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Comparison of radiography to magnetic resonance imaging (MRI) can help objectively assess the value and limitations of radiographs in orthopaedic disease processes. The tarsus and proximal suspensory origin of the metatarsus are commonly imaged regions for lameness. The knowledge gained by comparison between imaging modalities will aid in improving accuracy of radiographic interpretation.To compare the radiographic and MRI findings of the proximal third metatarsal bone (MTIII) and proximal suspensory ligament using MRI as the gold standard.Retrospective observational study.Single hindlimbs of 35 horses with radiographic and high-field (3Tesla (3T)) MRI studies were blindly evaluated by two board-certified veterinary radiologists and a radiology resident. Severity and location of the following parameters were assessed: radiographic MTIII sclerosis and lucent regions, MRI endosteal metatarsal sclerosis and bone marrow lesions, plantar cortical proliferation and resorption, and proximal suspensory desmopathy (PSD).Radiographic osseous changes of MTIII were identified in 54% of limbs, whereas 40% limbs had osseous changes on MRI: 43% of limbs had PSD on MRI. No significant association was found between the presence of radiographic changes in MTIII and PSD on MRI (P = .7). A statistically significant association and positive correlation was found between the severity of radiographic changes and MTIII plantar cortical proliferation and resorption on MRI (P = .01).Retrospective study with no histopathology. Ability to correlate findings with lameness was limited by the lack of standardised time intervals between onset of lameness, diagnostic analgesia and advanced imaging.Radiographic bony changes of proximal MTIII do not reliably predict presence or severity of PSD but are associated with osseous changes at the proximal MTIII. The presence of radiographic changes should warrant additional diagnostics in the region prior to making conclusions about the presence or absence of PSD.La comparaison de la radiographie avec l'imagerie par résonance magnétique (IRM) peut assister dans l’évaluation objective de la valeur et des limites des radiographies pour les processus pathologiques orthopédiques.Comparer les trouvailles radiographiques et d’IRM du métatarsien principal proximal (MTIII) et de la portion proximale du ligament suspenseur du boulet, en utilisant l’IRM comme référence. TYPE D’ÉTUDE: Étude de observationnelle rétrospective. MÉTHODES: Les images radiographiques et d’IRM à haut champ (3 Tesla (3T)) d'un seul membre postérieur chez 35 chevaux ont été évalués à l'aveugle par deux radiologistes vétérinaires diplômés et un résident en radiologie. La sévérité et localisation des paramètres suivants ont été documentés : sclérose et régions lytiques radiographiques du MTIII, sclérose métatarsienne de l'endostéum à l’IRM et lésions de la moelle osseuse, prolifération et résorption plantaire corticale et desmopathie du ligament suspenseur du boulet (DLSB). RÉSULTATS: Des changements radiographiques osseux du MTIII ont été identifiés sur 54 % des membres contre 40% des membres ayant des changements osseux à l’IRM. 43% des membres avaient une DLSB à l’IRM. Aucune association significative n'a pu être identifiée entre la présence de changements radiographiques du MTIII et DLSB à l’IRM (P = 0.7). Une association statistiquement significative et une corrélation positive a été identifiée entre la sévérité des changements radiographiques et la résorption/prolifération plantaires corticales du MTIII à l’IRM (P = 0.01).Étude rétrospective sans histopathologie. La possibilité de corréler les données de l'examen de boiterie a été limitée par le manque d'intervalle de temps standardisés entre l'apparition de la boiterie, l'analgésie diagnostique et l'imagerie avancée.Ces trouvailles démontrent que les changements osseux radiographiques du MTIII proximal ne peuvent prédirent de façon fiable la présence ni la sévérité de DLSB, mais ils sont par contre associés aux changements osseux du MTIII proximal à l'IRM. La présence de changements radiographiques justifie l'utilisation de méthodes diagnostiques additionnelles du MTIII proximal avant de conclure sur la présence ou l'absence de DLSB.

Blood flow restriction (BFR) has become a key rehabilitative tool for human orthopaedic conditions. With modernised technology and evolution of clinical application, patient-specific delivery of occlusion percentages is now considered the standard of care in human patients due to improved therapeutic outcomes and minimised safety risks. Safety validation and limb occlusion pressure (LOP) data for horses, however, is lacking.1) To determine if BFR exposure resulted in forelimb biomechanical gait dysfunction as safety validation and 2) To investigate inter-horse and inter-limb LOP differences.Controlled in vivo experiment.Daily unilateral forelimb BFR was performed in four horses over 56 days. Clinical examinations and objective gait analyses were performed on days 0, 28 and 56. Daily LOP values were determined by Doppler evaluation to deliver 80% vascular occlusion at a walk. A linear mixed model evaluated for differences in lameness, kinetic and kinematic gait parameters.There were no significant differences in forelimb lameness (range of grades 0-2 across all forelimbs), kinematic or kinetic gait parameters over time or between BFR-exposed and control (contra-lateral) limbs (P 0.05). Clinically apparent complications related to BFR such as thrombosis or dermatitis were not appreciated. Significant differences in mean LOP values between various horses (P 0.001) and measured left (204.48mm Hg) and right (173.78mmHg) forelimbs (P 0.001) were observed. Mean LOP and standard deviation across all readings was 189.1 ± 22.2mm Hg.Optimal BFR occlusion percentages and protocols with documented clinical efficacy are unknown. Small study population.Exposure to BFR did not result in forelimb biomechanical dysfunction in four horses. Applied pressures of 75-151 mm Hg would likely simulate a range of 50-80% vascular occlusion in horses, but inherent physiological variation between horses and forelimbs warrants incorporation of individual pressures.

