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Engiles JB, Stewart H, Janes J, Kennedy LA. A diagnostic pathologist's guide to carpal disease in racehorses. J Vet Diagn Invest 2017; 29:414-430. [PMID: 28580838 DOI: 10.1177/1040638717710238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
As a pathologist, postmortem examination of the equine carpus can be daunting. The anatomy is complex and oftentimes, small or subtle lesions have significant impact on lameness and secondary lesions such as catastrophic musculoskeletal fractures and other injuries. In performance horses, particularly racehorses, the carpus is a common site of injury and source of lameness. Given the predisposition of racehorses to developing carpal disease, familiarity with clinically relevant anatomy and common developmental, degenerative, traumatic, and inflammatory processes are imperative for thorough postmortem examination. Our aim is (1) to provide a concise summary of clinically relevant anatomy and function that serves as a guide for postmortem evaluation of the equine carpus, and (2) to review common carpal injuries and diseases in actively training, racing, or retired racehorses, including developmental lesions (incomplete ossification, osteochondromata), infectious and inflammatory lesions (septic arthritis and tenosynovitis), and degenerative and traumatic lesions (degenerative and traumatic osteoarthritis, osteochondral fragmentation, and polyostotic catastrophic "breakdown" fractures). Representative gross and histologic images are presented along with corresponding antemortem and postmortem diagnostic images, and a review of current scientific literature pertaining to the pathogenesis of these equine carpal lesions.
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Affiliation(s)
- Julie B Engiles
- Department of Pathobiology, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA (Engiles).,Gail Holmes Orthopaedic Research Center, Department of Clinical Studies, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO (Stewart).,Department of Veterinary Science, Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY (Janes, Kennedy)
| | - Holly Stewart
- Department of Pathobiology, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA (Engiles).,Gail Holmes Orthopaedic Research Center, Department of Clinical Studies, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO (Stewart).,Department of Veterinary Science, Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY (Janes, Kennedy)
| | - Jennifer Janes
- Department of Pathobiology, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA (Engiles).,Gail Holmes Orthopaedic Research Center, Department of Clinical Studies, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO (Stewart).,Department of Veterinary Science, Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY (Janes, Kennedy)
| | - Laura A Kennedy
- Department of Pathobiology, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA (Engiles).,Gail Holmes Orthopaedic Research Center, Department of Clinical Studies, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO (Stewart).,Department of Veterinary Science, Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY (Janes, Kennedy)
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Abstract
Bone, despite its relatively inert appearance, is a tissue that is capable of adapting to its environment. Wolff’s law, first described in the 19th century, describes the ability of bone to change structure depending on the mechanical forces applied to it. The mechanostat model extended this principle and suggested that the amount of strain a bone detects depends on bone strength and the amount of muscle force applied to the bone. Experimental studies have found that low-magnitude, high-frequency mechanical loading is considered to be the most effective at increasing bone formation. The osteocyte is considered to be the master regulator of the bone response to mechanical loading. Deformation of bone matrix by mechanical loading is thought to result in interstitial fluid flow within the lacunar–canalicular system, which may activate osteocyte mechanosensors, leading to changes in osteocyte gene expression and ultimately increased bone formation and decreased bone resorption. However, repetitive strain applied to bone can result in microcracks, which may propagate and coalesce, and if not repaired predispose to catastrophic fracture. Osteocytes are a key component in this process, whereby apoptotic osteocytes in an area of microdamage promote targeted remodeling of the damaged bone. If fractures do occur, fracture repair can be divided into 2 types: primary and secondary healing. Secondary fracture repair is the most common and is a multistage process consisting of hematoma formation and acute inflammation, callus formation, and finally remodeling, whereby bone may return to its original form.
