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Topic:Metacarpal Bone
The metacarpal bone in horses is a key component of the equine forelimb, consisting primarily of the third metacarpal bone, commonly referred to as the cannon bone, and the smaller second and fourth metacarpal bones, known as splint bones. These bones provide structural support and play a vital role in weight-bearing and locomotion. The third metacarpal bone is the largest and most prominent, extending from the carpus (knee) to the fetlock joint. Its strength and integrity are essential for the horse's ability to perform various physical activities. The second and fourth metacarpal bones are positioned on either side of the third metacarpal and are remnants of evolutionary development. They can be involved in conditions such as splints, where inflammation occurs due to stress or trauma. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, function, and clinical aspects of metacarpal bones in horses, including their role in equine biomechanics and common pathologies.
Frequency distributions of 174 fractures of the distal condyles of the third metacarpal and metatarsal bones in 167 Thoroughbred racehorses (1999-2009). Although fractures of the metacarpal and metatarsal condyles are the most common long-bone fractures of Thoroughbred horses in training, limited data on variations in morphology and incidence have been published. Additionally, grouped analyses of previous studies from the UK and USA would permit comparison between study groups and the creation of a substantial pool of international data. Methods: Retrospective analysis of case records of horses with fractures of the distal condyles of third metacarpal/metatarsal bones seen over the last 10 years at Newmarket Equine Hospital. The current series...
Exostoses on the palmar or plantar aspect of the diaphysis of the third metacarpal or metatarsal bone in horses: 16 cases (2001-2010). To characterize the clinical features, diagnostic procedures, treatment, and outcome for horses with an exostosis on the palmar or plantar cortex of the third metacarpal bone (MC3) or third metatarsal bone (MT3). Methods: Retrospective case series. Methods: 16 horses. Methods: Records from 2001 through 2010 were evaluated to identify horses with radiographic and ultrasonographic evidence of an exostosis on an MC3 or MT3. Signalment, history, lameness examination results, diagnostic imaging results, surgical and histopathologic findings, treatment, and outcome were evaluated. Results: 9 horses ...
Effects of a novel hydrogel on equine bone healing: a pilot study. To examine the efficacy and biocompatibility of a thiolated gelatin-thiolated carboxymethyl hyaluronan (CMHA-SGX) sponge as an osteoconductive device in an equine second and fourth metacarpal bone defect model. Methods: Seven millimetre segmental ostectomies were created bilaterally in the second and fourth metacarpal bones of four horses. The left and right metacarpal defects were randomly assigned to (1) be filled with a CMHA-SGX sponge (treated) or (2) were left unfilled (control). The duration of the study was nine weeks. Bone healing was evaluated using serial radiology, as well as histol...
Evaluation of direct in vivo gene transfer in an equine metacarpal IV ostectomy model using an adenoviral vector encoding the bone morphogenetic protein-2 and protein-7 gene. To evaluate gene transfer in an equine metacarpal IV (MCIV) ostectomy model using adenoviral vectors encoding the human bone morphogenetic protein-2 and protein-7 gene (Ad-BMP-2/-7). Methods: Healthy adult horses (n = 15). Methods: A plate stabilized, critical size 1.5 cm ostectomy was created in left and right MCIV. The ostectomy site was injected with either Ad-green fluorescent protein (Ad-GFP) or Ad-hBMP-2/-7 at completion of surgery; the same treatment was assigned to both the left and right forelimb of each horse (n = 5 horses/group). Bone healing was evaluated radiographically every 2 w...
Effect of a solution of hyaluronic acid-chondroitin sulfate-N-acetyl glucosamine on the repair response of cartilage to single-impact load damage. To investigate effects of 1% hyaluronic acid-chondroitin sulfate-N-acetyl glucosamine (HCNAG) on the damage repair response in equine articular cartilage. Methods: Articular cartilage from 9 clinically normal adult horses. Methods: Full-thickness cartilage disks were harvested from the third metacarpal bone. Cartilage was single-impact loaded (SIL) with 0.175 J at 0.7 m/s and cultured in DMEM plus 1 % (vol/vol) HCNAG or fibroblastic growth factor (FGF)-2 (50 ng/mL). Histologic and immunohistochemical techniques were used to identify tissue architecture and apoptotic cells and to immunolocalize...
