Lack of association between serum keratan sulfate concentrations and cartilage changes of osteoarthritis after transection of the anterior cruciate ligament in the dog

Comprehensive Study on Scoring and Grading Systems for Predicting the Severity of Knee Osteoarthritis

Knee Osteoarthritis (KOA) is a degenerative joint ailment characterized by cartilage loss, which can be seen using imaging modalities and converted into imaging features. The older population is the most affected by knee OA, which affects 16% of people worldwide who are 15 years of age and older. Due to cartilage tissue degradation, primary knee OA develops in older people. In contrast, joint overuse or trauma in younger people can cause secondary knee OA. Early identification of knee OA, according to research, may be a successful management tactic for the condition. Scoring scales and grading systems are important tools for the management of knee osteoarthritis as they allow clinicians to measure the progression of the disease's severity and provide suggestions on suitable treatment at identified stages. The comprehensive study reviews various subjective and objective knee evaluation scoring systems that effectively score and grade the KOA based on where defects or changes in articular cartilage occur. Recent studies reveal that AI-based approaches, such as that of DenseNet, integrating the concept of deep learning for scoring and grading the KOA, outperform various state-of-the-art methods in order to predict the KOA at an early stage.

Comparison between in vitro and in vivo cartilage overloading studies based on a systematic literature review

Methodological differences between in vitro and in vivo studies on cartilage overloading complicate the comparison of outcomes. The rationale of the current review was to (i) identify consistencies and inconsistencies between in vitro and in vivo studies on mechanically-induced structural damage in articular cartilage, such that variables worth interesting to further explore using either one of these approaches can be identified; and (ii) suggest how the methodologies of both approaches may be adjusted to facilitate easier comparison and therewith stimulate translation of results between in vivo and in vitro studies. This study is anticipated to enhance our understanding of the development of osteoarthritis, and to reduce the number of in vivo studies. Generally, results of in vitro and in vivo studies are not contradicting. Both show subchondral bone damage and intact cartilage above a threshold value of impact energy. At lower loading rates, excessive loads may cause cartilage fissuring, decreased cell viability, collagen network de-structuring, decreased GAG content, an overall damage increase over time, and low ability to recover. This encourages further improvement of in vitro systems, to replace, reduce, and/or refine in vivo studies. However, differences in experimental set up and analyses complicate comparison of results. Ways to bridge the gap include (i) bringing in vitro set-ups closer to in vivo, for example, by aligning loading protocols and overlapping experimental timeframes; (ii) synchronizing analytical methods; and (iii) using computational models to translate conclusions from in vitro results to the in vivo environment and vice versa. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-11, 2018.

Relationship between foot function and medial knee joint loading in people with medial compartment knee osteoarthritis

BACKGROUND

Dynamic joint loading, particularly the external knee adduction moment (KAM), is an important surrogate measure for the medio-lateral distribution of force across the knee joint in people with knee osteoarthritis (OA). Foot motion may alter the load on the medial tibiofemoral joint and hence affect the KAM. Therefore, this study aimed to investigate the relationship between tibia, rearfoot and forefoot motion in the frontal and transverse planes and the KAM in people with medial compartment knee OA.

METHOD

Motion of the knee, tibia, rearfoot and forefoot and knee moments were evaluated in 32 patients with clinically and radiographically-confirmed OA, predominantly in the medial compartment. Pearson's correlation coefficient was used to investigate the association between peak values of tibia, rearfoot and forefoot motion in the frontal and transverse planes and 1st peak KAM, 2nd peak KAM, and the knee adduction angular impulse (KAAI).

