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Bolam SM, Zhu MF, Lim KS, Konar S, Oliver MH, Buckels E, Matthews BG, Callon KE, Woodfield T, Workman J, Monk AP, Coleman B, Cornish J, Munro JT, Musson DS. Combined Growth Factor Hydrogel Enhances Rotator Cuff Enthesis Healing in Rat But Not Sheep Model. Tissue Eng Part A 2023; 29:449-459. [PMID: 37171123 DOI: 10.1089/ten.tea.2022.0215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Abstract
We hypothesized that a combined growth factor hydrogel would improve chronic rotator cuff tear healing in a rat and sheep model. Insulin-like growth factor 1, transforming growth factor β1, and parathyroid hormone were combined into a tyraminated poly-vinyl-alcohol (PVA-Tyr) hydrogel and applied directly at the enthesis. In total, 30 Sprague-Dawley rats and 16 Romney ewes underwent unilateral rotator cuff tenotomy and then delayed repairs were performed after 3-4 weeks. The animals were divided into a control group (repair alone) and treatment group. The rotator cuffs were harvested at 12 weeks after surgery for biomechanical and histological analyses of the repair site. In the rat model, the stress at failure and Young's modulus were higher in the treatment group in comparison with the control group (73% improvement, p = 0.010 and 56% improvement, p = 0.028, respectively). Histologically, the repaired entheses in the treatment group demonstrated improved healing with higher semi-quantitative scores (10.1 vs. 6.55 of 15, p = 0.032). In the large animal model, there was no observable treatment effect. This PVA-Tyr bound growth factor system holds promise for improving rotator cuff healing. However, our approach was not scalable from a small to a large animal model. Further tailoring of this growth factor delivery system is still required. Level of Evidence: Basic Science Study; Biomechanics and Histology; Animal Model Impact Statement Previous studies using single-growth factor treatment to improve enthesis healing after rotator cuff repair have reported promising, but inconsistent results. A novel approach is to combine multiple growth factors using controlled-release hydrogels that mimic the normal healing process. In this study, we report that a combined growth factor hydrogel can improve the histological quality and strength of rotator cuff repair in a rat chronic tear model. This novel hydrogel growth factor treatment has the potential to be used in human clinical applications to improve healing after rotator cuff repair.
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Affiliation(s)
- Scott M Bolam
- Department of Medicine, University of Auckland, Grafton, New Zealand
- Department of Orthopedic Surgery, Auckland City Hospital, Grafton, New Zealand
| | - Mark F Zhu
- Department of Medicine, University of Auckland, Grafton, New Zealand
- Department of Orthopedic Surgery, Auckland City Hospital, Grafton, New Zealand
| | - Khoon S Lim
- Department of Orthopedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand
| | - Subhajit Konar
- Department of Medicine, University of Auckland, Grafton, New Zealand
| | - Mark H Oliver
- Liggins Institute, University of Auckland, Grafton, New Zealand
| | - Emma Buckels
- Department of Molecular Medicine and Pathology, University of Auckland, Grafton, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Grafton, New Zealand
| | - Brya G Matthews
- Department of Molecular Medicine and Pathology, University of Auckland, Grafton, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Grafton, New Zealand
| | - Karen E Callon
- Department of Medicine, University of Auckland, Grafton, New Zealand
| | - Tim Woodfield
- Department of Orthopedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand
| | - Josh Workman
- Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand
| | - A Paul Monk
- Department of Orthopedic Surgery, Auckland City Hospital, Grafton, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Grafton, New Zealand
| | - Brendan Coleman
- Department of Orthopedic Surgery, Middlemore Hospital, Otahuhu, New Zealand
| | - Jillian Cornish
- Department of Medicine, University of Auckland, Grafton, New Zealand
| | - Jacob T Munro
- Department of Medicine, University of Auckland, Grafton, New Zealand
- Department of Orthopedic Surgery, Auckland City Hospital, Grafton, New Zealand
| | - David S Musson
- Department of Medicine, University of Auckland, Grafton, New Zealand
- Department of Nutrition and Dietetics, University of Auckland, Grafton, New Zealand
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Vaysman M, Alben M, Todd M, Ruotolo C. Pharmacologic Enhancement of Rotator Cuff Repair: A Narrative Review. Orthop Rev (Pavia) 2022; 14:37782. [PMID: 36072503 PMCID: PMC9441107 DOI: 10.52965/001c.37782] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2024] Open
Abstract
