axial loading. We introduced a 14 mm wide defect near the insertion from either the articular or bursal side of the tendon to three depths (3 mm, 7 mm & full) progressively. For each condition, tendons were sinusoidally stretched (4% at 0.5 Hz) while insertion and mid-substance strains were tracked with surface markers. For a fixed load, grip-to-grip strain increased significantly compared to intact for both cuts. Insertion strain increased significantly for the bursal-side defect immediately but not for the articular-side until the 66% cut. Mid-substance tissue strain showed no significant change for partial thickness articular-side defects and a significant decrease for bursal-side defects after the 66% cut. All full thickness cuts exhibited negligible mid-substance tissue strain change. Our results suggest that the tendon strain patterns are more sensitive to defects on the bursal side, and that partial thickness tears tend to induce localized strain concentrations in regions adjacent to the damaged tissue.

Extracellular Vesicle-Educated Macrophages Promote Early Achilles Tendon Healing

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Partial-width injuries of the rat rotator cuff heal with fibrosis

“…Depending on the location and severity of the tear, clinical recommendations for surgery and physical therapy vary substantially (3,4). For partial-width tears, conservative treatments (e.g., physical therapy) are encouraged before surgical intervention (4–6). The success of rotator cuff repair depends on the health of the cuff at time of repair (7–11) as well as the restoration of the morphology and strength of the attachment (12–17).…”

Exosome-educated macrophages and exosomes differentially improve ligament healing

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