Equine Midcarpal Joint Research Articles

Intra-articular ketamine administration in equine midcarpal joint: clinical, biochemical and cytological evaluations.

Summary Providing suitable analgesia following diagnostic and therapeutic arthroscopic surgeries, that are considered to cause some degree of postoperative pain, is a necessity in equine practice. The aim of the present study was to evaluate the equine synovial fluid biochemical and cytological changes as well as clinical assessments of the joint following intra-articular administration of ketamine. Six adult healthy donkeys were selected after clinical examination. Synovial fluid samples were taken from both middle carpal joints after routine preparation. Ketamine 2 mg/kg and 100 mg lidocaine 2% were administered to the right and left joints, respectively. Synovial fluid collection from the joints was performed at 12, 24, 48 and 192 h after medication. Cytological examination, total protein, glucose, specific gravity, alkaline phosphates (ALP), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), viscosity and quality of mucin clot were measured. Joint circumference, flexion test and lameness examination, stimulation of the joint skin area and radiographic examination were performed as clinical evaluations. Comparison of treatments was performed by nonparametric sign test and Wilcoxon rank sum test. Significance level was set to P≤0.05. In the ketamine group, increased joint circumference, positive flexion test and negative response to the ball-point pressure of the joint skin area were seen, unlike that of lidocaine. Mucin clot quality test and viscosity, the amount of total nucleated cell count (TNCC), mononuclear and neutrophil count, specific gravity, total protein content, ALP, AST and LDH of the ketamine treated joints revealed considerable differences between various sampling times compared to the 0 time and also between the ketamine and lidocaine groups (P>0.05). It was concluded that intra-articular ketamine administration in equine carpal joint resulted in acute inflammatory changes, and failed to demonstrate analgesia; therefore, it is not safe to the joint environment and is not recommended as a local analgesic following arthroscopic surgeries.

Influence of early conditioning exercise on the development of gross cartilage defects and swelling behavior of cartilage extracellular matrix in the equine midcarpal joint

To investigate the influence of early conditioning exercise on the development of gross cartilage defects and swelling behavior of cartilage extracellular matrix (ECM) in the midcarpal joint of horses. 12 Thoroughbreds. 6 horses underwent early conditioning exercise from birth to 18 months of age (CONDEX group), and 6 horses were used as control animals (PASTEX group). The horses were euthanized at 18 months of age, and the midcarpal joints were harvested. Gross defects of the cartilage surface were classified and mapped. Opposing surfaces of the third and radial carpal bones were used to quantify swelling behavior of the cartilage ECM. A wide range of gross defects was detected in the cartilage on the opposing surfaces of the bones of the midcarpal joint; however, there was no significant difference between the CONDEX and PASTEX groups. Similarly, no significant difference in swelling behavior of the cartilage ECM was evident between the CONDEX and PASTEX groups. In the study reported here, we did not detect negative influences of early conditioning exercise on the prevalence of gross defects in cartilage of the midcarpal joint or the quality of the cartilage ECM as defined by swelling behavior. These results suggested that early conditioning exercise may be used without negative consequences for the midcarpal joint and the cartilage ECM of the third and radial carpal bones.

Synovial Membrane Microarthroscopy of the Equine Midcarpal Joint

To evaluate the value of microarthroscopy in the equine midcarpal joint using the vital stains methylene blue, trypan blue, neutral red, and Janus green B to observe components of the synovial lamina propria, vascular architecture, and synoviocytes. Experimental. Ten horses. Microarthroscopy of left and right midcarpal joints was performed with and without vital staining of the synovium. Four vital stains (methylene blue, trypan blue, neutral red, and Janus green B) were evaluated, with each stain used in 5 joints. Synovial biopsy specimens were collected from the dorsomedial and dorsolateral aspects of the joint. All dyes were biocompatible. At x 60 without vital staining, synovial surface topography, vascular network, and translucency were observed. Intra-articular vital dyes improved evaluation of synovial surface topography. At x 150 with vital staining, individual synoviocytes were clearly identified with all dyes, except neutral red. Although methylene blue provided the best in vivo microscopic differentiation of the structure of the intima, trypan blue had superior retention in conventionally processed synovial biopsies. Methylene blue, trypan blue, neutral red, and Janus green B stains can be used safely for microarthroscopy. Good visualization of cells and vascular network can be obtained by microarthroscopy, and microarthroscopic evaluation of the synovium compares favorably with conventional histologic evaluation of biopsy specimens. Microarthroscopy may be beneficial in both research and clinical diagnosis of equine articular diseases.