The equine model of posttraumatic osteoarthritis (OA) mimics certain aspects of the naturally occurring disease, both in horses and humans. The objective of this study was to assess articular cartilage degeneration in a posttraumatic OA model using the established macroscopic and microscopic scoring systems and compare them with a novel surface topography analysis. OA was induced in the carpal joint of 15 (n = 15) mixed breed horses. Surface changes on the articular cartilage were characterized using osteochondral blocks from the third carpal bone (C3) and radial carpal bone using surface topography, standard histological grading, and gross evaluation of the joints. Significant differences were observed between OA and non-OA joints for gross evaluation scores. Microscopic scores of hematoxylin and eosin and Safranin O and Fast Green-stained sections demonstrated no differences between OA and non-OA joints. However, articular cartilage from the induced OA joint had significantly greater surface topography measurements compared with the sham treatment group, consistent with the changes seen on gross evaluation of joints. No significant correlations were noted between surface roughness measurements, histological assessment, and gross evaluation scores. The results suggest that surface topography analysis may provide a reliable objective approach to assess early changes in the cartilage surface in OA.

Over the past three decades, electrohydraulic extracorporeal shock wave therapy (ESWT) as a treatment modality for equine orthopaedic disorders has sparked exponential interest among practitioners, but its clinical applications are quickly evolving and a current review highlighting modernised equine clinical use is lacking. The objective of this review is to summarise the most current ESWT technology, evidence for its use, proposed mechanisms of action and clinical applications in horses while also highlighting the areas requiring further investigation. The three ways to generate a shock wave are through electrohydraulic, electromagnetic or piezoelectric mechanisms, but over the last decade, electrohydraulic systems have predominated due to the ability to focus and control a therapeutic waveform. Shock waves' primary physical effect is believed to be via mechanotransduction leading to cellular activation and downstream signalling. Experimentally, ESWT's effects on osseous, connective tissue and wound healing via various mechanisms of action have been reported both in the human and veterinary literature. Clinical trials have investigated ESWT's orthopaedic application including osteoarthritis, thoracolumbar pain, navicular syndrome, tendinopathy and proximal suspensory desmopathy, with its concomitant use with biologics representing an area of active research. Direct ESWT protocol comparisons in terms of long-term efficacy with variables of energy, depth and exposed tissue types are still lacking with evidence-based recommendations being largely anecdotal. Technical advancements to facilitate the safe and judicious use of ESWT include human and equine hearing protection, light sedation and/or patient restraint. Efforts to ensure the safe and judicious use of ESWT and its analgesic effects are ongoing.

BACKGROUND Osteoarthritis is a common clinical condition in the performance horse. In the last 10 years, there has been substantial growth in understanding of the disease and in the development of novel therapies. OBJECTIVES To document changes in clinical use of joint therapies over the past 10 years. We also aimed to understand how newly developed therapies have been added to routine clinical practice. STUDY DESIGN Survey of veterinary professionals. METHODS We administered an electronic survey to members of the American Association of the Equine Practitioners. Questions from a similar survey in 2009 were repeated and new questions were added. The responses were tabulated, analysed and compared to those of the previous survey. RESULTS A total of 407 completed surveys were returned. There were no significant differences between the current and previous surveys with respect to demographic parameters. Triamcinolone acetonide (TA) remained the most common corticosteroid used to treat high-motion joints. Methylprednisolone acetate (MPA) remained the most common corticosteroid to treat low-motion joints. The use of MPA for high-motion joints was significantly more common in 2009 than in 2019 (odds ratio [OR]: 2.38, 95% confidence interval [CI]: 1.66-3.42, P = .001). Biological therapies became more popular, and the likelihood of respondents reporting having used autologous conditioned serum was substantially higher in 2019 than in 2009 (OR: 4.24, 95% CI: 3.16-5.68, P

OBJECTIVE To assess whether the combination of hyaluronan, sodium chondroitin sul-fate, and N-acetyl-d-glucosamine (HCSG) lubricates articular cartilage in vitro and modulates joint lubrication in vivo. ANIMALS 16 healthy adult horses. PROCEDURES The effects of HCSG injections on SF lubricant properties and joint health, immediately after injury and 2 weeks later, were analyzed by use an equine osteochondral fracture model of post-traumatic osteoarthritis (OA). Middle carpal joints of adult horses were randomly assigned to 1 of 4 surgical treatment groups as follows: normal nonsurgical group (n = 8), normal sham-surgical group (8), OA-induced surgical group with HCSG injection (8), or OA-induced surgical group with saline (0.9% NaCl) solution injection (8). Synovial fluid was aspirated periodically and analyzed for boundary lubrication function and lubricant molecules. At 17 days, joints were screened for gross pathological changes. RESULTS Induction of OA led to an impairment of SF lubrication function and diminished hyaluronan concentration in a time-dependent manner following surgery, with HCSG injection lessening these effects. Certain friction coefficients approached those of unaffected normal equine SF. Induction of OA also caused synovial hemorrhage at 17 days, which was lower in joints treated with HCSG. CONCLUSIONS AND CLINICAL RELEVANCE After induction of OA, equine SF lubricant function was impaired. Hyaluronan-sodium chondroitin sulfate–N-acetyl-d-glucosamine injection restored lubricant properties at certain time points and reduced pathological joint changes.

