Cartilage-derived biomarkers of osteoarthritis in synovial fluid of dogs with naturally acquired rupture of the cranial cruciate ligament

OBJECTIVE: To compare synovial fluid biomarkers of cartilage metabolism in joints with naturally acquired or experimentally induced cranial cruciate ligament (CCL) rupture and determine correlations with stage and severity of disease in dogs. ANIMALS: 95 dogs with ruptured CCL, 8 dogs with experimentally ruptured CCL, and 24 healthy dogs. PROCEDURES: Synovial fluid was assayed for chondroitin sulfate neo-epitopes 3B3(-) and 7D4 and glycosaminoglycan (GAG) concentration. Results were correlated with demographic data, duration of lameness, radiographic osteoarthritis score, and intra-articular lesions. RESULTS: The 7D4 concentrations and 7D4:GAG in synovial fluid from joints with naturally acquired CCL rupture and experimental CCL transection were similar and significantly greater than values for healthy control joints. The 3B3(-) concentrations in the CCL-deficient groups were not significantly different, although only values in the naturally acquired CCL rupture group were significantly greater than those in the healthy control group. Within the naturally acquired CCL rupture group there was a significant correlation between 3B3(-) and 7D4 concentrations. However, there were no significant correlations between biomarker concentrations and continuous demographic or disease-related variables or differences in biomarker concentrations with different categories of disease. CONCLUSIONS AND CLINICAL RELEVANCE: Synovial fluid biomarker concentrations were significantly increased in joints with secondary osteoarthritis associated with naturally acquired or experimental CCL rupture; however, lack of apparently simple relationships with demographic variables or stage or severity of disease limits their clinical usefulness.     

Comparison of the effects of caudal pole hemi-meniscectomy and complete medial meniscectomy in the canine stifle joint

OBJECTIVE: To compare the effects of caudal pole hemi-meniscectomy (CPHM) and complete medial meniscectomy (MM), specifically with respect to development of secondary osteoarthritis, in the stifle joints of clinically normal dogs. ANIMALS: 14 large-breed dogs. PROCEDURE: Unilateral CPHM (7 dogs) or MM (7) was performed, and the left stifle joints served as untreated control joints. Gait was assessed in all dogs before surgery and at 4, 8, 12, and 16 weeks postoperatively. After euthanasia, joints were evaluated grossly; Mankin cartilage scores, subchondral bone density assessment, and articular cartilage proteoglycan extraction and western blot analyses of 3B3(-) and 7D4 epitopes were performed. RESULTS: Weight distribution on control limbs exceeded that of treated limbs at 4 and 16 weeks after surgery in the CPHM group and at 4 and 8 weeks after surgery in the MM group; weight distribution was not significantly different between the 2 groups. After 16 weeks, incomplete meniscal regeneration and cartilage fibrillation on the medial aspect of the tibial plateau and medial femoral condyle were detected in treated joints in both groups. Mankin cartilage scores, subchondral bone density, and immunoexpression of 3B3(-) or 7D4 in articular cartilage in CPHM- or MM-treated joints were similar; 7D4 epitope concentration in synovial fluid was significantly greater in the MM-treated joints than in CPHM-treated joints. CONCLUSIONS AND CLINICAL RELEVANCE: Overall severity of secondary osteoarthritis induced by CPHM and MM was similar. Investigation of 7D4 epitope concentration in synovial fluid suggested that CPHM was associated with less disruption of chondrocyte metabolism.     

Assessment of the effects of age and joint disease on hydroxyproline and glycosaminoglycan concentrations in synovial fluid from the metacarpophalangeal joint of horses

OBJECTIVE: To assess the effects of age and joint disease on hydroxyproline and glycosaminoglycan (GAG) concentrations in synovial fluid from the metacarpophalangeal joint of horses and evaluate the association of those concentrations with severity of osteoarthritis and general matrix metalloproteinase (MMP) activity. SAMPLE POPULATION: Synovial fluid was collected from the metacarpophalangeal joints of foals at birth (n = 10), 5-month-old foals (10), 11-month-old foals (5), and adult horses (73). PROCEDURE: Hydroxyproline and GAG concentrations were determined in synovial fluid samples. The severity of osteoarthritis in adult joints was quantified by use of a cartilage degeneration index (CDI) and assessment of general MMP-activity via a fluorogenic assay. RESULTS: Hydroxyproline and GAG concentrations in synovial fluid were highest in neonates and decreased with age. Concentrations reached a plateau in adults by 4 years and remained constant in healthy joints. In synovial fluid from osteoarthritic joints, hydroxyproline and GAG concentrations were not increased, compared with unaffected joints, but hydroxyproline were significantly correlated with the CDI and general MMP activity. There was no significant correlation between GAG concentration and CDI value or MMP activity. CONCLUSIONS AND CLINICAL RELEVANCE: Changes in hydroxyproline concentration in synovial fluid appeared to indicate damage to collagen of the articular cartilage. In joints with osteoarthritis, the lack of high GAG concentration in synovial fluid and the absence of a significant correlation between GAG concentration and CDI values or MMP activity may severely limit the usefulness of this marker for monitoring equine joint disease.     

