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.
In vitro comparison of metaphyseal and diaphyseal placement of centrally threaded, positive-profile transfixation pins in the equine third metacarpal bone. To evaluate in vitro holding power and associated microstructural and thermal damage from placement of positive-profile transfixation pins in the diaphysis and metaphysis of the equine third metacarpal bone. Methods: Third metacarpal bones from 30 pairs of adult equine cadavers. Methods: Centrally threaded positive-profile transfixation pins were placed in the diaphysis of 1 metacarpal bone and the metaphysis of the opposite metacarpal bone of 15 pairs of bones. Tensile force at failure for axial extraction was measured with a materials testing system. An additional 15 pairs of metacarpal bone...
In vitro comparison of the use of two large-animal, centrally threaded, positive-profile transfixation pin designs in the equine third metacarpal bone. To compare the in vitro holding power and associated microstructural damage of 2 large-animal centrally threaded positive-profile transfixation pins in the diaphysis of the equine third metacarpal bone. Methods: 25 pairs of adult equine cadaver metacarpal bones. Methods: Centrally threaded positive-profile transfixation pins of 2 different designs (ie, self-drilling, self-tapping [SDST] vs nonself-drilling, nonself-tapping [NDNT] transfixation pins) were inserted into the middiaphysis of adult equine metacarpal bones. Temperature of the hardware was measured during each step of insertion with ...
Influence of exercise on bone mineral density of immature cortical and trabecular bone of the equine metacarpus and proximal sesamoid bone. Bone mineral density (BMD) and cross-sectional area (CSA), measured using peripheral quantitative computed tomography, were determined in the left third metacarpal bone (MCIII) and left medial proximal sesamoid bone (psb) in 3 differently exercised groups of foals. Group(box) (n = 14) was confined to a box stall from birth to age 5 months, Group(training) (n = 14) was kept in similar box stalls but additionally given a daily exercise programme consisting of an increasing number of gallop sprints and Group(pasture) (n = 15) remained at pasture. At 5 months of age, 8 foals from each group were r...
Gait and speed as exercise components of risk factors associated with onset of fatigue injury of the third metacarpal bone in 2-year-old Thoroughbred racehorses. To determine the degree to which components of the training program of 2-year-old Thoroughbred racehorses influence their susceptibility to fatigue injury of the third metacarpal bone (bucked shins). Methods: 226 two-year-old Thoroughbred racehorses. Methods: Daily training information and health reports on 2-year-old Thoroughbreds were compiled from records provided from 5 commercial stables. For each horse, data (exercise variables) were collected that comprised distance jogged (approx speed of 5 m/s), galloped (approx 11 m/s), and breezed (approx 15 to 16 m/s) until a single instance of buc...
Influence of interleukin-1beta and hyaluronan on proteoglycan release from equine navicular hyaline cartilage and fibrocartilage. Proteoglycan (PG) release, in response to recombinant human interleukin-1beta (rh-IL-1beta), was measured in cartilage explants obtained from the equine distal sesamoid bone (navicular bone). Fibrocartilage from the surface of the navicular bone apposing the deep digital flexor tendon and hyaline cartilage from the surface of the navicular bone articulating with the middle phalanx were labelled with 35SO4. Hyaline cartilage from the distal metacarpus was used as a control tissue. Following radiolabel incorporation, the three cartilage types were treated with rh-IL-1beta (100 U/mL) in the prese...
Pythiosis with bone lesions in a pregnant mare. A 9-year-old pregnant mare was referred for evaluation of a nonhealing wound of 8 weeks' duration on the lateral aspect of the left forelimb. A soft tissue mass encircled the proximal two thirds of the metacarpus; radiography revealed a moderate periosteal reaction affecting metacarpal bone i.v. Histologic and immunohistochemical examinations revealed eosinophilic granulomatous inflammation and Pythium sp in the soft tissues. The mare was treated for 12 days with antimicrobials, medicated wound dressings, debridement, and i.v. administration of sodium iodide; radiography revealed progression o...
Postexercise and positional variation in mechanical properties of the radius in young horses. The metacarpal of the horse is severely loaded during vigorous exercise. Metacarpal specimens have a greater impact strength in young horses that have been exercised than in those that have only been walked. We did not find a corresponding difference in the radius of the same horses. We show that cranial (anterior) cortical bone from the radius, which is loaded in tension during locomotion, has a greater Young's modulus, and tensile and bending strength, than bone from the caudal (posterior) cortex, which is loaded in compression. Caudal bone is, however, stronger in compression. The differenc...
