Longitudinal in vivo cationic contrast-enhanced computed tomography classifies equine articular cartilage injury and repair.

Cationic contrast-enhanced computed tomography (CECT) capitalizes on increased contrast agent affinity to the charged proteoglycans in articular cartilage matrix to provide quantitative assessment of proteoglycan content with enhanced images. While high resolution microCT has demonstrated success, we investigate cationic CECT use in longitudinal in vivo imaging at clinical resolution. We hypothesize that repeated administration of CA4+ will have no adverse side effects or complications, and that sequential in vivo imaging assessments will distinguish articular cartilage repair tissue from early degenerative and healthy cartilage in critically sized chondral defects. In an established equine translational preclinical model, lameness and synovial effusion scores are similar to controls after repeated injections of CA4+ (eight injections over 16 weeks) compared to controls. Synovial fluid total protein, leukocyte concentration, and sGAG and PGE2 concentrations and articular cartilage and synovial membrane scores are also equivalent to controls. Longitudinal in vivo cationic CECT attenuation in repair tissue is significantly lower than peripheral to (adjacent) and distantly from defects (remote sites) by 4 weeks (p < 0.001), and this difference persists until 16 weeks. At the 6- and 8-week time points, the adjacent locations exhibit significantly lower cationic CECT attenuation compared with the remote sites, reflecting peri-defect degeneration (p < 0.01). Cationic CECT attenuation at clinical resolution significantly correlates with cationic CECT (microCT) (r = 0.69, p < 0.0001), sGAG (r = 0.48, p < 0.0001), and ICRS II histology score (r = 0.63, p < 0.0001). In vivo cationic CECT imaging at clinical resolution distinguishes fibrous repair tissue from degenerative and healthy hyaline cartilage and correlates with molecular tissue properties of articular cartilage.

Substantial variability exists in the interpretation of survey radiographs among equine veterinarians.

BACKGROUND: Radiographs are a common diagnostic tool utilised during pre-purchase examinations, yet differences surround their interpretation among equine veterinarians. OBJECTIVES: (1) To determine veterinarians' subjective impressions of a spectrum of radiographic abnormalities regarding suitability for purchase; (2) To determine how veterinarians' years in practice, primary discipline or board certification status influence their subjective impression of radiographic abnormalities, and (3) To determine how horses' discipline, current level of work (working at intended level vs. future prospect) and buyer intent (sell vs. retain ownership) influence veterinarians' subsequent recommendation. STUDY DESIGN: Worldwide electronic survey of veterinary professionals. METHODS: Four radiographic series of navicular bones, tarsi, and stifles, representing varying degrees of pathological change (normal, mild, moderate and marked) were presented. Respondents (n = 211) graded their level of concern from 1 (no concern) to 10 (very concerned) based on the radiographs and case scenarios presented. RESULTS: Overall, as the grade of pathological change increased for each anatomical location, so did the level of veterinarian concern, but a wide range of answers were submitted for all grades of pathology. Board certified practitioners had a higher level of concern over marked radiographic changes of the navicular bone for both western performance and English sport horses as well as prospect horses (mean = 7.2 vs. 6.1; P = 0.009; 95% CI for difference = [0.3, 2.0]). Board certified respondents had a lower level of concern over marked radiographic changes of the tarsus regardless of the performance status of the horse (mean = 7.1 vs. 8.0; P = 0.008; 95% CI for difference = [-1.5, -0.2]). Western performance horse practitioners had a lower level of concern over mild radiographic changes of the tarsus regardless of the performance status of the horse (mean = 3.3 vs. 4.2; P = 0.009; 95% CI for difference = [-1.6, -0.2]). MAIN LIMITATIONS: Only one example of each pathological grade per anatomical region was presented. CONCLUSIONS: On survey radiographs, the perceived clinical relevance of radiographic abnormalities among equine practitioners differs widely, making purchase recommendations highly variable.

Advances in Regional Vascular Injection Techniques for the Delivery of Stem Cells to Musculoskeletal Injury Sites.