Histopathological Findings in the Medial Palmar and Dorsomedial Intercarpal Ligaments of the Equine Midcarpal Joint; Book Review

Medial palmar intercarpal ligaments (MPICL) and dorsomedial intercarpal ligaments (DMICL) from the midcarpal joints of 11 adult horses in training were examined histopathologically. These were compared with ligaments from seven horses less than 12 months of age, and 10 grossly enlarged DMICLs of adult horses. Tearing of the MPICL was observed in 15 of 22 joints from adult horses. Collagen fibre bundles of the MPICLs generally were disorganized and poorly aligned, and there were large areas of loose connective tissue. In young horses there was more parallel alignment of collagen bundles and less loose connective tissue. Collagen bundles of adult DMICLs were well organized and showed parallel alignment, whereas in foals the structure appeared more like that of fibrous joint capsule. Grossly enlarged DMICLs in adults consistently had discrete areas of fibrovascular infiltration. Degeneration of the MPICL was associated with increasing age and could explain the high incidence of tearing of the ligament. Enlargement of the DMICL was associated with low-grade tearing and repair.

Postmortem lesions in the intercarpal ligaments of the equine midcarpal joint.

To determine the frequency of damage to the medial palmar intercarpal ligament (MPICL), and the range of sizes of the dorsomedial intercarpal ligament (DMICL) of the midcarpal joint in horses with no history of carpal joint disease. Cadaver limbs were collected from 72 horses with no history of carpal joint disease. One hundred and forty-two midcarpal joints were dissected and the MPICL and DMICL were examined. Measurements were made with a digital micrometer. MPICL tearing was present in 88 of 96 joints from horses 2 years and older. Tears were predominantly of the dorsolateral bundle and complete rupture of the dorsolateral and dorsomedial bundles was not observed. Tearing was not present in foals less than 4 months of age and the severity of tearing increased significantly with age (P < 0.0001). Severity of tearing was significantly greater in racing Standardbreds than racing Thoroughbreds (P < 0.01), but there was no significant difference between racing and non-racing horses. The lateromedial thickness of the DMICL ranged from 0.4 mm to 2.6 mm in horses 2 years and older. Lateromedial thickness increased significantly with age, and was significantly greater in racing Standardbreds than racing Thoroughbreds (P < 0.01). There was no significant difference between racing and nonracing horses. Damage confined to the dorsolateral bundle of the MPICL is a common finding in horses over 1 year of age and is probably of little clinical significance. Complete rupture of both dorsolateral and dorsomedial bundles is uncommon in horses with no history of midcarpal joint disease. Variation in size of the DMICL is observed in horses of all ages, but is most marked in 2-year-old horses.

The intercarpal ligaments of the equine midcarpal joint, Part 2: The role of the palmar intercarpal ligaments in the restraint of dorsal displacement of the proximal row of carpal bones.

To determine the relative contributions of the palmar intercarpal ligaments in the midcarpal joint to the restraint of dorsal displacement of the proximal row of carpal bones. A biomechanical study of cadaver equine carpi. Eight equine forelimbs from six thoroughbred horses. With joints in full extension, the radius was dorsally displaced while midcarpal joint displacement was measured. The restraining force at a joint displacement of 1.5 mm was determined from the load-displacement curve. A ligament or pair of ligaments was then cut and the testing procedure repeated. Their contribution to restraining force was calculated as the percentage change in restraining force after the ligament was sectioned. Relative cross-sectional areas of the ligaments tested were measured at the level of the midcarpal joint. The collateral ligaments were the major contributors to the restraint of dorsal displacement (P < .001). In all joints, the palmar intercarpal ligaments contributed a greater proportion than the palmar carpal ligament (PCL) (P < .05). The mean percentage (+/-SEM) contributions to the restraint of dorsal displacement were 62.8 +/- 3.4 for the collateral ligaments, 14.5 +/- 1.4 for the PCL, and 22.7 +/- 2.2 for the palmar intercarpal ligaments. Mean cross-sectional area expressed as a percentage (+/-SEM) of the total ligamentous area were 9.0 +/- 0.3 for the palmar intercarpal ligaments, 27.1 +/- 3.0 for the PCL, and 63.8 +/- 2.8 for the collateral ligaments. Despite the small size of the palmar intercarpal ligaments, they play an important role in the restraint of dorsal displacement of the proximal row of carpal bones. Interpretation, as well as prevention and treatment of intercarpal ligament tearing requires an understanding of their function.