Topographical mapping of biochemical properties of articular cartilage in the equine fetlock joint. The aim of this study was to evaluate topographical differences in the biochemical composition of the extracellular matrix of articular cartilage of the normal equine fetlock joint. Water content, DNA content, glycosaminoglycan (GAG) content and a number of characteristics of the collagen network (total collagen content, levels of hydroxylysine- (Hyl) and the crosslink hydroxylysylpyridinoline, (HP) of articular cartilage in the proximal 1st phalanx (P1), distal 3rd metacarpal bone (MC), and proximal sesamoid bones (PSB) were determined in the left and right fetlock joint of 6 mature horses (a...
Effect of exercise on bone density in distal regions of the equine third metacarpal bone in 2-year-old thoroughbreds. The present study addressed the question of whether training induces changes in bone density in the younger racehorse in regions relevant to the genesis of the common sagittal condylar fracture pattern and, if so, the nature of such alteration. Third metacarpal bones (McIII) were obtained from 12 experimental Thoroughbred, unbroken fillies, age 18.1-21.0 months at entry to the study. Six (Group E) undertook 19 weeks of progressive high intensity exercise on a high-speed treadmill at 3% incline. Six (Group C) walked 40 min each day. Clinical bone density was studied by Computed Tomography (CT) ...
In vitro transmission and attenuation of impact vibrations in the distal forelimb. An in vitro model was developed and validated in vivo to quantify the attenuation of impact vibrations, transmitted through the lower equine forelimb and to assess the effects of horseshoeing on this attenuation. The transsected forelimbs of 13 horses were equipped with custom-made hollow bone screws in the 4 distal bones, on each of which a tri-axial accelerometer could be mounted. The limbs were then preloaded while the impact was simulated by dropping a weight on the steel plate on which the hoof was resting. At the hoof wall, the distal, middle and proximal phalanx and at the metacarpal bo...
Radiographic measures of bone shape in young thoroughbreds during training for racing. The aim of this study was to determine if changes in the shape of the third metacarpal bone (MC3) during the first preparation for racing in young Thoroughbred racehorses could be measured radiographically. Lateral radiographs of each MC3 were taken when the horses commenced training, every 2 weeks for 10 weeks, and again at 6 months after the start of training. The width of the dorsal cortex (DC), palmar cortex (PC), and medulla (M) were measured at a position 2.5 cm distal to the nutrient foramen before the subject of each radiograph was identified. The following ratios were calculated: z = ...
Results of bone scintigraphy in racing standardbred horses: 64 cases (1992-1994). To document anatomic patterns of scintigraphic uptake and related orthopedic disease associated with racing activity in Standardbred horses. Methods: Retrospective study. Methods: 64 Standardbred horses evaluated for lameness. Methods: Medical records at the time of discharge were reviewed, and information regarding signalment; history; results of lameness examination, scintigraphy, and radiography; diagnosis; and treatment were obtained. Results: 274 areas of increased radiopharmaceutical uptake were identified. Scintigrams of 218 limbs (106 forelimbs, 112 hind limbs) were available for revie...
An in vitro biomechanical comparison of an interlocking nail system and dynamic compression plate fixation of ostectomized equine third metacarpal bones. To compare the mechanical properties of two stabilization methods for ostectomized equine third metacarpi (MC3): (1) an interlocking nail system and (2) two dynamic compression plates. Animal or Sample Population-Ten pairs of adult equine forelimbs intact from the midradius distally. Methods: Ten pairs of equine MC3 were divided into two test groups (five pairs each): caudocranial four-point bending and torsion. Interlocking nails (6 hole, 13-mm diameter, 230-mm length) were placed in one randomly selected bone from each pair. Two dynamic compression plates one dorsally (12 hole, 4.5-mm broad)...
Results of treatment of 145 fractures of the third metacarpal/metatarsal condyles in 135 horses (1986-1994). The objectives of this study were to correlate condylar fracture characteristics and type of treatment with subsequent capacity for athletic ability, and to determine the characteristics of healing that affect prognosis after fracture fixation. Medical records, post operative radiographic studies and race records were examined for 135 horses sustaining 145 fractures. Sixty-five percent of horses overall started in a race post injury (SPI) in a mean time of 9.7 months with a mean of 13.7 races post injury. Having raced pre-injury did not confer an advantage to starting post injury, though nonst...