Vascular injections of stem cells are a pertinent alternative to direct intralesional injections when treating multiple or extensive lesions or with lesions impossible to reach directly. Extensive research using stem cell tracking has shown that intra-arterial injections without the use of a tourniquet should be preferred over venous or arterial regional limb perfusion techniques using a tourniquet. The median artery is used for the front limbs and the cranial tibial artery for the hind limbs. Proper efficacy studies are still lacking but early clinical work seems promising.

Comparison of Ultrasound and Magnetic Resonance Imaging for Identifying Soft Tissue Abnormalities in the Palmar Aspect of the Equine Digit.

Damage to the soft tissue structures of the digit is a common source of equine lameness. While magnetic resonance imaging (MRI) allows for the most complete diagnostic imaging of the equine digit, ultrasound is more readily available and less expensive. This prospective diagnostic accuracy study compares ultrasound to MRI for the diagnosis of injuries visible with ultrasound within the digit, including the deep digital flexor tendon (DDFT), collateral sesamoidean ligament (CSL), and navicular bursa. Clinical patients underwent an MRI of the digit and a blinded ultrasound of the digit between the heel bulbs, and results of the two modalities were compared. A total of 70 ultrasound and MRI exams of 45 horses were included. Ultrasound had good sensitivity (85%), moderate specificity (60%), and accuracy of 70% for evaluating the dorsal tearing of the DDFT. Accuracy was lower for navicular bursa effusion (67%), navicular bursa proliferation (61%), and CSL enlargement (61%). Tearing of the DDFT distal to the navicular bone was identified with MRI in 27 limbs, 20 of which also had dorsal damage proximal to the navicular bone identified with ultrasound. Ultrasound evaluation remains a useful screening tool, particularly for the assessment of DDFT tearing proximal to the navicular bone but risks under-diagnosing pathology to the navicular bursa and CSL. Clinically significant concurrent damage to the distal DDFT and other osseous and soft tissues in the hoof capsule is unlikely to be identified without MRI.

Contrast administration via ultrasound-guided injection of the cranial tibial artery results in contrast enhancement of the soft tissues of the metatarsus in horses undergoing CT.

Delivery of mesenchymal stem cells (MSC) via intravascular techniques to treat diffuse and/or inaccessible soft tissue injuries has grown in popularity. The purpose of the current prospective, analytical pilot study was to utilize CT to validate this novel technique and provide additional evidence to support its use for injectate delivery to specific soft tissue structures. Of particular interest was the proximal suspensory ligament, which presents a challenging injection target. Six adult horses without lameness underwent CT of the distal hindlimbs. Scans were obtained prior to ultrasound-guided catheterization of the cranial tibial artery, in addition to early and delayed scans acquired following intra-arterial contrast administration. Region of interest analysis of the superficial and deep digital flexor tendons and suspensory ligament was used to assess contrast enhancement within these structures. Linear mixed models were used to determine statistical significance. Significant (P < 0.05) mean contrast enhancement was seen in all postinjection time points in all soft tissue structures of interest. This indicates that ultrasound-guided injection of the cranial tibial artery results in perfusion of injectate throughout the distal hind limb, including the major soft tissue structures of the metatarsus. This provides further support for this technique as a method of MSC delivery to multifocal or inaccessible injury of these structures, including the proximal suspensory ligament.

A Randomized, Self-Controlled Case Series Evaluating Core Osteostixis of Osseous Cyst-Like Lesions of the Navicular Bone to Improve Lameness in Horses with Podotrochlear Syndrome.