The effect of implanting gentamicin-impregnated polymethylmethacrylate beads in the tarsocrural joint of the horse

OBJECTIVE: To determine the effect of intra-articular gentamicin-impregnated polymethylmethacrylate (PMMA) beads inserted in the equine tarsocrural joint on the synovial fluid, synovial lining, and cartilage, and to determine the peak and sustainable gentamicin concentrations in synovial fluid and plasma. STUDY DESIGN: Pharmacokinetic, cytologic, and histologic study of the effect of gentamicin-impregnated PMMA on normal equine tarsocrural joints. ANIMALS: Five healthy adult horses. METHODS: Gentamicin-impregnated PMMA bead strands (3 strands each of 40 beads, with each strand containing 100 mg gentamicin) were surgically inserted into one radiographically normal tarsocrural joint in 5 horses. Each horse had both joints flushed with 1 L of lactated Ringer's solution before bead administration. Synovial fluid total protein concentration, white blood cell (WBC) count, gentamicin concentration, synovial histology, cartilage integrity, and cartilage glycosaminoglycan (GAG) concentrations were determined. RESULTS: Gentamicin concentration (mean +/- SEM peak concentration, 27.9 +/- 2.27 microg/mL) occurred in the first 24 hours and remained above 2 microg/mL for 9 days. Gentamicin concentrations in control joints and the plasma remained below detectable levels. The synovial fluid WBC count for treated joints was increased compared with control joints for 72 hours, but was similar at day 6. The synovial protein concentration in gentamicin-treated joints remained increased for 21 days. Synovium in treated joints had diffuse synovitis, whereas control joints had less fibrovascular proliferation. Superficial cartilage erosion was present in all treated joints. There was no difference in the GAG content of treated and control joint cartilage. CONCLUSIONS: Short-term implantation of gentamicin (300 mg)-impregnated PMMA beads can provide therapeutic levels of gentamicin (>2 microg/mL) in the normal tarsocrural joint for 9 days; however, gentamicin-impregnated PMMA beads induce synovitis and superficial cartilage erosion. CLINICAL RELEVANCE: Temporary intra-articular administration of antibiotic-impregnated PMMA may be an effective way to treat septic joints that require constant high concentrations of antibiotics.     

In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondrial defect model

The uptake and distribution of intramuscularly (IM) administered tritium-labeled polysulfated glycosaminoglycan (³H-PSGAG) in serum, synovial fluid, and articular cartilage of eight horses was quantitated, and hyaluronic acid (HA) concentration of the middle carpal joint was evaluated in a pharmacokinetic study. A full-thickness articular cartilage defect, created on the distal articular surface of the left radial carpal bone of each horse served as an osteochondral defect model. ³H-PSGAG (500 mg) was injected IM, between 14 and 35 days after creation of the defects. Scintillation analysis of serum and synovial fluid, collected from both middle carpal joints at specific predetermined times up to 96 hours post-injection, revealed mean ³H-PSGAG concentrations peaked at 2 hours post-injection. ³H-PSGAG was detected in cartilage and subchondral bone 96 hours post-injection in samples from all eight horses. There were no statistically significant differences in ³H-PSGAG concentration of synovial fluid or cartilage between cartilage defect and control (right middle carpal) joints.

HA assay of synovial fluid revealed concentrations significantly increased at 24, 48, and 96 hours post-injection in both joints. The concentration nearly doubled 48 hours post-injection. However, no statistically significant differences were found between synovial concentrations of HA in cartilage defect and control joints.

³H-PSGAG administered IM to horses, was distributed in the blood, synovial fluid, and articular cartilage. HA concentrations in synovial fluid increased after IM administration of polysulfated glycosaminoglycan.     