RESULTS

Lateral tilt of the tibia was significantly associated with increased 1st peak KAM (r = 0.60, p < 0.001), 2nd peak KAM (r = 0.67, p = 0.001) and KAAI (r = 0.82, p = 0.001). Increased peak rearfoot eversion was significantly correlated with decreased 2nd peak KAM (r = 0.59, p < 0.001) and KAAI (r = 0.50, p = 0.004). Decreased rearfoot internal rotation was significantly associated with increased 2nd peak KAM (r = -0.44, p = 0.01) and KAAI (r = -0.38, p = 0.02), while decreased rearfoot internal rotation relative to the tibia was significantly associated with increased 2nd peak KAM (r = 0.43, p = 0.01). Significant negative correlations were found between peak forefoot eversion relative to the rearfoot and 2nd peak KAM (r = -0.53, p = 0.002) and KAAI (r = -0.51, p = 0.003) and between peak forefoot inversion and 2nd peak KAM (r = -0.54, p = 0.001) and KAAI (r = -0.48, p = 0.005).

CONCLUSION

Increased rearfoot eversion, rearfoot internal rotation and forefoot inversion are associated with reduced knee adduction moments during the stance phase of gait, suggesting that medial knee joint loading is reduced in people with OA who walk with greater foot pronation. These findings have implications for the design of load-modifying interventions in people with knee OA.

Translational animal models using veterinary patients - An example of canine osteoarthritis (OA)

Background and purpose The use of laboratory animals in pain research has powerfully contributed to our detailed understanding of the physiological mechanisms of pain. Animal models also represent an essential tool to screen and select novel drug molecules with potentially analgesic properties. Despite of the inevitable input of laboratory animal trials, recent studies have shown that animal pain models have repeatedly failed to predict clinical analgesic efficacy and adverse side effects of potential drug molecules in human pain patients. This paper provides a review of the laboratory animal models of OA, which have been developed to test efficacy of novel analgesics. The paper also presents spontaneous OA in canine veterinary patients, and methods to observe chronic pain in nonverbal dogs. Methods PubMed data base was searched as a reference list to locate most relevant articles. A number of 118 articles including 4 reviews were located. Web pages of 4 establishments and 2 private organizations were also accessed. Results The clinical expression and pathogenesis of naturally occurring OA in dogs is considered an analogous disease that occurs in humans, including pain and lameness. OA may occur in any joint in dogs as well as in humans. Primary idiopathic OA in dogs is rare, but certain breeds may be predisposed to it. For the most part, canine OA is considered secondary to acquired or congenital musculoskeletal disorders. Concomitant factors, such as aging and obesity, likely accelerate progression. However, mechanical factors appear to predominate in the etiopathogenesis of canine spontaneous OA. Both subjective (validated questionnaire) and objective (gait analysis) tools are available to measure OA related pain in dogs. Information on the prevalence of canine OA is limited, but rough surveys suggest that 11 million dogs in the United States and 5 million in Europe could suffer from OA. Ethical considerations concerning the use of privately owned dogs can be resolved by a careful experimental design. Conclusion Canine spontaneous OA could serve as a translational animal model that would more closely mimick clinical OA related pain conditions in humans. Privately owned dogs would make a solution to fix the gap between animal pain models and clinical trials when testing potential analgesic drug molecules. Close interdisciplinary cooperation would guarantee that both scientific and ethical intentions would be achieved. Implications The predictability of translational pain research would improve by using privately owned dogs as chronic pain models when testing novel analgesics.

The highly accurate anteriolateral portal for injecting the knee

Background

The extended knee lateral midpatellar portal for intraarticular injection of the knee is accurate but is not practical for all patients. We hypothesized that a modified anteriolateral portal where the synovial membrane of the medial femoral condyle is the target would be highly accurate and effective for intraarticular injection of the knee.

Methods

83 subjects with non-effusive osteoarthritis of the knee were randomized to intraarticular injection using the modified anteriolateral bent knee versus the standard lateral midpatellar portal. After hydrodissection of the synovial membrane with lidocaine using a mechanical syringe (reciprocating procedure device), 80 mg of triamcinolone acetonide were injected into the knee with a 2.0-in (5.1-cm) 21-gauge needle. Baseline pain, procedural pain, and pain at outcome (2 weeks and 6 months) were determined with the 10 cm Visual Analogue Pain Score (VAS). The accuracy of needle placement was determined by sonographic imaging.

