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.
Janczarek I, Kędzierski W, Tkaczyk E, Kaczmarek B, Łuszczyński J, Mucha K.This study aimed to assess the impact of various types of warm-up on the metacarpal and metatarsal surface temperature in jumping sport horses in comparison to leisure horses, which work usually less intensively. Six clinically healthy sport geldings, contestants in showjumping competitions, and six geldings used for leisure riding were included in the study. The experiment was conducted for four consecutive days, during which the horses were warmed up by walking and trotting for various durations. Images were taken with a FLUKE Ti9 thermal imager to determine the resting, post-effort, and rec...
Grzeskowiak RM, Alghazali KM, Hecht S, Donnell RL, Doherty TJ, Smith CK, Anderson DE, Biris AS, Adair HS.To determine the effect of a novel scaffold, designed for use in bone regeneration, on healing of splint bone segmental defects in mares. Methods: In vivo experimental study. Methods: Five adult mares (4-10 years old; mean weight, 437.7 kg ± 29 kg). Methods: Bilateral 2-cm full-thickness defects were created in the fourth metacarpal bones (MCIV) of each horse. Each defect was randomly assigned to either a novel scaffold treatment (n = 5) or an untreated control (n = 5). The scaffold was composed of polyurethane, hydroxyapatite, and decellularized bone particles. Bone healing was...
Paris A, Beccati F, Pepe M.To report the type, prevalence, and risk factors for the development of orthopedic injuries in endurance horses. Methods: 235 endurance horses. Methods: Medical records of horses examined between January 2007 and December 2018 were reviewed. Recorded data were birth; breed; sex; dates of first and last examinations; presence of any conformation fault, lameness, positive flexion test result, and orthopedic injury; starts in endurance competitions; level of athletic activity; professional status of trainer or rider; and whether an orthopedic injury developed in > 1 limb or during or within 2 day...
Shaffer SK, Sachs N, Garcia TC, Fyhrie DP, Stover SM.To assess the motion of the proximal sesamoid bones (PSBs) relative to the third metacarpal bone (MC3) of equine forelimbs during physiologic midstance loads. Methods: 8 musculoskeletally normal forelimbs (7 right and 1 left) from 8 adult equine cadavers. Methods: Each forelimb was harvested at the mid-radius level and mounted in a material testing system so the hoof could be moved in a dorsal direction while the radius and MC3 remained vertical. The PSBs were instrumented with 2 linear variable differential transformers to record movement between the 2 bones. The limb was sequentially loaded ...
Shan R, Johnston AS, Rosanowski SM, O'Shea J, Riggs CM.Transverse stress fracture of the palmar cortex of the distal aspect of the third metacarpal bone (TSF PCD McIII) is poorly documented. Objective: To describe the typical signalment of this injury, the common clinical and radiological signs and prognosis. Methods: A retrospective hospital-based case series with follow-up of racing records. Methods: All cases of TSF PCD McIII diagnosed among racehorses in training at the Hong Kong Jockey Club between 2011 and 2019 were identified. Clinical records were reviewed and documented signs were recorded for each case. Findings from a predefined list of...
Johnston GCA, Ahern BJ, Woldeyohannes SM, Young AC.Equine advanced imaging research involving racehorse fetlock pathology commonly uses cadaver limbs and a freeze-thaw process. The presence of short tau inversion recovery (STIR) signal intensity in the distal third metacarpal/metatarsal bone is of particular interest and may be clinically relevant in the diagnosis of horses at risk of fracture. However, little is known about the effect of the freeze-thaw process on the MRI appearance of STIR hyperintensity in these bones. This study compares the low-field MRI appearance of the distal third metacarpal/metatarsal bone from cadaver limbs of Thoro...
Ravanetti P, Hamon M, Lechartier A, Zucca E.Surgical repair of unicortical fractures of the distal condyles of the third metacarpal/metatarsal bones (MCIII/MTIII) has been described. In the present case, a bioabsorbable screw was used to stabilize a unicortical fracture in the palmar aspect of the medial condyle of MCIII in a National Hunt Thoroughbred racehorse. The clinical, radiographic, and magnetic resonance imaging findings before and after surgery were recorded. Eighteen weeks after surgery, the lameness had resolved and the bone surrounding the fracture had recovered its normal architecture. One year after surgery, the horse was...
