Equine Metacarpophalangeal Joint Research Articles

Non-invasive electroarthrography measures cartilage in live horses and correlates to direct measurements of cartilage streaming potentials in weight bearing regions of equine metacarpophalangeal joints

ObjectiveTo perform non-invasive Electroarthrography (EAG) on live horses and establish relationships between EAG and direct measurements of cartilage streaming potentials in weight bearing areas of the equine metacarpophalangeal joint. DesignEAG was performed bilaterally on the metacarpophalangeal joints of live horses (n=3). Separate experiments used metacarpophalangeal joint explants (n=11) to measure EAG obtained during simulated loading followed by direct measurements of cartilage streaming potentials on joint surfaces using the Arthro-BST probe. Joints were assigned to relatively normal (n=5) and mildly degraded (n=6) groups based on histological scoring of Safranin-O/Fast Green stained sections. ResultsEAG, involving application of electrodes to skin surrounding the joint and repeated weight shifting, was well-tolerated in live horses. One pair of distal forelimbs were available for analogous ex vivo EAG testing and measurements were strongly correlated to in vivo EAG measurements obtained on the same joints (r=0.804, p=0.016, n=8). Both indirect (EAG) and direct (Arthro-BST) measurements of cartilage streaming potentials distinguished between normal and mildly degraded cartilage with statistically significant differences at 5 of 6 and 4 of 6 electrodes during simulated standing and walking, respectively. Strong and moderate correlations for weight bearing regions on the dorsal phalanx and central metacarpus were detected during both standing and walking. At the metacarpus/sesamoid interface a moderate correlation occurred during walking. ConclusionNon-invasive EAG was used successfully in a clinical scenario and correlated to direct measurements of streaming potentials in weight bearing cartilage. These data support the potential of EAG to contribute to the diagnosis and treatment of degenerative joint diseases.

Influence of microarchitecture on stressed volume and mechanical fatigue behaviour of equine subchondral bone

Fractures of the equine metacarpophalangeal (MCP) joint are among the most common and fatal injuries experienced by racehorses. These bone injuries are a direct result of repetitive, high intensity loading of the skeleton during racing and training and there is consensus that they represent a mechanical fatigue phenomenon. Existing work has found the fatigue life of bone to be strongly determined by bone microarchitecture and the resulting stressed volume (i.e., the volume of bone stressed above assumed yield). The purpose of this study was to quantify the influence of bone microarchitecture on the mechanical fatigue behaviour of equine subchondral bone from the MCP joint across a wide variety of sample types. Forty-eight subchondral bone samples were prepared from the third metacarpal (MC3) and proximal phalanx (P1) of 8 horses and subsequently imaged using high resolution micro-computed tomography (μCT) to quantify microarchitectural features of interest, including bone volume fraction, tissue mineral density, pore size, pore spacing, and pore number. Samples were cyclically loaded in compression to a stress of 70 MPa, and fatigue life was defined as the number of cycles until failure. Finite element models were created from the μCT images and used to quantify stressed volume. Based on the expected log point-wise predictive density, stressed volume was a strong predictor of fatigue life in both the MC3 and P1. A regional analysis indicated fatigue life was more strongly associated with bone volume fraction in the superficial (r2 = 0.32, p < 0.001) and middle (r2 = 0.70, p < 0.001) regions of the subchondral bone, indicating the prominent role that the cortical plate played in the fatigue resistance of equine subchondral bone. By improving our understanding of the variance in fatigue life measurements, this research helps clarify the underlying mechanisms of the mechanical fatigue process and provides a basic understanding of subchondral bone injuries in the equine fetlock joint.

Radiographic texture of the trabecular bone of the proximal phalanx in horses with metacarpophalangeal osteoarthritis.

Osteoarthritis (OA) is a prevalent condition in horses, leading to changes in trabecular bone structure and radiographic texture. Although fractal dimension (FD) and lacunarity have been applied to quantify these changes in humans, their application in horses remains nascent. This study evaluated the use of FD, bone area fraction (BA/TA), and lacunarity in quantifying trabecular bone differences in the proximal phalanx (P1) in 50 radiographic examinations of equine metacarpophalangeal joints with varying OA degrees. In the dorsopalmar view, regions of interest were defined in the trabecular bone of the proximal epiphysis, medial and lateral to the sagittal groove of P1. Lower BA/TA values were observed medially in horses with severe OA (P=0.003). No significant differences in FD and lacunarity were found across OA degrees (P>0.1). FD, BA/TA, and lacunarity were not effective in identifying radiographic texture changes in the P1 trabecular bone in horses with different metacarpophalangeal OA degrees.

