Revascularization of Transcortical Vessels Improves Tendon-to-Bone Healing for Rotator Cuff Repair

Rotator cuff tear is a prevalent musculoskeletal disorder with a high postoperative retear rate. Transcortical vessels (TCVs) are capillaries that cross cortical bone and represent key elements of bone microcirculation. However, the possible intervention and influence of TCVs for rotator cuff repair (RCR) have rarely been studied. To investigate the effect of TCV-mediated revascularization in RCR and the mechanism of potential intervention. Controlled laboratory study. Sprague-Dawley rats (N = 135) with supraspinatus tendon tear and delayed repair were randomly assigned into 3 groups based on footprint preparation: (1) cortical bone freshening up by debridement to expose cancellous bone, (2) cortical bone preservation as the control group, and (3) cortical bone preservation with oral D-sphingosine as a TCV-stimulating factor. Oxidative stress was measured using fluorescent probes; hypoxia and inflammation levels were measured via immunosorbent assay; and RCR and TCVs were evaluated with biomechanical and immunostaining assays. Cortical bone preservation inhibited the revascularization of TCVs during RCR (< .01), while freshening up or D-sphingosine treatment promoted TCV formation by reducing oxidative stress (< .05 for all). Revascularization of TCVs alleviated hypoxia and inflammation-derived chronic tendinopathy after 6 weeks (< .05 for all) and improved the biomechanical properties of rotator cuff at 12 weeks (< .05). Footprint freshening up or D-sphingosine treatment improves tendon-to-bone healing, suggesting the importance of TCV-mediated revascularization for RCR. Revascularization therapy such as cortical bone freshening up or D-sphingosine has the potential to improve RCR.