Evaluation of the effects of intra-articular injection of dimethylsulfoxide on normal equine articular tissues

To evaluate the effects of intra-articular injection of dimethylsulfoxide (DMSO) on normal equine articular structures, 7 adult horses with clinically normal carpi were allotted to 2 treatment groups (group A, n = 4; group B, n = 3). In each horse after collection of synovial fluid samples, the right antebrachial carpal and middle carpal joints were aseptically injected with 2 ml of a 40% solution of 90% medical grade DMSO in lactated Ringer solution, and the corresponding joints of the left forelimb (controls) were injected with 2 ml of lactated Ringer solution. In group-A horses, 2 ml of synovial fluid was obtained prior to injections of 40% DMSO at 24 hours and 72 hours, for a total of 3 injections. At necropsy, synovial fluid, synovial membrane, and articular cartilage specimens were obtained. Group-B horses were injected with 40% DMSO in the same sequence; however, the series was repeated following a 1-week interval. Clinical evaluation of these horses revealed no evidence of carpal inflammation associated with any injection in any group. Synovial fluid analysis of DMSO-injected and control joints revealed insignificant differences in leukocyte counts and total protein content. There was no evidence of cartilage degradation on gross, histologic, or histochemical evaluation of any of the joints. Intercellular matrix staining of the articular cartilage failed to reveal any observable difference in glycosaminoglycan content between injection with DMSO or lactated Ringer solution.     

Changes in concentrations of biochemical markers of osteoarthritis following surgical repair of ruptured cranial cruciate ligaments in dogs.

OBJECTIVE: To investigate longitudinal changes in concentrations of the 1/20/5D4 epitope (5D4) of keratan sulfate and total sulfated glycosaminoglycans (S-GAG) in synovial fluid and serum of dogs with cranial cruciate ligament (CCL) rupture that was repaired via intra-articular surgery. ANIMALS: 58 dogs with a ruptured CCL and osteoarthritis of the affected (index) joint. PROCEDURE: Prior to surgical repair of the ruptured CCL, 5D4 concentration was measured in serum and synovial fluid samples by use of an inhibition ELISA, and total S-GAG concentration was measured in synovial fluid samples by use of a direct dye-binding assay. Ruptured CCL were repaired surgically, using an intra-articular fascial graft. Dogs were reexamined 1.5, 7, and 13 months after surgery, and 5D4 and S-GAG concentrations in synovial fluid and serum were measured again. RESULTS: Serum 5D4 concentrations did not change significantly during the study. Concentrations of 5D4 in synovial fluid (expressed as a ratio of S-GAG concentration) did change significantly with time. In the index joint, the 5D4:S-GAG decreased from 0.19 at the beginning of the study to 0.09 1.5 months after surgery, but 7 months after surgery, the ratio increased again to 0.20. CONCLUSIONS AND CLINICAL RELEVANCE: Results support the hypothesis that serum concentration of 5D4 is not a useful marker of osteoarthritis in dogs. Surgical intervention transiently reduced the concentration of 5D4 in synovial fluid but had no effect on S-GAG concentration.     

Glycosaminoglycans in horses with osteoarthritis

Horse articular cartilage glycosaminoglycans (GAGs) were measured in synovial fluids from 48 joints affected with osteoarthritis (OA), 22 normal joints, four joints with osteochondritis, three joints with traumatic arthritis and seven joints infected with bacteria. Serum and urine from individual horses were also examined for the presence of GAGs. High levels of GAGs were found in synovial fluids (SF) from horses with OA. In each case, the level was higher in the synovial fluid than in the serum or urine from the same horse. Horses with OA showed high GAG levels in SF, serum and urine compared to horses with normal and infected joints. High levels were also found in horses with osteochondritis and traumatic arthritis. Levels of synovial fluid GAG reflect cartilage destruction in arthritis and may be useful for monitoring disease progression in the equine species.     