Results

The lateral midpatellar and anteriolateral portals resulted in equivalent clinical outcomes including procedural pain (VAS midpatellar: 4.6 ± 3.1 cm; anteriolateral: 4.8 ± 3.2 cm; p = 0.77), pain at outcome (VAS midpatellar: 2.6 ± 2.8 cm; anteriolateral: 1.7 ± 2.3 cm; p = 0.11), responders (midpatellar: 45%; anteriolateral: 56%; p = 0.33), duration of therapeutic effect (midpatellar: 3.9 ± 2.4 months; anteriolateral: 4.1 ± 2.2 months; p = 0.69), and time to next procedure (midpatellar: 7.3 ± 3.3 months; anteriolateral: 7.7 ± 3.7 months; p = 0.71). The anteriolateral portal was 97% accurate by real-time ultrasound imaging.

Conclusion

The modified anteriolateral bent knee portal is an effective, accurate, and equivalent alternative to the standard lateral midpatellar portal for intraarticular injection of the knee.

Trial Registration

ClinicalTrials.gov: NCT00651625

Foot posture in people with medial compartment knee osteoarthritis

Background

Foot posture has long been considered to contribute to the development of lower limb musculoskeletal conditions as it may alter the mechanical alignment and dynamic function of the lower limb. This study compared foot posture in people with and without medial compartment knee osteoarthritis (OA) using a range of clinical foot measures. The reliability of the foot measures was also assessed.

Methods

The foot posture of 32 patients with clinically and radiographically-confirmed OA predominantly in the medial compartment of the knee and 28 asymptomatic age-matched healthy controls was investigated using the foot posture index (FPI), vertical navicular height and drop, and the arch index. Independent t tests and effect size (Cohen's d) were used to investigate the differences between the groups in the foot posture measurements.

Results

Significant differences were found between the control and the knee OA groups in relation to the FPI (1.35 ± 1.43 vs. 2.46 ± 2.18, p = 0.02; d = 0.61, medium effect size), navicular drop (0.02 ± 0.01 vs. 0.03 ± 0.01, p = 0.01; d = 1.02, large effect size) and the arch index (0.22 ± 0.04 vs. 0.26 ± 0.04, p = 0.04; d = 1.02, large effect size). No significant difference was found for vertical navicular height (0.24 ± 0.03 vs. 0.23 ± 0.03, p = 0.54; d = 0.04, negligible effect size).

Conclusion

People with medial compartment knee OA exhibit a more pronated foot type compared to controls. It is therefore recommended that the assessment of patients with knee OA in clinical practice should include simple foot measures, and that the potential influence of foot structure and function on the efficacy of foot orthoses in the management of medial compartment knee OA be further investigated.

Biomarkers of cartilage turnover. Part 2: Non-collagenous markers

Osteoarthritis (OA) results in the destruction and breakdown of articular cartilage matrix. Breakdown of the cartilage proteoglycan component results in the generation of constituent fragments that can be detected in the blood, synovial fluid or urine. Non-collagenous, non-proteoglycan components of cartilage can also be detected following their release as a result of turnover and disease. OA also alters the circulating profile of metabolites in the body. Metabolomic strategies have been used to distinguish populations with OA from normal populations by the creation of a metabolomic 'fingerprint' attributable to the disease. This paper is the second part of a two-part review and describes some of the techniques used to measure the concentrations of some of these 'non-collagenous' biomarkers, and how the application of these measurements assists the study of joint disease. Collagen-based biomarkers were discussed in part one.

Correlation between radiographic findings of osteoarthritis and arthroscopic findings of articular cartilage degeneration within the patellofemoral joint

OBJECTIVES

To correlate radiographic findings of osteoarthritis on axial knee radiographs with arthroscopic findings of articular cartilage degeneration within the patellofemoral joint in patients with chronic knee pain.

SUBJECTS AND METHODS

The study group consisted of 104 patients with osteoarthritis of the patellofemoral joint and 30 patients of similar age with no osteoarthritis of the patellofemoral joint. All patients in the study group had an axial radiograph of the knee performed prior to arthroscopic knee surgery. At the time of arthroscopy, each articular surface of the patellofemoral joint was graded using the Noyes classification system. Two radiologists retrospectively reviewed the knee radiographs to determine the presence of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts. The sensitivity and specificity of the various radiographic features of osteoarthritis for the detection of articular cartilage degeneration within the patellofemoral joint were determined.