INTRODUCTION As rotator cuff repairs (RCRs) are among the most common procedures in upper extremity orthopedics, healing augmentation using pharmacologic enhancement of the repaired rotator cuff muscle is of particular interest. OBJECTIVE The purpose of this study is to review the current understanding of Matrix Metalloproteinases (MMPs), Doxycycline, Testosterone, Estrogen, Growth hormone/ IGF-1, Vitamin D, and Vitamin C as a means to mitigate deleterious effects and propagate factors that support healing following RCR. METHODS A review of English language articles in PubMed and Medline was conducted in December of 2020. All articles describing the current understanding of the aforementioned therapies were reviewed. Studies were excluded if they were non-English or reported incomplete results. RESULTS Matrix metalloproteinases (MMP's) are fundamental to the healing process after rotator cuff tears through a delicate balance of various proteases that can be modulated by doxycycline through inhibition. While testosterone has shown to induce replication and differentiation of the tendon stem-cells, estrogen agonists have been shown to decrease inflammation and muscle atrophy. Though growth hormone being associated with elevated collagen synthesis and decreased anoxic damage when present, clinical studies have shown inconclusive and adverse effects on rotator cuff healing. Patients with Vitamin D deficiency have shown to have increased fatty infiltration in rotator cuff muscle while Vitamin C functions as an antioxidant that increases collagen and fibroblast proliferation. CONCLUSION As manipulation of pharmacologic factors shows potential for enhancing healing following RCRs, future studies are needed to establish a viable augmentation strategy to improve patient outcomes.
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Affiliation(s)
| | - Matthew Alben
- Orthopedic Surgery, Nassau University Medical Center; Osteopathic Medicine, New York Institute of Technology
| | - Matthew Todd
- Orthopedic Surgery, Nassau University Medical Center; Osteopathic Medicine, Des Moines College of Osteopathic Medicine
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Zhu M, Lin Tay M, Lim KS, Bolam SM, Tuari D, Callon K, Dray M, Cornish J, Woodfield TBF, Munro JT, Coleman B, Musson DS. Novel Growth Factor Combination for Improving Rotator Cuff Repair: A Rat In Vivo Study. Am J Sports Med 2022; 50:1044-1053. [PMID: 35188803 DOI: 10.1177/03635465211072557] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND The lack of healing at the repaired tendon-bone interface is an important cause of failure after rotator cuff repair. While augmentation with growth factors (GFs) has demonstrated promise, the ideal combination must target all 3 tissue types at the tendon-bone interface. HYPOTHESIS The GF combination of transforming growth factor beta 1, Insulin-like growth factor 1, and parathyroid hormone will promote tenocyte proliferation and differentiation and improve the biomechanical and histological quality of the repaired tendon-bone interface. STUDY DESIGN Controlled laboratory study. METHODS In vitro, human tenocytes were cultured in the presence of the GF combination for 72 hours, and cell growth assays and the expression of genes specific to tendon, cartilage, and bone were analyzed. In vivo, adult rats (N = 46) underwent detachment and repair of the left supraspinatus tendon. A PVA-tyramine gel was used to deliver the GF combination to the tendon-bone interface. Histological, biomechanical, and RNA microarray analysis was performed at 6 and 12 weeks after surgery. Immunohistochemistry for type II and X collagen was performed at 12 weeks. RESULTS When treated with the GF combination in vitro, human tenocytes proliferated 1.5 times more than control (P = .04). The expression of scleraxis increased 65-fold (P = .013). The expression of Sox-9 (P = .011), type I collagen (P = .021), fibromodulin (P = .0075), and biglycan (P = .010) was also significantly increased, while the expression of PPARγ was decreased (P = .007). At 6 and 12 weeks postoperatively, the quality of healing on histology was significantly higher in the GF group, with the formation of a more mature tendon-bone interface, as confirmed by immunohistochemistry for type II and X collagen. The GF group achieved a load at failure and Young modulus >1.5 times higher at both time points. Microarrays at 6 weeks demonstrated upregulation of genes involved in leukocyte aggregation (S100A8, S100A9) and tissue mineralization (Bglap, serglycin, Fam20c). CONCLUSION The GF combination promoted protendon and cartilage responses in human tenocytes in vitro; it also improved the histological appearance and mechanical properties of the repair in vivo. Microarrays of the tendon-bone interface identified inflammatory and mineralization pathways affected by the GF combination, providing novel therapeutic targets for further research. CLINICAL RELEVANCE The use of this GF combination is translatable to patients and may improve healing after rotator cuff repair.
