Search Results

Abstract

Objective—To determine the outcome of horses with basal fractures of the proximal sesamoid bone from which a fracture fragment involving a portion of the base of the bone was removed arthroscopically and to determine whether fragment size was associated with outcome.

Design—Retrospective study.

Animals—26 horses.

Procedure—Dorsopalmar and axial-abaxial lengths of the fracture fragment were measured on the dorsopalmar and mediolateral radiographic views, respectively, and percentage of the base of the sesamoid bone involved was estimated. Fractures were classified as grade 1 (≤ 25% of the base involved) or grade 2 (> 25% but < 100% of the base involved). Outcome was classified as successful if the horse started at least 2 races or unsuccessful if the horse started only 1 race or failed to return to racing.

Results—There were 24 racehorses and 2 nonracehorses. Twelve (50%) of the racehorses returned to racing and started at least 2 races. Eight of 14 horses with grade-1 fractures and 4 of 10 horses with grade- 2 fractures had a successful outcome. Ten of 16 horses without associated articular disease had successful outcomes, compared with 2 of 8 horses with associated articular disease. However, fragment size and presence of associated articular disease were not significantly associated with outcome.

Conclusions and Clinical Relevance—Horses with basal fractures of the proximal sesamoid bone from which a fracture fragment involving a portion of the base of the bone is removed arthroscopically have a fair prognosis for return to racing. (J Am Vet Med Assoc 2000;217:236–240)

Abstract

Objective—To determine the effects of exercise at an early age on tissues in the metacarpophalangeal joints of horses.

Animals—Twelve 18-month-old horses.

Procedures—All horses were pasture reared, but 6 horses had additional exercise starting at 3 weeks of age until 18 months of age. At that time, computed tomography, articular cartilage metabolism evaluation, and histologic assessments of synovial membrane, articular cartilage, and subchondral bone were performed.

Results—Exercised horses had fewer gross lesions, less articular cartilage matrix staining in the dorsal aspect of the condyle, greater bone fraction in the dorsolateral aspect of the condyle, and higher bone formation rate, compared with nonexercised horses.

Conclusions and Clinical Relevance—Exercise at a young age may be protective to joints, although more research is needed to characterize changes in articular cartilage matrix. Results suggested that exercise can be safely imposed at an early age.

Abstract

Objective—To determine whether decreases in peak vertical force of the hind limb after transection of the cranial cruciate ligament (CrCL) would be indicative of medial meniscal damage in dogs.

Animals—39 purpose-bred adult male Walker Hounds.

Procedure—The right CrCL was transected arthroscopically. Force plate measurements of the right hind limb were made prior to and 2, 4, 10, and 18 weeks after transection of the CrCL. Only dogs with ≥ 10% decreases in peak vertical force after week 2 were considered to have potential meniscal damage. Dogs that did not have ≥ 10% decreases in peak vertical force at any time point after week 2 were assigned to group 1. Group 2 dogs had ≥ 10% decreases in peak vertical force from weeks 2 to 4 only. Group 3 and 4 dogs had ≥ 10% decreases in peak vertical force from weeks 4 to 10 only or from weeks 10 to 18 only, respectively. Damage to menisci and articular cartilage was graded at week 18, and grades for groups 2 to 4 were compared with those of group 1.

Results—The percentage change in peak vertical force and impulse area was significantly different in groups 2 (n = 4), 3 (4), and 4 (4) at the end of each measurement period (weeks 4, 10, and 18, respectively) than in group 1 (27). The meniscal grade for groups 2 to 4 was significantly higher than for group 1. A ≥ 10% decrease in peak vertical force had sensitivity of 52% and accuracy of 72% for identifying dogs with moderate to severe medial meniscal damage.

Conclusions and Clinical Relevance—In dogs with transected or ruptured CrCLs, force plate analysis can detect acute exacerbation of lameness, which may be the result of secondary meniscal damage, and provide an objective noninvasive technique that delineates the temporal pattern of medial meniscal injury. ( Am J Vet Res 2005;66:156–163)

Abstract

Objective—To compare articular cartilage from horses with naturally developing osteochondrosis (OC) with normal articular cartilage and healing cartilage obtained from horses with experimentally induced osteochondral fractures.

Sample Population—109 specimens of articular cartilage from 78 horses.

