The influence of tenoscopic approaches on radiocarpal joint perforation during carpal sheath tenoscopy in horses.

OBJECTIVE: To report the frequency of radiocarpal joint (RCJ) perforation during two proximolateral carpal sheath (CS) approaches and to investigate whether the presence or absence of a natural communication between the RCJ and CS. STUDY DESIGN: Experimental, randomized, controlled study. SAMPLE POPULATION: Twelve adult horses and 12 cadaver front limbs. METHODS: Proximolateral CS tenoscopy was performed on both carpi of 12 horses under general anaesthesia. Limbs were randomly assigned into two groups. In group 1, the instrument portal was centered at the level of the distal radial physeal remnant (PR). In group 2, the instrument portal was centered 2 cm proximal to the PR. Immediately after tenoscopy, dye-coloured fluid was instilled arthroscopically into the dorsolateral RCJ, and the open tenoscopic portals were evaluated for leakage. Twelve cadaver front limbs were examined for naturally occuring RCJ and CS communication by using positive-contrast computed tomography (CT). Frequency of perforations were compared with McNemar's test for two matched proportions. RESULTS: In group 1, 10 of 12 RCJ were perforated during tenoscopy, and, in group 2, four of 12 RCJ were perforated (P = 0.03). No diffusion of contrast from the RCJ to the CS was detected by CT. CONCLUSION: Perforation of the RCJ was common when CS instrument portals were placed at the level of the PR. No natural communication was detected between the RCJ and CS. CLINICAL SIGNIFICANCE: Carpal sheath tenoscopic instrument portals may need to be placed >2 cm proximal to the PR to prevent inadvertent RCJ perforation, especially in horses undergoing tenoscopic treatment of a septic CS.

Prevalence of osteochondral lesions in the fetlock and hock joints of Standardbred horses that survived bacterial infection before 6 months of age.

BACKGROUND: Young Standardbred horses frequently develop fragments in joints. Some fragments represent osteochondrosis; others are considered developmental, but it is uncertain whether they result from preceding osteochondrosis. Osteochondrosis occurs as a consequence of failure of the cartilage canal blood supply and ischaemic chondronecrosis. In heritably predisposed foals, failure was associated with incorporation of vessels into bone. However, bacterial vascular failure was also recently documented in foals suffering spontaneous infections, proving that bacteria can cause osteochondral lesions in foals up to 150 days old. The aim was to determine prevalence of fetlock and hock lesions at screening age in Standardbred horses that survived infections before 6 months of age, and compare this to prevalence reported in the literature. METHODS: The material consisted of 28 Standardbred horses; 17 males and 11 females that presented and were diagnosed clinically with bacterial infections from 1 to 150 days of age (average: 41.3 days). A screening set of 8 radiographic projections was available from all 28 horses at 7-85 months of age (average: 23.6 months). Lesion prevalence was compared to three previously reported Standardbred cohorts. RESULTS: Osteochondral lesions were detected in one or more joints of 19/28 horses (67.9%); in the fetlock joint of 14/28 horses (50%) and the hock joint of 11/28 horses (39.3%). These prevalences were ≥ 2 x higher than the corresponding prevalences in the comparison cohorts, and statistically significantly so in 5:6 comparisons (p-values from < 0.00001 to 0.01). In the sepsis cohort, there were an average of 2.3 affected joints and 2.5 lesions per affected horse, whereas there in the one comparable literature cohort were an average of 1.5 affected joints and 1.7 lesions per affected horse. CONCLUSIONS: Standardbred horses that survived bacterial infections before 6 months of age had more osteochondral lesions than literature comparison cohorts at screening age. The implication was that some of the lesions in this group were caused by bacteria. It may become necessary to develop methods for differentiating between acquired, septic and aseptic, heritably predisposed lesions.

Nonarticular osseous cyst-like lesions of the intermedioradial carpal bone may be incidental magnetic resonance imaging findings in dogs.