Lection J, Delvescovo B, Percival A, Wu T, Southard T, Diel de Amorim M, Cheong SH.In utero fracture and malunion of long bones is a rare condition in horses. Most foals with in utero fractures are aborted, and the identification of a fetal in utero fracture in a mare with dystocia has not been reported. A 7-year-old multiparous Standardbred mare presented to a referral center for correction of dystocia. Assisted vaginal delivery and controlled vaginal delivery attempts were unsuccessful mainly because of contracted tendons impeding mutation. As the foal was alive, a cesarean section was elected. The foal was delivered but ultimately euthanized because of the congenital abno...
Crawford KL, Finnane A, Greer RM, Phillips CJC, Woldeyohannes SM, Perkins NR, Ahern BJ.Musculoskeletal injuries (MSI) remain a concerning cause of racehorse morbidity and mortality with important ethical and welfare consequences. Previous research examining risk factors for MSI report inconsistent findings. Age is thought to affect MSI risk, but, to date, there have been no prospective studies comparing MSI in two-year-old versus older horses. This study aimed to: (1) determine the incidence of MSI for two-year-old and older horses, and whether this was affected by training track, season, or rainfall, and (2) determine the types of MSI affecting two-year-old and older horses, an...
Murray RC, Tranquille CA, Walker VA, Milmine RC, Bak L, Tacey JB, Bolas NM.Standing magnetic resonance (MR) images of proximal metacarpal/metatarsal regions are increasingly being acquired. This study aimed at describing ranges of abnormalities detected in sport/racehorses, using retrospective evaluation of magnetic resonance imaging (MRI) reports from horses with lameness isolated to proximal metacarpal/metatarsal regions with images acquired standing. It was hypothesized that MRI features are different between metacarpal and metatarsal regions and between horses doing different sports. Reports from 359 forelimbs and 64 hindlimbs were included. Palmar/plantar metaca...
Goldstein DM, Engiles JB, Rezabek GB, Ruff CB.The elongated, distally tapered limbs of horses are adapted for high-speed locomotion. Because these traits are artificially selected for in modern racehorses, they operate at a morphological extreme with a high risk of fracture. Racehorses are subject to different training and racing regimes depending on their breed and gait, and are therefore an interesting model to examine bone functional adaptation under variable biomechanically intense conditions. This study compares bone structural properties in the third metacarpal (MCIII) of Thoroughbred (n = 9) and Quarter Horse (n = 11) racehorses, u...
Donati B, Fürst AE, Del Chicca F, Jackson MA. The aim of this study was to determine the indications for, and complications of, plate removal surgery in horses that underwent internal fixation of limb fractures. Methods: Medical records of horses presented to our hospital between 1990 and 2015 for the removal of plates after treatment of limb fractures were reviewed. Data collected at the time of initial presentation, including signalment, history, fracture features and treatment and information about the indications, timing and complications of implant removal were reviewed. Results: The most common bones involved were the ulna ...
Dubois BB, Rodgerson DH.To describe a drilling technique for hemiepiphysiodesis of the distal lateral metacarpal physis and report the outcome of treated foals. Methods: Retrospective case series. Methods: Eleven thoroughbred foals. Methods: While horses were under general anesthesia, the lateral aspect of the distal metacarpal physis was approached through a single small incision by using a power drill. The drill bit was placed at the level of the physis under radiographic guidance. A 4.5-mm drill bit was passed several times through the lateral growth plate to remove the cartilage in a fan-like pattern. Postoperati...
Boorman S, Richardson DW, Hogan PM, Stefanovski D, Levine DG.To report the performance of thoroughbred racehorses after surgical repair of a medial condylar fracture of the third metacarpal/metatarsal bone. Methods: Retrospective cohort study. Methods: Forty-three horses surgically treated for medial condylar fractures, 30 with previous racing experience, 13 without previous racing experience (nonexperienced). Methods: Medical records (2009-2017) were reviewed for signalment, radiographic fracture characteristics, repair technique, and postoperative morbidity and mortality. Each experienced horse was matched with two horses randomly selected from its mo...