Background Correct diagnosis and characterisation of deep digital flexor tendon (DDFT) lesions in equine athletes allows targeted treatment and improved prognostication. Objectives To assess the prevalence and character of pathological change within the DDFT in the pastern with concurrent tendon injury distally. It is hypothesised that tendon lesions in the pastern will be associated with tendinopathy within the hoof capsule. Study design Retrospective descriptive case series. Methods Cases with DDFT lesions in the pastern and magnetic resonance imaging (MRI) or ultrasonography of the foot were evaluated retrospectively. Lesion location and type were recorded. Odds ratios were calculated to determine the associations between more distal tendinopathy and the presence of different DDFT lesion types in the pastern. Results Thirty-four MRI scans of 33 horses and 64 ultrasonographic exams of 58 horses were analysed. Lesion location and type were recorded. Distal DDFT lesions were found in 75% (95% CI: 66.0-84.0) of total cases of pastern DDF tendinopathy and in 97% (95% CI: 91.6-100.0) of cases with core lesions of the DDFT in the pastern. A core lesion in the pastern was significantly more likely (OR = 20.7, 95% CI: 2.2-191.0; P = .008) to be associated with injury in the foot than other types of pastern lesion. Main limitations MRIs of the foot were not obtained on all included limbs which did not allow for fully inclusive evaluation of DDFT lesions distal to the navicular bone. Conclusions DDFT pathological change in the pastern, particularly core lesions, is associated with additional tendinopathy within the hoof capsule. When a DDFT lesion is found in the pastern, further imaging of the tendon within the foot is indicated to direct appropriate treatment and improve prognostication.

Background: Microfracture augmentation can be a cost-effective single-step alternative to current cartilage repair techniques. Trypsin pretreatment combined with a growth factor–functionalized self-assembling KLD hydrogel (“functionalized hydrogel”) has been shown to improve overall cartilage repair and integration to surrounding tissue in small animal models of osteochondral defects. Hypothesis: Microfracture combined with trypsin treatment and a functionalized hydrogel will improve reparative tissue quality and integration as compared with microfracture alone in an equine model. Study Design: Controlled laboratory study. Methods: Bilateral cartilage defects (15-mm diameter) were created on the medial trochlear ridge of the femoropatellar joints in 8 adult horses (16 defects total). One defect was randomly selected to receive the treatment, and the contralateral defect served as the control (microfracture only). Treatment consisted of 2-minute trypsin pretreatment of the surrounding cartilage, subchondral bone microfracture, and functionalized hydrogel premixed with growth factors (platelet-derived growth factor and heparin-binding insulin-like growth factor 1). After surgery, all horses were subjected to standardized controlled exercise on a high-speed treadmill. Clinical evaluation was conducted monthly, and radiographic examinations were performed at 2, 16, 24, 32, 40, and 52 weeks after defect creation. After 12 months, all animals were euthanized. Magnetic resonance imaging, arthroscopy, gross pathologic evaluation of the joint, histology, immunohistochemistry, and biomechanical analyses were performed. Generalized linear mixed models (with horse as random effect) were utilized to assess outcome parameters. When P values were Results: Improved functional outcome parameters were observed for the treatment group, even though mildly increased joint effusion and subchondral bone sclerosis were noted on imaging. Microscopically, treatment resulted in improvement of several histologic parameters and overall quality of repaired tissue. Proteoglycan content based on safranin O–fast green staining was also significantly higher in the treated defects. Conclusion: Trypsin treatment combined with functionalized hydrogel resulted in improved microfracture augmentation. Clinical Relevance: Therapeutic strategies for microfracture augmentation, such as those presented in this study, can be cost-effective ways to improve cartilage healing outcomes, especially in more active patients.

BACKGROUND Pathology involving the oblique sesamoidean ligaments (OSLs) is commonly diagnosed during magnetic resonance imaging (MRI) of the equine distal limb. Presence of striations within the ligament and magic angle artefact can result in an incorrect diagnosis of pathological change. No studies have been performed using histopathology, the gold standard, to corroborate their imaging diagnosis. OBJECTIVES (a) To determine which MRI characteristics are associated with normal vs abnormal OSLs and (b) to evaluate the ability of MRI to correctly identify abnormal vs normal oblique sesamoidean ligaments using histopathology as the gold standard. STUDY DESIGN Observational, cross-sectional study. METHODS Cadaver limbs (n = 77) were obtained from horses (n = 21) subjected to euthanasia at the hospital. MRI and histopathology was performed on each of the limbs. MRI scoring was performed for multiple MRI characteristics, and each limb was deemed normal or abnormal. Histopathology scoring was performed to give an overall score of normal or abnormal. Mixed model logistic regression was performed to evaluate which MRI characteristics were associated with normal vs abnormal OSLs using backwards elimination and a significance level of

