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Topic:Bones
The skeletal system in horses comprises a complex structure of bones that provide support, protection, and mobility. Equine bones are involved in various physiological functions, including mineral storage and hematopoiesis. The bone structure in horses is categorized into different types, such as long bones, short bones, flat bones, and irregular bones, each serving specific roles in movement and stability. Research in this area explores topics such as bone development, remodeling, and the impact of nutrition and exercise on bone health. This page gathers peer-reviewed studies and academic articles that focus on the anatomy, physiology, and pathology of bones in horses, offering insights into conditions such as fractures, bone diseases, and the effects of aging on the equine skeletal system.
Resolution of lesions on STIR images is associated with improved lameness status in horses. Magnetic resonance (MR) imaging is important in diagnosing musculoskeletal injuries in horses. However, there is still much to learn regarding the significance of lesions identified in equine MR images. Of particular importance is the clinical significance of signal change as a function of pulse sequence. We hypothesized that a resolution of tendon, ligament, and bone marrow lesions on short-tau inversion recovery (STIR) images would be associated with a return to soundness, and that a persistence of tendon and ligament lesions on only T1-weighted (T1w) gradient recalled echo (GRE) images woul...
Using magnetic resonance imaging to diagnose nondisplaced fractures of the second phalanx in horses. Two horses presented with a history of severe lameness that was localised to the area around the second phalanx (P2) of one forelimb. Radiographs of the second phalanx of both horses were unremarkable, apart from some smooth periosteal new bone production on the dorsum of P2. Magnetic resonance imaging revealed a non-displaced fracture of P2 in both horses. One horse was euthanased because of a poor prognosis for racing, but the second horse was treated conservatively and salvaged for breeding. Magnetic resonance imaging is a newer imaging modality in horses and may be useful in diagnosing cas...
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...
An in vitro biomechanical comparison of a locking compression plate fixation and kerf cut cylinder fixation for ventral arthrodesis of the fourth and the fifth equine cervical vertebrae. To (1) define mechanical properties in flexion, extension, and left lateral bending of cadaveric equine 4th and 5th cervical (C4-C5) articulations, (2) compare biomechanical properties of C4-C5 when stabilized with a kerf cut cylinder (KCC) compared with a ventrally placed 4.5 mm locking compression plate (LCP). Methods: In vitro biomechanical investigation. Methods: Cadaveric adult equine cervical vertebral columns (n=54). Methods: Cervical vertebrae aged by horse dentition and size measured from radiographs were divided into 3 age groups then randomly allocated to 3 groups. The C4-C5 articul...
Optimisation of bone marrow aspiration from the equine sternum for the safe recovery of mesenchymal stem cells. Mesenchymal stem cell (MSC) therapy for orthopaedic disease is being used with increasing frequency; there is a need to define a safe, reliable and effective technique for the recovery of MSCs from the sternum of the horse. Objective: To describe an optimised safe technique for obtaining bone marrow-derived MSCs from the sternum of the Thoroughbred horse. Methods: The anatomical relationship of the sternum with the heart and internal anatomy was demonstrated in cadavers. Sternal anatomy was evaluated ultrasonographically and after midline sectioning. Sternebrae were examined histologically aft...
Effects of age and loading rate on equine cortical bone failure. Although clinical bone fractures occur predominantly under impact loading (as occurs during sporting accidents, falls, high-speed impacts or other catastrophic events), experimentally validated studies on the dynamic fracture behavior of bone, at the loading rates associated with such events, remain limited. In this study, a series of tests were performed on femoral specimens obtained post-mortem from equine donors ranging in age from 6 months to 28 years. Fracture toughness and compressive tests were performed under both quasi-static and dynamic loading conditions in order to determine the ef...
Clinical significance of osseous spurs on the dorsoproximal aspect of the third metatarsal bone. Osseous spurs on the dorsoproximal aspect of the third metatarsal bone (MtIII) are common, but their clinical significance is unknown. Objective: To verify the sites of insertion of the dorsal metatarsal ligament and the tendons of tibialis cranialis and fibularis tertius in order to determine if periarticular osteophytes and entheseophytes could be differentiated radiologically; and to determine the frequency of occurrence of osseous spurs on the dorsoproximal aspect of MtIII. Objective: The frequency of osseous spurs on the dorsoproximal aspect of MtIII would be higher in lame than in clinic...
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...
Assessment of bone response to conditioning exercise in the radius and tibia of young thoroughbred horses using pQCT. To assess the effect of conditioning exercise on bone parameters at multiple sites in the radius and tibia of young Thoroughbred horses. Methods: The left and right radius and tibia were obtained from twelve horses, six of which had received conditioning exercise and six which formed the control group. Each bone was scanned at 5% intervals along its entire length using pQCT. Results: Bone strength, bone area and periosteal circumference were significantly greater for the group of conditioned horses in both the radius and tibia. Volumetric bone mineral density was lower while bone mineral conte...