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Affiliation(s)
- Mark Zhu
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand
| | - Mei Lin Tay
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand
| | - Khoon S Lim
- Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand
| | - Scott M Bolam
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand
| | - Donna Tuari
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand
| | - Karen Callon
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand
| | - Michael Dray
- Department of Pathology, Waikato Hospital, Hamilton, New Zealand
| | - Jillian Cornish
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand
| | - Tim B F Woodfield
- Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand
| | - Jacob T Munro
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand.,Department of Orthopaedic Surgery, Auckland City Hospital, Auckland, New Zealand
| | - Brendan Coleman
- Department of Orthopaedic Surgery, Counties Manukau Health, Auckland, New Zealand
| | - David S Musson
- Bone and Joint Laboratory, School of Medicine, University of Auckland, Auckland, New Zealand
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Jones IA, Togashi R, Hatch GFR, Weber AE, Vangsness CT. Anabolic steroids and tendons: A review of their mechanical, structural, and biologic effects. J Orthop Res 2018; 36:2830-2841. [PMID: 30047601 DOI: 10.1002/jor.24116] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/13/2018] [Indexed: 02/04/2023]
Abstract
One of the suspected deleterious effects of androgenic-anabolic steroids (AAS) is the increased risk for tendon rupture. However, investigations to date have produced inconsistent results and it is still unclear how AAS influence tendons. A systematic review of the literature was conducted to identify studies that have investigated the mechanical, structural, or biologic effects that AAS have on tendons. In total, 18 highly heterogeneous studies were identified. Small animal studies made up the vast majority of published research, and contradictory results were reported frequently. All of the included studies focused on the potential deleterious effects that AAS have on tendon, which is striking given the recent use of AAS in patients following tendon injury. Rather than providing strong evidence for or against the use of AAS, this review highlights the need for additional research. Future studies investigating the use of AAS as a possible treatment for tendon injury/pathology are supported by reports suggesting that AAS may counteract the irreparable structural/functional changes that occur in the musculotendinous unit following rotator cuff tears, as well as studies suggesting that the purported deleterious effects on tendon may be transient. Other possible areas for future research are discussed in the context of key findings that may have implications for the therapeutic application of AAS. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2830-2841, 2018.
