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Irandoust S, Whitton RC, Muir P, Henak CR. Subchondral bone fatigue injury in the parasagittal condylar grooves of the third metacarpal bone in thoroughbred racehorses elevates site-specific strain concentration. J Mech Behav Biomed Mater 2024; 155:106561. [PMID: 38678748 DOI: 10.1016/j.jmbbm.2024.106561] [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] [Received: 08/24/2023] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/01/2024]
Abstract
Condylar stress fracture of the distal end of the third metacarpal/metatarsal (MC3/MT3) bones is a major cause of Thoroughbred racehorse injury and euthanasia worldwide. Functional adaptation to exercise and fatigue damage lead to structural changes in the subchondral bone that include increased modeling (resulting in sclerotic bone tissue) and targeted remodeling repair (resulting in focal resorption spaces in the parasagittal groove). Whether these focal structural changes, as detectable by standing computed tomography (sCT), lead to elevated strain at the common site of condylar stress fracture has not been demonstrated. Therefore, the goal of the present study was to compare full-field three-dimensional (3D) strain on the distopalmar aspect of MC3 bone specimens with and without focal subchondral bone injury (SBI). Thirteen forelimb specimens were collected from racing Thoroughbreds for mechanical testing ex vivo and underwent sCT. Subsequently, full-field displacement and strain at the joint surface were determined using stereo digital image correlation. Strain concentration was observed in the parasagittal groove (PSG) of the loaded condyles, and those with SBI in the PSG showed higher strain rates in this region than control bones. PSG strain rate in condyles with PSG SBI was more sensitive to CT density distribution in comparison with condyles with no sCT-detectable injury. Findings from this study help to interpret structural changes in the subchondral bone due to fatigue damage and to assess risk of incipient stress fracture in a patient-specific manner.
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Affiliation(s)
- Soroush Irandoust
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, 53706, USA; Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - R Christopher Whitton
- Equine Centre, Melbourne Veterinary School, University of Melbourne, Werribee, Vic, 3030, Australia
| | - Peter Muir
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Corinne R Henak
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA; Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, 53705, USA.
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Muir P, Whitton RC. Injury prevention in Thoroughbred racehorses. Equine Vet J 2024; 56:386-388. [PMID: 38578097 DOI: 10.1111/evj.14077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 02/09/2024] [Indexed: 04/06/2024]
Affiliation(s)
- Peter Muir
- School of Veterinary Medicine, Department of Surgical Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - R Chris Whitton
- Equine Centre, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia
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McPhee S, Kershaw LE, Daniel CR, Peña Fernández M, Cillán-García E, Taylor SE, Wolfram U. QCT-based computational bone strength assessment updated with MRI-derived 'hidden' microporosity. J Mech Behav Biomed Mater 2023; 147:106094. [PMID: 37741181 DOI: 10.1016/j.jmbbm.2023.106094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 08/10/2023] [Accepted: 08/26/2023] [Indexed: 09/25/2023]
Abstract
Microdamage accumulated through sustained periods of cyclic loading or single overloading events contributes to bone fragility through a reduction in stiffness and strength. Monitoring microdamage in vivo remains unattainable by clinical imaging modalities. As such, there are no established computational methods for clinical fracture risk assessment that account for microdamage that exists in vivo at any specific timepoint. We propose a method that combines multiple clinical imaging modalities to identify an indicative surrogate, which we term 'hidden porosity', that incorporates pre-existing bone microdamage in vivo. To do so, we use the third metacarpal bone of the equine athlete as an exemplary model for fatigue induced microdamage, which coalesces in the subchondral bone. N = 10 metacarpals were scanned by clinical quantitative computed tomography (QCT) and magnetic resonance imaging (MRI). We used a patch-based similarity method to quantify the signal intensity of a fluid sensitive MRI sequence in bone regions where microdamage coalesces. The method generated MRI-derived pseudoCT images which were then used to determine a pre-existing damage (Dpex) variable to quantify the proposed surrogate and which we incorporate into a nonlinear constitutive model for bone tissue. The minimum, median, and maximum detected Dpex of 0.059, 0.209, and 0.353 reduced material stiffness by 5.9%, 20.9%, and 35.3% as well as yield stress by 5.9%, 20.3%, and 35.3%. Limb-specific voxel-based finite element meshes were equipped with the updated material model. Lateral and medial condyles of each metacarpal were loaded to simulate physiological joint loading during gallop. The degree of detected Dpex correlated with a relative reduction in both condylar stiffness (p = 0.001, R2 > 0.74) and strength (p < 0.001, R2 > 0.80). Our results illustrate the complementary value of looking beyond clinical CT, which neglects the inclusion of microdamage due to partial volume effects. As we use clinically available imaging techniques, our results may aid research beyond the equine model on fracture risk assessment in human diseases such as osteoarthritis, bone cancer, or osteoporosis.
