Fatty Infiltration of the Torn Rotator Cuff Worsens Over Time in a Rabbit Model

Chronic rotator cuff tears can cause severe functional deficits. Addressing the chronic fatty and fibrotic muscle changes is of high clinical interest; however, the architectural and physiological consequences of chronic tear and repair are poorly characterized. We present a detailed architectural and physiological analysis of chronic tear and repair (both over 8 and 16 weeks) compared to age-matched control rabbit supraspinatus (SSP) muscles. Using female New Zealand White Rabbits (N=30, n=6/group) under 2% isofluorane anesthesia, the SSP was surgically isolated and maximum isometric force measured at 4-6 muscle lengths. Architectural analysis was performed, and maximum isometric stress was computed. Whole muscle length-tension curves were generated using architectural measurements to compare experimental physiology to theoretical predictions. Architectural measures are consistent with persistent radial and longitudinal atrophy over time in tenotomy that fail to recover after repair. Maximum isometric force was significantly decreased after 16 wks tenotomy and not significantly improved after repair. Peak isometric force reported here are greater than prior reports of rabbit SSP force after tenotomy. Peak stress was not significantly different between groups and consistent with prior literature of SSP stress. Muscle strain during contraction was significantly decreased after 8-wks of tenotomy and repair, indicating effects of tear and repair on muscle function. The experimental length-tension data was overlaid with predicted curves for each experimental group (generated from structural data), exposing the altered structure-function relationship for tenotomy and repair over time. Data presented here contribute to understanding the physiological implications of disease and repair in the rotator cuff

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Shoulder Function and Fatty Infiltration on MRI in Older Adults During Rehabilitation for Rotator Cuff Tear

Innovation in Aging ◽

10.1093/geroni/igab046.3433 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. 960-960

Author(s):

Derik Davis ◽

Ranyah Almardawi ◽

Omer Awan ◽

Lawrence Lo ◽

Sagheer Ahmed ◽

...

Keyword(s):

Older Adults ◽

Rotator Cuff ◽

Rotator Cuff Tear ◽

Fatty Infiltration ◽

Shoulder Function ◽

Control Cohort ◽

Cuff Tear ◽

Supraspinatus Tear ◽

Cohort Groups ◽

Over Time

Abstract Rotator cuff tear is highly prevalent in older adults, with supraspinatus tendon tear (STT) the most common. Shoulder rehabilitation is a major treatment strategy, but supraspinatus-muscle-fatty infiltration (FI) and shoulder function in older adults with rotator cuff tear primarily managed by physical therapy (PT) is inadequately documented. We tested the hypothesis that older adults receiving usual-care PT when stratified by supraspinatus tear-status differ in supraspinatus FI [by quantitative Dixon fat fraction (FF) and semi-quantitative Goutallier grade (GG) on MRI] and shoulder function [by the American Shoulder and Elbow Surgeons score (ASES-score)] over time. Longitudinal cohort study (pilot): adults 60-85 years, PT-cohort (n=15) and control-cohort (n=25). Participants completed both shoulder MRI and ASES survey at baseline and follow-up visits. Kruskal-Wallis test compared within cohort among 3 groups: no tear (no-STT), partial-thickness tear (pt-STT), full-thickness tear (ft-STT). Mann-Whitney U test compared equivalent groups between cohorts. Baseline PT-cohort groups differed for GG (p=0.033) [no tear, 0.50±0.50;pt-STT, 1.11±0.22;ft-STT, 1.50±0.50] without difference in age, BMI, comorbidity, or ASES-score. Baseline control-cohort groups differed for FF (p=0.034) [no-tear, 5.77%±1.16%;pt-STT, 7.14%±6.26%;ft-STT, 21.44%±10.44%], without difference in age, BMI, comorbidity, or ASES-score. Baseline no-tear groups for ASES-score (p=0.049) differed between cohorts: PT-cohort (58.87±8.21) versus control-cohort (83.98±21.89). Both cohorts showed no difference in Δ-FF or Δ-GG over time. PT-cohort groups differed for Δ-ASES-score over time (p=0.042)[no-tear, 16.65±4.69;pt-STT, -7.24±0.94;ft-STT, 4.48±3.45], but control-cohort groups did not (p>0.050). Our results suggest differences exist for supraspinatus FI and self-reported shoulder function among older adults receiving PT for rotator cuff tear when stratified by supraspinatus tear-status.