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Affiliation(s)
- Ian A Jones
- Department of Orthopaedic Surgery, Keck School of Medicine of USC, HCT 1520 San Pablo Street, Suite 2000, Los Angeles 90033, California
| | - Ryan Togashi
- Department of Orthopaedic Surgery, Keck School of Medicine of USC, HCT 1520 San Pablo Street, Suite 2000, Los Angeles 90033, California
| | - George F Rick Hatch
- Department of Orthopaedic Surgery, Keck School of Medicine of USC, HCT 1520 San Pablo Street, Suite 2000, Los Angeles 90033, California
| | - Alexander E Weber
- Department of Orthopaedic Surgery, Keck School of Medicine of USC, HCT 1520 San Pablo Street, Suite 2000, Los Angeles 90033, California
| | - C Thomas Vangsness
- Department of Orthopaedic Surgery, Keck School of Medicine of USC, HCT 1520 San Pablo Street, Suite 2000, Los Angeles 90033, California
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Rothrauff BB, Pauyo T, Debski RE, Rodosky MW, Tuan RS, Musahl V. The Rotator Cuff Organ: Integrating Developmental Biology, Tissue Engineering, and Surgical Considerations to Treat Chronic Massive Rotator Cuff Tears. TISSUE ENGINEERING PART B-REVIEWS 2017; 23:318-335. [PMID: 28084902 DOI: 10.1089/ten.teb.2016.0446] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The torn rotator cuff remains a persistent orthopedic challenge, with poor outcomes disproportionately associated with chronic, massive tears. Degenerative changes in the tissues that comprise the rotator cuff organ, including muscle, tendon, and bone, contribute to the poor healing capacity of chronic tears, resulting in poor function and an increased risk for repair failure. Tissue engineering strategies to augment rotator cuff repair have been developed in an effort to improve rotator cuff healing and have focused on three principal aims: (1) immediate mechanical augmentation of the surgical repair, (2) restoration of muscle quality and contractility, and (3) regeneration of native enthesis structure. Work in these areas will be reviewed in sequence, highlighting the relevant pathophysiology, developmental biology, and biomechanics, which must be considered when designing therapeutic applications. While the independent use of these strategies has shown promise, synergistic benefits may emerge from their combined application given the interdependence of the tissues that constitute the rotator cuff organ. Furthermore, controlled mobilization of augmented rotator cuff repairs during postoperative rehabilitation may provide mechanotransductive cues capable of guiding tissue regeneration and restoration of rotator cuff function. Present challenges and future possibilities will be identified, which if realized, may provide solutions to the vexing condition of chronic massive rotator cuff tears.
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Affiliation(s)
- Benjamin B Rothrauff
- 1 Department of Orthopaedic Surgery, Center for Cellular and Molecular Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania.,2 McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Thierry Pauyo
- 3 Division of Sports Medicine, Department of Orthopaedic Surgery, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Richard E Debski
- 2 McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Mark W Rodosky
- 3 Division of Sports Medicine, Department of Orthopaedic Surgery, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Rocky S Tuan
- 1 Department of Orthopaedic Surgery, Center for Cellular and Molecular Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania.,2 McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Volker Musahl
- 2 McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania.,3 Division of Sports Medicine, Department of Orthopaedic Surgery, University of Pittsburgh , Pittsburgh, Pennsylvania.,4 Orthopaedic Robotics Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh , Pittsburgh, Pennsylvania
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Impact of cyclic mechanical stimulation on the expression of extracellular matrix proteins in human primary rotator cuff fibroblasts. Knee Surg Sports Traumatol Arthrosc 2016; 24:3884-3891. [PMID: 26392342 DOI: 10.1007/s00167-015-3790-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 09/10/2015] [Indexed: 02/01/2023]
Abstract
PURPOSE Mechanical stimulation plays an important role in the development and remodelling of tendons. The aim of the study was to evaluate the effects of mechanical stimulation on the expression of extracellular matrix proteins in human primary rotator cuff (RC) fibroblasts. METHODS RC fibroblasts were isolated from patients with degenerative RC tears and characterized using flow cytometry and immunohistochemistry. Cells were stimulated using the Flexcell FX5K™ Tension System. The stimulation regime was a uniaxial sinusoidal waveform with 10 % elongation and a frequency of 0.5 Hz, whereby each cycle consists of 10-s strain and 30-s relaxation. Data were normalized to mechanically unstimulated control groups for every experimental condition. RT-qPCR was performed to determine relative mRNA levels, and collagen production was measured by a colorimetric assay. RESULTS The positive expression of CD91 and CD10, and negativity for CD45 and CD4 confirmed the fibroblast phenotype of RC primary cells. RT-qPCR revealed that 10 % continuous cyclic strain for 7 and 14 days induced a significant increase in the mRNA expression both on the matrix metalloproteinases MMP1, MMP3, MMP13, and MMP14 and on the extracellular matrix proteins decorin, tenascin-C, and scleraxis. Furthermore, mechanically stimulated groups produced significantly higher amounts of total collagen. CONCLUSION These results may contribute to a better understanding of strain-induced tendon remodelling and will form the basis for the correct choice of applied force in rehabilitation after orthopaedic surgery. These findings underline the fact that early passive motion of the joint in order to induce remodelling of the tendon should be included within a rehabilitation protocol for rotator cuff repair.