Characterisation of the type and location of fractures of the third metacarpal/metatarsal condyles in 135 horses in central Kentucky (1986-1994). The objective of this retrospective study was to provide a detailed description of the characteristics of condylar fractures represented in a population of 135 horses who sustained 145 fractures. Records and radiographic studies were examined. Fifty-nine percent of the horses were male and the majority Thoroughbreds. The distribution of fractures was 37% incomplete-nondisplaced, 30% complete-nondisplaced and 32% complete-displaced. The right front was more likely to sustain a complete-displaced fracture, whereas the left front was more likely to sustain an incomplete-nondisplaced fracture. For...
Effect of feed rate and drill speed on temperatures in equine cortical bone. To examine the amount of heat generated in equine cortical bone by a 6.2-mm drill, using low- and high-speed and controlled feed rate drilling. Methods: 10 metacarpal bones harvested from five 2-year-old draft-type horses. Methods: Drilling on metacarpal bones was done using a machine shop mill with which the feed rate and drill speed could be precisely controlled. Bones were drilled, using 6 combinations of feed rate (1, 2, and 3 mm advance/s) and drill speed (317 and 1,242 revolutions/min [rpm], with maximal temperatures recorded by thermocouples placed 1, 1.5, and 2 mm from the drill. Maxim...
Results of screw fixation combined with cortical drilling for treatment of dorsal cortical stress fractures of the third metacarpal bone in 56 Thoroughbred racehorses. The purpose of this study was to evaluate screw fixation with cortical drilling as a surgical treatment for dorsal cortical stress fractures of MCIII in the Thoroughbred racehorse. Details of age, sex, limb affected, fracture assessment, and post operative recommendations were obtained from medical records and radiographs. Fracture healing was assessed radiographically at the time of screw removal. Performance evaluation was determined from race records obtained from The Jockey Club Information System, Lexington, Kentucky. Fifty-six Thoroughbred racehorses were treated surgically for stress fr...
Acquired flexural deformity of the metacarpophalangeal joint in five horses associated with tendonous damage in the palmar metacarpus. Five cases of acquired flexural deformity of the metacarpophalangeal joint (MCPJ) in older horses and ponies were studied. The mean age of affected horses was 14-8 years. Four deformities developed following desmitis of the accessory ligament of the deep digital flexor tendon (ALDDFT) and superficial digital flexor tendon (SDFT) and one following tendonitis of the SDFT alone. All cases were markedly lame and demonstrated variable degrees of flexural deformity. Ultrasonographic examination was performed on all cases which revealed extensive adhesion formation between the ALDDFT and SDFT and red...
Three dimensional structure of the distal condyles of the third metacarpal bone of the horse. This study examined the three-dimensional (3D) microarchitecture of regions of the equine third metacarpal bone (McIII) commonly involved in distal condylar fractures. Limbs were obtained from Thoroughbred horses (neonates to age 24 years) destroyed for inoperable fractures and a variety of other conditions. Beams, blocks and sections were cut in the principal axes, some embedded in PMMA and others examined unembedded. Several methods were used to study the 3D structure, including conventional and confocal optical microscopy, scanning electron microscopy (SEM) and radiography. The mineralised ...
Structural variation of the distal condyles of the third metacarpal and third metatarsal bones in the horse. This study examined 3-dimensional (3D) distribution of sectors with contrasting density in the equine third metacarpal (McIII) and third metatarsal (MtIII) bones with a view to explaining the aetiology of distal condylar fractures. Macroradiography and computed tomographic (CT) imaging were used in the nondestructive study of bones obtained from horses, most of which were Thoroughbreds in race training. Distal condylar regions of McIII and MtIII were also studied in microradiographs of 100 microm thick mediolateral sections cut perpendicular to the dorsal and palmar/plantar articular surfaces....
Pathology of the distal condyles of the third metacarpal and third metatarsal bones of the horse. This study examined material from Thoroughbred horses, the majority of which had been in race training, for evidence of pathology in the third metacarpal (McIII) and third metatarsal (MtIII) bones which might be related to the occurrence of distal condylar fractures. Whole bone samples were studied and documented by macrophotography prior to macroradiography and computed tomographic (CT) imaging. Microradiographs were made from 100 microm thick mediolateral sections cut perpendicular to the dorsal and palmar/plantar articular surfaces of distal condylar regions of McIII and MtIII. Blocks were ...
Aetiopathogenesis of parasagittal fractures of the distal condyles of the third metacarpal and third metatarsal bones–review of the literature. Fractures are the cause of considerable morbidity and mortality among Thoroughbred racehorses. A significant proportion of these injuries occur in the absence of any particular traumatic incident. Evidence of prefracture pathology interpreted as fatigue damage has been identified in some such cases, but the aetiology of many of these so-called 'spontaneous' fractures remains obscure. Parasagittal fractures of the third metacarpal (McIII) and third metatarsal (MtIII) bones are one of the more common fractures to affect Thoroughbred racehorses. The configuration of each of these fracture types i...