Tendinopathy has been broadly characterized as alterations in cell proliferation, extracellular matrix turnover/synthesis, and inflammatory alterations. However, the underlying glucose metabolism pathways which contribute to these responses have not been well explored. The potential link between glucose metabolism and tendon pathology is interesting from a global standpoint since the development of spontaneous tendinopathy is associated with systemic metabolic disorders including diabetes mellitus. Therefore, the overarching goal of this study was to understand the potential pathogenic role of glucose metabolism-driven mechanisms in the development of tendinopathy. To test this, we have utilized an un-targeted metabolomics approach to discover pathways which may be altered following tendinopathic injury and treadmill running in an established murine model of TGF-β1 induced tendinopathy. While specific tendon glucose alterations were not observed via metabolomics or (18)F-fluoroeoxyglucose (FDG) Positron Emission Tomography/Micro-Computed Tomography Imaging ((18)F-FDG PET/CT), metabolites including creatinine, D-chiro-inositol, and lipids were dysregulated following tendon injury. CLINICAL RELEVANCE: As novel pathways for manipulation, the creatine pathway, myo-inositol pathway, and lipid signaling may lead to the development of enhanced preventative strategies and therapeutic options for all patients who suffer from tendon related injuries.

Proximal suspensory desmitis (PSD) is a frequent cause of lameness in the performance horse. Extracorporeal shockwave therapy (EST) and platelet rich plasma (PRP) have become common treatments for PSD yet clinical data on efficacy is limited. The main objective of this randomized, prospective clinical study was to compare long-term effectiveness of EST and PRP in Western performance horses. One hundred horses with lameness localized to the proximal suspensory ligament received treatment with either PRP or EST following baseline ultrasonographic evaluation. A veterinarian and agent evaluated the horses for lameness independently four days following the first treatment and long-term follow up was obtained from the agent at six and twelve months. Four days post treatment, horses treated with EST had significantly greater lameness improvement compared to PRP. At one-year horses with less severe baseline ultrasound changes (grades 0–1) appeared to respond better (degree of lameness) with EST treatment whereas horses with more severe ultrasound changes (grade 2) responded better to PRP. Horses with baseline lameness graded 1 or 2 were 5.1 times more likely to be back in work at 1 year compared to those presenting with grade 3 or 4. EST treatment was associated with going back to work 3.8 times more at one year compared to PRP independent of baseline ultrasound score. Both PRP and EST can be expected to yield favorable therapeutic responses in Western performance horses with lameness localized to the proximal suspensory region. Baseline ultrasound may guide treatment selection.

Focal cartilage defects caused by joint injury have a limited capacity to self-repair and, if left untreated, can lead to the early onset of osteoarthritis. The current standard of care, microfracture surgery, induces an endogenous repair response, but typically results in poorly integrated fibrocartilage, rather than native hyaline cartilage. The objective of this study was to test the hypothesis that a self-assembling peptide hydrogel functionalized with the proanabolic growth factor heparin-binding insulin-like growth factor-1 (HB-IGF-1) may improve integration between native cartilage and neotissue when combined with a brief enzymatic pretreatment to the defect site. This enzymatic pretreatment releases proteoglycans from the walls of the surrounding native cartilage in a controlled manner and, thereby, creates space for newly synthesized repair tissue to anchor and integrate with adjacent host cartilage. We used an in vitro model in which a cylindrical annulus of native cartilage was pretreated with trypsin over a 2-min period and then filled with a chondrocyte-seeded [KLDL](3) hydrogel functionalized with proanabolic HB-IGF-1 that had been premixed into the gel. This procedure was deemed to be clinically tractable in the context of ongoing parallel animal studies as a method to augment the microfracture procedure. The trypsin pretreatment depleted proteoglycan content of adjacent cartilage in a controlled manner without inducing cell death. The addition of HB-IGF-1 was found to stimulate matrix biosynthesis both in the surrounding cartilage and the chondrocyte-seeded KLD scaffold, and to enhance mechanical integration of neotissue into native matrix. IMPACT STATEMENT: A critical attribute for the long-term success of cartilage defect repair is the strong integration between the repair tissue and the surrounding native tissue. Current approaches utilized by physicians fail to achieve this attribute, leading to eventual relapse of the defect. This article demonstrates the concept of a simple, clinically viable approach for enhancing tissue integration via the combination of a safe, transient enzymatic treatment with a locally delivered, retained growth factor through an in vitro hydrogel/cartilage explant model.

© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. The objective of this study was to improve cartilage repair and integration using self-assembling KLD hydrogel functionalized with platelet-derived growth factor-BB and heparin-binding insulin-like growth factor-1 with associated enzymatic trypsin pre-treatment of the native cartilage. Bilateral osteochondral defects were created at the central portion of the femoral trochlear groove of 48 skeletally mature, white New Zealand rabbits. One limb received a randomly assigned treatment and the contralateral limb served as the control. Treated defects were exposed to trypsin for 2 min and filled with self-assembling KLD hydrogel only, or associated to growth factors. All control limbs received KLD hydrogel alone or received only trypsin but not hydrogel. Ninety days post-defect creation, the rabbits were euthanized and magnetic resonance imaging, radiography, macroscopic evaluation, histology, and immunohistochemistry of the joint and repaired tissue were performed. Mixed model analyses of variance were utilized to assess the outcome parameters and individual comparisons were performed using Least Square Means procedure and differences with p-value ' 0.05 were considered significant. Trypsin enzymatic pre-treatment improved cellular morphology, cluster formation and subchondral bone reconstitution. Platelet-derived growth factor-BB improved subchondral bone healing and basal integration. Heparin-binding insulin-like growth factor-1 associated with platelet-derived growth factor improved tissue and cell morphology. The authors conclude that self-assembling KLD hydrogel functionalized with platelet-derived growth factor and heparin-binding insulin-like growth factor-1 with associated enzymatic pre-treatment of the native cartilage with trypsin resulted in an improvement on the cartilage repair process. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2307–2315, 2019.