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Camenzind RS, Wieser K, Fessel G, Meyer DC, Snedeker JG. Tendon Collagen Crosslinking Offers Potential to Improve Suture Pullout in Rotator Cuff Repair: An Ex Vivo Sheep Study. Clin Orthop Relat Res 2016; 474:1778-85. [PMID: 27090262 PMCID: PMC4925414 DOI: 10.1007/s11999-016-4838-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 04/11/2016] [Indexed: 01/31/2023]
Abstract
BACKGROUND The suture-tendon interface is often the weakest link in tendon to bone repair of massive rotator cuff tears. Genipin is a low-toxicity collagen crosslinker derived from the gardenia fruit that has been shown to augment collagen tissue strength and mechanically arrest tendon-tear progression. QUESTION/PURPOSE The purpose of the current study was to evaluate whether genipin crosslinking can sufficiently augment the suture-tendon interface to improve suture pullout strength using simple single-loop sutures and the modified Mason-Allen technique. The study also aimed to assess whether time of genipin treatment is a relevant factor in efficacy. METHODS In an ex vivo (cadaveric) sheep rotator cuff tendon model, a total of 142 suture pullout tests were performed on 32 infraspinatus tendons. Each tendon was prepared with three single-loop stitches. Two groups were pretreated by incubation in genipin solution for either 4 hours or 24 hours. Two corresponding control groups were incubated in phosphate buffered saline for the same periods. The same test protocol was applied to tendons using modified Mason-Allen technique stitch patterns. Each suture was loaded to failure on a universal materials testing machine. Suture pullout force, stiffness, and work to failure were calculated from force-displacement data, and then compared among the groups. RESULTS Median single-loop pullout force on tendons incubated for 24 hours in genipin yielded an approximately 30% increase in maximum pullout force for single-loop stitches with a median of 73 N (range, 56-114 N) compared with 56 N (range, 40-69 N; difference of medians = 17 N; p = 0.028), with corresponding increases in the required work to failure but not stiffness. Genipin treatment for 4 hours showed no added benefit for suture-pullout behavior (46 N, [range, 35-95 N] versus 45 N, [range, 28-63 N]; difference of medians, 1 N; p = 1). No tested genipin crosslinking conditions indicated benefit for tendons grasped using the modified Mason-Allen technique after 4 hours (162 N, [range, 143-193 N] versus 140 N, [range, 129-151 N]; difference of medians, 22 N; p = 0.114) or after 24 hours of crosslinking (172 N, [range, 42-183 N] versus 164 N [range, 151-180 N]; difference of medians, 8 N; p = 0.886). CONCLUSION Exogenous collagen crosslinking in genipin can markedly improve resistance to pullout at the tendon-suture interface for simple stitch patterns while the modified Mason-Allen stitch showed no benefit in an ex vivo animal model. CLINICAL RELEVANCE Tendon strength augmentation by genipin pretreatment offers the potential to improve suture retention properties. Future studies are warranted for the development of clinically viable intraoperative delivery strategies and in vivo testing for safety and efficacy.