As magnetic resonance imaging (MRI) becomes more readily available and more frequently utilized in the assessment of canine carpal lameness, both normal variations and early pathologic conditions must be recognized to optimize patient care and provide accurate diagnosis. On cross sectional studies of the canine carpus, cyst-like lesions have been detected at the dorsolateral aspect of the intermedioradial carpal bone. The cross-sectional imaging and histologic properties of these lesions have not been described. The purpose of this observational study is to evaluate the MRI and histologic features of these cyst-like lesions in a cohort of clinically sound dogs. It was hypothesized that the lesions would show features similar to intraosseous ganglion cysts of the human wrist. Twenty-five cadaveric canine carpi were obtained and a total of 13 lesions were detected on MRI. Based on MRI, six carpi with lesions of varying size and one normal carpus were submitted for histological evaluation. Five of the abnormal carpi had nonarticular cyst-like lesions; one specimen with a positive magnetic resonance image for a cyst-like lesion had no cyst-like lesion on histology. Conspicuity of a medium-size lesion as evaluated on radiographs was poor. Given the presence of these nonarticular cyst-like lesions in a population of clinically sound patients, their clinical importance is uncertain. The development of these lesions may relate to altered mechanics or genetic predispositions, requiring additional study.

Modification of the metal endoprosthesis limb-salvage procedure for excision of a large distal radial osteosarcoma in a dog: A case report.

OBJECTIVE: To report modification of the endoprosthesis surgical limb-salvage technique to treat a locally extensive osteosarcoma in a dog and associated functional outcome. STUDY DESIGN: Clinical case report. ANIMALS: One client-owned dog. METHODS: A 9-year-old dog was presented for treatment of a locally extensive distal radial osteosarcoma. A limb-salvage surgery was performed with a second-generation Veterinary Orthopedic Implants (VOI) endoprosthesis to reconstruct the radial segmental and carpal osseous defect. The endoprosthesis was stabilized with a 16-mm-wide locking VOI limb-salvage plate. The level of the osteotomy of the radius/ulna was 3 cm proximal to the periosteal reaction seen on radiographs, and the distal osteotomy extended through the proximal metacarpal bones (II-V), 3 cm from the distal extent of the soft tissue component of the tumor. A 3.5-mm SOP (String of Pearls) plate was used as adjunct fixation. RESULTS: The postoperative functional outcome was classified as acceptable. Ambulation was normal, with mild subjective lameness on the treated limb at examinations 20, 43, and 63 days after surgery. The dog was euthanized 92 days after surgery because of progressive metastatic disease. CONCLUSION: The modified endoprosthetic technique allowed complete excision of the carpal joint, which resulted in acceptable functional outcomes in the dog described here. CLINICAL SIGNIFICANCE: Distal ostectomies may include part of the manus during limb salvage surgery of locally extensive distal radial osteosarcoma and using an endoprosthesis implant to reconstruct the defect.

Bicipital Tendinopathy and Carpal Valgus Following a Distant Direct Thoracoabdominal Skin Flap in a German Shepherd with Necrotizing Fasciitis.

A 4 mo old German shepherd dog was presented following an acute onset lameness and swelling of the thoracic limb. Clinical signs, surgical findings, and culture results were consistent with a diagnosis of necrotizing fasciitis. Initial management consisted of extensive surgical debridement, wound lavage, and bandaging. Surgical closure was achieved with an axillary fold flap and distant direct single-pedicle thoracoabdominal flap. Three mo later, following deterioration of the lameness that was associated with carpal valgus, carpal subluxation, and tendinopathy of the distal radial insertion of the biceps brachii tendon, a closing wedge pancarpal arthrodesis and tenotomy of the biceps brachii tendon was performed. We hypothesize that extensive soft tissue trauma and subsequent fibrosis and tendon contracture following soft tissue reconstruction contributed to the complications seen. To the authors' knowledge, this is the first report of carpal valgus deformity and biceps brachii tendinopathy following a distant direct skin flap and axillary skin fold flap.