RESULTS

The sensitivity of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts for the detection of articular cartilage degeneration within the patellofemoral joint was 73%, 37%, 4%, and 0% respectively. The specificity of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts for the detection of articular cartilage degeneration within the patellofemoral joint was 67%, 90%, 100%, and 100% respectively.

CONCLUSION

Marginal osteophytes were the most sensitive radiographic feature for the detection of articular cartilage degeneration within the patellofemoral joint. Joint-space narrowing, subchondral sclerosis, and subchondral cysts were insensitive radiographic features of osteoarthritis, and rarely occurred in the absence of associated osteophyte formation.

The effects of growth and disease in serum keratan sulfate concentration in dogs

The purpose of this study is to investigate keratan sulfate (KS) concentration in the serum of puppies and the effects of age, body weight, breed and diseases. Serum samples from six neonatal dogs (4 Beagles, 2 Labrador Retrievers), and from 127 adult dogs with various diseases were collected at a Teaching Animal Hospital. Canine serum KS concentration was measured by inhibition enzyme-linked immunosorbent assay (ELISA). Samples from puppies were evaluated for growth-related changes, and samples from patients were evaluated for age, body weight, breed and disease-related changes. Serum KS concentration was high in puppies from birth to 4 months of age. KS values started to decrease from 4 months to 9 months of age, and then gradually reached to the plateau. Though in the small sample, mean KS concentration in a Labrador Retriever was higher than in Beagles during the first 10 months. The values of serum KS showed body weight-related increase within retrievers among teaching hospital population and there was significant increase in body weight-related change. Cartilage metabolism is high in canine immature joint and that activity continues for 5 months, and that higher in Labrador Retrievers rather than in Beagles. There was no effect from other factors, including age, body weight, breed and disease in all patients. Serum KS concentration of Retrievers is higher than Beagles, and that value increased with gain of body weight. We suggest that Retriever have higher cartilage metabolism with growth or ageing.

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.

Biomarkers of joint tissue metabolism in canine osteoarthritic and arthritic joint disorders

OBJECTIVE

To explore the levels of matrix metalloprotease-3 (MMP-3), tissue inhibitor of metalloproteases-1 (TIMP-1), 5D4 keratan sulfate, and two 3B3 chondroitin-sulfate epitopes in several canine osteoarthritic and inflammatory arthropathies.

METHODS

Blood and synovial fluid were obtained from 103 dogs with rupture of the anterior cruciate ligament (ACLR), osteochondritis dissecans (OCD), fragmented coronoid process (FPC), patella luxation (PL), hip dysplasia (HD) or infectious arthritis. Dogs with non-musculosceletal disorders were used as controls. The biomarkers were measured by immunoassays.

RESULTS

Median levels of synovial MMP-3, TIMP-1 and molar ratios of MMP/TIMP-1 were significantly higher in the arthritis than in the control group. The release of 5D4 keratan sulfate epitope and serum 3B3 neoepitope was reduced in arthritis patients. Increases in synovial TIMP-1 in OA were less pronounced and the molar ratio of MMP-3/TIMP-1 remained far below 1.0, demonstrating a surplus of the protease inhibitor. In osteoarthritic patients median levels of synovial 5D4 keratan sulfate were up-regulated after ACLR and PL and were inversely correlated with increasing duration of lameness. Serum TIMP-1 levels were significantly reduced in the joint disorder group when compared with the control group.

CONCLUSION

Our observations present the TIMP-1 serum level as a potential marker for the detection of degenerative changes in cartilage and also indicate that in canine OA, the MMP-3 mediated matrix destruction is not of major importance. However MMP-3 seems to be a sensitive marker for the local inflammation in canine arthritis.

