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Background: The objectives of this study were to characterize and compare the vascularity of arthroscopically repaired rotator cuff tendons at short-term and intermediate-term follow-up., Materials and Methods: Nineteen patients who underwent arthroscopic rotator cuff repair were prospectively monitored for an average of 21.2 months. Initial baseline, grayscale ultrasound images of the operated-on shoulder were obtained on all patients at 3 months and at a minimum of 10 months postoperatively. Perflutren-lipid microsphere contrast (DEFINITY, Lantheus Medical Imaging, North Billerica, MA, USA) was injected after baseline grayscale images and after exercise to obtain contrast-enhanced images of the repair. Three regions of interest--supraspinatus tendon, peribursal tissue, and bone anchor site--were evaluated before and after rotator cuff-specific exercises., Results: The peribursal tissue demonstrated the greatest blood flow, followed by the bone anchor site and tendon, in pre-exercise and postexercise states. Significantly less blood flow was observed in all regions of interest before exercise (P < .05) and only at the bone anchor site after exercise (P < .001) at latest follow-up compared with the 3-month values. Intratendinous blood flow remained relatively low at both evaluation points after surgical repair., Conclusion: Preliminary findings suggest that the peribursal tissue and bone anchor site are the main conduits of blood flow for the rotator cuff tendon after arthroscopic repair, with the supraspinatus tendon being relatively avascular. Blood flow of the repaired rotator cuff tendon decreases with time. Furthermore, exercise significantly enhances blood flow to the repaired rotator cuff., (Copyright © 2012. Published by Mosby, Inc.)

Objectives: To characterize the distribution of vascularity of the postoperative rotator cuff tendon using a maximum intensity projection technique after contrast-enhanced sonography., Methods: We retrospectively evaluated image data on 23 patients (11 male and 12 female) with intact rotator cuff repairs who had previously undergone contrast-enhanced sonography of their shoulders using lipid microspheres before and after a standardized exercise protocol. The patients were on average 3 months out from their surgery. Using offline image analysis software, a maximum intensity projection image was obtained for each patient, reflecting the regional vascular distribution within the repair and adjacent soft tissue. Subjective analysis was performed in 4 regions of interest: peribursal, articular medial, articular lateral, and suture anchor, independently by 2 musculoskeletal radiologists using a semiquantitative scale ranging from 0 to 4 for each region (0, no enhancement; 1, 1%-25% enhancement; 2, 26%-50%; 3, 51%-75%; and 4, 76%-100%). A combined vascularity score (0-8) was produced for each region and formed the basis for the subjective analysis., Results: Using a Mann-Whitney nonparametric test, the data showed significantly higher regional enhancement in the peribursal and suture anchor regions compared to the tendon (P < .001). Exercise resulted in a statistically significant increase in the extent of enhancement in all regions (P < .002). Inter-rater reliability analysis using a weighted κ statistic showed strong agreement (0.63-0.64) for the suture anchor site and moderate agreement for the others (peribursal, 0.35-0.39; articular medial, 0.45-0.55; and articular lateral 0.32-0.33)., Conclusions: The maximum intensity projection technique after contrast-enhanced sonography provides a topographic map of rotator cuff vascularity; the latter has been implicated as an important factor in promoting bone-tendon healing. Approximately 3 months after rotator cuff repair, the suture anchor and peribursal regions showed the most robust vascularity. Maximum intensity projection imaging further establishes that there is a global increase in vascular response at the repair site after exercise.