A diagnostic pathologist's guide to carpal disease in racehorses.

As a pathologist, postmortem examination of the equine carpus can be daunting. The anatomy is complex and oftentimes, small or subtle lesions have significant impact on lameness and secondary lesions such as catastrophic musculoskeletal fractures and other injuries. In performance horses, particularly racehorses, the carpus is a common site of injury and source of lameness. Given the predisposition of racehorses to developing carpal disease, familiarity with clinically relevant anatomy and common developmental, degenerative, traumatic, and inflammatory processes are imperative for thorough postmortem examination. Our aim is (1) to provide a concise summary of clinically relevant anatomy and function that serves as a guide for postmortem evaluation of the equine carpus, and (2) to review common carpal injuries and diseases in actively training, racing, or retired racehorses, including developmental lesions (incomplete ossification, osteochondromata), infectious and inflammatory lesions (septic arthritis and tenosynovitis), and degenerative and traumatic lesions (degenerative and traumatic osteoarthritis, osteochondral fragmentation, and polyostotic catastrophic "breakdown" fractures). Representative gross and histologic images are presented along with corresponding antemortem and postmortem diagnostic images, and a review of current scientific literature pertaining to the pathogenesis of these equine carpal lesions.

Biomechanical and histologic evaluation of the effects of underwater treadmill exercise on horses with experimentally induced osteoarthritis of the middle carpal joint.

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.

Anterior wrist and medial malleolus: the optimal sites for tissue selection in electric death through hand-to-foot circuit pathway.

Specific morphological changes may be absent in some cases of electrocution shocked by the voltage of 220 V or lower. In this study, we attempted to demonstrate that the anterior wrist and medial malleolus were the optimal sites with promising and significant changes in electric death through the hand-to-foot circuit pathway. We established an electric shock rat model and observed histopathologic changes in the anterior wrist and medial malleolus. The results showed that the current intensities in the left anterior wrist and right medial malleolus were remarkably higher than those in the other sites, and the nuclei long/short (L/S) axis ratios of the arterial endotheliocyte and the skeletal muscle cell in these two areas were significantly higher than those in other parts of the body. These findings suggested that the anterior wrist and/or medial malleolus soft tissues as the narrowest parts of the limbs could be used as promising and useful sites for the assessment of electrical shock death, especially in forensic pathologic evaluation.

Investigating integument alterations in cubicle housed dairy cows: which types and locations can be combined?

In this study, a data set of 2922 lactating dairy cows in a sample of 64 conventional and organic dairy farms with Holstein Friesian cows in Germany and 31 conventional dairy farms with the dual purpose breed Fleckvieh in Austria was used to screen for correlations between the occurrences of different integument alterations. All cows were housed in cubicle systems. Alterations were classified as hairless areas (H), scabs or wounds (W) or swellings (S) and assessed at 15 locations of the cows' body. Highest median farm prevalences were found at the joints of the legs, which are already commonly included in studies on integumentary alterations: median farm prevalence was 83% for S and 48% for H at the carpal joints, followed by H (38%) and S (20%) at the lateral tarsal joints and H at the lateral calcanei (20%). Additional body parts with notable median prevalences for H were the hip bones (13%), pin bones (12%) and sacrum (11%). Three cluster models, with 2, 5 and 14 clusters, were built by hierarchical clustering of prevalences of the 30 most relevant alteration location combinations. Clustering revealed that location overruled type of lesion in most cases. Occasionally, clusters represented body segments significantly distant from each other, for example the carpal joints and lateral and dorsal calcanei. However, some neighbouring areas such as the medial and lateral hock area should be analysed separately from each other for causal analysis as they formed distinct clusters.

Evaluation of application of a carpal brace as a treatment for carpal ligament instability in dogs: 14 cases (2008-2011).