Gilday R, Richard H, Beauchamp G, Fogarty U, Laverty S.The administration of bisphosphonate medications, which target osteoclastic-bone remodelling, to juvenile and adult racehorses is a matter of debate owing to concerns that these molecules remain bound to the bone-mineralised matrix and may interfere with subsequent bone growth, adaptation to exercise and healing of bone microdamage in equine athletes. Osteoclasts participate in endochondral ossification, subchondral bone remodelling and bone repair. There is a knowledge gap on the role of equine osteoclast biology in the growth and maturation of joint surfaces and this information is important...
Mundy LN, Lescun TB, Main RP, Hall Griffin T.To compare heat generation and mechanical bone damage achieved with 2 tapered and 1 cylindrical transfixation pin taps in third metacarpal bones from equine cadavers. Methods: 18 pairs (36 specimens) of third metacarpal bones from euthanized horses with no known metacarpal disease. Methods: In each bone, an investigator drilled 3 holes for placement of a 6.3-mm cylindrical transfixation pin, a 6.3-mm tapered pin using a prototype tapered tap, and a 6.3-mm tapered pin using a revised tapered tap. One bone of each pair was tapped by hand and the other with an electric drill. Temperatures of the ...
Ülke ÇG, Deniz SI, Nureddin Ç.Metacarpal tendon diseases are important problems that may cause a decrease in performance and even may finish sport life in equine athletes. In this study, it was aimed to evaluate the ratio of return to races and the time of staying away from races and also to detect the prognostic value of ultrasonographic findings in Thoroughbred and Arabian racehorses with metacarpal flexor tendon injury or peritendonitis. Of 120 cases, 84 (70.0%) returned to races. Among these, 82.1% had tendonitis (69/84) and 17.9% peritendonitis (15/84). Among the cases being unable to return to races, 91.7% had tendon...
Journal of biomechanicsDecember 24, 2019
Volume 100 109594 doi: 10.1016/j.jbiomech.2019.109594
Malekipour F, Hitchens PL, Whitton RC, Lee PV.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-dest...
Lescun TB, Adams SB, Main RP, Nauman EA, Breur GJ. The objectives of this study were to validate a finite element model of the equine distal limb transfixation cast and to determine the effect of six transcortical pin parameters on bone-pin interface (BPI) stresses in the third metacarpal bone. Methods: A transfixation cast finite element model was developed from a computed tomography scan of the third metacarpal bone and modelled pin elements. The model was validated by comparing strain measured around a 6.3-mm transfixation pin in the third metacarpal bone with the finite element model. The pin parameters of diameter, number, location,...
Labens R, Schramme MC, Murray RC, Bolas N.High-field MRI of the proximal metacarpal/metatarsal region has been associated with great diagnostic potential and clinical reports of standing low-field MRI of the forelimb suggest the same. To better understand diagnostic outcomes with standing low-field MRI of the proximal suspensory region, a prospective survey study was conducted and users of a widely available system questioned on their experience, operating procedures, and interpretation of standing low-field MRI findings. Response data included scores on a modified Likert scale from which weighted ratings were calculated for statistic...
Mouloodi S, Rahmanpanah H, Burvill C, Davies HMS.The hierarchical nature of bone makes it a difficult material to fully comprehend. The equine third metacarpal (MC3) bone experiences nonuniform surface strains, which are a measure of displacement induced by loads. This paper investigates the use of an artificial neural network expert system to quantify MC3 bone loading. Previous studies focused on determining the response of bone using load, bone geometry, mechanical properties, and constraints as input parameters. This is referred to as a forward problem and is generally solved using numerical techniques such as finite element analysis (FEA...