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Affiliation(s)
- Roland S. Camenzind
- Department of Orthopedics, Balgrist University Hospital, Forchstrasse 340, 8008 Zurich, Switzerland
| | - Karl Wieser
- Department of Orthopedics, Balgrist University Hospital, Forchstrasse 340, 8008 Zurich, Switzerland
| | - Gion Fessel
- Department of Orthopedics, Balgrist University Hospital, Forchstrasse 340, 8008 Zurich, Switzerland ,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Dominik C. Meyer
- Department of Orthopedics, Balgrist University Hospital, Forchstrasse 340, 8008 Zurich, Switzerland
| | - Jess G. Snedeker
- Department of Orthopedics, Balgrist University Hospital, Forchstrasse 340, 8008 Zurich, Switzerland ,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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Gerber C, Meyer DC, Flück M, Benn MC, von Rechenberg B, Wieser K. Anabolic Steroids Reduce Muscle Degeneration Associated With Rotator Cuff Tendon Release in Sheep. Am J Sports Med 2015; 43:2393-400. [PMID: 26304962 DOI: 10.1177/0363546515596411] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Chronic rotator cuff tendon tearing is associated with irreversible atrophy, fatty infiltration, and interstitial fibrosis of the corresponding muscle. HYPOTHESES Anabolic steroids can prevent musculotendinous degeneration during retraction and/or can reverse these changes after operative repair of the retracted musculotendinous unit in sheep. STUDY DESIGN Controlled laboratory study. METHODS The infraspinatus tendon was released in 18 alpine sheep. All sheep underwent repair of the retracted musculotendinous unit after 16 weeks and were sacrificed after 22 weeks; 6 sheep served as controls, 6 sheep were treated with weekly intramuscular injection of 150 mg of nandrolone decanoate after infraspinatus (ISP) repair (group N6W), and 6 sheep were treated with 150 mg of nandrolone decanoate immediately after tendon release (group N22W). Muscle biopsy specimens were taken before tendon release and after 16 and 22 weeks. Muscle volume and fatty infiltration (on MRI), myotendinous retraction, and muscle density (on computed tomography) were measured immediately after ISP release, after 6 weeks, and before ISP repair and sacrifice. RESULTS Muscle volume on MRI decreased to a mean (±SD) of 80% ± 8% of the original volume after 6 weeks, remained stable at 78% ± 11% after 16 weeks, and decreased further to 69% ± 9% after 22 weeks in the control group. These findings were no different from those in group N22W (72% ± 9% at 6 weeks, 73% ± 6% at 16 weeks, and 67% ± 5% at 22 weeks). Conversely, the N6W group did not show a decrease in ISP volume after repair; this finding differed significantly from the response in the control and N22W groups. Fatty infiltration (on MRI) continuously increased in the control group (12% ± 4% at tendon release, 17% ± 4% after 6 weeks, 50% ± 9% after 16 weeks, and 60% ± 8% after 22 weeks) and the N6W group. However, application of anabolic steroids at the time of tendon release (N22W group) significantly reduced fatty infiltration after 16 (16% ± 5%; P < .001) and 22 weeks (22% ± 7%; P < .001). CONCLUSION In a sheep model of rotator cuff tendon tear, further muscle atrophy can be prevented with the application of anabolic steroids starting immediately after tendon repair. In addition, fatty muscle infiltration can largely be prevented if the steroids are applied immediately after tendon release. CLINICAL RELEVANCE Study findings may lead to the development of treatment strategies to prevent or reduce muscle degeneration caused by rotator cuff tendon tearing.
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Affiliation(s)
- Christian Gerber
- Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Dominik C Meyer
- Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Martin Flück
- Laboratory for Muscle Plasticity, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Mario C Benn
- Musculoskeletal Research Unit, Center for Applied Biotechnology and Molecular Medicine, Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Brigitte von Rechenberg
- Musculoskeletal Research Unit, Center for Applied Biotechnology and Molecular Medicine, Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Karl Wieser
- Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
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