Cone-beam computed tomography produces images of numerically comparable diagnostic quality for bone and inferior quality for soft tissues compared with fan-beam computed tomography in cadaveric equine metacarpophalangeal joints.

Cone-beam computed tomography (CBCT) is an emerging modality for imaging of the equine patient. The objective of this prospective, descriptive, exploratory study was to assess visualization tasks using CBCT compared with conventional fan-beam CT (FBCT) for imaging of the metacarpophalangeal joint in equine cadavers. Satisfaction scores were numerically excellent with both CBCT and FBCT for bone evaluation, and FBCT was numerically superior for soft tissue evaluation. Preference tests indicated FBCT was numerically superior for soft tissue evaluation, while preference test scoring for bone was observer-dependent. Findings from this study can be used as background for future studies evaluating CBCT image quality in live horses.

The influence of a tension band fixation as an adjunct for arthrodesis of the metacarpophalangeal joint in the horse.

To determine the influence of a stainless-steel cable (SSC) tension band fixation as an adjunct to a locking compression plate (LCP) for arthrodesis of the equine metacarpophalangeal (MCP) joint. Experimental. An ex vivo biomechanical paired equine cadaver limb study. Five MCP joint pairs were collected from adult Thoroughbred horses, euthanized for reasons unrelated to orthopedic disease. Each pair of MCP joints were randomly implanted with either a dorsally placed 5.5 mm LCP and a palmarly placed 2.0 mm SSC or a dorsally placed 5.5 mm LCP alone. Each construct was tested in cyclic loading followed by single cycle to failure in axial compression. Displacement at a target load of 1 kN over 3600 cycles at 1 Hz was recorded prior to single cycle to failure testing. In cyclic testing, displacement was not significantly different between the first and last 5% of testing cycles regardless of construct. Maximum displacement of each construct during cyclic testing was <1.1 mm. In single cycle testing, the observed yield point did not reveal any difference between LCP and LCP-SSC (p = .440). The maximum load at failure was significantly higher in LCP-SSC compared to constructs with the LCP alone (p = .046). The addition of the SSC to the LCP did not statistically affect construct displacement during cyclic loading or construct yield load during subsequent single cycle to failure. This study provided much needed information regarding the necessity of a tension band SSC application in the arthrodesis of the MCP/MTP joint in horses.

Expression of cannabinoid (CB1 and CB2) and cannabinoid-related receptors (TRPV1, GPR55, and PPARα) in the synovial membrane of the horse metacarpophalangeal joint.

The metacarpophalangeal joint undergoes enormous loading during locomotion and can therefore often become inflamed, potentially resulting in osteoarthritis (OA). There are studies indicating that the endocannabinoid system (ECS) modulates synovium homeostasis, and could be a promising target for OA therapy. Some cannabinoid receptors, which modulate proliferative and secretory responses in joint inflammation, have been functionally identified in human and animal synovial cells. To characterize the cellular distribution of the cannabinoid receptors 1 (CB1R) and 2 (CB2R), and the cannabinoid-related receptors transient receptor potential vanilloid type 1 (TRPV1), G protein-related receptor 55 (GPR55) and peroxisome proliferator-activated receptor alpha (PPARα) in the synovial membrane of the metacarpophalangeal joint of the horse. The dorsal synovial membranes of 14 equine metacarpophalangeal joints were collected post-mortem from an abattoir. The dorsal synovial membranes of 14 equine metacarpophalangeal joints were collected post-mortem from an abattoir. The expression of the CB1R, CB2R, TRPV1, GPR55, and PPARα in synovial tissues was studied using qualitative and quantitative immunofluorescence, and quantitative real-time reverse transcriptase PCR (qRT-PCR). Macrophage-like (MLS) and fibroblast-like (FLS) synoviocytes were identified by means of antibodies directed against IBA1 and vimentin, respectively. Both the mRNA and protein expression of the CB2R, TRPV1, GPR55, and PPARα were found in the synoviocytes and blood vessels of the metacarpophalangeal joints. The synoviocytes expressed the mRNA and protein of the CB1R in some of the horses investigated, but not in all. Given the expression of the CB1R, CB2R, TRPV1, GPR55, and PPARα in the synovial elements of the metacarpophalangeal joint, these findings encouraged the development of new studies supporting the use of molecules acting on these receptors to reduce the inflammation during joint inflammation in the horse.