In vivo osteoinductivity of gelatin β-tri-calcium phosphate sponge and bone morphogenetic protein-2 on an equine third metacarpal bone defect. This study evaluated the therapeutic effects of a gelatin-β-TCP sponge (sponge) incorporating BMP-2 (BMP-2/sponge) on bone regeneration in equines. Six bone defects were created in third metacarpals of five thoroughbred horses, and a total of six treatments were applied in a randomized manner. The treatments were BMP-2/sponge, BMP-2/gelatin hydrogel sheet (sheet), free BMP-2, bFGF/sheet, plain sponge, and plain sheet. The defects were monitored for 16 weeks by radiography and then examined by histological analysis. Radiographic evaluation scores of bone regeneration revealed significantly gre...
Magnetic resonance imaging-detected adaptation and pathology in the distal condyles of the third metacarpus, associated with lateral condylar fracture in Thoroughbred racehorses. Lateral condylar (LC) fractures of the third metacarpus (McIII) are a common reason for euthanasia in racehorses, and may be the result of repetitive overloading or cumulative pathological change. Magnetic resonance imaging (MRI) allows monitoring of bone and cartilage to detect pathological and adaptive changes that may be precursors of fracture. Objective: To describe bone and cartilage MRI features in the distal condyles of McIII of Thoroughbred racehorses, with and without condylar fracture. Objective: 1) A greater degree of bone and cartilage adaptation or pathology will be seen in fractu...
Effect of sequential hole enlargement on cortical bone temperature during drilling of 6.2-mm-diameter transcortical holes in the third metacarpal bones of horse cadavers. To compare the bone temperature and final hole dimensions associated with sequential overdrilling (SO) and single 6.2-mm drill bit (S6.2DB) methods used to create transcortical holes in the third metacarpal bones (MCIIIs) of horse cadavers. Methods: 60 MCIIIs from 30 horse cadavers. Methods: In phase 1, hole diameter, tap insertion torque, peak bone temperature, and postdrilling bit temperature for 6.2-mm-diameter holes drilled in the lateral or medial cortical region of 12 MCIIIs via each of three 2-bit SO methods with a single pilot hole (diameter, 3.2, 4.5, or 5.5 mm) and the S6.2DB method ...
Ultrasonographic appearance of bony abnormalities at the dorsal aspect of the fetlock joint in geriatric cadaver horses. This article describes the ultrasonographic (US) appearance of bony abnormalities on the dorsal aspect of the third metacarpal/metatarsal bone of the equine fetlock in cadavers with radiographic signs of osteoarthrosis. After US, computed tomography was undertaken to better characterise the lesions. Twelve fetlock joints were collected and all had more than one bone abnormality on US. Normal subchondral bone appeared on US as a well-defined and regular hyperechoic line with distal acoustic shadowing. Bone abnormalities detected on US included (1) gaps in the proximal subchondral bone filled wi...
Detection of articular pathology of the distal aspect of the third metacarpal bone in thoroughbred racehorses: comparison of radiography, computed tomography and magnetic resonance imaging. To compare digital radiography (DR), computed tomography (CT), and magnetic resonance imaging (MRI) for detection of pathology of the distal aspect of the third metacarpal bone (MC3) and to assess whether arthrography would improve detection of articular cartilage or subchondral bone cracking. Methods: Cross-sectional study. Methods: Limb specimens from 17 Thoroughbred horses after catastrophic injury and 4 age-matched control horses. Methods: Standard DR, CT, and MRI images of the metacarpophalangeal joint were acquired before and after iohexol injection. Pathologic features detected with ima...