Introduction: Podotrochlear syndrome is a common cause of lameness in Quarter Horses involving both soft tissue and bony structures within the heel region. Current surgical treatment of podotrochlear syndrome addresses pathological changes affecting the soft tissue structures of the navicular region but does not address either edema or cyst-like lesions of the navicular bone. Objective: The objective of this randomized, self-controlled case series was to determine whether core osteostixis improved lameness in Quarter Horses with podotrochlear syndrome characterized by bilateral magnetic resonance imaging (MRI) findings of osseous cyst-like lesions of the navicular bone. Methods: Seven Quarter Horses that had not responded to standard medical management were included. Each horse had an affected forefoot randomly assigned to surgical treatment with navicular bursoscopy and core osteostixis; the contralateral limb was assigned to navicular bursoscopy only. Video recordings were used to assign lameness scores and make comparisons of each limb at baseline and 24 weeks post-operatively by an observer blinded to the surgical treatment. A second MRI was performed 24 weeks after surgery to reevaluate navicular bone edema, osseous cyst-like lesions of the navicular bone, and tears of the deep digital flexor tendon (DDFT). Results: Reduction of lameness score from baseline was significantly (P = 0.0254) greater for the limbs treated with core osteostixis than limbs treated with bursoscopy. New DDFT tears were noted in 3 of 7 limbs treated with core osteostixis and in 1 of 7 bursoscopy limbs. Conclusion: Results of this study suggest that core osteostixis of the navicular bone combined with navicular bursoscopy can improve lameness in horses with osseous cyst-like lesions. Further evaluation of this technique is warranted.

Radiographic changes of the proximal third metatarsal bone do not predict presence or severity of proximal suspensory desmopathy in a predominately Quarter Horse population.

BACKGROUND: 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. OBJECTIVE: To compare the radiographic and MRI findings of the proximal third metatarsal bone (MTIII) and proximal suspensory ligament using MRI as the gold standard. STUDY DESIGN: Retrospective observational study. METHODS: 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). RESULTS: 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). MAIN LIMITATIONS: 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. CONCLUSION: 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.

INTRODUCTION/CONTEXTE: 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. OBJECTIFS: 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). LIMITES PRINCIPALES: 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. CONCLUSIONS: 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.

Ultrasonographic Evaluation of the Suspensory Ligament in Quarter Horses Used for Cutting.

Ultrasound remains a mainstay in proximal suspensory ligament (PSL) evaluation. Despite recent improvements facilitating earlier diagnosis/treatment, needs exist for (1) characterization of normal ultrasonographic PSL cross-sectional area (CSA) in specific breeds/disciplines, (2) improved detection of early/subtle changes in the PSL, and (3) an understanding of suspensory ligament (SL) morphology change from work-related stress. The objectives of this study were to establish normal PSL CSA in Quarter Horses (QH) used for cutting via angle contrast ultrasonography, ultrasonographically monitor SL morphology as horses progress through training, and assess the impact of PSL disease on performance (Lifetime Earnings - $LTE). One hundred ten 2-year-old cutting horses had PSL ultrasound examination on all limbs, and examinations were repeated 2 years later on 51 remaining horses. PSL CSA at select locations was compared between time points and entire examinations subjectively graded by an equine radiologist. $LTE was obtained from the National Cutting Horse Association for each horse and analyzed by abnormality number, location, and development over time. A total of 267 PSL ultrasound examinations across both times points were measured and graded. Normal CSA was established by zone for forelimbs and hindlimbs. The prevalence of abnormal limbs increased between the 2-year-old and 4-year-old years, forelimb abnormalities were statistically more prevalent than hindlimb abnormalities at both time points, and osseous attachment abnormalities were statistically more prevalent than ligament abnormalities at both times points. No significant differences in PSL CSA change over time were seen in any group and there was no significant difference in $LTE among or between groups.

Influence of Chronic Lameness on Thoracolumbar Musculus Multifidus Structure in the Horse.

The clinical relationship between equine limb lameness and secondary back dysfunction is largely unknown. Proper function of the spine is critical to maintain the integrity of the kinetic chain and attenuate forces from the appendicular skeleton. The musculus multifidus (m. multifidus) is the primary muscle providing spinal intersegmental stabilization and a functional relationship between m. multifidus hypertrophy and equine postural stability has been established. The relationship between equine thoracolumbar m. multifidus cross-sectional area (CSA) and limb lameness is unknown. The objective was to evaluate ultrasonographic changes in thoracolumbar m. multifidus CSA in horses with chronic single limb lameness, compared with sound horses. We hypothesized that the CSA of m. multifidus, ipsilateral to the lame limb would be smaller than the contralateral side, and within the sound group there would be no difference between sides. Thirty-six horses were enrolled, with twelve horses per group: sound, forelimb lame, and hindlimb lame. M. multifidus CSA was measured ultrasonographically at multiple spinal levels and compared between groups, spinal levels, and sides. M. multifidus CSA at the spinal level T18 was significantly larger than at all other measured levels, regardless of group (P ≤ .05). CSA at all levels was significantly larger in sound horses than the forelimb lame group, regardless of side (P = .002). This is the first study to evaluate the impact of chronic lameness on the axial skeleton and showed a decrease in m. multifidus CSA with forelimb lameness. These results support that axial skeletal adaptation occurs in response to naturally occurring chronic lameness.