Agreement and Reliability of Lesion Detection in the Equine Metacarpo(Tarso)Phalangeal Joint Using Standing Low-Field MRI and Arthroscopy

Agreement and Reliability of Lesion Detection in the Equine Metacarpo(Tarso)Phalangeal Joint Using Standing Low-Field MRI and Arthroscopy

Differential gene expression analysis reveals pathways important in early post-traumatic osteoarthritis in an equine model

BackgroundPost-traumatic osteoarthritis (PTOA) is a common and significant problem in equine athletes. It is a disease of the entire joint, with the synovium thought to be a key player in disease onset and progression due to its role in inflammation. The development of effective tools for early diagnosis and treatment of PTOA remains an elusive goal. Altered gene expression represents the earliest discernable disease-related change, and can provide valuable information about disease pathogenesis and identify potential therapeutic targets. However, there is limited work examining global gene expression changes in early disease. In this study, we quantified gene expression changes in the synovium of osteoarthritis-affected joints using an equine metacarpophalangeal joint (MCPJ) chip model of early PTOA. Synovial samples were collected arthroscopically from the MCPJ of 11 adult horses before (preOA) and after (OA) surgical induction of osteoarthritis and from sham-operated joints. After sequencing synovial RNA, Salmon was used to quasi-map reads and quantify transcript abundances. Differential expression analysis with the limma-trend method used a fold-change cutoff of log2(1.1). Functional annotation was performed with PANTHER at FDR < 0.05. Pathway and network analyses were performed in Reactome and STRING, respectively.ResultsRNA was sequenced from 28 samples (6 preOA, 11 OA, 11 sham). “Sham” and “preOA” were not different and were grouped. Three hundred ninety-seven genes were upregulated and 365 downregulated in OA synovium compared to unaffected. Gene ontology (GO) terms related to extracellular matrix (ECM) organization, angiogenesis, and cell signaling were overrepresented. There were 17 enriched pathways, involved in ECM turnover, protein metabolism, and growth factor signaling. Network analysis revealed clusters of differentially expressed genes involved in ECM organization, endothelial regulation, and cellular metabolism.ConclusionsEnriched pathways and overrepresented GO terms reflected a state of high metabolic activity and tissue turnover in OA-affected tissue, suggesting that the synovium may retain the capacity to support healing and homeostasis in early disease. Limitations of this study include small sample size and capture of one point post-injury. Differentially expressed genes within key pathways may represent potential diagnostic markers or therapeutic targets for PTOA. Mechanistic validation of these findings is an important next step.

Small Non-Coding RNAome of Ageing Chondrocytes.

Ageing is a leading risk factor predisposing cartilage to osteoarthritis. However, little research has been conducted on the effect of ageing on the expression of small non-coding RNAs (sncRNAs). RNA from young and old chondrocytes from macroscopically normal equine metacarpophalangeal joints was extracted and subjected to small RNA sequencing (RNA-seq). Differential expression analysis was performed in R using package DESeq2. For transfer RNA (tRNA) fragment analysis, tRNA reads were aligned to horse tRNA sequences using Bowtie2 version 2.2.5. Selected microRNA (miRNAs or miRs) and small nucleolar RNA (snoRNA) findings were validated using real-time quantitative Polymerase Chain Reaction (qRT-PCR) in an extended cohort of equine chondrocytes. tRNA fragments were further investigated in low- and high-grade OA human cartilage tissue. In total, 83 sncRNAs were differentially expressed between young and old equine chondrocytes, including miRNAs, snoRNAs, small nuclear RNAs (snRNAs), and tRNAs. qRT-PCR analysis confirmed findings. tRNA fragment analysis revealed that tRNA halves (tiRNAs), tiRNA-5035-GluCTC and tiRNA-5031-GluCTC-1 were reduced in both high grade OA human cartilage and old equine chondrocytes. For the first time, we have measured the effect of ageing on the expression of sncRNAs in equine chondrocytes. Changes were detected in a number of different sncRNA species. This study supports a role for sncRNAs in ageing cartilage and their potential involvement in age-related cartilage diseases.