Shaktivesh , Malekipour F, Whitton C, Lee PVS.Standard fatigue testing of bone uses a single load and frequency applied until failure. However, in situ, the subchondral bone of Thoroughbred racehorses is subjected to a combination (or a spectrum) of loads and frequencies during training and racing. Objective: To investigate the use of a fatigue testing method for equine third metacarpal (McIII) subchondral bone under a spectrum of loading conditions which a racehorse is likely to experience during a fast workout. Methods: In vitro biomechanical experimental study. Methods: McIII subchondral bone specimens (n = 12) of racehorses were ha...
James OA, Elce Y, Cillán-Garcia E, Reardon RJM. The aim of this study was to determine whether a clamped drill guide can be used effectively to drill across equine distal third metacarpals and metatarsals and to compare accuracy and speed of a drilling with a hand-held drill guide. Methods: Eighty equine cadaver limbs were divided between four surgeons with varying experience. The limbs were randomly allocated to clamped or hand-held drill guides and placed in a stand in an upright/standing position on a metal table. Drilling times from cis- to trans cortices were measured. Post-drilling computed tomography images were used to assess ...
Barrett E, Arkins S.Few studies are available concerning prevalences of abnormalities in the Thoroughbred horse population. Objective: Determine the prevalence of commonly observed abnormalities in a National Hunt Thoroughbred population using results of pre-purchase examinations conducted at Thoroughbred sales venues. Methods: Retrospective cross-sectional study. Methods: Veterinary pre-purchase examination certificates for 13,603 3- and 4-year-old Thoroughbred National Hunt horses from Tattersalls Ireland, Goffs Ireland and Doncaster Bloodstock Sales Ltd. (DBS) Sales were analysed. All conditions noted by the v...
Fradinho MJ, Mateus L, Bernardes N, Bessa RJB, Caldeira RM, Ferreira-Dias G.Development of a healthy musculoskeletal system is of high concern for horse breeders and users. A longitudinal field study was performed in order to: (i) evaluate growth patterns and long-term changes on bone quality, bone metabolism, growth factors and metabolic variables in the Lusitano horse; and (ii) retrospectively assess whether these changes were related with radiographic findings regarding osteochondrosis-like lesions (OC) at the onset of training. Thirty-four Lusitano foals born and raised at four stud-farms, were periodically weighed (BW), and measured (withers height-WH) from birth...
Mouloodi S, Rahmanpanah H, Burvill C, Davies HMS.Shape is a key factor in influencing mechanical responses of bones. Considered to be smart viscoelastic and inhomogeneous materials, bones are stimulated to change shape (model and remodel) when they experience changes in the compressive strain distribution. Using reverse engineering techniques via computer-aided design (CAD) is crucial to create a virtual environment to investigate the significance of shape in biomechanical engineering. Nonetheless, data are lacking to quantify the accuracy of generated models and to address errors in finite element analysis (FEA). In the present study, rever...
Tirosh-Levy S, Perl S, Valentine BA, Kelmer G.Hepatoblastoma was diagnosed in a 3-year-old Thoroughbred gelding presented with forelimb lameness with bilateral fatigue fractures of the proximal third metacarpal bones. An abdominal mass was detected on ultrasound examination of the abdomen. Absolute erythrocytosis was diagnosed after clinical and haematological evaluation. The fractured metacarpal bones were surgically removed but complications after surgery were fatal. The liver mass was diagnosed as a hepatoblastoma based on histology and immunochemical staining. The combination of hepatoblastoma and fatigue fractures has not been descri...
Walmsley EA, Jackson M, Wells-Smith L, Whitton RC.Subchondral bone injury at the palmar/plantar aspect of the condyles of the third metacarpal/metatarsal bone (MC/MT3) commonly causes lameness and poor performance in racehorses. Injury occurs due to repetitive loading, the magnitude of which may be influenced by the position of the distal phalanx relative to the ground surface, i.e. the solar angle. The association of solar angle and injury at the palmar/plantar condyles of distal MC/MT3 therefore warrants investigation. Objective: Investigate the relationship between solar angle and radiopharmaceutical uptake at the palmar/plantar aspect of ...