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Affiliation(s)
- Samuel McPhee
- School of Engineering and Physical Sciences, Institute of Mechanical, Process and Energy Engineering, Heriot-Watt University, Edinburgh, UK
| | - Lucy E Kershaw
- Centre for Cardiovascular Sciences and Edinburgh Imaging, The University of Edinburgh, Edinburgh, UK
| | - Carola R Daniel
- Royal (Dick) School of Veterinary Studies and the Roslin Institute, The University of Edinburgh, Edinburgh, UK
| | - Marta Peña Fernández
- School of Engineering and Physical Sciences, Institute of Mechanical, Process and Energy Engineering, Heriot-Watt University, Edinburgh, UK
| | | | - Sarah E Taylor
- Royal (Dick) School of Veterinary Studies and the Roslin Institute, The University of Edinburgh, Edinburgh, UK
| | - Uwe Wolfram
- School of Engineering and Physical Sciences, Institute of Mechanical, Process and Energy Engineering, Heriot-Watt University, Edinburgh, UK.
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Shaffer SK, Stover SM, Fyhrie DP. Training drives turnover rates in racehorse proximal sesamoid bones. Sci Rep 2023; 13:205. [PMID: 36707527 PMCID: PMC9883508 DOI: 10.1038/s41598-022-26027-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 12/08/2022] [Indexed: 01/29/2023] Open
Abstract
Focal bone lesions are often found prior to clinically relevant stress-fractures. Lesions are characterized by low bone volume fraction, low mineral density, and high levels of microdamage and are hypothesized to develop when bone tissue cannot sufficiently respond to damaging loading. It is difficult to determine how exercise drives the formation of these lesions because bone responds to mechanical loading and repairs damage. In this study, we derive steady-state rate constants for a compartment model of bone turnover using morphometric data from fractured and non-fractured racehorse proximal sesamoid bones (PSBs) and relate rate constants to racing-speed exercise data. Fractured PSBs had a subchondral focus of bone turnover and microdamage typical of lesions that develop prior to fracture. We determined steady-state model rate constants at the lesion site and an internal region without microdamage using bone volume fraction, tissue mineral density, and microdamage area fraction measurements. The derived undamaged bone resorption rate, damage formation rate, and osteoid formation rate had significant robust regression relationships to exercise intensity (rate) variables, layup (time out of exercise), and exercise 2-10 months before death. However, the direction of these relationships varied between the damaged (lesion) and non-damaged regions, reflecting that the biological response to damaging-loading differs from the response to non-damaging loading.
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Affiliation(s)
- Sarah K Shaffer
- Department of Orthopaedic Surgery, School of Medicine, University of California, Davis, USA.