Non-invasive Electroarthrography Measures Load-Induced Cartilage Streaming Potentials via Electrodes Placed on Skin Surrounding an Articular Joint.

We aimed to demonstrate that electroarthrography (EAG) measures streaming potentials originating in the cartilage extracellular matrix during load bearing through electrodes adhered to skin surrounding an articular joint. Equine metacarpophalangeal joints were subjected to simulated physiological loads while (1) replacing synovial fluid with immersion buffers of different electrolyte concentrations and (2) directly degrading cartilage with trypsin. An inverse relationship between ionic strength and EAG coefficient was detected. Compared to native synovial fluid, EAG coefficients increased (P < 0.05) for 5 of 6 electrodes immersed in 0.1X phosphate-buffered saline (PBS) (0.014 M NaCl), decreased (P < 0.05) for 4 of 6 electrodes in 1X PBS (0.14 M NaCl), and decreased (P < 0.05) for all 6 electrodes in 10X PBS (1.4 M NaCl). This relationship corresponds to similar studies where streaming potentials were directly measured on cartilage. EAG coefficients, obtained after trypsin degradation, were reduced (P < 0.05) in 6 of 8, and 7 of 8 electrodes, during simulated standing and walking, respectively. Trypsin degradation was confirmed by direct cartilage assessments. Streaming potentials, measured by directly contacting cartilage, indicated lower cartilage stiffness (P < 10-5). Unconfined compression data revealed reduced Em, representing proteoglycan matrix stiffness (P = 0.005), no change in Ef, representing collagen network stiffness (P = 0.15), and no change in permeability (P = 0.24). Trypsin depleted proteoglycan as observed by both dimethylmethylene blue assay (P = 0.0005) and safranin-O stained histological sections. These data show that non-invasive EAG detects streaming potentials produced by cartilage during joint compression and has potential to become a diagnostic tool capable of detecting early cartilage degeneration.

Physiologic effects of long-term immobilization of the equine distal limb.

To describe the effects of distal limb immobilization and remobilization in the equine metacarpophalangeal joint. Randomized, prospective experimental study. Eight healthy, skeletally mature horses. One forelimb of each horse was immobilized in a fiberglass cast for 8 weeks; this was followed by 12 weeks of a treadmill-based training program after the cast had been removed. Clinical examinations, radiography, computed tomography (CT), nuclear scintigraphy, MRI, and histomorphometry were used to examine the third metacarpal (MC3), proximal phalanx, proximal sesamoid bones, and associated soft tissues in each horse. Serum and synovial fluid were collected for biomarker analyses. Distal limb immobilization resulted in persistent lameness (P < .001), effusion (P = .002), and a decreased range of motion (P = .012) as well as radiographically visible fragments (P = .036) in the cast forelimb. Bone density was decreased (P < .001) in MC3 according to CT, and trabecular bone fluid was increased (P < .001) according to MRI in the cast forelimb. The cast forelimbs had a change (P = .009) in the appearance of the deep digital flexor tendon according to MRI immediately after removal of the cast. Numerous clinical, radiographic, CT, and MR abnormalities were visible at the end of the study period. Eights weeks of cast immobilization induced changes in bone, cartilage, and periarticular soft tissues that were not reversed after 12 weeks of remobilization. Cast application should be used judiciously in horses with musculoskeletal injuries, balancing appropriate stabilization with potential morbidity secondary to cast placement.

Assessment of Intra- and Inter-observer Measurement Variability in a Radiographic Metacarpophalangeal Joint Osteophytosis Scoring System for the Horse.