Recombinant equine growth hormone administration: effects on synovial fluid biomarkers and cartilage metabolism in horses

REASONS FOR PERFORMING STUDY: Recombinant equine growth hormone (reGH) has recently been evaluated for effects on body condition and wound healing. It has the potential to influence articular cartilage via stimulation of IGF-1. OBJECTIVES: To investigate effects of administration on synovial joint metabolism. METHODS: Six mature horses were given 20 microg/kg bwt reGH daily for 8 weeks by i.m. injection. Three control horses were injected with sterile water. Serum and synovial fluid samples were collected at 6, 8, 11 and 16 weeks for GH and IGF-1 assays. Articular cartilage harvested at week 16 was evaluated by Western analysis using monoclonal antibodies BC-13, BC-4, 8-A-4 and CH-3. RESULTS: Concentrations of IGF-1 in serum and synovial fluid were significantly elevated (P < 0.05) at 6 and 8 weeks in the reGH group. Glycosaminoglycan concentrations in synovial fluid were significantly less than controls at these time points, suggesting that reGH may modulate proteoglycan metabolism in articular cartilage. In the reGH group, there were not any alterations in synovial fluid content of 3B3(-) epitope or aggrecan metabolite, or in aggrecan or link protein catabolites retained within cartilage, that might be expected with development of osteoarthritis. CONCLUSIONS: Intramuscular administration of reGH may be a more efficient means of delivery of IGF-1 to joints for cartilage resurfacing initiatives. POTENTIAL RELEVANCE: We found no alterations in cartilage metabolism indicative of development of osteoarthritis.     

Measurement of articular cartilage stiffness of the femoropatellar, tarsocrural, and metatarsophalangeal joints in horses and comparison with biochemical data

OBJECTIVE: To determine normal cartilage stiffness values in different weight-bearing and non-weight-bearing areas of 3 different equine joints, and to evaluate the relationship between cartilage stiffness and glycosaminoglycan (GAG) and collagen content. STUDY DESIGN: Compressive stiffness of the articular cartilage was measured in 8 horse cadaver femoropatellar (FP), tarsocrural (TC), and metatarsophalangeal (MT) joints. Gross evaluation, collagen content, GAG content, and histologic appearance were assessed for each measurement location. ANIMALS: Eight equine cadavers (4 intact females, 4 castrated males; 7 Quarter Horse or Quarter Horse type, 1 Arabian; aged 4-12 years, weighing 400-550 kg). METHODS: The articular surfaces of 8 equine cadaver FP, TC, and MT joints were grossly evaluated for signs of articular cartilage pathology. Stiffness at preselected sites (FP joint-6 sites; TC joint-3 sites; MT joint-4 sites) was determined using an arthroscopic indentation instrument. Biochemical composition (collagen, GAG content) and histologic evaluation (modified Mankin score) were assessed for each measurement site. RESULTS: All cartilage from all sites evaluated was determined to be normal based on macroscopic and histologic assessments. No significant correlation between Mankin scores and cartilage stiffness values was observed. Site differences in cartilage stiffness were measured in all 3 joints (P<.001). GAG or collagen content had a significant positive correlation with stiffness values in 6 of 13 sites (P<.05, r>0.622, r2>0.387). CONCLUSION: Relative cartilage stiffness values measured in healthy equine joints are site dependent and can be measured using an indentation device intended for arthroscopic application. CLINICAL RELEVANCE: An indentation instrument provided an objective means of determining relative compressive stiffness of articular cartilage. Further research needs to be performed to confirm the site and joint differences observed in this study in clinically normal horses and to determine if the tester can be used clinically to predict articular cartilage pathology.     

Relationship between synovial fluid levels of glycosaminoglycans, hydroxyproline and general MMP activity and the presence and severity of articular cartilage change on the proximal articular surface of P1