Longitudinal characterization of synovial fluid biomarkers in the canine meniscectomy model of osteoarthritis

Damage to the meniscus can lead to posttraumatic osteoarthritis. Early markers of joint injury and tissue disease may be useful in developing and administering clinical treatment. We investigated the effects of total medial meniscectomy on biomarkers measured serially in synovial lavage fluid each month for 3 months. Following meniscectomy in dogs, four biomarkers were evaluated: cartilage oligomeric matrix protein, keratan sulfate epitope (5D4), the 3B3(-) neoepitope of chondroitin-6-sulfate, and the 3B3(+) chondroitinase-generated epitope of chondroitin-6-sulfate. Meniscectomy led to statistically significant elevations of all four biomarkers, with levels peaking at 4 weeks. By 12 weeks, the level of the 5D4 epitope returned to the preoperative baseline level whereas that of cartilage oligomeric matrix protein, 3B3(-), and 3B3(+) remained above the baseline. Concentrations of these biomarkers in the knees not operated on did not change significantly from the baseline. The levels of cartilage oligomeric matrix protein and 3B3(-) relative to 3B3(+) remained constant in all knees. In contrast, the level of 5D4 relative to 3B3(+) declined over time in the knee operated on but remained constant in the knee not operated on. These results demonstrate a quantitative change in the molecular components of synovial fluid after meniscectomy, as well as a qualitative change evinced by an alteration in the relative proportions of these epitopes. Extensive analyses showed a strong correlation between serum levels of 3B3(-) from the femoral and cephalic veins; however, serum 3B3(-) was not correlated with synovial fluid 3B3(-). These findings support the hypothesis that the concentrations of select cartilage biomarkers in synovial fluid are altered following meniscectomy and are promising tools for objectively monitoring the induction of osteoarthritis in this model system.

Denaturation of type II collagen in articular cartilage in experimental murine arthritis. Evidence for collagen degradation in both reversible and irreversible cartilage damage

Degradation of type II collagen is thought to be a key step in the destruction of articular cartilage in patients with rheumatoid arthritis or osteoarthritis. The aim of this study was to investigate whether type II collagen degradation is associated with cartilage destruction. Type II collagen degradation was studied in two murine arthritis models, zymosan-induced arthritis (ZIA), which develops reversible articular cartilage damage based on proteoglycan analysis, and antigen-induced arthritis (AIA), in which there is irreversible damage to the cartilage. Type II collagen degradation was assayed immunohistochemically using the COL2-3/4m antibody which recognizes denatured type II collagen, such as is produced by collagenase cleavage. In both models, degradation of type II collagen was observed in the non-calcified articular cartilage of arthritic but not of control knees. In the patella-femoral compartment, collagen denaturation started to increase on day 3 (ZIA) and day 7 (AIA) and remained high on day 14. In contrast, in the tibia-femoral compartment, type II collagen breakdown was not increased before 14 days in either model. By 28 days, collagen denaturation was strongly reduced in the patella-femoral compartment in the ZIA model, but persisted in the tibia-femoral compartment in both models. In conclusion, increased type II collagen degradation was found in articular cartilage of both ZIA and AIA animals. Since ZIA does not develop irreversible cartilage destruction, this indicates that cartilage may have the ability to withstand a limited degree of type II collagen degradation without developing irreversible damage.

Serum markers of articular cartilage damage and repair

Joint cartilage is a dynamic tissue that reacts to trauma, inflammation, and other insults by attempting to repair its matrix. This reaction results in the release of cartilage macromolecules into the body fluids. Analysis of these fluids has identified a limited number of at least somewhat tissue-specific markers of altered cartilage metabolism. Analyses of serum are less specific and less sensitive than analyses of synovial fluid, but their use as research tools in clinical studies, drug development, and experimental work in animal models is increasing.

Synovial fluid markers in osteoarthritis

Exploration of the mechanisms responsible for breakdown and repair of articular cartilage in osteoarthritis has promoted interest in the potential use of cartilage-derived molecules as markers of cartilage metabolism in this disease. Many of the macromolecules detectable in synovial fluid have been evaluated as possible surrogate markers of the severity or activity of disease processes. Measurements of the synovial fluid concentration of any marker without due consideration of the fate of the molecule in the joint cavity are likely to be misleading and insufficient to cement a relationship between marker concentration and the severity of articular pathology.