The study evaluated the intra- and inter-observer measurement variability of an osteophytosis metacarpophalangeal joint scoring system. Ten (n = 10) dorso/palmar, latero/medial, and oblique views of equine metacarpophalangeal joints affected by osteoarthritis were examined. Nine assessment points were graded (scale: 0–3) twice by five veterinary students (inexperienced group, I) and four equine veterinary surgeons (expert group, E). The grades for each of the nine factors were summed to obtain the osteophytosis score. The variability between the two measurements was −2.04 ± 3.5, 95% CI −3.04 to −1.03 for the I group. For the E group, they were 0 ± 1.43, 95% CI −0.45 to 0.45. In the evaluation of the same radiographs, the I group had a coefficient of variability (CV) of 37.29%. The correlation was r = 0.90%. The CV between groups was 28.85%. The mean difference between the two observations was -0.03 ± 0.29 in the E group and 0.22 ± 0.77 in the I group. The I group showed a greater CV when the score was low (r = −0.78) compared to the E group, where the CV was independent of severity of osteophytosis (r = −0.47). The osteophytosis scoring system is an easily applicable and feasible system to be used by observers with different levels of experience, but inexpert observers may need additional training or may need to be helped by reference images. These data are validated by the low inter- and intra-observer measurement variability results in the E group. Therefore, the scoring system proposed seems to be a repeatable instrument applicable to the radiographic score of the severity of metacarpophalangeal joint osteoarthritis.

Effect of Fatigue on Equine Metacarpophalangeal Joint Kinematics—A Single Horse Pilot Study

The objective was to validate a scientific method for characterizing equine metacarpophalangeal joint (MCPJ) motion in the nonfatigued and fatigued states using a single horse at trot, slow canter, and fast canter. One healthy Thoroughbred gelding exercised on a treadmill to exhaustion (fatigued state) (heart rate >190 BPM and blood lactate >10 mmol/L) while bilateral MCPJ angular data were acquired using electrogoniometry. Blood lactate and heart rate reflected transition from nonfatigued to fatigued states with increasing exercise duration and treadmill speed. Electrogoniometry consistently demonstrated: increase in mean MCPJ maximum extension angle with onset of fatigue; altered extension and flexion angular velocities with onset of fatigue; and increasing stride duration and decreasing stride frequency with onset of fatigue. The method allowed a preliminary but comprehensive characterization of the dynamic relationship between MCPJ kinematics and fatigue, prompting the need for multisubject studies that may enhance our ability to moderate exercise-related distal limb injury in equine athletes.

Synovial nerve fiber density decreases with naturally-occurring osteoarthritis in horses

To measure the nerve fiber density in synovial membranes from healthy and OA equine joints and to investigate the relationship between synovial innervation and OA severity, synovial vascularity and synovitis. Twenty-five equine metacarpophalangeal joints were collected post-mortem. The joints were dissected and the macroscopic lesions of the articular cartilage were scored. Synovial membrane specimens (n=50) were harvested, fixed, sectioned and scored histologically. Immunohistochemical staining and immunofluorescence with S-100 protein, that identifies nerve fibers, and ⍺-actin, that stains vascular smooth muscle, were also performed on site-matched specimens and the relationships between these tissues was interrogated. The nerve fiber density was higher in the superficial layer (≤200μm) of the synovium when compared to the deeper layer in control equine joints (mean difference (95% C.I.): 0.054% (0.018%, 0.11%)). In osteoarthritic joints, synovial innervation decreased in the superficial layer with increasing macroscopic OA score (β (SEM), 95% C.I.:-0.0061 (0.00021),-0.0011,-0.00017). The blood vessel density was also higher in the superficial layer of the synovium compared to the deep layer in the control (mean difference (95% C.I.): 1.1% (0.36%, 2.3%)) and OA (mean difference (95% C.I.): 0.60% (0.22%, 1.2%)) equine joints. Moreover, considering all synovial specimens, higher nerve fiber density in the deep layer positively correlated with blood vessel density (β (SEM), 95% C.I.: 0.11 (0.036), 0.035, 0.18). The reduction in nerve fiber density with advanced cartilage degeneration suggests that peripheral neuropathy is associated with equine OA. Whether this link is associated with neuropathic pain, requires further investigation.