Procedure—Morphologic characteristics, proteoglycan (PG), and type II collagen were analyzed in articular cartilage of OC specimens (group 1), matched healing cartilage obtained 40 days after experimentally induced osteochondral fractures (group 2), and matched normal cartilage from the same sites (group 3).

Results—79 specimens of OC cartilage were obtained from horses. Ex vivo PG synthesis was significantly greater in the femoral cartilage, compared with synthesis in the tibial cartilage, and significantly greater for groups 1 and 2, compared with group 3. For groups 1 and 2, femoral fragments had significantly greater PG content, compared with PG content in tibial fragments. Keratan sulfate content was significantly less in group 3, compared with groups 1 and 2. Cartilage from the OC specimens had loss of structural architecture. The OC tissue bed stained positive for chondroitin sulfate and type II collagen, but the fracture bed did not.

Conclusions and Clinical Relevance—Our analyses could not distinguish articular cartilage from horses with OC and a healing fracture. Both resembled an anabolic, reparative process. Immunohistochemical analysis suggested a chondromyxoid tissue in the OC bed that was morphologically similar to fibrous tissue but phenotypically resembled hyaline cartilage. Thus, tissue in the OC bed may be degenerative cartilage, whereas tissue in the fracture bed may be reparative fibrous callus. (Am J Vet Res 2005;66:1881–1890)

Abstract

Objective—To evaluate the use of serum concentrations of biochemical markers of bone metabolism (osteocalcin [OC], bone-specific alkaline phosphatase [BS-ALP], and deoxypyridinoline [DPYR]) to compare healing in infected versus noninfected fractures and in fractures with normal repair versus delayed (nonunion) repair in rabbits.

Animals—32 female 9- to 10-month-old New Zealand White rabbits.

Procedure—A femoral fracture defect was made in each rabbit. Rabbits were assigned to the following groups: the bone morphogenetic-2 gene treatment group with either noninfected nonunion or infected (ie, inoculation of defects with Staphylococcus aureus) nonunion fractures or the luciferase (control) gene treatment group with either noninfected nonunion or infected nonunion fractures. Serum samples were obtained before surgery (time 0) and 4, 8, 12, and 16 weeks after surgery. Callus formation and lysis grades were evaluated radiographically at 16 weeks.

Results—Serum OC and BS-ALP concentrations decreased from time 0 at 4 weeks, peaked at 8 weeks, and then decreased. Serum DPYR concentration peaked at 4 weeks and then decreased, independent of gene treatment group or fracture infection status. Compared with rabbits with noninfected fractures, those with infected fractures had lower serum OC and BS-ALP concentrations at 4 weeks, higher serum OC concentrations at 16 weeks, and higher serum DPYR concentrations at 4, 8, and 16 weeks. Combined serum OC, BS-ALP, and DPYR concentrations provided an accuracy of 96% for prediction of fracture infection status at 4 weeks.

Conclusions and Clinical Relevance—Measurement of multiple serum biochemical markers of bone metabolism could be useful for clinical evaluation of fracture healing and early diagnosis of osteomyelitis. ( J Am Vet Med Assoc 2003;64:727–735)

Abstract

Objective—To evaluate the temporal pattern of prostaglandin (PG) E₂ concentrations in synovial fluid after transection of the cranial cruciate ligament (CCL) in dogs and to correlate PGE₂ concentrations with ground reaction forces and subjective clinical variables for lameness or pain.

Animals—19 purpose-bred adult male Walker Hounds.

Procedure—Force plate measurements, subjective clinical analysis of pain or lameness, and samples of synovial fluid were obtained before (baseline) and at various time points after arthroscopic transection of the right CCL. Concentrations of PGE₂ were measured in synovial fluid samples, and the PGE₂ concentrations were correlated with ground reaction forces and clinical variables.

Results—The PGE₂ concentration increased significantly above the baseline value throughout the entire study, peaking 14 days after transection. Peak vertical force and vertical impulse significantly decreased by day 14 after transection, followed by an increase over time without returning to baseline values. All clinical variables (eg, lameness, degree of weight bearing, joint extension, cumulative pain score, effusion score, and total protein content of synovial fluid, except for WBC count in synovial fluid) increased significantly above baseline values. Significant negative correlations were detected between PGE₂ concentrations and peak vertical force (r, –0.5720) and vertical impulse (r, –0.4618), and significant positive correlations were detected between PGE₂ concentrations and the subjective lameness score (r, 0.5016) and effusion score (r, 0.6817).