| | - Susan M Stover
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA
| | - David P Fyhrie
- Department of Orthopaedic Surgery, School of Medicine, University of California, Davis, USA
- Department of Biomedical Engineering, University of California, Davis, USA
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Malekipour F, Hitchens PL, Whitton RC, Vee-Sin Lee P. Effects of in vivo fatigue-induced microdamage on local subchondral bone strains. J Mech Behav Biomed Mater 2022; 136:105491. [PMID: 36198232 DOI: 10.1016/j.jmbbm.2022.105491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 01/31/2022] [Accepted: 09/26/2022] [Indexed: 11/26/2022]
Abstract
Biomechanical strain is a major stimulus of subchondral bone (SCB) tissue adaptation in joints but may also lead to initiation and propagation of microcracks, highlighting the importance of quantifying the intratissue strain in subchondral bone. In the present study, we used micro computed tomography (μCT) imaging, mechanical testing, and digital image correlation (DIC) techniques to evaluate the biomechanical strains in equine SCB under impact compression applied through the articular surface. We aimed to investigate the effects of in vivo accumulated microdamage in equine SCB on the distribution of mechanical impact strain through the articular cartilage. Under the applied strain of 2.0 ± 0.1% (mean ± standard deviation, n=15) to the articular surface of cartilage-bone plugs, the overall thickness of the SCB developed eSCBOverall = 0.7 ± 0.2% in all specimens. Contours of high strains in specimens without microdamage (NDmg) aligned parallel to the cartilage-bone interface with peak tensile, ϵt, and compressive, ϵc, strains of 0.5 ± 0.3% and 1.2 ± 0.4%, respectively at the time of peak compression (n=7). In damaged specimens (Dmg), contours of high strains aligned with the cracks in the imaged plane with peak strains of ϵt= 1.2 ± 0.8% and ϵc= 3.5 ± 2.2%, respectively (n=7). Microdamage was the main predictor of the normalised compressive and tensile strains across the SCB thickness. Results of multivariable analyses revealed presence of microdamage, distance from the articular surface and TMD were the main predictors of normalised compressive and tensile strain. Strain was greater in the superficial bone, particularly for specimens with microdamage. In vivo fatigue-induced microdamage is an important predictor of local subchondral bone strains.
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Affiliation(s)
- Fatemeh Malekipour
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Peta L Hitchens
- Equine Centre, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, VIC, 3030, Australia
| | - R Chris Whitton
- Equine Centre, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, VIC, 3030, Australia
| | - Peter Vee-Sin Lee
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, 3010, Australia.
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Malek G, Richard H, Beauchamp G, Laverty S. An in vitro model for discovery of osteoclast specific biomarkers towards identification of racehorses at risk for catastrophic fractures. Equine Vet J 2022; 55:534-550. [PMID: 35616632 DOI: 10.1111/evj.13600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 05/12/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Focal bone microcracks with osteoclast recruitment and bone lysis, may reduce fracture resistance in racehorses. As current imaging does not detect all horses at risk for fracture, the discovery of novel serum biomarkers of bone resorption or osteoclast activity could potentially address this unmet clinical need. The biology of equine osteoclasts on their natural substrate, equine bone, has never been studied in vitro and may permit identification of specific biomarkers of their activity. OBJECTIVES 1) Establish osteoclast cultures on equine bone, 2) Measure biomarkers (tartrate resistant acid phosphatase isoform 5b (TRACP-5b) and C-terminal telopeptide of type I collagen (CTX-I)) in vitro and 3) Study the effects of inflammation. STUDY DESIGN In vitro experiments. METHODS Haematopoietic stem cells, from 5 equine sternal bone marrow aspirates, were differentiated into osteoclasts and cultured either alone or on equine bone slices, with or without pro-inflammatory stimulus (IL-1β or LPS). CTX-I and TRACP-5b were immunoassayed in the media. Osteoclast numbers and bone resorption area were assessed. RESULTS TRACP-5b increased over time without bone (p < 0.0001) and correlated with osteoclast number (r = 0.63, p < 0.001). CTX-I and TRACP-5b increased with time for cultures with bone (p = 0.002; p = 0.02 respectively), correlated with each other (r = 0.64, p < 0.002) and correlated with bone resorption (r = 0.85, p < 0.001; r = 0.82, p < 0.001 respectively). Inflammation had no measurable effects. MAIN LIMITATIONS Specimen numbers limited. CONCLUSIONS Equine osteoclasts were successfully cultured on equine bone slices and their bone resorption quantified. TRACP-5b was shown to be a biomarker of equine osteoclast number and bone resorption for the first time; CTX-I was also confirmed to be a biomarker of equine bone resorption in vitro. This robust equine specific in vitro assay will help the study of osteoclast biology.