Development of an equine carpal groove model to study early changes in osteoarthritis - a pilot study

Purpose: The cartilage groove model has been shown to be an effective model for investigation of early degenerative joint changes in various animal models, including recently in the equine metacarpophalangeal (MCP) joint. In this pilot study, we investigated: 1) if the groove model induces comparable cartilage degeneration in the equine middle carpal as in the MCP joint and 2) if a modified method for disrupting the collagen network without tissue loss, in combination with loading, also leads to cartilage degeneration. Methods: In two adult Shetland ponies, the dorsal aspect of the condyles of the third metacarpal bone (MCP joint) and the proximal surface of the radial facet of the third carpal bone (middle carpal joint) were grooved as described in the literature, using a hooked arthroscopic probe with a sharpened tip (“blunt grooves”). In the contra-lateral limb, grooves were made with a surgical mini blade that was clamped in a custom-made device (“sharp grooves”). After two weeks of box rest, the ponies were subjected to an eight-week training protocol on a treadmill. Clinical lameness was evaluated weekly. Synovial fluid was collected from the middle carpal joint before surgery and at two and 10 weeks postoperatively for analysis of glycosaminoglycan (GAG) levels and matrix metalloproteinase (MMP) activity. At 10 weeks, ponies were euthanized and osteochondral samples harvested for macroscopic, histologic and gene expression analysis of matrix components. Additionally, “fresh” grooves were made in the MCP and middle carpal joints of cadaver limbs to compare the microscopic appearance of grooves with and without a period of in vivo loading. Results: After 6-8 weeks post-operatively, regular stumbling and mild lameness were observed in both ponies during training. Macroscopically, grooves made by both techniques could be identified and adjacent tissue was affected, mainly in the carpal joints. Safranin-O stained histology sections clearly showed degenerative changes for cartilage with blunt grooves (i.e., loss of staining, fibrillation and cell clustering around the lesions), whereas only very mild changes were observed in cartilage with sharp grooves (Fig.1). Microscopy scores in both blunt and sharp grooved joints were higher at 10 weeks (12.4 and 7.3, respectively) compared with grooved cadaver joints (5.5 and 3.0) according to the OARSI equine microscopic grading system. Synovial fluid GAG concentrations dropped dramatically at two weeks after surgery, whereas MMP activity showed a clear increase. However, at 10 weeks, both markers returned to approximately baseline levels (Fig. 2). Carpal cartilage showed an upregulation of collagen 2, aggrecan and COMP, particularly where blunt grooves were made (Fig. 3). Conclusions: The groove model can be used in the equine carpus for the induction of cartilage degeneration. Contrary to the current paradigm, only disruption of the collagen network seemed not to lead to cartilage degeneration within 10 weeks after surgery. This would imply a crucial role for tissue loss. Synovial fluid GAG concentration and MMP activity do not seem to be sensitive markers once the initial inflammatory reaction has disappeared. A more extensive “omics-approach” could provide a better reflection of subtle changes in joint homeostasis in this early stage of degenerative joint changes. Confirmation in a larger number of animals is necessary, as is research on the long-term fate of the sharp lesions.

Correlations between the equine metacarpophalangeal joint angulation and toe conformation in statics.

The angulation of the equine fetlock determines the load of associated tendons and probably their predisposition for injuries. However, it is questionable how the individual toe conformation and tendon properties interact with the dorsal metacarpophalangeal joint angle (DMPJ). Data are needed for a tangible evaluation of the equine limb conformation for more specific orthopaedic treatment. The aim was to evaluate the correlation between the DMPJ, toe conformation and cross-sectional area (CSA) of both flexor tendons; the superficial digital flexor tendon (SDFT) and deep digital flexor tendon (DDFT). Thirty Warmblood horses were available for the study. Lateromedial radiographs of the toe and fetlock and transverse ultrasound images of both flexor tendons were obtained from three zones. The DMPJ, length and angle of the phalanges and CSA SDFT/DDFT were measured. In addition, hoof angle, wither height, age, and sex were documented. Correlations were calculated using Pearson’s test. A paired t-test was used to evaluate left–right differences. Length and angle of the proximal and middle phalanx were significantly associated with the DMPJ (r = -0.28 – -0.45, p<0.001-0.04). Neither the angle of the hoof and distal phalanx nor the CSA SDFT/DDFT, showed a noticeable correlation with the DMPJ. Significant left–right differences occurred for the DMPJ (p<0.002) and the angle of the proximal and middle phalanx (p<0.01 – 0.002). A moderate negative correlation was shown between the DMPJ and wither height (r = - 0.31, p=0.04). Results represent only a specific population. The study provides only a static evaluation of a dynamic situation. In a clinical context, it might be useful to focus on the angulation and length of the pastern to evaluate the individual load affecting the DMPJ and its associated structures. These findings might be relevant for orthopaedic treatments and shoeing recommendations.