Osteoarthritis. Joint anatomy, physiology, and pathobiology

Normal cartilage is a complex material consisting of a solid matrix composed primarily of collagen and proteoglycan, which is saturated with water. It is not a homogenous material. The interaction of the physical and biochemical structures of cartilage is necessary to allow the normal function of providing nearly frictionless motion, wear resistance, joint congruence, and transmission of load to subchondral bone. Chondrocytes are responsible for synthesizing and maintaining this material. Osteoarthritis occurs when there is disruption of normal cartilage structure and homeostasis. Osteoarthritis results from a complex interaction of biochemical and biomechanical factors that occur concurrently and serve to perpetuate degradative change. The progressive pathologic change that occurs in osteoarthritis has been characterized, not only for articular cartilage but also for periarticular tissues. The occurrence of mechanical and biochemical changes is well established, but the role of each in the etiopathogenesis of osteoarthritis is not rigidly defined. It is likely that there are multiple etiologies sharing common pathways of physical and chemical disruption. (see Fig. 1). The changes associated with osteoarthritis ultimately have an impact on the patient through decreased ability to use the joint or the production of pain, or both. Unfortunately, once these changes are severe enough to be recognized clinically, they are likely to be irreversible with current treatments. Nevertheless, understanding the basic mechanisms involved in the development and progression of osteoarthritis provides a basis for establishing a reasonable expectation for the patient and a rational plan for medical and surgical treatment of this condition.

Effects of exercise on knee joints with osteoarthritis: a pilot study of biologic markers

OBJECTIVE

To determine the effects of low intensity weight-bearing exercise on osteoarthritis (OA) of the knee.

METHODS

Synovial fluid keratan sulfate (KS) and hydroxyproline were measured as markers of cartilage degradation. The Arthritis Impact Measurement Scales (AIMS) were used to measure health status, and a visual analog scale for pain assessment was used before and after intervention. An exercise (EX) group (n = 15) received a thrice-weekly 12-week low intensity exercise program and a weekly educational program, and a minimal treatment (Min RX) group (n = 15) received only the education program.

RESULTS

Pain levels declined in the EX group, and the Min RX group showed improvement on the AIMS. Synovial fluid was obtained in 11 subjects before and after the intervention. Levels of KS and hydroxyproline did not change.

CONCLUSION

Further study of exercise effects should include both clinical and biologic parameters to examine the outcome of exercise as a therapeutic intervention in OA of the knee.

Changes in glycosaminoglycan epitope levels in knee joint fluid following injury

OBJECTIVE

To measure the levels of epitope on the chondroitin sulfate (CS) and keratan sulfate (KS) chains of proteoglycan fragments in synovial fluids from injured and contralateral uninjured knees of patients with traumatic cruciate ligament and/or meniscus damage.

METHODS

Enzyme-linked immunosorbent assays were used to determine the levels of monoclonal antibody epitopes 3-B-3 and 7-D-4 (CS), and 5-D-4 (KS), in paired joint fluids from the injured and uninjured knees of trauma patients.

RESULTS

Levels of the CS epitopes were increased in the trauma joint fluids from most patients, with higher levels of 3-B-3 epitope in 12 of the 16 patients, but the difference did not achieve significance; however, 7-D-4 levels were higher in 15 patients, and the difference was highly significant (P = 0.0005). In contrast, the KS epitope detected by 5-D-4 was decreased in 13 of 15 patients, and the difference was significant (P = 0.0074).

CONCLUSION

The increased level of 7-D-4 epitope on proteoglycans in joint fluid from injured knees may reflect the response of the articular cartilage to acute trauma resulting in altered expression of specific CS epitopes on cartilage proteoglycans. The fall in KS epitope levels may reflect the synthesis of proteoglycans that have lower KS content.