BACKGROUND The range of diagnostic modalities available to evaluate superficial digital flexor tendon (SDFT) injury includes magnetic resonance imaging (MRI), computed tomography (CT) and ultrasonography (US). Direct, comprehensive comparison of multi-modality imaging characteristics to end-point data has not previously been performed using a model of tendinopathy but is required to obtain a better understanding of each modality's diagnostic capabilities. OBJECTIVE To compare CT, MRI and US evaluation to outcome measures for histologic, biochemical and biomechanical parameters using an equine surgical model of tendinopathy. STUDY DESIGN Controlled experiment. METHODS Lesions were surgically created in both forelimb SDFTs of eight horses and imaged using MRI, CT and US at seven time points over 12 months. Imaging characteristics were then correlated to end point histologic, biochemical and biomechanical data using lasso regression. Longitudinal lesion size was compared between imaging modalities. RESULTS Lesion to tendon isoattenuation on CT evaluation correlated with the greatest levels of aggrecan deposition. A significant correlation between cellular density and percentage of tendon involvement on the T2-weighted sequence and signal intensity on the proton density fat saturated (PD FS) sequence was appreciated at the 12-month time point (P = .006, P = .02 respectively). There was no significant correlation between end-point data and US or contrast imaging characteristics. Cross sectional area lesion to tendon measurements were significantly largest on CT evaluation, followed by MRI and then US (P

Background Hemoderivatives such as autologous conditioned serum (ACS) and platelet-rich plasma (PRP) have been used as potential disease-modifying therapies in musculoskeletal disorders such as osteoarthritis (OA). These therapies are based on the delivery of multiple growth factors and anti-inflammatory cytokines that are known to participate in inflammatory processes. The variability of cytokine content due to the autologous nature of the product, the non-availability for immediate use and need for storage at low temperatures are limitations for its use in the field. An allogeneic freeze-dried conditioned serum (CS) and PRP would provide field clinicians with a more practical approach to use such products in daily practice. Based on in vitro preliminary data, this experimental study aimed to test the in vivo safety of allogeneic freeze-dried CS and PRP in healthy joints, using the horse as a model. Results Eight horses were randomly assigned and treated with PRP or CS. Horses had three joints injected with ALLO-FD PRP or CS, and three contralateral joints injected with the AUTO version of the same product, by a blinded clinician. Horses were evaluated clinically, and had synovial fluid collected at different time points and evaluated for cell content, PGE2 and protein. Both CS and PRP products triggered a self-limiting and mild inflammatory response in equine healthy joints. This was indicated by the transient increase in nucleated cell count, PGE2 and total protein in synovial fluid. This mild inflammatory response did not result in significant lameness and was not different among the groups. Conclusions The allogeneic freeze-dried PRP and CS showed to be overall safe and not dissimilar compared to their autologous frozen version in equine healthy joints. Further studies are necessary to evaluate the modulatory effects of these therapies in a clinical setting.

Back pain and inflammation of the epaxial musculature is a significant problem in all equine athletes. Treatment of back pain can be challenging and often requires a multimodal approach. In humans, bio-electromagnetic energy regulation therapy (BEMER) has been reported to be effective in pain modulation. With its increased use in people comes a similar robust application in veterinary medicine unfortunately, there is unsubstantiated evidence for this type of therapy in horses. Objectives of this study were to assess analgesic responses and biomechanical outcome variables using a bio-electromagnetic energy regulation therapy blanket, and to evaluate serum biomarkers as a method to monitor the treatment effects in horses with thoracolumbar epaxial muscle pain. Cohort study of 8 horses treated for 3 consecutive days. Horses with naturally-occurring thoracolumbar epaxial muscle pain were used in this study. Objective outcome variables were recorded daily for 5 days, which included spinal evaluation, mechanical nociceptive thresholds, electromyography, kinematics, kinetics, and serum biomarkers. BEMER blanket therapy significantly improved thoracolumbar epaxial muscle nociceptive thresholds. Center of pressure displacement as a measure of postural stability was significantly improved as well as significant gains in spinal flexibility were demonstrated at study completion. A significant treatment effect was not appreciated in measures of muscle tone, ground reaction forces or serum biomarkers. Limitations include the lack of a control group and a definitive structural diagnosis of thoracolumbar epaxial muscle pain. The BEMER blanket produced significant clinical and biomechanical effects in horses with back pain.