Keller SA, Valet S, Martens A, Weisse B, Fürst AE, Kümmerle JM. The aim of this study was to evaluate cyclic fatigue behaviour of a new pin with a thread run-out design in comparison with three other types of pins commonly used for equine transfixation pin casting. Methods: Twenty-four pairs of equine cadaveric third metacarpal bones (MC3) equipped with one transfixation pin placed horizontally in the distal metaphysis were tested using a simplified model, mimicking the biomechanical situation of equine transfixation pin casting. A 6.3/8.0-mm Imex Duraface pin with thread run-out design (ITROP) was compared with a 6.1-mm smooth Steinmann pin (SSP), a...
Tozaki T, Miyake T, Kikuchi M, Kakoi H, Hirota KI, Kusano K, Ishikawa Y, Nomura M, Kushiro A, Nagata SI.Thoroughbred racehorses are produced by mating small numbers of Arabian stallions and native British mares, and have been improved by selection of horseracing performance for about 300 years. While these improvements led to good performance as racehorses, they exposed horses to numerous medical disorders, aggravated by extensive exercise. Fractures are frequent medical disorders in Thoroughbred racehorses. In this study, fracture heritability was estimated using 3,927 Japanese Thoroughbred racehorses to elucidate the risk of racehorse fractures. The heritability estimates of all examined frac...
O'Brien T, Baker TA, Brounts SH, Sample SJ, Markel MD, Scollay MC, Marquis P, Muir P.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...
Doube M, Firth EC, Boyde A.To interrelate articular calcified cartilage thickness, mineralisation density, tidemark count and tidemark linear accretion rate by site in the equine third metacarpal distal condyle. To determine the effects of exercise during early life on articular calcified cartilage. Methods: Six of 12 pasture-raised Thoroughbred horses were exercised from 10 days old. Calcein labels were given 19 and 8 days prior to euthanasia at 18 months old. Osteochondral specimens were cut from the distal third metacarpal condyle and imaged using confocal scanning light microscopy (CSLM) and quantitative backscatter...
Firth EC, Rogers CW, van Weeren PR, Barneveld A, McIlwraith CW, Kawcak CE, Goodship AE, Smith RK.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...
Ahern BJ, Richardson DW, Boston RC, Schaer TP.To determine the rate of postoperative infection (POI) for internal fixation repaired equine long bone fractures and arthrodeses and identify associated risk factors. Methods: Case series. Methods: Horses (n=192) with fracture repair of the third metacarpal and metatarsal bones, radius, ulna, humerus, tibia, and femur, or arthrodesis with internal fixation. Methods: Medical records (1990-2006) were reviewed for signalment, anatomic location, fracture classification and method of repair, technique and surgical duration, bacterial species isolated, postoperative care, onset of POI, and outcome. ...
Boyde A, Firth EC.The aim was to survey articular calcified cartilage (ACC) and subchondral bone in the palmar and dorsal regions of the condyles of the third metacarpal bone (Mc3) of young horses with minimal or no signs of musculo-skeletal abnormality. Back-scattered electron scanning electron microscopy (BSE SEM) was conducted on polymethyl methacrylate-embedded mediolateral slices and macerated wedges of the right distal Mc3 from seven each of trained and untrained 2-year-old Thoroughbred horses. Furrows or grooves visible to the naked eye in the mineralizing front (MF) of ACC are the commonest "lesion" and...
McCarthy RN, Jeffcott LB.The effects of exercise and relative inactivity on cortical bone were compared in young horses. Two groups were used; one was given a 14-week programme of exercise (n = 6) and the other kept as unexercised controls (n = 6). The first nine weeks of exercise involved trotting and cantering (2 to 4 km d-1 at speeds up to 12 m s-1) on a treadmill set at an incline of 3 degrees. Over the next five weeks the horses were trained at near maximal speeds (that is, up to 14.5 m s-1) with no incline of the treadmill. At the end of the programme marked differences in cortical porosity and distribution of s...