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Affiliation(s)
- Gwladys Malek
- Comparative Orthopaedic Research Laboratory, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte, St-Hyacinthe, QC, Canada
| | - Hélène Richard
- Comparative Orthopaedic Research Laboratory, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte, St-Hyacinthe, QC, Canada
| | - Guy Beauchamp
- Comparative Orthopaedic Research Laboratory, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte, St-Hyacinthe, QC, Canada
| | - Sheila Laverty
- Comparative Orthopaedic Research Laboratory, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, 3200 Sicotte, St-Hyacinthe, QC, Canada
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Imaging and Gross Pathological Appearance of Changes in the Parasagittal Grooves of Thoroughbred Racehorses. Animals (Basel) 2021; 11:ani11123366. [PMID: 34944142 PMCID: PMC8697963 DOI: 10.3390/ani11123366] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/18/2021] [Accepted: 11/21/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Early detection of racehorses at risk of stress fracture is key to reducing the number of horses with catastrophic fractures while racing. Bone changes are often visible in the limbs of Thoroughbred racehorses in work, particularly in the fetlock region. However, it is currently unknown whether some of these changes indicate an impending fracture or are a healthy adaptation to high-speed exercise. This study looks at imaging and gross changes in a specific area (parasagittal grooves (PSGs) of the cannon bone) and the utility of X-ray, computed tomography (CT) and magnetic resonance imaging (MRI) to detect the changes. All fetlock joints were assessed from twenty horses that died during racing or training, including horses with and without fetlock fracture. Overall, X-ray was poor for detecting PSG changes. Some PSG changes on CT and MRI were common in Thoroughbred racehorses and possibly represent normal bone adaptation when seen in clinical cases. However, certain CT and MRI findings were more prevalent in horses with a fracture, possibly indicating microdamage accumulation and increased risk of fracture. Bilateral advanced imaging is recommended in clinical cases of suspected fetlock pathology. Abstract (1) Background: Parasagittal groove (PSG) changes are often present on advanced imaging of racing Thoroughbred fetlocks and have been suggested to indicate increased fracture risk. Currently, there is limited evidence differentiating the imaging appearance of prodromal changes in horses at risk of fracture from horses with normal adaptive modelling in response to galloping. This study aims to investigate imaging and gross PSG findings in racing Thoroughbreds and the comparative utility of different imaging modalities to detect PSG changes. (2) Methods: Cadaver limbs were collected from twenty deceased racing/training Thoroughbreds. All fetlocks of each horse were examined with radiography, low-field magnetic resonance imaging (MRI), computed tomography (CT), contrast arthrography and gross pathology. (3) Results: Horses with fetlock fracture were more likely to have lateromedial PSG sclerosis asymmetry and/or lateral PSG lysis. PSG lysis was not readily detected using MRI. PSG subchondral bone defects were difficult to differentiate from cartilage defects on MRI and were not associated with fractures. The clinical relevance of PSG STIR hyperintensity remains unclear. Overall, radiography was poor for detecting PSG changes. (4) Conclusions: Some PSG changes in Thoroughbred racehorses are common; however, certain findings are more prevalent in horses with fractures, possibly indicating microdamage accumulation. Bilateral advanced imaging is recommended in racehorses with suspected fetlock pathology.
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Ayodele BA, Hitchens PL, Wong ASM, Mackie EJ, Whitton RC. Microstructural properties of the proximal sesamoid bones of Thoroughbred racehorses in training. Equine Vet J 2020; 53:1169-1177. [PMID: 33244781 DOI: 10.1111/evj.13394] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/14/2020] [Accepted: 11/19/2020] [Indexed: 12/01/2022]
Abstract
BACKGROUND Proximal sesamoid bone fractures are common catastrophic injuries in racehorses. Understanding the response of proximal sesamoid bones to race training can inform fracture prevention strategies. OBJECTIVES To describe proximal sesamoid bone microstructure of racehorses and to investigate the associations between microstructure and racing histories. STUDY DESIGN Cross-sectional. METHODS Proximal sesamoid bones from 63 Thoroughbred racehorses were imaged using micro-computed tomography. Bone volume fraction (BVTV) and bone material density (BMD) of the whole bone and four regions (apical, midbody dorsal, midbody palmar and basilar) were determined. Generalised linear regression models were used to identify the associations between bone parameters and race histories