The effect of the sagittal ridge angle on cartilage stress in the equine metacarpo-phalangeal (fetlock) joint

Fatigue failure of bones of the metacarpo-phalangeal (fetlock, MCP) joint is common in thoroughbred racehorses. Stresses within the fetlock joint cartilages are affected by the morphology of the third metacarpal bone (MC3) and proximal phalangeal bone, and the steepness of the median sagittal ridge of MC3 is believed to be associated with fracture. This study investigated the influence of the steepness of the sagittal ridge on cartilage stress distribution using a finite element model of the joint. Changes to the steepness of the sagittal ridge were made by applying a parabolic function to the mesh, creating four different models with sagittal ridge angles ranging from 95° to 105°. In the fetlock joint of Thoroughbred racehorses, sagittal ridge angles of >100° were associated with higher Von Mises stresses in cartilage at the palmar aspect of the condylar groove than such stresses in joints with sagittal ridge angles of <100°. Stresses were high in the specific region where fractures are known to originate in MC3. This aspect of morphology of the fetlock joint thus appears to play an important role in the magnitude and distribution of cartilage stresses, which, when acting on the underlying hard tissues of the articular calcified cartilage and subchondral bone may play a role in the initiation of fatigue fracture in the third metacarpal bone.

CORRELATION OF ARTICULAR CARTILAGE THICKNESS MEASUREMENTS MADE WITH MAGNETIC RESONANCE IMAGING, MAGNETIC RESONANCE ARTHROGRAPHY, AND COMPUTED TOMOGRAPHIC ARTHROGRAPHY WITH GROSS ARTICULAR CARTILAGE THICKNESS IN THE EQUINE METACARPOPHALANGEAL JOINT.

Veterinary Radiology & UltrasoundVolume 58, Issue 2 p. 237-237 CorrigendumFree Access CORRELATION OF ARTICULAR CARTILAGE THICKNESS MEASUREMENTS MADE WITH MAGNETIC RESONANCE IMAGING, MAGNETIC RESONANCE ARTHROGRAPHY, AND COMPUTED TOMOGRAPHIC ARTHROGRAPHY WITH GROSS ARTICULAR CARTILAGE THICKNESS IN THE EQUINE METACARPOPHALANGEAL JOINT This article corrects the following: CORRELATION OF ARTICULAR CARTILAGE THICKNESS MEASUREMENTS MADE WITH MAGNETIC RESONANCE IMAGING, MAGNETIC RESONANCE ARTHROGRAPHY, AND COMPUTED TOMOGRAPHIC ARTHROGRAPHY WITH GROSS ARTICULAR CARTILAGE THICKNESS IN THE EQUINE METACARPOPHALANGEAL JOINT Erin G. Porter, Matthew D. Winter, Barbara J. Sheppard, Clifford R. Berry, Jorge A. Hernandez, Volume 57Issue 5Veterinary Radiology & Ultrasound pages: 515-525 First Published online: August 1, 2016 First published: 13 March 2017 https://doi.org/10.1111/vru.12462AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL In Porter et al.1 the following information was not published in Results and Discussion sections. Results section, page 520, first column: The new information should have been inserted at the end of the second paragraph. “The pixel dimensions calculated from the MRI and CT parameters used in the study are provided in Table 1. In our study, the average diagonal pixel measurement used for measuring cartilage thickness on MRI was about 0.79 mm. The average gross cartilage thickness on the third metacarpal bone was 1.03 mm and on the proximal phalanx was 1.15 mm. This indicates an error in measurement of about 77% for the third metacarpal bone and 69% for the proximal phalanx.2 Table 1. The pixel dimensions calculated from the MRI and CT parameters MRI Pulse sequence Vertical Resolution (mm) Horizontal resolution (mm) Diagonal resolution (mm) PD-FS 0.53 0.47 0.71 T1-FS 0.76 0.45 0.88 SSFP 0.67 0.45 0.81 SPGR-FS 0.58 0.47 0.75 CT arthrography 0.29 0.29 0.41 Discussion section, page 521, second column: The new information should have been inserted at the end of the first paragraph describing limitations of the study. “Some of the cartilage thickness measurements in this study were too small for the spatial resolution capabilities of magnetic resonance imaging system. The spatial resolution of the computed tomographic system was adequate to support the measurements made.” ACKNOWLEDGMENTS We would like to thank Manuel Arreola, PhD for his help in assessing the system resolution. We apologize for these errors. REFERENCE 1Porter EG, Winter MD, Sheppard BJ, Berry CR, Hernandez JA. Correlation of articular cartilage thickness measurements made with magnetic resonance imaging, magnetic resonance arthrography, and computed tomographic arthrography with gross articular cartilage thickness in the equine metacarpophalangeal joint. Vet Radiol Ultrasound 2016; 57: 515– 525. Volume58, Issue2March/April 2017Pages 237-237 ReferencesRelatedInformation