BACKGROUND Similar to other high-level athletic disciplines, the western performance horse experiences a variety of orthopaedic conditions as a result of rigorous sport-specific physical demands. While musculoskeletal injury rates have been quantified in other equine disciplines, these data are lacking for the western performance athlete. OBJECTIVES To identify the most common anatomical regions of lameness in western performance horses being evaluated at the nation's largest sanctioned shows over a 10-year study period. STUDY DESIGN Retrospective review of clinical records. METHODS Records of diagnostic analgesia of western performance horses competing at nationally sanctioned shows were retrospectively reviewed over a 10-year period to identify affected limb(s) and lameness localisation patterns. RESULTS A total of 2267 lameness examinations on 2512 horses were included. The average lameness grade was 2.21/5 with 1504/2267 (56%) cases being primarily forelimb in origin while 1173/2267 (44%) were hindlimb related. Forelimb lameness localised to the distal limb in 40% of cases. The proximal metatarsus/distal tarsus was an identified source of lameness in 16% of cases, followed by the stifle in 9% of cases. All-around western performance horses most commonly presented with a single hindlimb lameness (315/1188, 26.5%) in contrast to reining horses that presented with a single forelimb lameness (135/616, 22%). DISCUSSION Determining the source of lameness through diagnostic analgesia remains challenging, but the continued assessment of response to diagnostic analgesia may help characterise discipline-specific injuries in western performance horses. MAIN LIMITATIONS Retrospective review of subjective responses to diagnostic analgesia. CONCLUSIONS The distal forelimb and distal tarsus/proximal metatarsus were the two most common anatomical regions of lameness based on response to diagnostic analgesia.

High field magnetic resonance imaging (MRI) is increasingly used for horses with suspected stifle disease, however there is limited available information on normal imaging anatomy and potential incidental findings. The aim of this prospective, anatomic study was to develop an optimized high field MRI protocol for evaluation of the equine stifle and provide detailed descriptions of the normal MRI appearance of the stifle soft tissues, using ultrasound and gross pathological examination as comparison tests. Nine cadaver limbs were acquired from clinically normal horses. Stifles were evaluated ultrasonographically and then by an extensive 1.5 T MRI protocol. Subsequently, all stifles were evaluated for gross pathologic change. Findings were compared between gross evaluation and MRI imaging and described. No soft tissue structure abnormalities were identified on any evaluation. Specific descriptive findings of the meniscotibial, meniscofemoral, collateral, patellar and cruciate ligaments, and the menisci were reported. The high field MRI protocol described in this study provided high spatial and contrast resolution of the soft tissue structures, and this in turn allowed visualization of detailed structural characteristics, such as striations and variations in signal intensity. Findings supported the use of high field MRI as a modality for the evaluation of the soft tissues of the equine stifle. As clinical availability of this modality increases in the future, authors anticipate that new stifle diseases will be detected that have not previously been identified with other imaging modalities.

Radiographic flexor cortical lysis indicates advanced degenerative change and its earlier recognition may improve case outcome. Aims of this prospective, diagnostic accuracy study were to determine effects of radiographic beam angle and observer on accuracy of lesion detection. The sample included 36 limbs from 31 horses. Palmaroproximal-palmarodistal oblique (skyline) radiographs were acquired at standard (n = 38) and more shallow (alternate) angles (n = 58). Images were independently reviewed by four experience levels of five observers each (n = 20) for the presence and severity of flexor cortical lysis. Observers also reported their confidence in these answers. Responses were compared based on seeing a standard skyline or multiple projections. The definitive presence (or absence) and severity of lysis was based upon radiologist consensus agreement. When assessed by observer, the identification of lysis and the assessment of its severity was most similar to that of radiologists when observers of all levels of experience were able to view multiple skyline projections (P = 0.399, P = 0.174). Using multiple views to detect lysis resulted in improved sensitivity (85.3% vs. 97.2%, P < 0.001), decreased specificity (82.8% vs. 74.5%, P = 0.03), and improved interobserver agreement (86.0% vs. 90.2%, P = 0.21). On average, observers of all levels of experience became more confident viewing multiple projections (P < 0.001). Skyline radiographs using a flatter angle of incidence improve radiographic detection and characterization of flexor cortical lysis severity, may allow the beam to be tangential to the more distal portion of the navicular bone, and are recommended when flexor cortical lysis is suspected.

OBJECTIVE To determine accuracy for a technique of needle redirection at a single craniolateral site for injection of 3 compartments of the equine stifle joint, describe the external needle position, and identify the location of the needle tip within each joint compartment. SAMPLE 24 equine cadaver stifle joints. PROCEDURES Stifle joints were placed in a customized stand. After the needle was placed, external needle position was measured and recorded. Each joint compartment (medial and lateral compartments of the femorotibial joint and the femoropatellar joint) was injected with a solution containing iodinated contrast medium, water, and dye. Radiography, assessment of intra-articular location of the needle tip, and gross dissection were performed to determine success of entering each joint compartment. Student t tests and an ANOVA were used to compare mean values. RESULTS Overall accuracy was 19 of 24 (79.1%), and accuracy for individual joint compartments was at least 21 of 24 (87.5%). Mean depth of needle insertion to access each compartment of the stifle joint was 5.71 cm. Mean angle of insertion (relative to the long axis of the tibia) was 82.1°, 80.3°, and 18.5° for the medial compartment of the femorotibial joint, lateral compartment of the femorotibial joint, and femoropatellar joint, respectively, and 28° medial, 7.3° lateral, and 1.3° lateral for the medial compartment of the femorotibial joint, lateral compartment of the femorotibial joint, and femoropatellar joint, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results supported that this was an accurate technique for successful injection of the 3 equine stifle joint compartments.