of the horses. RESULTS The mean sesamoid BVTV was 0.79 ± 0.08 and BMD was 806.02 ± 24.66 mg HA/ccm. BVTV was greater in medial sesamoids compared with lateral sesamoids (0.80 ± 0.07 vs 0.79 ± 0.08; P < .001) predominantly due to differences in the apical region (medial-0.76 ± 0.08 vs lateral-0.72 ± 0.07; P < .001). BVTV in the midbody dorsal region (0.86 ± 0.06) was greater than other regions (midbody palmar-0.79 ± 0.07, basilar-0.78 ± 0.06 and apical-0.74 ± 0.08; P < .001). BVTV was greater in sesamoids with more microcracks on their articular surface (Coef. 0.005; 95% CI 0.001, 0.009; P = .01), greater extent of bone resorption on their abaxial surface (Grade 2-0.82 ± 0.05 vs Grade 1-0.80 ± 0.05 or Grade 0-0.79 ± 0.06; P = .006), in horses with a low (0.82 ± 0.07) or mid handicap rating (0.78 ± 0.08) compared with high rating (0.76 ± 0.07; P < .001), in 2- to 5-year-old horses (0.81 ± 0.07) compared with younger (0.68 ± 0.08) or older horses (0.77 ± 0.08; P < .001) and in horses that commenced their racing career at less than 4 years of age (0.79 ± 0.08 vs 0.77 ± 0.77; P < .001). BMD was greater in the midbody dorsal (828.6 ± 19.6 mg HA/ccm) compared with other regions (apical-805.8 ± 21.8, midbody palmar-804.7 ± 18.4 and basilar-785.0 ± 17.1; P < .001), in horses with a handicap rating (low-812.1 ± 20.0, mid-821.8 ± 21.3 and high-814.6 ± 19.4) compared with those with no rating (791.08 ± 24.4, P < .001), in females (806.7 ± 22.0) and geldings (812.2 ± 22.4) compared with entires (792.7 ± 26.2; P = .02) and in older horses (<2-year-old-763.7 ± 24.8 vs 2- to 5-year-old-802.7 ± 23.4, and 6- to 12-year-old-817.8 ± 20.0; P = .002). MAIN LIMITATIONS Data were cross-sectional. CONCLUSIONS Densification of the proximal sesamoid bones is associated with the commencement of racing in younger horses and the presence of bone fatigue-related pathology. Lower sesamoid BVTV was associated with longevity and better performance.
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Affiliation(s)
- Babatunde A Ayodele
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Peta L Hitchens
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Adelene S M Wong
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Eleanor J Mackie
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - R Christopher Whitton
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
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Distribution of mechanical strain in equine distal metacarpal subchondral bone: A microCT-based finite element model. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2020. [DOI: 10.1016/j.medntd.2020.100036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Malekipour F, Hitchens PL, Whitton RC, Lee PVS. Effects of in vivo fatigue-induced subchondral bone microdamage on the mechanical response of cartilage-bone under a single impact compression. J Biomech 2019; 100:109594. [PMID: 31924348 DOI: 10.1016/j.jbiomech.2019.109594] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/03/2019] [Accepted: 12/21/2019] [Indexed: 11/30/2022]
Abstract
Subchondral bone (SCB) microdamage is prevalent in the joints of human athletes and animals subjected to high rate and magnitude cyclic loading of the articular surface. Quantifying the effect of such focal in vivo fatigue-induced microdamage on the mechanical response of the tissue is critical for the understanding of joint surface injury and the development of osteoarthritis. Thus, we aimed to quantify the mechanical properties of cartilage-bone from equine third metacarpal (MC3) condyles, which is a common area of accumulated microdamage due to repetitive impact loading. We chose a non-destructive technique, i.e. high-resolution microcomputed tomography (µCT) imaging, to identify various degrees of in vivo microdamage in SCB prior to mechanical testing; because µCT imaging can only identify a proportion of accumulated microdamage, we aimed to identify racing and training history variables that provide additional information on the prior loading history of the samples. We then performed unconfined high-rate compression of approximately 2% strain at 45%/s strain rate to simulate a cycle of gallop and used real-time strain measurements using digital image correlation (DIC) techniques to find the stiffness and shock absorbing ability (relative energy loss) of the cartilage-bone unit, and those associated with cartilage and SCB. Results indicated that stiffness of cartilage-bone and those associated with the SCB decreased with increasing grade of damage. Whole specimen stiffness also increased, and relative energy loss decreased with higher TMD, whereas bone volume fraction of the SCB was only associated negatively with the stiffness of the bone. Overall, the degree of subchondral bone damage observed with µCT was the main predictor of stiffness and relative energy loss of the articular surface of the third metacarpal bone of Thoroughbred racehorses under impact loading.