Examining the Effects of the Oral Supplement Biota orientalis in the Osteochondral Fragment-Exercise Model of Osteoarthritis in the Horse.

Osteoarthritis (OA) is a common problem in horses. Several oral supplements have been proposed as treatments for horses with OA. The object of this study was to evaluate the use of the oil extract from the seeds of Biota orientalis (BO) for the treatment of experimentally induced OA in horses. OA was induced in 16, 2-5 year old horses in one middle carpal joint on Day 0; the other limb underwent a sham operation. Once daily oral treatment with BO or placebo was initiated on Day 0 and continued to Day 70. All horses were exercised 5 days a week starting on Day 14 through Day 70. The horses were evaluated every other week for lameness and serum GAG concentration as well as weekly synovial fluid assessment. Magnetic resonance imaging was performed on Day 7 and 70. Radiographic changes were assessed on Day 0, 14, and 70. On Day 70 tissue from the middle carpal joint was assessed macroscopically and histologically. All outcome parameters were compared between treatment groups to identify effects of treatment. Compared to placebo a significant decrease was found in synovial fluid prostaglandin E2 concentration and white blood cell counts in horses treated with BO. There was a significant reduction in radiographic scores for subchondral lysis of the radial carpal bone, osteophyte formation, subchondral sclerosis of the radial carpal bone, and total radiographic score for the horses treated with BO. There was no significant difference between treatment groups in clinical lameness findings, MRI findings, macroscopic grading or histologic grading. This study suggests a significant anti-inflammatory effect from oral BO that should be further investigated in clinical OA.

Complex central nervous system malformations in a Dutch Warmblood foal.

A neonatal Dutch Warmblood colt was evaluated for inability to stand, incoordination and intention tremor. Despite partial improvement in clinical signs during the first 4 days of hospitalization, neurological deficits remained. Magnetic resonance imaging identified a unilateral infratentorial arachnoid cyst-like lesion with ipsilateral compression and displacement of the cerebellar hemisphere, absent corpus collosum, polymicrogyria, suspect leukoencephalopathy, and noncompressive occipitoatlantal malformation. Improvement in clinical signs during the first 6 months of life suggests that horses can survive with complex congenital neurological malformations, but prognosis for athletic performance is poor. The accessibility of magnetic resonance imaging should improve the diagnostic accuracy of central nervous system disorders in neonatal foals in which congenital malformations are suspected. Euthanasia often is elected in foals with suspected congenital central nervous system disorders because of poor prognosis for athletic performance, limiting understanding of clinical progression in these cases.

Deep digital flexor tendon lesions in the pastern are associated with the presence of distal tendinopathy.

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.

Dangerous Behavior and Intractable Axial Skeletal Pain in Performance Horses: A Possible Role for Ganglioneuritis (14 Cases; 2014-2019).