Influence of the chemical shift artifact on measurements of compact bone thickness in equine distal limb MR images. The effect of the chemical shift artifact, resulting from misregistration or phase cancellation at the interface between compact and trabecular bone, on apparent bone thickness was quantified in six isolated equine limbs. Sagittal T1-weighted spin echo (SE) and in-phase three-dimensional spoiled gradient echo (SPGR) images were acquired twice with a 1.5 T magnetic resonance (MR) unit, switching the frequency encoding direction between acquisitions. Out-of-phase SPGR images were also obtained. MR images with different frequency encoding directions were compared with each other and to radiograph...
The use of small (2.7 mm) screws for arthroscopically guided repair of carpal chip fractures. Removal of large chip fractures of the carpal bones and the osteochondral deficits that result, have been associated with a worse prognosis than removal of small fragments in similar locations. Objective: Reducing the articular defects by repair of large osteochondral fragments may have advantages over removal. Methods: Horses with osteochondral chip fractures that were of sufficient size and infrastructure to be repaired with small (2.7 mm diameter) AO/ASIF cortex screws were identified and repair effected by arthroscopically guided internal fixation. Results: Thirty-three horses underwent su...
Are bi-axial proximal sesamoid bone fractures in the British Thoroughbred racehorse a bone fatigue related fracture? A histological study. To investigate whether microfractures and alterations in the trabecular bone area are associated with catastrophic bi-axial proximal sesamoid bone fractures (PSBF). Methods: Proximal sesamoid bones (PSB) from 10 racehorses with PSBF and from 10 control racehorses without musculoskeletal injury were examined using the bulk basic fuchsin method. Bone histomorphometric and microfracture analysis was performed, and cases and controls compared using two-sample t-test, paired t-test, and Mann-Whitney U test. Results: There was no significant difference in the microfracture density and the trabecular...
Acute lameness associated with osseous metastasis of a peri-renal carcinoma in a horse. We present a case of aggressive metastatic carcinoma in a horse that was initially presented for shoulder lameness. Although radiography and scintigraphy were useful for localising a lesion in the proximal humerus, subsequent development of non-specific signs of systemic disease prompted further evaluation. Haematology and blood biochemistry, urinalysis and ultrasonography were all instrumental in identifying renal involvement. A diagnosis of a peri-renal mass causing secondary renal failure prompted euthanasia of the horse because of the poor prognosis. Antemortem findings were supported by n...
Is there an association between ossification of the cartilages of the foot and collateral desmopathy of the distal interphalangeal joint or distal phalanx injury? Associations between degree of ossification of the cartilages of the foot and injuries to other structures of the foot have been suggested, but have not been investigated by large scale studies. Objective: To describe the frequency of grade >3 ossification of the cartilages of the foot (possibly significant ossification, PSO), mediolateral symmetry of ossification and left-right symmetry between feet; and to investigate associations between PSO and injury of either the collateral ligaments (CLs) of the distal interphalangeal (DIP) joint or the distal phalanx. Objective: Possibly significant os...
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...
A weighted osteon morphotype score outperforms regional osteon percent prevalence calculations for interpreting cortical bone adaptation. Using circularly polarized light microscopy,we described a weighted-scoring method for quantifying regional distributions of six secondary osteon morphotypes(Skedros et al.: Bone 44 (2009) 392-403). This osteon morphotype score (MTS) strongly correlated with "tension" and "compression" cortices produced by habitual bending. In the present study, we hypothesized that the osteon MTS is superior to a relatively simpler method based on the percent prevalence (PP) of these osteon morphotypes. This was tested in proximal femoral diaphyses of adult chimpanzees and habitually bent bones: calcanei from...
Chronic laminitis: foot management. Laminitis is a disease of the suspensory apparatus of the distal phalanx, which can advance to the chronic stage with varying degrees of structural failure. Because the disease may ultimately lead to mechanical failure of the digit, a foot management plan is required to effectively and mechanically treat these cases. Many laminitis cases can be successfully rehabilitated back to athletic soundness, light use, breeding, or pasture soundness, whereas others suffer from permanent instability and never enjoy an acceptable level of comfort. To understand how to minimize damage in the acute laminiti...
Supporting limb laminitis. Supporting limb laminitis poses a threat to all horses suffering from severe unilateral lameness. Despite its devastating effects, relatively little is known about the precise pathologic processes that lead to its development. This article reviews the potential mechanisms of supporting limb laminitis, and the authors present some preliminary data based on advanced imaging and computer-based modeling techniques aimed at further elucidating the etiology of this unique form of laminitis. Gaining a better understanding of the pathologic processes that lead to supporting limb laminitis is essential...
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...
In vitro comparison of two centrally threaded, positive-profile transfixation pin designs for use in third metacarpal bones in horses. To compare heat generation during insertion, pullout strength, and associated microdamage between a self-tapping positive profile transfixation pin (STTP) and nontapping positive profile transfixation pin (NTTP). Methods: 30 pairs of third metacarpal bones (MC3s) from adult equine cadavers. Methods: One MC3 of each pair was assigned to the STTP group; the other was assigned to the NTTP group. The assigned pin was inserted into the diaphysis in a lateral to medial direction. Bone temperature increase during pilot-hole drilling and pin insertion was recorded at 1 mm from the final thread positio...