Background: There has been limited in-vivo assessment of rotator cuff vascularity following repair. This study aims to characterize the vascularity of the shoulder 3 months following supraspinatus tendon repair., Methods: Twenty-nine patients (average age, 61.4 years) underwent Perflutren lipid microsphere contrast-enhanced shoulder ultrasound examinations 3 months after arthroscopic rotator cuff repair. Each shoulder was scanned at rest and following exercise using linear phased array 9-MHz transducer optimized to detect the contrast agent. Blood flow was quantified off-line using ultrasound imaging quantification and analysis software (QLAB, Philips, Andover, MA). Peak enhancement (vascular volume) and rate of rise (perfusion) were determined for 3 regions of interest: peribursal area, supraspinatus tendon, and anchor site., Results: Peak enhancement and rate of rise were greatest in the peribursal soft tissue and anchor site. Resting peak enhancement and rate of rise were significantly lower within the tendon compared to the other 2 regions (P < .001). Exercise resulted in increased enhancement and rate-of-rise to all 3 regions, but had a significant predilection towards increasing vascular volume within the peri-bursal region (P = .026)., Conclusion: At 3 months following repair, the majority of blood flow to the repair is derived from the peribursal soft tissues and the anchor site. The tendon, particularly those with a defect at 3 months, is relatively avascular. Though limited by inclusion of only a single time point, this study introduces a new technique to quantify vascularity following supraspinatus repairs and suggests that the surrounding vascular milieu may play a role in tendon healing., Level of Evidence: Basic Science.

A bioresorbable patch used for augmentation of rotator cuff repair was evaluated to determine if it would increase strength of cuff repairs associated with tendon defects and also show histologic incorporation over time. Forty goats underwent rotator cuff repairs of the infraspinatus tendon bilaterally. Tendons were detached and a defect was created prior to repair. One side was repaired and augmented with a 4 cm2 polylactic acid patch in each animal. On the other side, the same size defect was repaired in the same manner but without the patch to serve as a control. Animals were sacrificed at 3, 6, 12, and 24 weeks. Ultimate load to failure and histology were reported. No significant difference in load to failure was found between groups. A cellular fibrous tissue occupied the patch at 6 weeks, which over time matured into a dense, homogeneous fibrous tissue with alignment of collagen between the scaffold bundles.

Background: Most rotator cuff surgery is performed on chronic tears. As there is no animal model in which to examine the physiology of muscle and tendon injury and repair in this setting, we developed a chronic rotator cuff injury model in sheep., Methods: The infraspinatus tendon was released in thirty-six female sheep. Biopsy specimens were obtained from the muscle and were analyzed for fat content. The force generated by the muscle with supramaximal stimulation was recorded intraoperatively. A control group (twelve sheep) underwent an immediate tendon repair. In the remaining twenty-four sheep, the tendon was wrapped in a dura substitute to prevent scarring and was repaired at six weeks (eight sheep) and eighteen weeks (sixteen sheep) after release. In the immediate repair group, four animals were killed at six weeks; four, at twelve weeks; and four, at twenty weeks. In the six-week delayed repair group, four animals were killed at twelve weeks and four were killed at twenty weeks after the repair. In the eighteen-week delayed repair group, eight animals were killed at twelve weeks; four, at twenty weeks; and four, at thirty weeks after the repair. Muscle biopsies and testing were repeated prior to killing of the animals., Results: The average force of muscle contraction decreased 3.6 lb (1.6 kg) by six weeks after the injury and 3.9 lb (1.8 kg) by eighteen weeks after the injury. After the repair, the force of contraction in the six-week group improved by 0.8 lb (0.4 kg) at twelve weeks postoperatively and by 1.3 lb (0.6 kg) at twenty weeks postoperatively. In contrast, no improvement occurred in the eighteen-week group until thirty weeks after the repair, at which time a 0.9-lb (0.4-kg) improvement was noted. There was a twelvefold increase in intramuscular fat concentration; this lipid infiltration was partially reversed after the tendon repair. Isolated tendon samples demonstrated an increase in the modulus of elasticity after chronic detachment that partially corrected after the tendon repair in the earlier (six-week) repair group., Conclusions: We found that earlier repair of the tendon results in a more rapid recovery of both muscle function and tendon elasticity compared with a more delayed repair. We concluded that there may be a "point of no return" in rotator cuff injury after which the elasticity of the muscle-tendon unit does not return to normal.