Proximal sesamoid bone microdamage is localized to articular subchondral regions in Thoroughbred racehorses, with similar fracture toughness between fracture and controls

Luedke, Lauren K.; Ilevbare, Phoebe; Noordwijk, Kira J; Palomino, P. Martín; McDonough, Sean P.; Palmer, Scott E.; Basran, Parminder S.; Donnelly, Eve; Reesink, Heidi L.

doi:10.1111/vsu.13816

Cited by 5 publications

(2 citation statements)

References 35 publications

(123 reference statements)

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“…Exercise related proximal sesamoid bone (PSB) fracture is the most common fatal injury in many racing populations 21 – 23 . Consistent fracture configurations, a subchondral focus of stress remodeling and microdamage, and association with training indicate that PSB fractures are stress fractures 17 , 19 , 25 – 28 . We reported a focal subchondral low density and microdamaged lesion in fractured and contralateral limb intact medial PSBs of Thoroughbred racehorses; this lesion was not found in Control racehorses 17 , 25 .…”

Section: Introductionmentioning

confidence: 89%

Training drives turnover rates in racehorse proximal sesamoid bones

Shaffer

Stover

Fyhrie

2023

Sci Rep

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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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Section: Introductionmentioning

confidence: 89%

Training drives turnover rates in racehorse proximal sesamoid bones

Shaffer

Stover

Fyhrie

2023

Sci Rep

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“…Contrast‐enhanced μCT techniques, using lead uranyl acetate (LUA) or barium sulphate as radiocontrast microdamage labels, have been used in trabecular and cortical bone for three‐dimensional quantification of bone microdamage (Brock et al., 2013 ; Hernandez et al., 2014 ; Lambers et al., 2013 ; Schaffler et al., 1994 ; Tang & Vashishth, 2007 ). We and others have utilised LUA to label bone microdamage in SCB from the equine fetlock joint; however, the suitability of this method for quantifying SCB has not been determined (Luedke et al., 2022 ; Pearce et al., 2022 ). In SCB, the hyaline articular cartilage adheres at the articular surface and is adjacent to the site from where microcracks propagate.…”

Section: Introductionmentioning

confidence: 99%

Assessment of subchondral bone microdamage quantification using contrast‐enhanced imaging techniques

Ayodele,

Malekipour,

Pagel

et al. 2024

Journal of Anatomy

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Bone microdamage is common at subchondral bone (SCB) sites subjected to repeated high rate and magnitude of loading in the limbs of athletic animals and humans. Microdamage can affect the biomechanical behaviour of bone under physiological loading conditions. To understand the effects of microdamage on the mechanical properties of SCB, it is important to be able to quantify it. The extent of SCB microdamage had been previously estimated qualitatively using plain microcomputed tomography (μCT) and a radiocontrast quantification method has been used for trabecular bone but this method may not be directly applicable to SCB due to differences in bone structure. In the current study, SCB microdamage detection using lead uranyl acetate (LUA) and quantification by contrast‐enhanced μCT and backscattered scanning electron microscopy (SEM) imaging techniques were assessed to determine the specificity of the labels to microdamage and the accuracy of damaged bone volume metrices. SCB specimens from the metacarpus of racehorses, with the hyaline articular cartilage (HAC) removed, were grouped into two with one group subjected to ex vivo uniaxial compression loading to create experimental bone damage. The other group was not loaded to preserve the pre‐existing in vivo propagated bone microdamage. A subset of each group was stained with LUA using an established or a modified protocol to determine label penetration into SCB. The μCT and SEM images of stained specimens showed that penetration of LUA into the SCB was better using the modified protocol, and this protocol was repeated in SCB specimens with intact hyaline articular cartilage. The percentage of total label localised to bone microdamage was determined on SEM images, and the estimated labelled bone volume determined by μCT in SCB groups was compared. Label was present around diffuse and linear microdamage as well as oblique linear microcracks present at the articular surface, except in microcracks with high‐density mineral infills. Bone surfaces lining pores with recent mineralisation were also labelled. Labelled bone volume fraction (LV/BV) estimated by μCT was higher in the absence of HAC. At least 50% of total labels were localised to bone microdamage when the bone area fraction (B.Ar/T.Ar) of the SCB was greater than 0.85 but less than 30% when B.Ar/T.Ar of the SCB was less than 0.85. To adjust for LUA labels on bone surfaces, a measure of the LV/BV corrected for bone surface area (LV/BV BS−1) was used to quantify damaged SCB. In conclusion, removal of HAC and using a modified labelling protocol effectively stained damaged SCB of the metacarpus of racehorses and represents a technique useful for quantifying microdamage in SCB. This method can facilitate future investigations of the effects of microdamage on joint physiology.

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Advancements in Subchondral Bone Biomechanics: Insights from Computed Tomography and Micro-Computed Tomography Imaging in Equine Models

Malekipour,

Whitton,

Lee

2024

Curr Osteoporos Rep

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Purpose of Review This review synthesizes recent advancements in understanding subchondral bone (SCB) biomechanics using computed tomography (CT) and micro-computed tomography (micro-CT) imaging in large animal models, particularly horses. Recent Findings Recent studies highlight the complexity of SCB biomechanics, revealing variability in density, microstructure, and biomechanical properties across the depth of SCB from the joint surface, as well as at different joint locations. Early SCB abnormalities have been identified as predictive markers for both osteoarthritis (OA) and stress fractures. The development of standing CT systems has improved the practicality and accuracy of live animal imaging, aiding early diagnosis of SCB pathologies. Summary While imaging advancements have enhanced our understanding of SCB, further research is required to elucidate the underlying mechanisms of joint disease and articular surface failure. Combining imaging with mechanical testing, computational modelling, and artificial intelligence (AI) promises earlier detection and better management of joint disease. Future research should refine these modalities and integrate them into clinical practice to enhance joint health outcomes in veterinary and human medicine.

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Proximal sesamoid bone microdamage is localized to articular subchondral regions in Thoroughbred racehorses, with similar fracture toughness between fracture and controls

Cited by 5 publications

References 35 publications

Training drives turnover rates in racehorse proximal sesamoid bones

Training drives turnover rates in racehorse proximal sesamoid bones

Assessment of subchondral bone microdamage quantification using contrast‐enhanced imaging techniques

Advancements in Subchondral Bone Biomechanics: Insights from Computed Tomography and Micro-Computed Tomography Imaging in Equine Models

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