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Affiliation(s)
- Fatemeh Malekipour
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC 3010, Australia
| | - Peta L Hitchens
- Equine Centre, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, VIC 3030, Australia
| | - R Chris Whitton
- Equine Centre, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, VIC 3030, Australia
| | - Peter Vee-Sin Lee
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC 3010, Australia.
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11
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Whitton RC, Ayodele BA, Hitchens PL, Mackie EJ. Subchondral bone microdamage accumulation in distal metacarpus of Thoroughbred racehorses. Equine Vet J 2018; 50:766-773. [PMID: 29660153 DOI: 10.1111/evj.12948] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 03/31/2018] [Indexed: 11/28/2022]
Abstract
BACKGROUND Microdamage accumulation leads to subchondral bone injury and/or fracture in racehorses. An understanding of this process is essential for developing strategies for injury prevention. OBJECTIVES To quantify subchondral bone microdamage in the third metacarpal bone of Thoroughbred racehorses at different stages of the training cycle. STUDY DESIGN Cross-sectional. METHODS Bone blocks from the palmar aspect of the medial condyles of third metacarpal bones from 46 racing Thoroughbred horses undergoing post-mortem were examined with micro computed tomography (microCT) to detect calcified microcracks, and light microscopy to quantify bulk stained microcracks. Racing and training histories were obtained for comparison with microdamage data using regression modelling. RESULTS Subchondral bone microcracks were observed in all bones with at least one method. Microdamage grade was greater in older horses, levelling-off for horses 5 years and older (quadratic term P = 0.01), and with lower bone material density in the parasagittal groove (P = 0.02). Microcrack density was higher in older horses (P = 0.004), and with higher bone volume fraction (BV/TV) in the parasagittal groove in horses in training (interaction effect, P = 0.01) and lower in horses resting from training (P = 0.02). MAIN LIMITATIONS Cross-sectional data only. Incomplete detection of microdamage due to the limits of resolution of microCT and lack of three-dimensional imaging with microscopy. Multicollinearity between variables that indicated career progression (e.g. age, number of career starts, duration of training period) was detected. CONCLUSIONS Fatigue damage in the distal metacarpal subchondral bone is common in Thoroughbred racehorses undergoing post-mortem and appears to accumulate throughout a racing career. Reduced intensity or duration of training and racing and/or increased duration of rest periods may limit microdamage accumulation. Focal subchondral bone sclerosis indicates the presence of microdamage.
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Affiliation(s)
- R C Whitton
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia
| | - B A Ayodele
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia
| | - P L Hitchens
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia
| | - E J Mackie
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia
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12
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Martig S, Hitchens PL, Stevenson MA, Whitton RC. Subchondral bone morphology in the metacarpus of racehorses in training changes with distance from the articular surface but not with age. J Anat 2018; 232:919-930. [PMID: 29446086 DOI: 10.1111/joa.12794] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2018] [Indexed: 02/04/2023] Open
Abstract
The repetitive large loads generated during high-speed training and racing commonly cause subchondral bone injuries in the metacarpal condyles of racehorses. Adaptive bone modelling leads to focal sclerosis at the site of highest loading in the palmar aspect of the metacarpal condyles. Information on whether and how adaptive modelling of subchondral bone changes during the career of a racehorse is sparse. The aim of this cross-sectional study was to describe the changes in subchondral bone micromorphology in the area of highest loading in the palmar aspect of the metacarpal condyle in thoroughbred racehorses as a function of age and training. Bone morphology parameters derived from micro-CT images were evaluated using principal component analysis and mixed-effects linear regression models. The largest differences in micromorphology were observed in untrained horses between the age of 16 and 20 months. Age and duration of a training period had no influence on tissue mineral density, bone volume fraction or number and area of closed pores to a depth of 5.1 mm from the articular surface in 2- to 4-year-old racehorses in training. Horses with subchondral bone injuries had more pores in cross-section compared with horses without subchondral bone injuries. Differences in bone volume fraction were due to the volume of less mineralised bone. Tissue mineral density increased and bone volume fraction decreased with increasing distance from the articular surface up to 5.1 mm from the articular surface. Further research is required to elucidate the biomechanical and pathophysiological consequences of these gradients of micromorphological parameters in the subchondral bone.