Three-dimensional kinematics of the equine metacarpophalangeal joint using x-ray reconstruction of moving morphology - a pilot study.

X-ray reconstruction of moving morphology (XROMM) uses biplanar videoradiography and computed tomography (CT) scanning to capture three-dimensional (3D) bone motion. In XROMM, morphologically accurate 3D bone models derived from CT are animated with motion from videoradiography, yielding a highly accurate and precise reconstruction of skeletal kinematics. We employ this motion analysis technique to characterize metacarpophalangeal joint (MCPJ) motion in the absence and presence of protective legwear in a healthy pony. Our in vivo marker tracking precision was 0.09 mm for walk and trot, and 0.10 mm during jump down exercises. We report MCPJ maximum extension (walk: -27.70 ± 2.78° [standard deviation]; trot: -33.84 ± 4.94°), abduction/adduction (walk: 0.04 ± 0.24°; trot: -0.23 ± 0.35°) and external/internal rotations (walk: 0.30 ± 0.32°; trot: -0.49 ± 1.05°) indicating that the MCPJ in this pony is a stable hinge joint with negligible extra-sagittal rotations. No substantial change in MCPJ maximum extension angles or vertical ground reaction forces (GRFv) were observed upon application of legwear during jump down exercise. Neoprene boot application yielded -65.20 ± 2.06° extension (GRFv = 11.97 ± 0.67 N/kg) and fleece polo wrap application yielded -64.23 ± 1.68° extension (GRFv = 11.36 ± 1.66 N/kg), when compared to naked control (-66.11 ± 0.96°; GRFv = 12.02 ± 0.53 N/kg). Collectively, this proof of concept study illustrates the benefits and practical limitations of using XROMM to document equine MCPJ kinematics in the presence and absence of legwear.

Semi-automated International Cartilage Repair Society scoring of equine articular cartilage lesions in optical coherence tomography images.

Arthroscopic optical coherence tomography (OCT) is a promising tool for the detailed evaluation of articular cartilage injuries. However, OCT-based articular cartilage scoring still relies on the operator's visual estimation. To test the hypothesis that semi-automated International Cartilage Repair Society (ICRS) scoring of chondral lesions seen in OCT images could enhance intra- and interobserver agreement of scoring and its accuracy. Validation study using equine cadaver tissue. Osteochondral samples (n = 99) were prepared from 18 equine metacarpophalangeal joints and imaged using OCT. Custom-made software was developed for semi-automated ICRS scoring of cartilage lesions on OCT images. Scoring was performed visually and semi-automatically by five observers, and levels of inter- and intraobserver agreement were calculated. Subsequently, OCT-based scores were compared with ICRS scores based on light microscopy images of the histological sections of matching locations (n = 82). When semi-automated scoring of the OCT images was performed by multiple observers, mean levels of intraobserver and interobserver agreement were higher than those achieved with visual OCT scoring (83% vs. 77% and 74% vs. 33%, respectively). Histology-based scores from matching regions of interest agreed better with visual OCT-based scoring than with semi-automated OCT scoring; however, the accuracy of the software was improved by optimising the threshold combinations used to determine the ICRS score. Images were obtained from cadavers. Semi-automated scoring software improved the reproducibility of ICRS scoring of chondral lesions in OCT images and made scoring less observer-dependent. The image analysis and segmentation techniques adopted in this study warrant further optimisation to achieve better accuracy with semi-automated ICRS scoring. In addition, studies on in vivo applications are required.