Liquid chromatography electrospray ionization tandem mass spectrometry for the detection of mesocarb abuse in horse doping. A method is described for the determination of mesocarb abuse in equestrian sport by combining gradient liquid chromatography and electrospray ionization tandem mass spectrometry. Mesocarb was administrated orally to two horses at a dose of 50 µg/kg. Urine samples were collected up to 120 h post administration. Hydrolyzed and conjugated urine fractions were handled using liquid-liquid extraction (LLE). The identity of the parent drug and metabolites was confirmed using liquid chromatography combined with tandem mass spectrometry (MS/MS). Mesocarb and seven metabolites were detected in horse...
Magnetic resonance imaging findings in the carpus and proximal metacarpal region of 50 lame horses. There is limited information on magnetic resonance imaging (MRI) findings in the carpus and proximal metacarpal region of lame horses. Objective: To document MRI findings in horses with lameness localised to the carpus and/or proximal metacarpal region. Methods: Clinical records of horses that underwent MRI of the carpus and/or proximal metacarpal region at the Animal Health Trust between January 2003 and September 2010 were reviewed. Magnetic resonance images of all horses and available radiographs, ultrasonographic and scintigraphic images were assessed. When possible, MRI findings were rela...
The effect of previous conditioning exercise on diaphyseal and metaphyseal bone to imposition and withdrawal of training in young Thoroughbred horses. This study recorded the response to training of the diaphysis of the proximal phalangeal bone and the third metacarpal bone (Mc3) and the Mc3 proximal metaphysis. Nineteen 2- and 3-year old horses in training were exposed either to spontaneous exercise at pasture (PASTEX group) or additional imposed exercise (CONDEX group) from a very young age. Quantitative computed tomography scans were analysed for bone mineral content, size, bone mineral density, periosteal and endosteal circumference, cortical thickness and an estimate of bone strength. The bones of the CONDEX horses were bigger and stron...
Incomplete longitudinal fractures and fatigue injury of the proximopalmar medial aspect of the third metacarpal bone in 55 horses. Previous descriptions of incomplete longitudinal fractures and fatigue injury of the proximopalmar aspect of the third metacarpal bone (McIII) have focused on diagnostic imaging findings, especially in racehorses. Objective: To document the case details, clinical features, response to diagnostic analgesia, diagnostic imaging findings and follow-up data in a large group of horses with an incomplete longitudinal fracture or fatigue injury of the proximopalmar medial aspect of the McIII. Methods: Horses were included in the study if pain was localised to the proximopalmar aspect of the metacarpal...
Assessment of a bone biopsy technique for measuring tiludronate in horses: a preliminary study. This study assessed the feasibility of measuring tiludronate in horses using a minimally invasive bone biopsy technique. Eight horses were treated with intravenous (IV) tiludronate [1 mg/kg bodyweight (BW)], either once (n = 4) or twice, 28 d apart (n = 4). The horses that were treated once were euthanized on days 1, 43, 57, or 92 and those that were treated twice, were euthanized on days 112, 154, 194, or 364. Bone samples were taken bilaterally from each horse at 4 sites: the third metacarpal bone (MCIII), the 13th rib (R13), the tuber coxae (TC), and the cuboid bone (CB). Test samples were ...
Cartilage damage involving extrusion of mineralisable matrix from the articular calcified cartilage and subchondral bone. Arthropathy of the distal articular surfaces of the third metacarpal (Mc3) and metatarsal (Mt3) bones in the Thoroughbred racehorse (Tb) is a natural model of repetitive overload arthrosis. We describe a novel pathology that affects the articular calcified cartilage (ACC) and subchondral bone (SCB) and which is associated with hyaline articular cartilage degeneration. Parasagittal slices cut from the palmar quadrant of the distal condyles of the left Mc3/Mt3 of 39 trained Tbs euthanized for welfare reasons were imaged by point projection microradiography, and backscattered electron (BSE) scann...
Metacarpal geometry changes during Thoroughbred race training are compatible with sagittal-plane cantilever bending. Bending of the equine metacarpal bones during locomotion is poorly understood. Cantilever bending, in particular, may influence the loading of the metacarpal bones and surrounding structures in unique ways. Objective: We hypothesised that increased amounts of sagittal-plane cantilever bending may govern changes to the shape of the metacarpal bones of Thoroughbred racehorses during training. We hypothesised that this type of bending would require a linear change to occur in the combined second moment of area of the bones for sagittal-plane bending (I) during race training. Methods: Six Thorough...