REASONS FOR PERFORMING STUDY: Osteoarthritis (OA) is one of the most prevalent and disabling chronic conditions affecting horses and leads to degeneration of articular cartilage. Diagnosis is based on clinical signs in combination with radiography, which is relatively insensitive and provides only an indication of accumulated damage. Alternative methods, such as molecular markers, are therefore needed that can quantitatively, reliably and sensitively detect osteoarthritic changes in the joints at an early stage of the disease. If such markers are to be used reliably, it is important to know the relationship between marker concentration and cartilage composition. OBJECTIVES: To study the relationship between cartilage composition, synovial fluid levels of glycosaminoglycans (GAGs), hydroxyproline (Hyp) and general matrix metalloproteinase (MMP) activity, and the presence and severity of articular cartilage damage on the articular surface of P1. METHODS: Synovial fluid (SF) was collected from the metacarpophalangeal joints of 60 mature horses, and levels of GAGs, Hyp and general MMP activity were determined. Further, GAG and denatured collagen content of the articular cartilage were determined at the dorsal articular margin of P1 (site 1) and central cavity (site 2). The presence and severity of cartilage change was quantified using the cartilage degeneration index (CDI), measured at the same 2 sites. Correlations between SF parameters, cartilage composition and degree of cartilage degeneration were sought using correlation analysis. RESULTS: There was no correlation between GAG or Hyp content of SF and the amount of GAGs or denatured collagen, respectively, in cartilage. In joints with moderate to severe cartilage damage, the GAG content of site 1 was significantly lower than in joints with no to minimal cartilage change (P = 0.005) and there was a negative correlation between the amount of denatured collagen and GAG content at site 1 in all joints (r = -039, P = 0.002). Further, in joints with moderate to severe cartilage damage, there was a significant positive correlation between MMP activity in SF and Hyp levels in SF (r = 0.72, P < 0.001) and CDI at sites 1 (r = 0.46, P = 0.03) and 2 (r = 0.43, P = 0.04). CONCLUSIONS: General MMP activity in joints with moderate to severe cartilage damage is related to the severity of those cartilage changes and to Hyp levels in SF. Glycosaminoglycan levels in SF are not directly related to MMP activity, GAG content of articular cartilage or severity of cartilage change. POTENTIAL RELEVANCE: Glycosaminoglycan levels in SF are not helpful for the early detection of cartilage lesions. In damaged joints, Hyp levels may give an indication of the severity of cartilage change as they are strongly related to MMP activity, but do not qualify as markers for the presence or absence of cartilage lesions.     

Povidone-iodine lavage treatment of experimentally induced equine infectious arthritis

Both tarsocrural joints of 4 horses were inoculated with 1.5 X 10(5) colony-forming units of Staphylococcus aureus. On days 1, 3, and 6, each horse had one tarsocrural joint lavaged with a balanced electrolyte solution and had the contralateral tarsocrural joint lavaged with 0.1% povidone-iodine solution. All horses were orally administered trimethoprim (5 mg/kg)/sufadiazine (25 mg/kg) combination twice daily and phenylbutazone (2 g) once daily for the duration of the study (21 days). On days 0, 1, 3, 6, 9, 14, and 21, synovial fluid specimens were collected and analyzed for color, clarity, total protein concentration, WBC count and differential, and mucin clot-forming ability. Synovial fluid specimens collected on days 1, 3, 6, 9, 14, and 21 were bacteriologically cultured. On day 21, all horses were euthanatized, the tarsocrural joints were opened and examined, synovial membrane specimens were collected, bacteriologically cultured, and histologically evaluated, and articular cartilage specimens were histochemically evaluated. Repeated measures analysis of variance were used to evaluate differences between lavage solutions and among days for objective measurements. A paired t test was used to evaluate differences between solutions for the indices of synovial membrane inflammation and articular cartilage staining intensity with safranin-O-fast green. To be considered significant, the probability of a type-I error was less than 0.05. Significant differences were not found between joints lavaged with electrolyte solution vs povidone-iodine solution for synovial total protein concentration, WBC count, results of synovial fluid and membrane bacteriologic culture, synovial membrane inflammation, or articular cartilage glycosaminoglycan concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of continuous intra-articular infusion of gentamicin on synovial membrane and articular cartilage in the tarsocrural joint of horses

OBJECTIVE: To determine the effects of a continuous intra-articular infusion of gentamicin on the synovial membrane and articular cartilage in the tarsocrural joint of horses. ANIMALS: 6 healthy adult horses. PROCEDURE: A balloon infusion system attached to a catheter placed in the plantarolateral pouch of both tarsocrural joints in each horse was used for continuous gentamicin solution (GM) or balanced electrolyte solution (BES) delivery for 5 days. Cartilage and synovial membrane specimens were collected on day 5 from 3 horses and on day 14 from the remaining 3 horses. Both infused joints from each horse were assessed, using gross evaluation and histologic scoring systems. RESULTS: Significant differences in the histologic scores of synovial membrane specimens between the GM- and BES-treated joints at either 5 or 14 days were not observed. Safranin-O-fast green staining scores were similar between cartilage specimens from GM- and BES-treated joints. Although the synovial membrane histologic scores and safranin-O-fast green staining scores improved from day 5 to 14, the changes in scores were not significant. Loss of synovial intimal cells from villi was found more commonly in sections of synovial membrane from GM-treated joints, compared with BES-treated joints. CONCLUSIONS AND CLINICAL RELEVANCE: Continuous infusion of GM into the tarsocrural joint of horses does not have significant effects on histologic scores of articular cartilage or synovial membrane, compared with those infused with BES. Continuous infusion of GM into the tarsocrural joint of horses for 5 days is an acceptable method for the treatment of septic arthritis.     