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Affiliation(s)
- Sandra Martig
- Equine Centre, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Vic., Australia
| | - Peta L Hitchens
- Equine Centre, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Vic., Australia
| | - Mark A Stevenson
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Vic., Australia
| | - R Chris Whitton
- Equine Centre, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Vic., Australia
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13
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Hitchens PL, Pivonka P, Malekipour F, Whitton RC. Mathematical modelling of bone adaptation of the metacarpal subchondral bone in racehorses. Biomech Model Mechanobiol 2018; 17:877-890. [PMID: 29344755 DOI: 10.1007/s10237-017-0998-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/23/2017] [Indexed: 02/02/2023]
Abstract
In Thoroughbred racehorses, fractures of the distal limb are commonly catastrophic. Most of these fractures occur due to the accumulation of fatigue damage from repetitive loading, as evidenced by microdamage at the predilection sites for fracture. Adaptation of the bone in response to training loads is important for fatigue resistance. In order to better understand the mechanism of subchondral bone adaptation to its loading environment, we utilised a square root function defining the relationship between bone volume fraction [Formula: see text] and specific surface [Formula: see text] of the subchondral bone of the lateral condyles of the third metacarpal bone (MCIII) of the racehorse, and using this equation, developed a mathematical model of subchondral bone that adapts to loading conditions observed in vivo. The model is expressed as an ordinary differential equation incorporating a formation rate that is dependent on strain energy density. The loading conditions applied to a selected subchondral region, i.e. volume of interest, were estimated based on joint contact forces sustained by racehorses in training. For each of the initial conditions of [Formula: see text] we found no difference between subsequent homoeostatic [Formula: see text] at any given loading condition, but the time to reach equilibrium differed by initial [Formula: see text] and loading condition. We found that the observed values for [Formula: see text] from the mathematical model output were a good approximation to the existing data for racehorses in training or at rest. This model provides the basis for understanding the effect of changes to training strategies that may reduce the risk of racehorse injury.
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Affiliation(s)
- Peta L Hitchens
- Equine Centre, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, VIC, 3030, Australia.
| | - Peter Pivonka
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - Fatemeh Malekipour
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, 3010, Australia
| | - R Chris Whitton
- Equine Centre, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, VIC, 3030, Australia
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14
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Williamson AJ, Sims NA, Thomas CDL, Lee PVS, Stevenson MA, Whitton RC. Biomechanical testing of the calcified metacarpal articular surface and its association with subchondral bone microstructure in Thoroughbred racehorses. Equine Vet J 2017; 50:255-260. [DOI: 10.1111/evj.12748] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 08/02/2017] [Indexed: 11/27/2022]
Affiliation(s)
- A. J. Williamson
- Faculty of Veterinary and Agricultural Sciences University of Melbourne Melbourne Australia
| | - N. A. Sims
- St Vincent's Institute of Medical Research and Department of Medicine St. Vincent's Hospital University of Melbourne Melbourne Australia
| | - C. D. L. Thomas
- Melbourne Dental School University of Melbourne Melbourne Australia
| | - P. V. S. Lee
- Department of Mechanical Engineering, Melbourne School of Engineering University of Melbourne Melbourne Australia
| | - M. A. Stevenson
- Faculty of Veterinary and Agricultural Sciences University of Melbourne Melbourne Australia
| | - R. C. Whitton
- Faculty of Veterinary and Agricultural Sciences University of Melbourne Melbourne Australia
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15
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Bani Hassan E, Mirams M, Ghasem-Zadeh A, Mackie EJ, Whitton RC. Role of subchondral bone remodelling in collapse of the articular surface of Thoroughbred racehorses with palmar osteochondral disease. Equine Vet J 2015; 48:228-33. [DOI: 10.1111/evj.12415] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 01/01/2015] [Indexed: 11/29/2022]
Affiliation(s)
- E. Bani Hassan
- Faculty of Veterinary Science; University of Melbourne; Victoria Australia
| | - M. Mirams
- Faculty of Veterinary Science; University of Melbourne; Victoria Australia
| | - A. Ghasem-Zadeh