Racing prognosis after cumulative stress-induced injury of the distal portion of the third metacarpal and third metatarsal bones in Thoroughbred racehorses: 55 cases (2000-2009). To evaluate the diagnostic features, results of free-choice exercise treatment, prognosis, and postinjury racing performance of Thoroughbred racehorses with cumulative stress-induced bone injury (CSBI) of the distal portion of the third metacarpal and third metatarsal bones (MC3/MT3). Methods: Retrospective case series. Methods: 55 Thoroughbred racehorses with CSBI of the distal portion of MC3/MT3. Methods: Data on signalment, history, and radiographic, scintigraphic, and lameness examination findings were reviewed. Horses with lameness localized to the distal portion of MC3/MT3, and that did ...
Patterns of scintigraphic uptake in the fetlock joint of Thoroughbred racehorses and the effect of increased radiopharmaceutical uptake in the distal metacarpal/tarsal condyle on performance. The effect of palmar osteochondral disease lesions on performance of Thoroughbred (TB) racehorses is unclear. There is a need to describe patterns of radiopharmaceutical uptake (IRU) in fetlock joints of TB racehorses and to evaluate post scintigraphy performance. Objective: IRU in the metacarpal (MC) and metatarsal (MT) condyles is more common than IRU in the parasagittal grooves and is associated with poorer post diagnosis performance than controls. Methods: Location of IRU within the fetlock region was identified and graded subjectively in TB racehorses. Performance variables were determine...
In vitro biomechanical comparison of dynamic compression plates with a rough contact surface and a polished contact surface for fixation of osteotomized equine third metacarpal bones. To compare the number of cycles to failure of 4.5 mm broad dynamic compression plates (DCP), 4.5 mm broad limited-contact dynamic compression plates (4.5-LC-DCP), and 5.5 mm broad limited-contact dynamic compression plates (5.5-LC-DCP) having a rough (denoted by a prefix R-) versus a standard smooth contact surface for the fixation of osteotomized equine 3rd metacarpal (MC3) bones. Methods: Experimental. Methods: Fifteen pairs of adult equine cadaveric MC3 bones. Methods: Fifteen pairs of equine MC3 were divided into 3 test groups (5 pairs each) for comparison of (1) R-DCP fixation with DCP fi...
Magnetic resonance anatomy of the carpus of the horse described from images acquired from low-field and high-field magnets. Cadaver carpi of 30 mature horses with no history of carpal or proximal metacarpal pain were examined using low-field (0.27 T) and high-field (1.5 T) magnetic resonance imaging (MRI). Normal MRI anatomy in transverse, sagittal, and dorsal plane images was determined by comparison with anatomical specimens and standard texts. Subchondral bone and cortical bone thickness measurements were obtained from standardised sites. There was variable subchondral bone thickness in the radius and carpal bones; subchondral bone thickness was consistently larger at dorsal compared with palmar sites in the...
Mild exercise early in life produces changes in bone size and strength but not density in proximal phalangeal, third metacarpal and third carpal bones of foals. Exercise or lack of it in early life affects chondro-osseous development. Two groups of horses were used to investigate the effects of age and exercise regimen on bone parameters of diaphyseal, metaphyseal, epiphyseal and cuboidal bones of the distal limb of Thoroughbreds. One group had exercised only spontaneously from an early age at pasture (PASTEX group), while the other group of horses were exposed to a 30% greater workload through additional defined exercise (CONDEX). Longitudinal data from peripheral quantitative computed tomography (pQCT) were obtained from eight scan sites of the left...
The effect of sequence selection and field strength on detection of osteochondral defects in the metacarpophalangeal joint. Six cadaver forelimbs were imaged in two high-field magnetic resonance (MR) systems and one low-field MR system following the creation of osteochondral defects on the palmar distal aspect of the third metacarpal bone. The following sequences were performed using all three systems: proton density (PD) turbo spin echo, T2* gradient echo (GRE), T2-weighted fast spin echo, and short tau inversion recovery. In addition, 3D T1 GRE sagittal standard and motion insensitive sequences were obtained using the low-field system. PD fat saturated and 3D T1-weighted spoiled GRE images with and without fat su...