OBJECTIVE To evaluate the effects of exercise in an underwater treadmill (UWT) on forelimb biomechanics and articular histologic outcomes in horses with experimentally induced osteoarthritis of the middle carpal joint. ANIMALS 16 horses. PROCEDURES An osteochondral fragment was induced arthroscopically (day 0) in 1 middle carpal joint of each horse. Beginning on day 15, horses were assigned to exercise in a UWT or in the UWT without water (simulating controlled hand walking) at the same speed, frequency, and duration. Thoracic and pelvic limb ground reaction forces, thoracic limb kinematics, and electromyographic results for select thoracic limb muscles acting on the carpi were collected on days -7 (baseline), 14, 42, and 70. Weekly evaluations included clinical assessments of lameness, response to carpal joint flexion, and goniometric measurements of thoracic limb articulations. At study conclusion, articular cartilage and synovial membrane from the middle carpal joints was histologically examined. RESULTS Exercise in a UWT significantly reduced synovial membrane inflammation and resulted in significant clinical improvements with regard to symmetric thoracic limb loading, uniform activation patterns of select thoracic limb muscles, and return to baseline values for carpal joint flexion, compared with results for horses with simulated hand walking. CONCLUSIONS AND CLINICAL RELEVANCE Overall improvements in thoracic limb function, joint range of motion, and synovial membrane integrity indicated that exercise in a UWT was a potentially viable therapeutic option for the management of carpal joint osteoarthritis in horses.

OBJECTIVE To determine the effects of altering location of right forelimb and pelvic sensors on kinematic data obtained with a commonly used inertial sensor system during gait analysis of trotting horses. DESIGN Experimental study. ANIMALS 12 horses with mild to moderate lameness of at least 1 hind limb, with or without lameness of the forelimbs. PROCEDURES All horses were examined while trotting on a high-speed treadmill. The right forelimb sensor was tested at 3 anatomic locations in random order: dorsal midline and 2 cm medial and lateral to that midline. During another treadmill session, the pelvic sensor was tested at 5 anatomic locations in random order: dorsal midline, 2 cm to the right and left of midline, and 2 cm cranial and caudal to the tubera sacrale on the midline. Laterality of the pelvic sensor was analyzed in 2 ways: sensor toward the right or left and sensor toward or away from the lame or lamest hind limb. Maximum and minimum differences in head and pelvic motion and vector sum values were ranked and compared with values for the midline location by means of mixed-model ANOVA. RESULTS Altering the location of the right forelimb sensor by 2 cm medially or laterally had no significant effect on forelimb or hind limb kinematics. However, location of the pelvic sensor had a significant effect on minimum difference in pelvic motion, regardless of whether the data were analyzed by laterality (right vs left) or toward versus away from the lame hind limb. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study indicated that a 2-cm change in the location of the pelvic sensor during kinematic gait analysis had a significant effect on hind limb kinematic data of the system used. Therefore, placement of this sensor needs to be anatomically accurate.

Mesenchymal stem cells (MSCs) have emerged as a promising treatment for orthopaedic disease. Well-established equine models of posttraumatic osteoarthritis, focal cartilage healing, and tendonitis provide a platform for testing safety and efficacy of biologic therapies such as MSCs in a species with naturally occurring disease. Horses routinely experience similar conditions that mirror human musculoskeletal injury, including osteoarthritis, meniscal injuries, and Achilles tendinopathy, which provide relevant clinical models for therapeutic interventions. The use of MSCs in equine models of osteoarthritis and focal cartilage healing has yielded encouraging results. When MSCs have been used in equine models of tendonitis or tendonosis, most clinical and experimental studies have been consistently positive. Currently, the relationship among MSC lifespan, persistence within the injured site, administration methods, and treatment efficacy remains unclear, resulting in widespread interest in cell tracking. We conclude that equine models of musculoskeletal disease can provide important preclinical insights into the likely efficacy and mechanisms of activity of MSCs for the treatment of human orthopaedic injuries.

Background High prevalence of musculoskeletal disorders in racehorses and its impact on horse welfare and racing economics call for improved measures of injury diagnosis and prevention. Serum biomarkers of bone and cartilage metabolism have previously shown promise in prediction of musculoskeletal injuries in horses. This study aimed to re-evaluate usability of the predictive serum biomarkers identified in North American Thoroughbred racehorses in a geographically distinct group of Polish Thoroughbreds. Results Serum concentrations of bone and cartilage biomarkers: osteocalcin, c-terminal telopeptide of type I collagen, total glycosaminoglycans (GAG), chondroitin sulfate epitope and c-propeptide of type II procollagen (CPII) were evaluated in the beginning and the next 3 months of one racing season in a cohort of twenty-six 2-year-old Polish racehorses. Exit criteria were diagnosis of musculoskeletal injury, leading to > 5 days off training (n = 8), or completion of 3 study months with no training interruptions (n = 18). Normalized results and matching archival data from 35 2-year-old North American racehorses was used for logistic regression analysis to identify universal predictors of injury. Mean GAG and CPII levels were lower in injured group comparing to control, which is consistent with previous findings in racehorses. These biomarkers were also identified as predictors of injury in the mixed population model. Population origin had no significant effect on predictive value of evaluated biomarkers (Wald test p = 0.137). Decreased osteocalcin and increased c-terminal telopeptide of type I collagen levels in injured horses comparing to controls were specific for Polish population and signalized disruption in bone turnover homeostasis. Conclusions Changes in serum GAG and CPII in racehorses at risk of injury appear to be similar across distinct populations while dynamics of serum bone marker is more population-specific. Electronic supplementary material The online version of this article (10.1186/s12917-019-1799-7) contains supplementary material, which is available to authorized users.