- Department of Endocrinology and Medicine, Austin Health; University of Melbourne; Victoria Australia
| | - E. J. Mackie
- Faculty of Veterinary Science; University of Melbourne; Victoria Australia
| | - R. C. Whitton
- Faculty of Veterinary Science; University of Melbourne; Victoria Australia
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16
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Holmes JM, Mirams M, Mackie EJ, Whitton RC. Thoroughbred horses in race training have lower levels of subchondral bone remodelling in highly loaded regions of the distal metacarpus compared to horses resting from training. Vet J 2014; 202:443-7. [PMID: 25296852 DOI: 10.1016/j.tvjl.2014.09.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 08/31/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
Abstract
Bone is repaired by remodelling, a process influenced by its loading environment. The aim of this study was to investigate the effect of a change in loading environment on bone remodelling by quantifying bone resorption and formation activity in the metacarpal subchondral bone in Thoroughbred racehorses. Sections of the palmar metacarpal condyles of horses in race training (n = 24) or resting from training (n = 24) were examined with light microscopy and back scattered scanning electron microscopy (BSEM). Bone area fraction, osteoid perimeter and eroded bone surface were measured within two regions of interest: (1) the lateral parasagittal groove (PS); (2) the lateral condylar subchondral bone (LC). BSEM variables were analysed for the effect of group, region and interaction with time since change in work status. The means ± SE are reported. For both regions of interest in the training compared to the resting group, eroded bone surface was lower (PS: 0.39 ± 0.06 vs. 0.65 ± 0.07 per mm, P = 0.010; LC: 0.24 ± 0.04 vs. 0.85 ± 0.10 per mm, P < 0.001) and in the parasagittal groove osteoid perimeter was higher (0.23 ± 0.04% vs. 0.12 ± 0.02%). Lower porosity was observed in the subchondral bone, reflected by a higher bone area fraction in the LC of the training group (90.8 ± 0.6%) compared to the resting group (85.3 ± 1.4%, P = 0.0010). Race training was associated with less bone resorption and more bone formation in the subchondral bone of highly loaded areas of the distal metacarpus limiting the replacement of fatigued bone. Periods of reduced intensity loading are important for facilitating subchondral bone repair in Thoroughbred racehorses.
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Affiliation(s)
- J M Holmes
- Faculty of Veterinary Science, University of Melbourne, 250 Princes Hwy, Werribee 3030, Australia
| | - M Mirams
- Faculty of Veterinary Science, University of Melbourne, 250 Princes Hwy, Werribee 3030, Australia
| | - E J Mackie
- Faculty of Veterinary Science, University of Melbourne, 250 Princes Hwy, Werribee 3030, Australia
| | - R C Whitton
- Faculty of Veterinary Science, University of Melbourne, 250 Princes Hwy, Werribee 3030, Australia.
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17
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Trope GD, Ghasem-Zadeh A, Anderson GA, Mackie EJ, Whitton RC. Can high-resolution peripheral quantitative computed tomography imaging of subchondral and cortical bone predict condylar fracture in Thoroughbred racehorses? Equine Vet J 2014; 47:428-32. [DOI: 10.1111/evj.12312] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 06/19/2014] [Indexed: 11/26/2022]
Affiliation(s)
- G. D. Trope
- Faculty of Veterinary Science; University of Melbourne; Werribee Victoria Australia
| | - A. Ghasem-Zadeh
- Department of Endocrinology and Medicine, Austin Health; University of Melbourne; Parkville Victoria Australia
| | - G. A. Anderson
- Faculty of Veterinary Science; University of Melbourne; Werribee Victoria Australia
| | - E. J. Mackie
- Faculty of Veterinary Science; University of Melbourne; Werribee Victoria Australia
| | - R. C. Whitton
- Faculty of Veterinary Science; University of Melbourne; Werribee Victoria Australia
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18
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Martig S, Chen W, Lee PVS, Whitton RC. Bone fatigue and its implications for injuries in racehorses. Equine Vet J 2014; 46:408-15. [DOI: 10.1111/evj.12241] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/26/2014] [Indexed: 11/30/2022]
Affiliation(s)
- S. Martig
- Faculty of Veterinary Science; The University of Melbourne; Werribee Victoria Australia
| | - W. Chen
- Department of Mechanical Engineering, Melbourne School of Engineering; The University of Melbourne; Parkville Victoria Australia
| | - P. V. S. Lee
- Department of Mechanical Engineering, Melbourne School of Engineering; The University of Melbourne; Parkville Victoria Australia
| | - R. C. Whitton
- Faculty of Veterinary Science; The University of Melbourne; Werribee Victoria Australia
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