Introduction: Dangerous behavior is considered an undesired trait, often attributed to poor training or bad-tempered horses. Unfortunately, horses with progressive signs of dangerous behavior are often euthanized due to concerns for rider safety and limitations in performance. However, this dangerous behavior may actually originate from chronic axial skeleton pain. This case series describes the medical histories and clinical presentations of horses presented for performance limitations and dangerous behavior judged to be related to intractable axial skeleton pain. Material and Methods: Fourteen horses that developed severe performance limitations resulting in euthanasia were included. A complete spinal examination and behavioral responses, gait and neurologic evaluations, diagnostic imaging, gross pathologic and histopathologic examinations of the axial skeleton were performed on all horses. A tentative diagnosis of the affected spinal region was formulated using medical records, owner and trainer complaints, and antemortem examination findings. The selected spinal regions were further examined with gross and histopathologic evaluations of the associated osseous, soft tissue and neural tissues. Results: Ten horses showed severe behavioral responses during the myofascial and mobilization examinations. Based on an aggregate evaluation, the cervicothoracic and lumbosacral regions were the most common regions believed to be the primary area of concern. All horses had moderate to severe ganglionitis present at multiple vertebral levels. Subdural and epidural hemorrhage or hematomas were a common finding (71%) in the cervicothoracic and lumbosacral regions. Discussion: In this case series, neuropathic (i.e., structural) pain was judged to be the underlying cause of dangerous behavior. The dorsal root ganglia (DRG) serve an important role in relaying peripheral sensory information to the central nervous system and ganglionitis has been associated with neuropathic pain syndromes. This series highlights the need for more in-depth understanding of pain behavior and its clinical presentation and progression in chronic or severely affected horses. Limitations of the study are the lack of age-matched control DRG and the incomplete collection of DRG from every vertebral level of interest.

Foot shape and radiographs of free-ranging Nubian giraffe in Uganda.

Foot health in zoo giraffe has been a topic of recent research, although little is known about the foot health of free-ranging giraffe. This study describes the foot shape and radiographic pathological changes in 27 young adult Nubian giraffe (Giraffa camelopardalis camelopardalis) from a translocation in Uganda (August 2017). Giraffe feet were observed to have a concave sole, the hoof wall was longest by the toe tip, and the weight-bearing surface of the foot was primarily along the periphery of the foot including hoof wall, parts of the heel, and the edge of the sole. Radiographs showed that pedal osteitis and sesamoid bone cysts were relatively uncommon (3/24 giraffe with osteitis, 1/24 giraffe with sesamoid cysts), and that no giraffe in the study had P3 joint osteoarthritis, P3 rotation, or P3 fractures. Radiographs consistently demonstrated a positive palmar/plantar angle with the sole of the hoof thicker at the heel than by the toe tip, with the non weight-bearing palmar/plantar angle measuring 1.6°- 4.3°. This is the first systematic review of foot shape and radiographs in free-ranging giraffe and demonstrates a low prevalence of foot pathologies. This study suggests qualitative differences in foot shape, foot health, radiographic anatomy, and foot pathologies when comparing free-ranging and zoo giraffe. Further research is needed to identify why these differences occur and whether husbandry modifications could help improve zoo giraffe foot health and prevent associated lameness.

Microfracture Augmentation With Trypsin Pretreatment and Growth Factor-Functionalized Self-assembling Peptide Hydrogel Scaffold in an Equine Model.

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 <.05, pairwise comparisons were made using least squares means. 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.

Longitudinal tendon healing assessed with multi-modality advanced imaging and tissue analysis.

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 < .001). MAIN LIMITATIONS: Experimentally induced tendon injury with singular end-point data correlation. CONCLUSIONS: Lesion isoattenuation on CT evaluation suggested scar tissue deposition, while T2-weighted hyperintensity indicated hypercellular tendinopathy even in chronic stages of healing. Non contrast-enhanced MRI and CT evaluation correlated most closely to cellular characteristics of surgically damaged tendons assessed over a twelve month study period. Ultrasonographic evaluation underestimates true lesional size and should be interpreted with caution.

Equine Cervical Pain and Dysfunction: Pathology, Diagnosis and Treatment.

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.

Multimodal Imaging to Identify and Characterize a P3 Cystic Lesion and Pathologic Fracture.

Lameness remains a common cause of retirement in the equine athlete and among hobby enthusiasts. The distal limb is one of the most frequently imaged areas, and recent advances in diagnostic imaging capabilities help practicing veterinarians differentiate normal variants from informative pathology. Although acute, non-weight-bearing lameness is commonly associated with etiologies, such as fractures, abscesses, and laminitis, other uncommon differentials such as cystic lesions and neoplasia might also be considered. This report describes the characterization of a large, cystic lesion in the third phalanx (P3), which resulted in an acute, pathologic fracture. The lesion was fully characterized with the use of postmortem magnetic resonance imaging, gross pathology, and histopathology.