Malik CL, Stover SM, Martin RB, Gibeling JC.Previous studies of the fracture properties of cortical bone have suggested that the fracture toughness increases with crack length, which is indicative of rising R-curve behavior. Based on this indirect evidence and the similarity of bone to ceramic matrix composites, we hypothesized that bone would exhibit rising R-curve behavior in the transverse orientation and that the characteristics of the R-curves would be regionally dependent within the cortex due to variations in bone microstructure and toughening mechanisms. To test these hypotheses, we conducted R-curve experiments on specimens fro...
Verheyen KL, Henley WE, Price JS, Wood JL.Dorsometacarpal disease (DMD) is common in young Thoroughbred (TB) racehorses, often interfering with their training programme. No reports exist on incidence rate or associated risk factors in the UK. Objective: To estimate the incidence rate of DMD in TB horses in training for flat racing in the UK and identify associated risk factors, particularly in relation to training regimens. Methods: Data were drawn from a large prospective study in which TB horses in 13 training yards were monitored for a period of up to 2 years, recording daily training information and details of musculoskeletal inju...
Gonzalez LM, Schramme MC, Robertson ID, Thrall DE, Redding RW.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 ...
Gross TS, McLeod KJ, Rubin CT.Three triple-element rosette strain gages were attached to the equine third metacarpal midshaft to record site-specific strains engendered by locomotion. The distribution of strains acting upon the midshaft cross section were characterized using a combined beam theory and finite element model analysis that did not presume the manner by which the bone was inertially loaded. A medium-speed trot (3.6 ms-1) was chosen as a representative speed and gait, with normal and shear strains, and strain energy density (SED) distributions determined throughout the stance and subsequent swing phase. Importan...
Fretz PB, Cymbaluk NF, Pharr JW.Long-bone growth at the distal ends of the radial bones, the distal ends of the 3rd metacarpal bones, the distal ends of the 3rd metatarsal bones, and the proximal ends of the proximal phalangeal bones (of thoracic and pelvic limbs) was quantitatively analyzed in 9 Thoroughbred-Quarter Horse foals from birth to 2 years of age. Metal growth markers were surgically implanted in the bones of the animals at 2 to 4 days of age. Radiographs of the bones were made on the day of surgical manipulation, the next day, and then once a week for 8 months, and once a month thereafter for an additional 18 mon...
Da Costa Gómez TM, Barrett JG, Sample SJ, Radtke CL, Kalscheur VL, Lu Y, Markel MD, Santschi EM, Scollay MC, Muir P.Functional adaptation of bone normally protects the skeleton from fracture during daily activity. Accumulation of microcracking and loss of osteocytes have been implicated in the regulation and initiation of targeted (reparative) remodeling of bone and, in certain situations, the development of fatigue or stress fracture. We performed a histologic study of the dorsal cortex of the mid-diaphysis of the third metacarpal (Mc-III) bone of Thoroughbred racehorses after bones were bulk-stained in basic fuchsin and transverse calcified sections were prepared. The Thoroughbred racehorse is an extreme ...
Crawford KL, Finnane A, Greer RM, Phillips CJC, Woldeyohannes SM, Perkins NR, Ahern BJ.Musculoskeletal injuries (MSI) remain a concerning cause of racehorse morbidity and mortality with important ethical and welfare consequences. Previous research examining risk factors for MSI report inconsistent findings. Age is thought to affect MSI risk, but, to date, there have been no prospective studies comparing MSI in two-year-old versus older horses. This study aimed to: (1) determine the incidence of MSI for two-year-old and older horses, and whether this was affected by training track, season, or rainfall, and (2) determine the types of MSI affecting two-year-old and older horses, an...
Watanabe T, Hosaka Y, Yamamoto E, Ueda H, Sugawara K, Takahashi H, Takehana K.The distribution pattern of collagen fibril diameter in the equine superficial digital flexor tendon (SDFT) is known to differ in central and peripheral areas of some regions. This study reports the essence of collagen fibril differences among different regions of the equine SDFT by transmission electron microscopic (TEM) and high-voltage electron microscopic observations and biochemical analysis. The distribution of large collagen fibrils increased but the density of collagen fibrils decreased from the proximal metacarpal region to the distal metacarpal region. Large collagen fibrils with an ...