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Effect of hypercholesterolemia on fatty infiltration and the quality of tendon-to-bone healing in a rabbit model of a chronic rotator cuff tear: Electrophysiological, biomechanical, and histological analyses

Asia-Pacific Journal of Sports Medicine Arthroscopy Rehabilitation and Technology ◽

10.1016/j.asmart.2016.07.011 ◽

2016 ◽

Vol 6 ◽

pp. 15

Author(s):

Seok Won Chung ◽

H. Park ◽

Jieun Kwon ◽

Sae Hoon Kim ◽

Joo Han Oh

Keyword(s):

Rotator Cuff ◽

Rotator Cuff Tear ◽

Bone Healing ◽

Fatty Infiltration ◽

Rabbit Model ◽

Cuff Tear

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Fatty Infiltration Does Not Progress After Rotator Cuff Repair in a Rabbit Model

Arthroscopy The Journal of Arthroscopic and Related Surgery ◽

10.1016/j.arthro.2008.03.004 ◽

2008 ◽

Vol 24 (8) ◽

pp. 936-940 ◽

Cited By ~ 24

Author(s):

L. Joseph Rubino ◽

Dominic C. Sprott ◽

Harold F. Stills ◽

Lynn A. Crosby

Keyword(s):

Rotator Cuff ◽

Rotator Cuff Repair ◽

Fatty Infiltration ◽

Rabbit Model ◽

Cuff Repair

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Adipose Stem Cell–Derived Exosomes Decrease Fatty Infiltration and Enhance Rotator Cuff Healing in a Rabbit Model of Chronic Tears

The American Journal of Sports Medicine ◽

10.1177/0363546520908847 ◽

2020 ◽

Vol 48 (6) ◽

pp. 1456-1464 ◽

Cited By ~ 3

Author(s):

Chongyang Wang ◽

Qingxiang Hu ◽

Wei Song ◽

Weilin Yu ◽

Yaohua He

Keyword(s):

Stem Cell ◽

Rotator Cuff ◽

Bone Healing ◽

Fatty Infiltration ◽

Biomechanical Testing ◽

Rabbit Model ◽

Saline Group ◽

Adipose Stem Cell ◽

Sham Surgery ◽

Cuff Repair

Background: Fatty infiltration and poor tendon-bone healing in chronic rotator cuff tears (RCTs) are associated with unsatisfactory prognosis. Adipose stem cell–derived exosomes (ASC-Exos), having multiple biological effects, can prevent muscle degeneration in acute RCTs. However, the effects of ASC-Exos on fatty infiltration and tendon-bone healing in chronic RCTs remain unknown. Purpose: To study the effects of ASC-Exos on fatty infiltration and tendon-bone healing in a chronic RCT rabbit model. Study Design: Controlled laboratory study. Methods: At week 0, we randomly allocated 35 rabbits to receive sham surgery (14 rabbits) or establish a bilateral RCT model (21 rabbits, detachment of the supraspinatus tendon). At week 6, a total of 7 rabbits received sham surgery, and 7 rabbits with RCT were sacrificed for fatty infiltration assay. The remaining 14 rabbits with bilateral RCTs were randomly assigned to a saline group (7 rabbits that received local saline injection and rotator cuff repair) or an ASC-Exos group (7 rabbits that received local ASC-Exos injection and rotator cuff repair). At week 18, all rabbits were sacrificed for histological examination and biomechanical testing. Results: At week 18, the ASC-Exos group showed significantly lower fatty infiltration (14.01% ± 2.85%) compared with the saline group (21.79% ± 3.07%) ( P < .001), and no statistical difference compared with the time of repair (10.88% ± 2.64%) ( P = .127). For tendon-bone healing, the ASC-Exos group showed a higher histological score and more newly regenerated fibrocartilage at the repair site than did the saline group. Regarding biomechanical testing, the ASC-Exos group showed significantly higher ultimate load to failure, stiffness, and stress than the saline group. Conclusion: Local injection of ASC-Exos in chronic RCTs at the time of repair could prevent the progress of fatty infiltration, promote tendon-bone healing, and improve biomechanical properties. Clinical Relevance: ASC-Exos injection may be used as a cell-free adjunctive therapy to inhibit fatty infiltration and improve rotator cuff healing in the repair of chronic RCTs.

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Non-Operative Management of Rotator Cuff Tears

The Open Orthopaedics Journal ◽

10.2174/1874325001610010349 ◽

2016 ◽

Vol 10 (1) ◽

pp. 349-356 ◽

Cited By ~ 9

Author(s):

M. Petri ◽

M. Ettinger ◽

S. Brand ◽

T. Stuebig ◽

C. Krettek ◽

...