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Song JQ, Dong F, Li X, Xu CP, Cui Z, Jiang N, Jia JJ, Yu B. Effect of treadmill exercise timing on repair of full-thickness defects of articular cartilage by bone-derived mesenchymal stem cells: an experimental investigation in rats. PLoS One 2014; 9:e90858. [PMID: 24595327 PMCID: PMC3940955 DOI: 10.1371/journal.pone.0090858] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 02/06/2014] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVE Current medical practice for the treatment of articular cartilage lesions remains a clinical challenge due to the limited self-repair ability of articular cartilage. Both experimental and clinical researches show that moderate exercise can improve articular cartilage repair process. However, optimal timing of moderate exercise is unclear. We aimed to evaluate the effect of timing of moderate treadmill exercise on repair of full-thickness defects of articular cartilage. DESIGN Full-thickness cartilage defects were drilled in the patellar groove of bilateral femoral condyles in a total of 40 male SD rats before they were randomly assigned into four even groups. In sedentary control (SED) group, no exercise was given; in 2-week (2W), 4-week (4W) and 8-week groups, moderate treadmill exercise was initiated respectively two, four and eight weeks after operation. Half of the animals were sacrificed at week 10 after operation and half at week 14 after operation. Femoral condyles were harvested for gross observation and histochemical measurement by O'Driscoll scoring system. Collagen type II was detected by immunohistochemistry and mRNA expressions of aggrecan and collagen type II cartilage by RT-PCR. RESULTS Both 10 and 14 weeks post-operation, the best results were observed in 4W group and the worst results appeared in 2W group. The histochemistry scores and the expressions of collagen type II and aggrecan were significantly higher in 4W group than that in other three groups (P<0.05). CONCLUSIONS Moderate exercise at a selected timing (approximately 4 weeks) after injury can significantly promote the healing of cartilage defects but may hamper the repair process if performed too early while delayed intervention by moderate exercise may reduce its benefits in repair of the defects.
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Affiliation(s)
- Jin-qi Song
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Fu Dong
- Department of Orthopaedics, Beihai People's Hospital of Guangxi Province, Bei Hai, Guangxi Province, China
| | - Xue Li
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Chang-peng Xu
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Zhuang Cui
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Nan Jiang
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Jun-jie Jia
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Bin Yu
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
- Key Laboratory of Bone and Cartilage Regenerative Medicine of Guangdong Province, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
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Kim W, McArdle BH, Kawcak CE, McIlwraith CW, Firth EC, Broom ND. Histomorphometric evaluation of the effect of early exercise on subchondral vascularity in the third carpal bone of horses. Am J Vet Res 2013; 74:542-9. [PMID: 23531061 DOI: 10.2460/ajvr.74.4.542] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate histomorphometric changes in the cartilage and subchondral bone of the third carpal bone associated with conditioning exercise in young Thoroughbreds. ANIMALS Nine 18-month-old Thoroughbreds. Procedures-Both third carpal bones of 9 horses (4 exercised spontaneously at pasture only and 5 given additional conditioning exercise beginning at a mean age of 3 weeks) were evaluated. Histomorphometric variables (hyaline and calcified cartilage thickness and collagen orientation; vascular channel area, number, and orientation; and osteochondral junction rugosity) of the third carpal bone, sampled at 4 dorsopalmar sites in the radial facet, were compared between the exercised and nonexercised groups. RESULTS The vascular channel area measured at the 4 dorsopalmar sites was larger in the exercised group than in the control group, but none of the variables were significantly different between groups. Both groups had significant site-specific variations in all measured variables. Most importantly, the vascular channel area was highest in the most dorsal aspect. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the mild exercise imposed in both groups during the developmental period appeared to be associated with an increase in the vascular channel area beneath the calcified cartilage layer in the third carpal bone. This increased vascular channel area could also be associated with high stress in the dorsal aspect of the radial facet, a region that is known to be vulnerable to osteochondral fragmentation.
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Affiliation(s)
- Woong Kim
- Tissue Mechanics Laboratory, Department of Chemical and Materials Engineering, Faculty of Engineering, Faculty of Science, University of Auckland, Auckland 1142, New Zealand
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