Vascularity of the Rotator Cuff After Arthroscopic Repair: Characterization Using Contrast-Enhanced Ultrasound (SS-36)

Abstract

Robust vascularity is present at the anchor site in the greater tuberosity three months after arthroscopic rotator cuff repair. Blood supply for the tendon-bone interface comes from the tuberosity. Persistent defects are common after rotator cuff repair; this suggests that the biology of tendon-bone healing in rotator cuff repair is suboptimal. To date, there has been limited in-vivo assessment of vascularity of the shoulder after rotator cuff repair. This study aims to characterize the vascularity of the rotator cuff tendon/bone interface after arthroscopic repair using contrast enhanced ultrasound. After obtaining Institutional Review Board approval, 13 patients (mean age:58.5) were enrolled in the study. Patients underwent arthroscopic single row rotator cuff repair with suture anchors (average 2 anchors doubly loaded with #2 nonabsorbable suture) of supraspinatus tears that averaged 2 cm x 1.25 cm in size. The patients then underwent lipid microsphere (Definity, 10μL/kg, Bristol Myers Squibb) contrast-enhanced shoulder ultrasound examinations three months after rotator cuff repair with images obtained at baseline, after contrast administration at rest, and after contrast administration following exercise to optimally visualize the blood flow to the shoulder. Qualitative and quantitative analysis of blood flow was performed using ultrasound imaging quantification and analysis software (QLAB; Philips, Andover, MA). Table 1 summarizes the vascularity data in the three regions of interest in intact repairs. A robust vascular response was seen at the anchor site in the greater tuberosity three months after rotator cuff repair. Comparatively little blood flow was observed in the rotator cuff tendon. Exercise recruited blood flow to all three regions of interest. 10 of 13 repairs were completely intact on ultrasound examination. Blood flow was diminished at the anchor site in repairs with a persistent defect. This study quantifies in vivo vascularity of the rotator cuff three months after arthroscopic repair. Three conclusions can be drawn from these data. 1) The rotator cuff is relatively avascular after repair at three months. 2) A robust vascular response occurs at the suture anchor site in the greater tuberosity. This suggests that the blood supply for healing of the tendon-bone interface after rotator cuff repair comes from the bony side. An intact repair may be necessary to foster angiogenesis at the repair site. 3) Exercise recruits blood flow to both the greater tuberosity and rotator cuff. This study is limited in that only one time point was considered. However, these data suggest that the repaired rotator cuff tendon is relatively avascular and that the blood supply to the tendon bone interface comes from the tuberosity.