OBJECTIVE: To determine whether carpal brace application is a viable treatment for dogs with unilateral carpal ligament instability. DESIGN: Retrospective case series. ANIMALS: 14 client-owned athletic dogs. PROCEDURES: Medical records were reviewed to identify dogs treated with a brace for unilateral carpal valgus or varus instability between August 2008 and August 2011. Treatment included passive motion and isometric strengthening exercises during brace application. RESULTS: Of the 14 dogs, 11 were considered to have returned to normal function; 11 of 12 dogs returned to agility competition. Carpal measurements before treatment indicated the affected limb had significantly greater valgus measurements (median, 30°; range, 30° to 35°), significantly greater varus measurements (median, 15°; range, 15° to 25°), and significantly less flexion (median, 37.5°; range, 30° to 45°), compared with results for the contralateral carpus. Long-term monitoring revealed no differences in measurements between affected and contralateral limbs. Valgus measurements of the affected carpus at brace removal (median, 15°; range, 15° to 20°) and at the end of long-term monitoring (median, 15°; range, 15° to 20°) were significantly lower than measurements before treatment (median, 30°; range, 30° to 35°). Dogs had significantly lower lameness scores (assessed on a scale of 0 to 5) at brace removal (median, 0; range, 0) and at the end of monitoring (median, 0; range, 0 to 2), compared with scores before treatment (median, 3; range, 1 to 3). CONCLUSIONS AND CLINICAL RELEVANCE: Application of a carpal brace resulted in improved stability and resolution or reduction in lameness in dogs with carpal ligament instability.

Rapid prototyping to design a customized locking plate for pancarpal arthrodesis in a giant breed dog.

This report describes the treatment of traumatic carpal hyperextension in a giant breed dog by pancarpal arthrodesis using a custom-made Fixin locking plate, created with the aid of a three-dimensional plastic model of the bones of the antebrachium produced by rapid prototyping technology. A three-year-old 104 kg male Mastiff dog was admitted for treatment of carpal hyperextension injury. After diagnosis of carpal instability, surgery was recommended. Computed tomography images were used to create a life-size three-dimensional plastic model of the forelimb. The model was used as the basis for constructing a customized 12-hole Fixin locking plate. The plate was used to attain successful pancarpal arthrodesis in the animal. Radiographic examination after 74 and 140 days revealed signs of osseous union of the arthrodesis. Further clinical and radiographic follow-up examination three years later did not reveal any changes in implant position or complications.

Frontal plane fractures of the accessory carpal bone and implications for the carpal sheath of the digital flexor tendons.

REASONS FOR PERFORMING STUDY: Accurate radiological and ultrasonographic descriptions of frontal plane fractures of the accessory carpal bone (ACB) are lacking, and implications of these fractures for the carpal sheath and its contents have not previously been reported. OBJECTIVES: Aims were as follows: 1) to describe the location and radiological features of frontal plane fractures of the ACB; 2) to document communication of displaced fractures with the carpal sheath and consequent injury to the deep digital flexor tendon (DDFT); 3) to describe ultrasonographic identification of lesions; and 4) to report tenoscopic evaluation and treatment. STUDY DESIGN: Retrospective case series. METHODS: Analysis of frontal plane fractures of the ACB referred to a single hospital between 2006 and 2012, including review of radiographic, ultrasonographic and tenoscopic images. RESULTS: Nine fractures were identified, of which 8 displaced fractures all communicated with the carpal sheath. Comminuted fragments and/or protruding fracture margins lacerated the lateral margin of the enclosed DDFT. This was identifiable ultrasonographically and confirmed at tenoscopy in 7 cases. Treatment in these horses consisted of removal of torn tendon tissue together with fragmentation and protuberant fracture edges, and 7 of 7 cases returned to work. One horse with a nondisplaced fracture was managed with immobilisation; the fracture healed, and the horse returned to work. One horse with a displaced fracture was retired to stud. CONCLUSIONS: Frontal plane fractures of the ACB occur palmar to the groove in its lateral margin for the tendon of insertion of ulnaris lateralis. Comminuted fragments can displace distally within the carpal sheath to a mid-metacarpal level or abaxially to lie extrathecally, lateral to the parent bone. Displaced fractures communicate with the carpal sheath and traumatise the DDFT.