Tiludronate infusion in the treatment of bone spavin: a double blind placebo-controlled trial. Tiludronate regulates bone remodelling through a decrease of the resorptive process and should therefore ameliorate the remodelling processes active in osteoarthritis of the distal tarsal joints ('bone spavin') and alleviate pain associated with abnormal bone lysis. Objective: To confirm the efficacy of tiludronate, administered as a single infusion at a dose of 1 mg/kg bwt, in the treatment of bone spavin in the horse. Methods: A double blind placebo controlled trial on 108 clinical cases of bone spavin was undertaken. The lameness score of the lamest limb was assessed following distal tarsal...
Catastrophic biaxial proximal sesamoid bone fractures in UK Thoroughbred races (1999-2004): horse characteristics and racing history. Catastrophic biaxial proximal sesamoid bone fractures (PSBF) have not yet been described in detail in the UK racing population. Objective: To determine the incidence and relative risk (RR) of PSBF in different types of racing in the UK; and to describe horse-level characteristics and racing histories of horses sustaining these injuries. Methods: Distal limbs were collected from all racehorses suffering catastrophic fractures during racing at all 59 racecourses in the UK, in a prospective study from February 1999 to December 2004. Post mortem investigation identified the anatomical location and...
Histopathology and computed tomography of age-associated degeneration of the equine temporohyoid joint. The aetiology of temporohyoid osteoarthropathy (THO) is unknown; both primary infectious and degenerative causes have been suggested. Objective: There is a significant association between increasing age and severity of temporohyoid joint degeneration. To examine the histopathology of the temporohyoid articulation in aged horses and to compare the appearance of the joint with computed tomography (CT) and peripheral quantitative CT (pQCT). Methods: pQCT scans of the temporohyoid articulations were obtained bilaterally from 31 horses (range age 1-44 years) post mortem and images were graded by 2 ...
Size and geometry of apical sesamoid fracture fragments as a determinant of prognosis in Thoroughbred racehorses. Analysis was performed to examine a method for refining the preoperative prognosis for horses that had surgery to remove apical fractures of the proximal sesamoid bones (PSBs). Objective: To determine if: 1) there was a difference in size or configuration of apical fractures between the different anatomical locations of the PSBs, which have been shown to affect the prognosis; and 2) the size or configuration could predict the prognosis for racehorses with these fractures. Methods: The study included 110 weanlings and yearlings and 56 training racehorses that underwent surgery to remove apical ...
Comparison of macrostructural and microstructural bone features in Thoroughbred racehorses with and without midbody fracture of the proximal sesamoid bone. To compare macrostructural and microstructural features of proximal sesamoid bones (PSBs) from horses with and without PSB midbody fracture to gain insight into the pathogenesis of PSB fracture. Methods: PSBs from 16 Thoroughbred racehorses (8 with and 8 without a PSB midbody fracture). Methods: Parasagittal sections of fractured and contralateral intact PSBs from horses with a PSB fracture and an intact PSB from age- and sex-matched control horses without a PSB fracture were evaluated for visual, radiographic, microradiographic, histologic, and his-tomorphometric differences in bone porosity,...
Lag screw fixation of dorsal cortical stress fractures of the third metacarpal bone in 116 racehorses. The effectiveness and best method to manage dorsal cortical stress fractures is not clear. This study was performed to evaluate the success of lag screw fixation of such fractures in a population of Thoroughbred racehorses. Objective: Lag screw fixation of dorsal cortical stress fractures is an effective surgical procedure allowing racehorses to return to their preoperative level of performance. Methods: The records of 116 racehorses (103 Thoroughbreds) admitted to Equine Medical Centre, California between 1986 and 2008 were assessed. Information obtained from medical records included subject ...
In vitro mechanical evaluation of a novel pin-sleeve system for external fixation of distal limb fractures in horses: a proof of concept study. To evaluate the efficacy of a novel pin-sleeve cast (PSC) system for external fixation of distal limb fractures in horses and to compare it with the transfixation pin cast (TPC) system. Methods: Experimental. Methods: One bone substitute each was used for the TPC and PSC systems. The PSC was tested in 4 configurations characterized by different pin preloads. Methods: Specimens were loaded in axial compression in the elastic range. Variables compared statistically were: bone substitute axial displacement and axial strain measured above implants with strain gauges. Pin preload was correlated wit...
The distal sesamoidean impar ligament: comparison between its appearance on magnetic resonance imaging and histology of the axial third of the ligament. There is limited knowledge about the interpretation of alterations in the distal sesamoidean impar ligament (DSIL) detected using magnetic resonance imaging (MRI) and their correlation with histopathology. Objective: There would be: 1) a correlation between histopathology and MRI findings; and 2) a relationship between MR abnormalities at the origin and the insertion of the DSIL, between insertion and body; and origin and body. Methods: Fifty limbs from 28 horses were examined using high-field MRI and histopathology. MR abnormalities of the DSIL, its origin on the navicular bone and its insert...