Birch HL, Smith TJ, Poulton C, Peiffer D, Goodship AE.Partial rupture occurs most often to the superficial digital flexor tendon (SDFT) of the forelimb at the mid-metacarpal level. In this study, we tested the hypothesis that the mid-metacarpal region of the SDFT has the smallest cross sectional area (CSA) and a similar collagen content to other regions and, therefore, represents a weak point in the tendon. The SDFT was collected from the forelimbs of 9 horses. Each tendon was marked at 7 different levels from the origin of the accessory ligament to the phalangeal region. The CSA, water content and collagen content was measured at each level. The...
Rubio-Martínez LM, Cruz AM, Gordon K, Hurtig MB.To characterize the mechanical properties of subchondral bone (SCB) of the distopalmar aspect of the condyles of the third metacarpal bone (MC3) and their correlations with structural aspects of MC3s in Thoroughbred racehorses. Methods: 12 pairs of MC3s from Thoroughbred racehorses euthanized for various reasons. Methods: MC3s were collected from horses with mild (n = 6) and with severe (6) SCB changes, as determined by micro-computed tomography (CT). Specimens of SCB plate and trabecular bone were cut from the distopalmar aspect of condyles and sagittal ridge and examined with 3-dimensional m...
Turner AS, Mills EJ, Gabel AA.Strain gauges were successfully bonded in vivo to the cranial, caudal, medial, and lateral aspects of the equine radium and tibia and to the dorsal, palmar, or plantar, medial, the lateral aspects of the metacarpus and metatarsus--all in the mid-diaphyseal region. Various activities were investigated, including walking, trotting or pacing, and standing up from anesthesia. The strain patterns showed that each stride produced a characteristic deformation cycle. The strains were measured and the axial loads were calculated as the horse performed certain activities. The tension band side of each b...
Reilly GC, Currey JD, Goodship AE.Exercise can have a profound effect on bone mass, but little is known of its effect on bone's material properties. In this experiment, our hypothesis was that a large difference in the training regimen of young thoroughbreds would produce a measurable difference in the mechanical properties of their bone material. When they were about 19 months old, eight thoroughbred racehorses were given one of two exercise regimens that lasted for 19 weeks: four horses (controls) were walked for 40 minutes a day but had no other exercise, and the remaining four (exercised) were additionally trotted for 20 m...
Henson FM, Getgood AM, Caborn DM, McIlwraith CW, Rushton N.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...
Westermann S, Buchner HH, Schramel JP, Tichy A, Stanek C.To assess effects of camera angle and distance on measurement and reproducibility of thermographically determined temperatures of the distolateral aspect of the forelimbs in horses. Methods: Evaluation study. Methods: 10 adult horses. Methods: Thermographic images of both forelimbs were obtained at 3 times during the day (replicates 1, 2, and 3); maximum surface temperature over 1 region (distolateral aspect of the third metacarpal bone and metacarpophalangeal joint) was measured. Standard images were obtained every 5 minutes for 1 hour with the camera positioned at an angle of 90° and a dist...
Stepnik MW, Radtke CL, Scollay MC, Oshel PE, Albrecht RM, Santschi EM, Markel MD, Muir P.To examine the fracture failure surfaces from Thoroughbred horses that had sustained a catastrophic condylar fracture. Methods: Bone specimens from the failure surface were obtained from 12 Thoroughbred racehorses with catastrophic injury and 2 non-racing horses with accidental long bone fracture. Methods: Bone specimens from the failure surface of each fracture were incubated with gold microspheres to label microcracks before examination at x50 to x60,000 using scanning electron microscopy. Microcracking at the failure surface was assessed using a visual analog scale. Results: Branching array...
Loughridge AB, Hess AM, Parkin TD, Kawcak CE.Changes in subchondral bone density, induced by the repetitive cyclical loading of exercise, may potentiate fatigue damage and the risk of fracture. Objective: To use computed tomography (CT) to characterise bone density patterns at the articular surface of the third metacarpal bone in racehorses with and without lateral condylar fractures. Methods: Case control METHODS: Computed tomographic images of the distal articulating surface of the third metacarpal bone were obtained from Thoroughbred racehorses subjected to euthanasia in the UK. Third metacarpal bones were divided into 3 groups based ...