A comparison of the Synthes 4.5-mm cannulated screw and the Synthes 4.5-mm standard cortex screw systems in equine bone. To determine risk of failure of the Synthes 4.5-mm cannulated screw system instrumentation in equine bone and to compare its application with the Synthes 4.5-mm standard cortex screw system. Methods: The maximum insertion torque of the cannulated and standard cortex screw systems were compared with the ultimate torsional strengths of the equipment. Pullout strength and ultimate tensile load of cannulated and standard cortex screws were also determined. Methods: Paired equine cadaver third metacarpal and third carpal bones. Methods: Maximum insertion torque and ultimate torsional strengths were...
Complete fractures of the third metacarpal or metatarsal bone in horses: 25 cases (1980-1996). To compare treatments of complete fractures of the third metacarpal (MC) or metatarsal (MT) bone in horses and to identify factors that could impact prognosis. Methods: Retrospective case series. Methods: 25 horses with fractures of the third MC or MT bone that were treated by use of internal fixation, external coaptation, or both. Methods: Medical records from the Veterinary Medical Data Base of horses treated for fractures of third MC or MT bone at Texas A&M University from 1980 to 1994 and Purdue University from 1980 to 1996 were reviewed. Information on signalment, results of physical ...
Effect of three types of half-limb casts on in vitro bone strain recorded from the third metacarpal bone and proximal phalanx in equine cadaver limbs. To determine effect of 3 half-limb casts on bone strains recorded from the proximal phalanx (P-1) and third metacarpal bone (MCIII) of equine cadaver limbs, using a mechanical testing machine. Methods: 12 equine cadaver limbs and 4 live horses. Methods: Bone strains were recorded at middorsal P-1 and the dorsal cortical aspect of the distal third of MCIII while limbs were variably loaded with 100 to 1,000 lb of force. To determine ability of the cast to protect the distal portion of the limb from weight-bearing loads, strains were recorded with the limb in 1 of the 3 casts and with it unsuppor...
Deconditioning reduces mineral content of the third metacarpal bone in horses. Diet and exercise are two management factors that affect bone density and strength. We proposed that bone density and calcium status would be affected by deconditioning for 12 wk and by dietary Ca concentration. Eleven highly conditioned Arabian horses were taken out of training and placed in stalls for 12 wk. Horses were walked on a mechanical walker in two 30-min sessions, 7 d/wk. Diets were designated CC (.36% Ca) and HC (.62% Ca). Data were collected every 21 d. Serum or plasma were analyzed for total and ionized Ca, parathyroid hormone, osteocalcin, hydroxyproline, electrolytes, and blood...
Incomplete oblique sagittal fractures of the dorsal cortex of the third metacarpal bone in six horses. To describe incomplete oblique sagittal dorsal cortical fractures of the equine third metacarpal bone, their surgical repair, and subsequent performance of the horses. Methods: Retrospective examination of medical records and racing performance. Methods: Six Thoroughbred race horses, 2 to 4 years of age. Methods: Radiographic confirmation of all fractures preceded general anesthesia and surgical correction. Three fractures were treated by intracortical compression using screws placed in lag fashion, and five fractures were treated by osteostixis. Race records were reviewed for each horse to de...
Ex vivo simulation of in vivo strain distributions in the equine metacarpus. The objective of this study was to examine several simple ex vivo loading conditions for the equine metacarpus, and to evaluate their ability to reproduce the mid-diaphyseal bone surface strain distributions previously reported in vivo at the walk and trot. Distributed axial compressive loads, and 9 different axial compressive point loads at -7.5 kN and -15 kN were applied to metacarpal-distal carpal bone preparations from 6 Thoroughbred horses, aged 1-5 years. The resulting dorsal, medial, palmar, and lateral mid-diaphyseal bone surface axial and shear strains were compared with previously re...
Longitudinal fractures of the condyles of the third metacarpal and metatarsal bones in racehorses: 224 cases (1986-1995). To determine type, distribution, and radiographic appearance of condylar fractures of the third metacarpal bone (MC-3) or third metatarsal bone (MT-3) in Thoroughbreds (TB), Standardbreds (SB), and Arabians, to assess long-term outcome of horses in which fractures were repaired surgically, and to identify variables associated with prognosis for return to racing. Methods: Retrospective study. Methods: 224 horses with 233 fractures. Methods: Medical records and radiographs obtained before and after treatment were reviewed. Racing performance before and after treatment was determined by reviewing...