The intercarpal ligaments of the equine midcarpal joint, Part 3: Clinical observations in 32 racing horses with midcarpal joint disease.

To characterize the clinical features of intercarpal ligament pathology and to determine the relationship among palmar intercarpal ligament tearing, dorsomedial intercarpal ligament (DMICL) hypertrophy, and other intraarticular lesions. Prospective clinical observations. Twenty-eight thoroughbred and four standardbred race horses. Clinical, radiographic, and arthroscopic examination of 53 midcarpal joints of 32 horses. Palmar intercarpal ligament tearing was observed in 30 joints of 22 horses. Some tearing of the medial palmar intercarpal ligament (MPICL) was present in 27 joints of 20 horses, and tearing of the lateral palmar intercarpal ligament in 9 joints of 7 horses. There was no correlation between the severity of clinical signs recorded and the degree of MPICL tearing. Joints with grade 2-4 MPICL tearing had significantly less cartilage and bone damage than joints with grade 1 or no ligament damage (P < .05). There was a significant inverse relationship between the number and size of intra-articular fractures, as assessed radiographically, and ligament damage (R = -.31). The DMICL was identified in all joints, and in 18 joints the ligament was enlarged. There was a significant correlation between MPICL damage and hypertrophy of the DMICL (R = .35). There was no correlation between DMICL hypertrophy and articular cartilage damage or subchondral bone damage. Severe subchondral bone and MPICL damage rarely occur in the same joint and DMICL hypertrophy may be associated with, rather than a cause of, joint disease. There are no clinical or radiographic findings that will differentiate intercarpal ligament injury from other carpal injuries. Diagnosis is only possible by arthroscopic examination of the midcarpal joint.

The intercarpal ligaments of the equine midcarpal joint, Part 1: The anatomy of the palmar and dorsomedial intercarpal ligaments of the midcarpal joint.

To describe in detail the structure of the medial palmar intercarpal ligament (MPICL), the lateral palmar intercarpal ligament (LPICL), and a dorsomedial intercarpal ligament (DMICL) of the equine midcarpal joint. Dissections of equine midcarpal joints. ANIMALS AND SAMPLE POPULATION: Ten carpal joints from eight thoroughbred horses. Detailed dissections of the midcarpal joint were performed, with particular attention paid to the MPICL, the LPICL, and the DMICL. The attachments and dimensions of these structures were recorded, as well as their behavior during joint movement. The DMICL arose from the dorsomedial surface of the radial carpal bone (CR) and coursed palmarodistally to insert on the dorsomedial aspect of the second carpal bone (C2). The LPICL attached proximally predominantly on the distal part of the palmaromedial surface of the ulnar carpal bone (CU). From here the ligament coursed distomedially and slightly palmarly to the proximal palmarolateral surface of the third carpal bone (C3). The structure of the MPICL was complex. It attached proximally to the distolateral surface of the CR and distally to the proximal palmaromedial surface of C3, and the proximal palmarolateral aspect of the C2. It could be divided into four fiber bundles in all carpi. The predominant direction of fibers was dorsoproximal to palmarodistal, whereas the palmaromedial bundle coursed palmaroproximal to dorsodistal. The orientation of their fibers indicate that the MPICL and DMICL primarily resist dorsomedial displacement of CR, whereas the LPICL resists dorsolateral displacement of the CU and intermediate carpal bone. An understanding of the structure of the intercarpal ligaments of the midcarpal joint is important in interpreting their function and the reasons for damage to their structure.

Biomechanical properties of third carpal articular cartilage in exercised and nonexercised horses

The relevance of site and exercise on the biomechanical properties of the articular cartilage from the equine third carpal bone were assessed by creep indentation testing. Six horses were exercised for 30 minutes three times weekly. Another six horses were housed in box stalls and were not exercised. At the conclusion of the study, one third carpal bone from each horse was harvested and the KLM biphasic material properties of cartilage were determined at 12 sites. There was a significant (p < 0.01) effect of site but not exercise on the cartilage aggregate modulus, which was significantly lower for sites on the dorsal aspect of the radial facet and for all sites on the intermediate facet as compared with sites on the palmar aspect of the radial facet of the third carpal bone. Exercise significantly increased the permeability constant at all sites when compared with the nonexercised group, but there was no difference between sites within groups. Exercise also significantly increased Poisson's ratio, but only at sites located on the palmar aspect of the radial facet. In general, both site and exercise influence the biomechanical behavior of third carpal articular cartilage. Inherent differences in cartilage biomechanical properties within a joint correlate with the location specificity of cartilaginous lesions in the equine midcarpal joint.