Conclusions and Clinical Relevance—Assessment of the acute inflammatory process by measurement of PGE₂ concentrations in synovial fluid may be correlated with the amount of pain or lameness in dogs. (Am J Vet Res 2004;65:1269–1275)

Abstract

Objective—To assess the clinical, biochemical, and histologic effects of extracorporeal shock wave therapy (ESWT) in the treatment of horses with experimentally induced osteoarthritis (OA).

Animals—Twenty-four 2- to 3-year-old horses without evidence of lameness.

Procedures—OA was induced arthroscopically in 1 middle carpal joint of each horse. Fourteen days after induction of OA, horses were treated with a sham ESWT probe (placebo; n = 8), polysulfated glycosaminoglycan (PSGAG) administered IM every 4 days for 28 days as a positive control treatment (8), or ESWT administered on days 14 and 28 with a focused shock wave unit (8). Evaluations included clinical assessments of degree of lameness every 2 weeks and weekly synovial fluid analyses. Horses were euthanized 70 days after induction of OA, and gross pathologic and histologic examinations of cartilage and synovial membrane specimens were performed at necropsy. A generalized linear mixed model was used to compare outcomes among treatment groups.

Results—No adverse treatment-related events were detected in any horse. The degree of lameness in horses treated with ESWT improved significantly, compared with the degree of lameness in placebo- or PSGAG-treated horses. No disease-modifying effects were evident in results for synovial fluid, synovial membranes, or cartilage from the ESWT- or PSGAG-treated horses.

Conclusions and Clinical Relevance—Although a disease-modifying effect of ESWT was not detected, the significant clinical effect of ESWT suggested that this modality should be considered for treatment of horses with OA in combination with another modality that does affect the disease process.

Abstract

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.

Abstract

Objective—To assess clinical, biochemical, and histologic effects of polysulfated glycosaminoglycan (PSGAG) or sodium hyaluronan administered intra-articularly in treatment of horses with experimentally induced osteoarthritis.

Animals—24 horses.

Procedures—Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. Eight horses received hyaluronan (20 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight horses received PSGAG (250 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight control horses received 2 mL of saline (0.9% NaCl) solution and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Clinical, radiographic, synovial fluid analysis, gross, histologic, histochemical, and biochemical findings were evaluated.

Results—No adverse treatment-related events were detected. Induced osteoarthritis caused a substantial change in lameness, response to flexion, joint effusion, and radiographic findings, and of these, synovial fluid effusion was reduced with PSGAG, compared with control horses. No changes in clinical signs were seen with PSGAG or hyaluronan, compared with control horses. Histologically, the degree of synovial membrane vascularity and subintimal fibrosis was significantly reduced with PSGAG treatment, compared with controls. Histologically, significantly less fibrillation was seen with hyaluronan treatment, compared with controls.

Conclusions and Clinical Relevance—Results indicated that PSGAG and hyaluronan had beneficial disease-modifying effects and are viable therapeutic options for osteoarthritis in horses.

Abstract

Objective—To compare the mesenchymal stem cell (MSC) yield and chondrogenic and osteogenic differentiation from 5- and 50-mL bone marrow aspirates from horses.

Animals—Six 2- to 5-year-old mixed-breed horses.

Procedures—2 sequential 5-mL aspirates were drawn from 1 ilium or sternebra. A single 50-mL aspirate was drawn from the contralateral ilium, and 2 sequential 50-mL aspirates were drawn from a second sternebra. The MSC yield was determined through the culture expansion process. Chondrogenesis and osteogenesis were evaluated by means of conventional laboratory methods.

Results—The second of the 2 sequential 50-mL sternal aspirates yielded few to no MSCs. Independent of location, the highest density of MSCs was in the first of the 2 sequential 5-mL fractions, although with subsequent culture expansion, the overall yield was not significantly different between the first 5-mL and first 50-mL fractions. Independent of location, chondrogenesis and osteogenesis were not significantly different among fractions. Independent of fraction, the overall cell yield and chondrogenesis from the ilium were significantly higher than that from the sternum.

Conclusions and Clinical Relevance—This study failed to detect an additional benefit of 50-mL aspirates over 5-mL aspirates for culture-expanding MSCs for equine clinical applications. Chondrogenesis was highest for MSCs from ilial aspirates, although it is not known whether chondrogenesis is indicative of activation of other proposed pathways by which MSCs heal tissues.