Comminuted fracture of the ulnar carpal bone in a Labrador retriever dog.

A 4-year-old male Labrador retriever dog was evaluated for acute lameness without weight-bearing in the right forelimb after an 8-meter fall. Radiographs revealed a comminuted fracture of the ulnar carpal bone that required removal of bone fragments. This appears to be the first report of such a condition.

Fracture comminutive de l'os ulnaire du carpe chez un Labrador retriever. Un Labrador male de 4 ans est examiné pour une boiterie aigue, avec suppression d'appui, apparue sur le membre antérieur droit à la suite d'une chute d'une hauteur de 8 mètres. L'examen radiographique montre une fracture comminutive de l'os ulnaire du carpe. Le retrait des fragments est effectué. A la connaissance de l'auteur c'est la première description d'une fracture comminutive de cet os nécessitant le retrait des fragments.(Traduit par l'auteur).

Bilateral carpal contracture in a neonatal addax (Addax nasomaculatus).

A neonate male addax calf displayed an inability to extend its forelimbs bilaterally (range of motion restricted to 45 degrees-50 degrees on full extension) with resultant inability to stand. Based on examination and radiographs, the congenital defect was attributed to contracted soft tissue structures (joint capsule and/or intercarpal ligaments). Splinting, support of the limbs, and physical therapy resulted in moderate improvement of the angle of contraction (full flexion to approximately 120 degrees on extension at day 10). The animal was able to walk with splints but died at 10 days from acute head trauma, presumably related to a traumatic fall caused by challenges with ambulation. Postmortem examination confirmed soft-tissue contracture of the forelimbs. Malposition of the calf in utero was considered a possible cause of the defect.

Carpal intra-articular blastomycosis in a Labrador retriever.

A 6-month-old male castrated Labrador retriever was presented for coughing and forelimb lameness. Blastomyces dermatitidis was identified in cytology of sputum and synovial fluid. Repeat arthrocentesis 7 months later revealed resolution of septic arthritis. Fungal septic arthritis should be considered for cases of monoarthritis and may respond to oral itraconazole treatment.

Blastomycose carpienne intra-articulaire chez un Labrador retriever. Un Labrador retriever mâle castré âgé de 6 mois a été présenté pour une toux et une boiterie du membre antérieur. Blastomyces dermatitidis a été identifié lors d'une cytologie de l'expectoration et du liquide synovial. Une nouvelle arthrocentèse 7 mois plus tard a révélé la résolution de l'arthrite septique. L'arthrite septique fongique devrait être considérée pour les cas de mono-arthrite et elle peut réagir au traitement à l'itraconazole oral.(Traduit par Isabelle Vallières).

Multiple joint metastasis of a transitional cell carcinoma in a dog.

An 8-year-old castrated male hound mix was referred to the Purdue University Veterinary Teaching Hospital for severe lameness, pollakiuria, and dyschezia. On presentation, the dog was nonweight bearing on the right rear limb and the right carpus was diffusely swollen. Synovial fluid analysis from the right carpus revealed a population of epithelial cells displaying marked anisocytosis, anisokaryosis, multinucleation, and prominent, variably sized nucleoli. A metastatic carcinoma with presumed prostatic or urothelial origin was diagnosed based on cytomorphology. Subsequent cytologic evaluation of peripheral lymph nodes revealed the presence of a similar neoplastic population. The dog was euthanized and synovial fluid from both stifle joints, as well as impression smears of the prostate gland, were collected. Carcinoma cells were identified in each stifle joint and in the prostate gland. Immunocytochemistry was performed on synovial fluid smears from 2 of the joints (right stifle and right carpus) and on impression smears of the prostate gland. The neoplastic population in the joints and prostate gland showed strong immunoreactivity to uroplakin III, a urothelial marker, indicating metastasis of a transitional cell carcinoma to multiple joints. In addition, evidence for epithelial to mesenchymal transition was identified using cytokeratin, an epithelial marker, and vimentin, a mesenchymal marker. A necropsy was performed and histopathology confirmed the presence of metastatic transitional cell carcinoma in various tissues. This case illustrates the importance of considering metastatic disease when a patient is presented with severe lameness and joint pain, and the clinical utility of synovial fluid cytology for diagnosis of metastasis in these cases.