Analysis of the subchondral microarchitecture of the distopalmar aspect of the third metacarpal bone in racing Thoroughbreds. To determine the anisotropic characteristics of the microarchitecture of the subchondral bone (SCB) plate and trabecular bone (TBB) of the distopalmar aspect of the metacarpal condyles in horses with different stages of SCB disease. Methods: 12 third metacarpal bone pairs from racing Thoroughbreds euthanized for diverse reasons. Methods: Both metacarpi were collected from horses with SCB changes that were mild (sclerosis and focal radiolucencies; n=6) or severe (multifocal radiolucencies and articular surface defects; 6). Sample blocks of SCB plate and TBB were collected from the distopalmar a...
Radiographic features of the dorsal condylar sagittal ridge of the third metacarpal and metatarsal bones in young Warmblood stallions. To describe the radiographic appearance of the dorsoproximal aspect of the sagittal ridge of the third metacarpal/metatarsal bone in Warmblood horses. Methods: The lateromedial radiographic projections of the metacarpo-/metatarsophalangeal joints performed on horses as a part of stallion selection were used. The dorsal aspect of the distal third metacarpal/metatarsal bone was divided in two areas. The appearance of the bone surface in area I was classified as normal, irregular, notch, indentation and lucency. For area II, the categories were normal, irregular, depression or lucency and flatten...
MRI features of metacarpo(tarso)phalangeal region lameness in 40 horses. Lameness originating from the metacarpo(tarso)phalangeal (MP) joint has a significant effect on the use and athletic competitiveness of a horse. The identification of the cause of lameness originating from the MP joint can be challenging, given the limitations of radiography, ultrasonography, and nuclear scintigraphy. Our purpose was to describe the injury types and incidence in magnetic resonance imaging (MRI) studies from 40 horses with lameness attributable to the MP joint region where it was not possible to reach a clinically plausible diagnosis using other imaging modalities. Horses were ...
Distribution of radiodense contrast medium after perineural injection of the palmar and palmar metacarpal nerves (low 4-point nerve block): an in vivo and ex vivo study in horses. Evidence-based information is limited on distribution of local anaesthetic solution following perineural analgesia of the palmar (Pa) and palmar metacarpal (PaM) nerves in the distal aspect of the metacarpal (Mc) region ('low 4-point nerve block'). Objective: To demonstrate the potential distribution of local anaesthetic solution after a low 4-point nerve block using a radiographic contrast model. Methods: A radiodense contrast medium was injected subcutaneously over the medial or the lateral Pa nerve at the junction of the proximal three-quarters and distal quarter of the Mc region (Pa inject...
Assessment of the mineral density and mineral content of the equine third metacarpal and first phalanx bone by dual energy x-ray absorptiometry. In the first part of this methodological study eleven metacarpi of 9 skeletally normal horses were examined from 4 directions by dual energy x-ray absorptiometry (DXA). The differences between the dorsopalmar-palmarodorsal and lateromedial-mediolateral (opposite sites) bone mineral density (BMD) values were found to be nonsignificant. In the second part of the study the precision of the Norland XR-26 densitometer was tested by measuring 34 metacarpal bones and 34 proximal phalanges, each of them three times, from a single direction. The difference between the individual measurements of the fir...
The effect of variable waveform low-intensity pulsed ultrasound in a fourth metacarpal osteotomy gap model in horses. The objective of this study was to evaluate the effects of variable waveform low-intensity ultrasound on the healing of a fracture gap of the fourth metacarpal bone in horses. A randomized, blinded, controlled trial was conducted in eight healthy adult horses. In each horse, a 1-cm osteotomy of the fourth metacarpal bone was created. One randomly selected metacarpal gap was treated daily with a 40-min session of ultrasound and the opposite gap was managed similarly with an inactive transducer. The fourth metacarpal bones were radiographed weekly. Fluorescent markers were administered at 14, 28...