Byron CR, Benson BM, Stewart AA, Stewart MC.To investigate in vitro effects of radial shock waves on membrane permeability, viability, and structure of chondrocytes and articular cartilage. Methods: Cartilage explants obtained from the third metacarpal and metatarsal bones of 6 horses. Methods: Equine cartilage was subjected to radial shock waves and then maintained as explants in culture for 48 hours. Treatment groups consisted of a negative control group; application of 500, 2,000, and 4,000 impulses by use of a convex handpiece (group A); and application of 500, 2,000, and 4,000 impulses by use of a concave handpiece (group B). Effec...
Roepstorff L, Wiestner T, Weishaupt MA, Egenvall E.The aim of this study was to compare an inertial motion system (IMS) to an optical based locomotion analysis system measuring limb sagittal segment angles in horses at the walk and trot. The metatarsal/metacarpal bones of two horses (20 trials) were fitted with optical system markers and an IMS. Between the systems, measuring range of motion (ROM) of the sagittal metatarsal/metacarpal bone angles, the IMS measured higher ROM than the optical system (bias 1.6°; precision at 1.96 standard deviation 1.9°). The same angle data were used to assess inter-limb symmetry by calculating phase shift be...
Peloso JG, Cohen ND, Vogler JB, Marquis PA, Hilt L.OBJECTIVE To compare bony changes of the third metacarpal bone (MC3) of Thoroughbred racehorse cadavers with (cases) or without (controls) catastrophic condylar fracture by use of standing MRI. SAMPLE 140 forelimbs from 26 case horses (both forelimbs) and 88 control horses (single forelimb). PROCEDURES Bone marrow lesions (BMLs), identified as a decrease in T1-weighted (T1W) signal and increases in T2*-weighted (T2*W) and short tau inversion recovery (STIR) signals, and dense bone volume percentage (DBVP), identified as decreases in T1W, T2*W, and STIR signals, in the distopalmar aspect of MC3...
Tsuzuki N, Otsuka K, Seo J, Yamada K, Haneda S, Furuoka H, Tabata Y, Sasaki N.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...
Martig S, Hitchens PL, Stevenson MA, Whitton RC.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 thorough...
Martin RB, Gibson VA, Stover SM, Gibeling JC, Griffin LV.In studying the flexural fatigue properties of the equine third metacarpal (cannon) bone, we previously found that the dorsal region was weaker monotonically, but more fatigue resistant, than the lateral region. Fatigue resistance was associated with fracture surfaces which demonstrated that secondary osteons had "pulled out" of the surrounding matrix; this never happened in lateral specimens. We therefore became interested in the osteonal structure of this bone, and began to study its birefringence patterns in circularly polarized light. We found that the predominant type of secondary osteon ...
Labens R, Schramme MC, Murray RC, Bolas N.High-field MRI of the proximal metacarpal/metatarsal region has been associated with great diagnostic potential and clinical reports of standing low-field MRI of the forelimb suggest the same. To better understand diagnostic outcomes with standing low-field MRI of the proximal suspensory region, a prospective survey study was conducted and users of a widely available system questioned on their experience, operating procedures, and interpretation of standing low-field MRI findings. Response data included scores on a modified Likert scale from which weighted ratings were calculated for statistic...
McCarty CA, Thomason JJ, Gordon KD, Burkhart TA, Milner JS, Holdsworth DW.To assess whether the transient stresses of foot impact with the ground are similar to those found during midstance loading and if the location of high stress correlate with the sites most commonly associated with mechanically induced osteoarthritis (OA). We compared impact stresses in subchondral bone between two subject-specific, three-dimensional, finite-element models of the equine metacarpophalangeal (MCP) joint-one with advanced OA and one healthy, and with similar published data on the stresses that occur at midstance. Methods: Two right MCP joints (third metacarpal and proximal phalanx...