Gentamicin concentrations in synovial fluid obtained from the tarsocrural joints of horses after implantation of gentamicin-impregnated collagen sponges

OBJECTIVE: To determine synovial fluid gentamicin concentrations and evaluate adverse effects on the synovial membrane and articular cartilage of tarsocrural joints after implantation of a gentamicin-impregnated collagen sponge. ANIMALS: 6 healthy adult mares. PROCEDURES: A purified bovine type I collagen sponge impregnated with 130 mg of gentamicin was implanted in the plantarolateral pouch of 1 tarsocrural joint of each horse, with the contralateral joint used as a sham-operated control joint. Gentamicin concentrations in synovial fluid and serum were determined for 120 hours after implantation by use of a fluorescence polarization immunoassay. Synovial membrane and cartilage specimens were collected 120 hours after implantation and evaluated histologically. RESULTS: Median peak synovial fluid gentamicin concentration of 168.9 microg/mL (range, 115.6 to 332 microg/mL) was achieved 3 hours after implantation. Synovial fluid gentamicin concentrations were < 4 microg/mL by 48 hours. Major histologic differences were not observed in the synovial membrane between control joints and joints implanted with gentamicin-impregnated sponges. Safranin-O fast green stain was not reduced in cartilage specimens obtained from treated joints, compared with those from control joints. CONCLUSIONS AND CLINICAL RELEVANCE: Implantation of a gentamicin-impregnated collagen sponge in the tarsocrural joint of horses resulted in rapid release of gentamicin, with peak concentrations > 20 times the minimum inhibitory concentration reported for common pathogens that infect horses. A rapid decrease in synovial fluid gentamicin concentrations was detected. The purified bovine type I collagen sponges did not elicit substantial inflammation in the synovial membrane or cause mechanical trauma to the articular cartilage.     

Samarium 153-labeled hydroxyapatite microspheres for radiation synovectomy in the horse: a study of the biokinetics, dosimetry, clinical, and morphologic response in normal metacarpophalangeal and metatarsophalangeal joints

OBJECTIVE: To determine the effects of Samarium-153 bound to hydroxyapatite microspheres (153SmM) when injected into the metacarpophalangeal and metatarsophalangeal joints of horses. STUDY DESIGN:- Horses were injected with 153SmM in metacarpophalangeal and metatarsophalangeal joints with the diagonal contralateral joints used as untreated controls. ANIMALS OR SAMPLE POPULATION: Twelve adult horses without pre-existing disease involving the metacarpo/metatarsophalangeal joints. METHODS: Horses were divided into three groups: high-dose Samarium-153 (12.5 to 17.0 millicurie [mCi]), intermediate dose (6.5 to 12.0 mCi), and low dose (3.5 to 6.0 mCi). Horses were examined daily for 7 days postinjection for clinical abnormalities, lameness, and surface and systemic radiation levels. One horse from each group was euthanatized at 14, 30, and 60 days postinjection and the effects of the 153SmM examined microscopically in the cartilage and synovial membrane. RESULTS: Intraarticular(153)SmM caused inflammation characterized by lameness, effusion, and regional edema for 48 to 72 hours. Minimal levels of active 153SmM were identified in the blood or urine and were well below the maximal tolerance of 1 mCi. Microscopically the radiation caused no effects on the articular cartilage. The synovectomy created was good but not ideal in that some areas did have necrosis into the subintimal regions and a few islands of intact intimal cells persisted. CONCLUSIONS: The use of 153SmM is an effective means of targeting the synovial intimal cells with minimal extrasynovial leakage of radiation. CLINICAL RELEVANCE: The metacarpophalangeal and metatarsophalangeal joints of the horse can be safely treated with 153SmM without damage to the cartilage or significant extracapsular leakage.     