Pressure-volume relationships in equine midcarpal joint.

The effects of joint angle, fluid infusion, history-dependence, and time dependence on the pressure-volume (PV) relationships of normal equine midcarpal joints were determined. Horses (n = 24 and 48 midcarpal joints) were anesthetized and placed in dorsal recumbency, and the four midcarpal joint pouches were cannulated for intra-articular pressure (IAP) measurements and recording. Fluid (synovial fluid or saline) was infused or withdrawn through the dorsal joint capsule. The PV curves were sigmoid and best described by IAP = A x e(B x volume) - C, where B is the fractional change in pressure per unit change of volume, and A and C are constants. Compartmentation was not observed. Elastance was greater at sub- than supra-atmospheric pressures, at 90 degrees than 135 degrees angles, and with saline than synovial fluid. Hysteresis was greater at 90 degrees than 135 degrees angle, and with synovial fluid than saline. Elastance progressively increased with sequential distention at high IAPs. IAP relaxation was a positive logarithmic relationship of IAP. These findings suggest an important role of synovial fluid in articular PV relationships and emphasize the role of joint angle, prior distention cycles, and decay of IAP with time in future studies investigating these phenomena.

Tearing of the medial palmar intercarpal ligament in the equine midcarpal joint.

Tearing of the medial palmar intercarpal ligament is described in 45 intercarpal (midcarpal) joints in 42 horses (37 racehorses, 5 non-racehorses). Of the 37 racehorses, there were 20 Quarter Horses, 14 Thoroughbreds and 3 Standardbreds. The patients had been referred for arthroscopic surgery for removal of osteochondral chip fragments that had been diagnosed radiographically or diagnostic arthroscopy of a persistent carpal problem. The problem was unilateral in 39 horses and bilateral in 3. The presenting clinical signs were lameness and/or persistent synovial effusion. In one instance, the presenting complaint was haemarthrosis. Osteochondral chip fragments were present in the joint affected with tearing in 23 horses. In 6 horses in which osteochondral fragments were present in other joints, the degree of synovial effusion was greatest in the midcarpal joint with ligamentous tearing. In most of the 22 midcarpal joints where carpal chip fragmentation and ligamentous tearing were present concomitantly, the degree of clinical compromise was greater than normally seen with that degree of osteochondral fragmentation. A ligament was designated as torn when a defect was present in the ligament. This usually took the form of frayed fibres suspended in the irrigating solution, presenting a transverse type of defect in the dorsal aspect of the lateral portion of ligament. However, longitudinal tearing was present in 1 case and tearing was noted in the palmar aspect of the ligament in 2 other cases. The shredded fibres were trimmed in most cases and this allowed better definition of the amount of ligament considered to be torn. The degree of damage ranged from 10% to 100% of the width considered to be torn.(ABSTRACT TRUNCATED AT 250 WORDS)

An arthroscopic biopsy procedure for obtaining osteochondral samples from the equine midcarpal joint.

An in vivo biopsy technique was developed to harvest cylindrical osteochondral core samples (2 mm diameter x 2 mm depth) from the articular surfaces of radial carpal bones in adult horses for use in osteoarthritis drug kinetic studies. A 25 degree arthroscope was introduced into the midcarpal joint through the dorsolateral surface, and a custom-built motorized core drill was introduced through the dorsomedial surface to create the osteochondral core samples. A total of 24 core samples were sequentially harvested in vivo, and 16 at postmortem, from eight horses on four different occasions within a 96-h period. Cores ranged in weight, from 5.0 to 19.0 mg with a median of 13.25 mg, mostly due to the amount of subchondral bone present. No evidence of carpal bone fractures was observed associated with core sample sites at postmortem. No tissue distortion or thermal damage occurred to the osteochondral core samples. No detrimental effects on the tissue surrounding the biopsy sites was detected on microscopic examination. This technique offers a simple and effective procedure for obtaining multiple in vivo osteochondral core samples at various time intervals for cartilage or osteoarthritis research or analysis of clinical joint disease in the horse.