Simple Summary Neck pain and dysfunction in the horse is becoming an increasingly important topic among riders, trainers and veterinarians. Some horses may present for a subtle performance decline, while others may show dramatic, dangerous behavior. It is important to recognize how to carefully evaluate the horse in an effort to understand the different types of pain that may be contributing to the different behaviors. The musculoskeletal and nervous systems may both play a role in the development of clinical signs. Recognizing that there are many diagnostic options as well as several treatments choices is important. This synopsis covers the disease processes that may contribute to the development of neck pain and dysfunction in the horse, as well as several possible diagnostic and treatment options. Abstract Interest in the cervical spine as a cause of pain or dysfunction is increasingly becoming the focus of many equine practitioners. Many affected horses are presented for poor performance, while others will present with dramatic, sometimes dangerous behavior. Understanding and distinguishing the different types of neck pain is a starting point to comprehending how the clinical presentations can vary so greatly. There are many steps needed to systematically evaluate the various tissues of the cervical spine to determine which components are contributing to cervical pain and dysfunction. Osseous structures, soft tissues and the central and the peripheral nervous system may all play a role in these various clinical presentations. After completing the clinical evaluation, several imaging modalities may be implemented to help determine the underlying pathologic processes. There are multiple treatment options available and each must be carefully chosen for an individual horse. Provided is a synopsis of the current knowledge as to different disease processes that can result in cervical pain and dysfunction, diagnostic approaches and treatment strategies. Improving the knowledge in these areas will ideally help to return horses to a state of well-being that can be maintained over time and through the rigors of their job or athletic endeavors.

The status of articular cartilage often defines the level, progression, and subsequent prognosis of joint disease in both human and equine athletes. Although methods to diagnose equine cartilage defects have significantly improved over the past decade, articular cartilage damage and ensuing osteoarthritis remain a challenge to treat. The following 2 categories of surgical options for cartilage repair in the horse are typically considered: palliative and reparative or restorative. Palliative surgical care consists of arthroscopic debridement and lavage, whereas reparative options involve the use of marrow stimulation techniques. Restorative or reparative surgical options are an area of active research, including the use of osteochondral grafting, autologous chondrocyte implantation (ACI), and augmentation with mesenchymal stem cells (MSCs). Subchondral bone microfracture coupled with intra-articular stem cell injection is currently considered to be the optimal treatment combination for equine patients with articular cartilage defects. Following arthroscopic surgery, the rehabilitative goals are to provide support to the affected limb, restore joint flexibility, stability, and manage perioperative pain. In addition, biologic therapy for the treatment of equine joint disease continues to be clinically employed and of investigational interest. With the large amount of ongoing in vitro research in bioprinted osteochondral constructs and potential extracellular matrix components, and the advantages of the in vivo equine model of articular cartilage repair as well as naturally occurring disease, it seems inevitable that the horse would be used to develop these novel techniques.

Purpose To describe T2 mapping values in arthroscopically determined International Cartilage Repair Society (ICRS) grades in damaged and healthy-appearing articular cartilage waste specimens from arthroscopic femoroacetabular impingement (FAI) treatment. Furthermore, we sought to compare ICRS grades of the specimens with biochemical, immunohistochemistry and histologic endpoints and assess correlations with T2 mapping. Methods Twenty-four patients were prospectively enrolled, consecutively, between December 2011 and August 2012. Patients were included if they were aged 18 years or older and met criteria that followed the clinical indications for arthroscopy to treat FAI. Patients with prior hip trauma including fracture or dislocation or who have undergone prior hip surgery were excluded. All patients received a preoperative sagittal T2 mapping scan of the hip joint. Cartilage was graded intraoperatively using the ICRS grading system, and graded specimens were collected as cartilage waste for histologic, biochemical, and immunohistochemistry analysis. Results Forty-four cartilage specimens (22 healthy-appearing, 22 damaged) were analyzed. Median T2 values were significantly higher among damaged specimens (55.7 ± 14.9 ms) than healthy-appearing specimens (49.3 ± 12.3 ms; P = .043), which was most exaggerated among mild (grade 1 or 2) defects where the damaged specimens (58.1 ± 16.4 ms) were significantly higher than their paired healthy-appearing specimens (48.7 ± 15.4 ms; P = .026). Severely damaged specimens (grade 3 or 4) had significantly lower cumulative H&E than their paired healthy-appearing counterparts ( P = .02) but was not statistically significant among damaged specimens with mild (grade 1 or 2) defects ( P = .198). Among healthy-appearing specimens, median T2 and the percentage of collagen fibers oriented parallel were significantly correlated (rho = 0.425, P = .048). Conclusions This study outlines the potential for T2 mapping to identify early cartilage degeneration in patients undergoing arthroscopy to treat FAI. Findings in ICRS grade 1 and 2 degeneration corresponded to an increase in T2 values. Further biochemical evaluation revealed a significant difference between healthy-appearing cartilage and late degeneration in cumulative H&E as well as significantly lower percentage of collagen fibers oriented parallel and a higher percentage of collagen fibers oriented randomly when considering all grades of cartilage damage. Level of Evidence Level II, prospective comparative study.