Effects of polysulfated glycosaminoglycan on chemical and physical defects in equine articular cartilage

The effect of intra-articular polysulfated glycosaminoglycan (PSG) on repair of chemical and physical articular cartilage injuries was evaluated in 8 horses. In each horse, a partial- and a full-thickness articular cartilage defect was made on the distal articular surface of the radial carpal bone. In the contralateral middle carpal joint, a chemical articular cartilage injury was induced by injecting 50 mg of Na monoiodoacetate (MIA). Four of the 8 horses were not treated (controls), and 4 horses were treated by intra-articular injection of 250 mg of PSG into both middle carpal joints once a week for 5 treatments starting 1 week after cartilage injury. Horses were maintained for 8 weeks. There was less joint circumference enlargement in PSG-treated horses in MIA-injected and physical defect carpi, compared with that in controls. In MIA-injected joints, there was less articular cartilage fibrillation and erosion, less chondrocyte death, and greater safranin-O staining for glycosaminoglycans in PSG-treated horses. Evaluation of joints in which physical defects were made revealed no differences between control and PSG-injected joints. None of the partial-thickness defects had healed. Full-thickness defects were repaired with fibrous tissue (which was more vascular and cellular in PSG-injected joints) and occasionally small amounts of fibrocartilage. Seemingly, PSG had chondroprotective properties in a model of chemically induced articular cartilage damage, whereas PSG had no obvious effect in a physical articular cartilage-defect model.     

Serum and synovial fluid concentrations of keratan sulfate and hyaluronan in dogs with induced stifle joint osteoarthritis following cranial cruciate ligament transection

OBJECTIVE: To examine longitudinal changes in serum and synovial fluid concentrations of keratan sulfate (KS) and hyaluronan (HA) after cranial cruciate ligament (CCL) transection in dogs. ANIMALS: 12 clinically normal adult mixed-breed dogs. PROCEDURE: Following CCL transection in the right stifle joint, KS and HA concentrations were determined in serum and neat (undiluted) synovial fluid prior to and 1, 2, 3, and 12 months after surgery. Postsurgical dilution of synovial fluid was corrected by use of urea as a passive marker. RESULTS: Synovial fluid KS and HA concentrations decreased at 1, 2, and 3 months after surgery in operated stifle joints, compared with baseline values. Synovial fluid KS concentration decreased in unoperated stifle joints at 1 month. A decrease in synovial fluid KS concentration was found in operated stifle joints, compared with unoperated stifle joints, at 2 and 3 months, and a decrease in synovial fluid HA concentrations was also found in operated stifle joints, compared with unoperated stifle joints, at 1, 2, and 3 months. Serum KS concentrations increased from baseline values at 3 months after surgery. Hyaluronan concentrations in operated stifle joints were lower than baseline values at 1, 2, and 3 months. Urea-adjusted synovial fluid concentrations revealed that dilution did not account for the decline in biomarker concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: The initial decrease and subsequent increase in synovial fluid concentrations of HA and KS may be caused by an acute inflammatory response to surgical intervention that negatively affects cartilage metabolism or an increase in production of immature proteoglycans.     

The effects of doxycycline on nitric oxide and stromelysin production in dogs with cranial cruciate ligament rupture

OBJECTIVE: To investigate the potential of doxycycline to reduce stromelysin and inducible nitric oxide synthase (iNOS) activity in dogs with osteoarthritis (OA) secondary to spontaneous cranial cruciate ligament (CCL) rupture. STUDY DESIGN: Prospective, clinical study. ANIMALS: Eighty-one dogs with OA secondary to CCL rupture and 54 normal dogs. METHODS: Dogs with OA secondary to CCL rupture were divided into 2 groups before surgery. The Doxy-CCl group received 3 to 4 mg/kg doxycycline orally every 24 hours for 7 to 10 days (n = 35). The CCL group received no treatment (n = 46). Synovial fluid, articular cartilage, synovial membrane, and CCL samples were collected during surgery (Doxy-CCL group and CCL group) or immediately after euthanasia from healthy dogs (control group). Synovial fluid samples were examined cytologically. Total nitric oxide (NOt) concentrations were measured in the supernatant of explant cultures of all tissue samples, and stromelysin activity was measured in the supernatant of explant cultures of cartilage. RESULTS: NOt concentrations measured in cartilage were significantly lower in the Doxy-CCL group than in the CCL group, but were not different from those measured in the control group. Doxycycline treatment did not have a significant effect on cartilage stromelysin levels. CONCLUSION: The findings in this study indicate that doxycycline inhibits NO production in cartilage in dogs with CCL rupture. CLINICAL RELEVANCE: Doxycycline may have a role in the treatment of canine OA by inhibiting NO production.