Keyword(s):

Rotator Cuff ◽

Fatty Infiltration ◽

Tendon Repair ◽

Operative Management ◽

Nonoperative Treatment ◽

Rotator Cuff Tears ◽

Patient Counseling ◽

Non Operative Management ◽

Tear Size ◽

Over Time

Background: The role of nonoperative management for rotator cuff tears remains a matter of debate. Clinical results reported in the literature mainly consist of level IV studies, oftentimes combining a mixed bag of tear sizes and configurations, and are contradictory to some extent. Methods: A selective literature search was performed and personal surgical experiences are reported. Results: Most studies show an overall success rate of around 75% for nonoperative treatment. However, the majority of studies also present a progression of tear size and fatty muscle infiltration over time, with however debatable clinical relevance for the patient. Suggested factors associated with progression of a rotator cuff tear are an age of 60 years or older, full-thickness tears, and fatty infiltration of the rotator cuff muscles at the time of initial diagnosis. Conclusion: Non-operative management is indicated for patients with lower functional demands and moderate symptoms, and/or of course for those refusing to have surgery. Close routinely monitoring regarding development of tear size should be performed, especially in patients that remain symptomatic during nonoperative treatment. To ensure judicious patient counseling, it has to be taken into account that 1) tears that are initially graded as reparable may become irreparable over time, and 2) results after secondary surgical therapy after failed nonoperative treatment are usually reported to be inferior to those who underwent primary tendon repair.

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The Biomechanical and Histological Processes of Rerouting Biceps to Treat Chronic Irreparable Rotator Cuff Tears in a Rabbit Model

The American Journal of Sports Medicine ◽

10.1177/03635465211062914 ◽

2022 ◽

pp. 036354652110629

Author(s):

Junjie Xu ◽

Yufeng Li ◽

Xueying Zhang ◽

Kang Han ◽

Zipeng Ye ◽

...

Keyword(s):

Rotator Cuff ◽

Failure Load ◽

Biceps Tendon ◽

Rabbit Model ◽

Rotator Cuff Tears ◽

Bicipital Groove ◽

Superior Capsular Reconstruction ◽

Over Time

Background: Recently, the biceps was rerouted into a newly fabricated bicipital groove for in situ superior capsular reconstruction (SCR), resulting in promising time-zero cadaveric and clinical outcomes. However, no studies have determined the in vivo biomechanical and histological processes after the biceps is transposed to a nonanatomic position. Purpose: To explore the in vivo biomechanical and histological processes of the rerouting biceps tendon to treat chronic irreparable rotator cuff tears (IRCTs) in a rabbit model. Study Design: Controlled laboratory study. Methods: A total of 94 skeletally mature male rabbits were used to create a chronic IRCT model in the supraspinatus tendon. Then, the biceps rerouting procedures were performed in rabbits with chronic IRCT. Eighteen rabbits were sacrificed at 1, 3, 6, 9, and 12 weeks postoperatively for biomechanical testing, micro—computed tomography scanning, and histological analysis. The biomechanical and histological changes of intra- and extra-articular portions of the rerouting biceps were evaluated at each time point, with the contralateral native superior capsule (NSC) and the native biceps (NB) as controls, respectively. The morphology and bone formation of the fabricated bicipital grooves were evaluated, with native grooves as controls. Results: The intra-articular rerouting biceps tendon was progressively remodeled over time, displaying denser fibers and more mature collagen than those of the NSC, with gradual improvements in the tendon-to-bone healing interface from 6 to 12 weeks. Consequently, the failure load and stiffness of the intra-articular rerouting biceps portion increased with time and were significantly higher than those of the NSC from 9 weeks. Similarly, the extra-articular portion of the rerouting biceps progressively healed into a new bicipital groove, as demonstrated by a smaller tendon-to-bone interface from 6 to 12 weeks, resulting in greater failure load and stiffness at 9 and 12 weeks than those of the NB attachment. The newly fabricated bicipital groove showed similar morphology to that of the native groove with sufficient trabecular bone formed underneath. Conclusion: The rerouting biceps could progressively remodel and heal into the newly fabricated bicipital groove over time, resulting in greater biomechanical performances in intra- and extra-articular portions than the NSC and the NB attachment. Clinical Relevance: The biceps rerouting technique may be a feasible procedure to perform in situ SCR to treat IRCT in the future clinical practice; however, more clinical evidence is required.

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