Is collagen fiber damage the cause of early softening in articular cartilage?

OBJECTIVE: Because collagen damage and cartilage softening have not yet been determined simultaneously in one study for the very early onset of osteoarthritis (OA), it remains questionable whether they are associated. The aim of the present study is therefore to evaluate whether indeed, initial collagen damage can be found when tissue softening occurs as a result of excessive mechanical loading. METHODS: To investigate this aim, a series of specific indentation loading protocols were designed to induce and monitor cartilage softening in osteochondral explants of bovine carpometacarpal joints. The experiment contained one control group (n = 6) in which no damage was induced and four experimental groups in which samples received either a constant load of 3 (n = 5), 6 (n = 5) or 15 N (n = 6), or an increasing load (n = 7) from 2 to 13 N in 11 steps. Moreover, to determine mechanically induced collagen damage, Col2-3/4M (cumulative collagen damage) and Col2-3/4C(short) (only enzymatic damage) staining were compared. RESULTS: The normalized peak and equilibrium reaction forces decreased in the groups that received increasing and 15 N peak loading. However, Col2-3/4M staining was negative in all samples, while enzymatic damage (Col2-3/4C(short)) appeared similar in experiments and in unloaded control groups. CONCLUSION: It was shown that a loading magnitude threshold exists above which softening occurs in cartilage. However, in samples that did show softening, we were unable to detect collagen damage. Thus, our results demonstrate that cartilage softening most likely precedes collagen damage.

Gene biomarkers in peripheral white blood cells of horses with experimentally induced osteoarthritis.

OBJECTIVE: To use microarray analysis to identify genes that are differentially expressed in horses with experimentally induced osteoarthritis. ANIMALS: 24 horses. PROCEDURES: During arthroscopic surgery, a fragment was created in the distal aspect of the radiocarpal bone in 1 forelimb of each horse to induce osteoarthritis. At day 14 after osteoarthritis induction, horses began exercise on a treadmill. Blood and synovial fluid samples were collected before and after surgery. At day 70, horses were euthanized and tissues were harvested for RNA analysis. An equine-specific microarray was used to measure RNA expression in peripheral WBCs. These data were compared with mRNA expression (determined via PCR assay) in WBCs, cartilage, and synovium as well as 2 protein biomarkers of cartilage matrix turnover in serum and synovial fluid. RESULTS: A metalloproteinase domain-like protein decysin-1 (ADAMDEC1), glucose-regulated protein (GRP) 94, hematopoietic cell signal transducer (HCST), Unc-93 homolog A (hUNC-93A), and ribonucleotide reductase M2 polypeptide (RRM2) were significantly differentially regulated in WBCs of horses with osteoarthritis, compared with values prior to induction of osteoarthritis. There was correlation between the gene expression profile in WBCs, cartilage, and synovium and the cartilage turnover proteins. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in WBCs were correlated when measured via microarray analysis and PCR assay. CONCLUSIONS AND CLINICAL RELEVANCE: Expression of ADAMDEC1, GRP94, HCST, hUNC-93A, and RRM2 was differentially regulated in peripheral WBCs obtained from horses with experimentally induced osteoarthritis. Gene expression of ADAMDEC1, hUNC-93A, and RRM2 in peripheral WBCs has the potential for use as a diagnostic aid for osteoarthritis in horses.