Healing of surgically created defects in the equine superficial digital flexor tendon: collagen-type transformation and tissue morphologic reorganization.
Abstract: Full-thickness defects were surgically created in the superficial digital flexor tendons of the front limbs of 20 horses. Tissues formed within the defect were evaluated histologically, and the collagen composition of the tissue was determined by immunofluorescence. Transformation occurred from loose fibrillar areas of types I and III collagen and pericellular types IV and V collagen to dense bundles of type I collagen fibers. Loose fibrillar areas of types I and III collagen were present after 24 weeks. Histologically, in horses killed after 2 weeks, the tissue within the defect was a randomly oriented mass of fibrovascular tissue. In horses killed after 24 weeks the tissue within the defect resembled normal tendon tissue.
Publication Date: 1985-10-01 PubMed ID: 4062012
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research studied the healing process of full-thickness defects in horse tendons, specifically focusing on the transformation of collagen types and changes in tissue morphology over time.
Objective and Methodology
- The researchers aimed to understand how surgically-created full-thickness defects in the superficial digital flexor tendons of horses healed over time.
- They operated on 20 horses, creating these defects in the tendons of their front limbs. Subsequently, they regularly evaluated the tissues forming within these defects, both histologically and through determining the collagen makeup using immunofluorescence – a technique that identifies specific biomolecules within a tissue using fluorescence.
Findings: Collagen Transformation
- Blue collagen (types IV and V) present around cells initially transformed into types I and III collagen that were loosely laid out in fibrillar structures.
- Over time, this loose type I and III collagen transformed further into densely packed bundles of type I collagen fibers, which mainly provide mechanical strength to tissues.
- Even after 24 weeks, some areas of the healed tissue still presented loose fibrillar areas of types I and III collagen.
Findings: Tissue Morphology
- Initially (2 weeks after surgery), the tissue forming within the defect was just a random mass of fibrovascular tissue, indicative of early-stage wound healing. Fibrovascular tissue is a rich mix of fibroblasts (cells that produce collagen and other fibers) and new blood vessels.
- However, after an extended period (24 weeks post-surgery), the tissue within the defect started to resemble normal tendon tissue, suggesting significant healing and reorganization of tissue structure.
Implications
- This study provides insights into how equine tendon tissues self-heal over time from significant surgical damage.
- The transformations and reorganizations were perhaps prompted by the body’s efforts to restore the tendons’ functionality, starting with rapid filling of the defect with fibrovascular tissue, followed by longer term establishment of collagen bundles. Understanding these mechanisms may help improve surgical procedures and treatment plans for tendon injuries in animals, and potentially, in humans.
Cite This Article
APA
Watkins JP, Auer JA, Gay S, Morgan SJ.
(1985).
Healing of surgically created defects in the equine superficial digital flexor tendon: collagen-type transformation and tissue morphologic reorganization.
Am J Vet Res, 46(10), 2091-2096.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Collagen
- Horse Diseases / pathology
- Horses / surgery
- Male
- Tendons / pathology
- Tendons / surgery
Citations
This article has been cited 13 times.- Peng C, Li H, Wang K, Chen G, Kong L, Ning R. Superior fulcrum reconstruction improve tendon-to-bone healing in irreparable massive rotator cuff tears compared with superior capsule reconstruction. Sci Rep 2025 Jul 1;15(1):21285.
- Hefferan SA, Blaker CL, Ashton DM, Little CB, Clarke EC. Structural Variations of Tendons: A Systematic Search and Narrative Review of Histological Differences Between Tendons, Tendon Regions, Sex, and Age. J Orthop Res 2025 May;43(5):994-1011.
- Duddy HR, Schoonover MJ, Hague BA. Outcome following local injection of a liquid amnion allograft for treatment of equine tendonitis or desmitis - 100 cases. BMC Vet Res 2022 Nov 7;18(1):391.
- Kataoka T, Mifune Y, Inui A, Nishimoto H, Kurosawa T, Yamaura K, Mukohara S, Matsushita T, Niikura T, Tabata Y, Kuroda R. Combined therapy of platelet-rich plasma and basic fibroblast growth factor using gelatin-hydrogel sheet for rotator cuff healing in rat models. J Orthop Surg Res 2021 Oct 16;16(1):605.
- Gaesser AM, Underwood C, Linardi RL, Even KM, Reef VB, Shetye SS, Mauck RL, King WJ, Engiles JB, Ortved KF. Evaluation of Autologous Protein Solution Injection for Treatment of Superficial Digital Flexor Tendonitis in an Equine Model. Front Vet Sci 2021;8:697551.
- Wagner FC, Gerlach K, Geiger SM, Gittel C, Böttcher P, Mülling CKW. Biplanar High-Speed Fluoroscopy of Pony Superficial Digital Flexor Tendon (SDFT)-An In Vivo Pilot Study. Vet Sci 2021 May 27;8(6).
- Kim TI, Jung W, Chung JY, Jeong H, Kim SH. Effect of a poloxamer-based thermosensitive gel on rotator cuff repair in a rabbit model: a controlled laboratory study. J Orthop Surg Res 2019 Jun 25;14(1):190.
- Nakanishi Y, Okada T, Takeuchi N, Kozono N, Senju T, Nakayama K, Nakashima Y. Histological evaluation of tendon formation using a scaffold-free three-dimensional-bioprinted construct of human dermal fibroblasts under in vitro static tensile culture. Regen Ther 2019 Dec;11:47-55.
- Kataoka T, Kokubu T, Muto T, Mifune Y, Inui A, Sakata R, Nishimoto H, Harada Y, Takase F, Ueda Y, Kurosawa T, Yamaura K, Kuroda R. Rotator cuff tear healing process with graft augmentation of fascia lata in a rabbit model. J Orthop Surg Res 2018 Aug 13;13(1):200.
- Jacobson E, Dart AJ, Mondori T, Horadogoda N, Jeffcott LB, Little CB, Smith MM. Focal experimental injury leads to widespread gene expression and histologic changes in equine flexor tendons. PLoS One 2015;10(4):e0122220.
- Kabuto Y, Morihara T, Sukenari T, Kida Y, Oda R, Arai Y, Sawada K, Matsuda K, Kawata M, Tabata Y, Fujiwara H, Kubo T. Stimulation of Rotator Cuff Repair by Sustained Release of Bone Morphogenetic Protein-7 Using a Gelatin Hydrogel Sheet. Tissue Eng Part A 2015 Jul;21(13-14):2025-33.
- Södersten F, Hultenby K, Heinegård D, Johnston C, Ekman S. Immunolocalization of collagens (I and III) and cartilage oligomeric matrix protein in the normal and injured equine superficial digital flexor tendon. Connect Tissue Res 2013;54(1):62-9.
- el Hawary R, Stanish WD, Curwin SL. Rehabilitation of tendon injuries in sport. Sports Med 1997 Nov;24(5):347-58.
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