Hyaluronan in canine arthropathies

Soluble hyaluronan (HA), which has been considered as a marker for joint disease in man, was measured in serum and synovial fluid (SF) from dogs with osteoarthritis (OA), rheumatoid arthritis (RA), and rupture of the cranial cruciate ligament (CCL) and from normal dogs (control). Dogs with OA and RA had significantly increased serum HA (P < 0.001) and decreased synovial fluid HA (P < 0.001), as did dogs with CCL rupture (serum, P < 0.05; synovial fluid, P < 0.005). In OA, HA was lower in the SF from the affected joint than in that from the clinically normal (inactive) contralateral joint; no such difference was seen in dogs with CCL rupture. Dogs with liver disease (portocaval shunts, viral infectious hepatitis, metastatic neoplasm and disease secondary to diabetes mellitus) had increased serum HA concentrations (P < 0.001). There was a significant overlap of HA values in the diseased and normal dogs. Therefore, it is unlikely that the measurement of this cartilage breakdown product would be of value for diagnosis or prognosis in canine arthropathies.

Differential levels of synovial fluid aggrecan aggregate components in experimental osteoarthritis and joint disuse

The levels of proteoglycan aggregate components (link protein, keratan sulfate epitope, and total sulfated glycosaminoglycan) were determined in the synovial fluid lavages of dogs with experimental osteoarthritis or disuse atrophy. A model of experimental osteoarthritis was created by transection of the anterior cruciate ligament of the right knee; studies were carried out 6 and 12 weeks after surgery. Joint disuse was studied at 4 and 8 weeks after initiation of the disuse. Recovery after disuse also was studied in joints that had 3 weeks of remobilization after 4 or 8 weeks of disuse. Synovial fluid lavages from the right knee joints of untreated animals were used as controls. The concentrations of keratan sulfate epitope, sulfated glycosaminoglycan, and link protein in the synovial fluid lavages at 6 and 12 weeks after transection of the anterior cruciate were elevated compared with the control values. Similar analysis of the fluid after disuse showed that the levels of keratan sulfate epitope and sulfated glycosaminoglycan were increased compared with the control levels and the levels after transection. However, the concentration of link protein in the fluid after disuse was not significantly different from the control level. The levels of keratan sulfate epitope and sulfated glycosaminoglycan in the synovial fluid lavages after disuse with recovery were high, but the levels of link protein remained low. The results indicate that the catabolism of proteoglycan aggregates in articular cartilage during early osteoarthritis and disuse is different. The determination of keratan sulfate epitope in synovial fluid lavages appears to provide a relatively general indication of proteoglycan catabolism, whereas increased levels of link protein may be more indicative of cartilage degeneration.

Measurement of glycosaminoglycans and keratan sulphate in canine arthropathies

Glycosaminoglycans (GAG) and keratan sulphate (KS) were measured in sera and synovial fluids from dogs with either osteoarthritis (OA) or rupture of the cranial cruciate ligament (CCL) and normal dogs. The dogs with OA had higher synovial fluid GAG levels (P < 0.002) and serum KS (P < 0.03) compared to the normal dogs. No significant differences in serum GAG were found in either group. In both OA and rupture of the CCL, GAG levels were increased in the synovial fluid from the affected joint compared with the clinically normal (inactive) contralateral joint. Neither GAG nor KS measurements correlated with serum and synovial fluid antibodies to collagen type II, synovial fluid white cell count or age of dog. It is unlikely that the measurement of these cartilage breakdown products is of value for diagnostic or prognostic use in canine arthropathies.

Chondroscopy: a new method for scoring chondropathy

The purpose of this study was to evaluate the performance (simplicity, reproducibility, relevance) of chondroscopy as a method for evaluating cartilage damage. Chondroscopy consisted in endoscopic evaluation of the knee using a 2.7-mm Storz arthroscope under local anesthesia and recorded on videotape. Scoring of chondropathy was based on physician's overall assessment using a 100-mm-length visual analogue scale (VAS) and size and grade of cartilage lesions. Reproducibility was evaluated by variability (coefficient of variation [CV]) in the reading of chondroscopic evaluations of five patients five times by one physician and one time each by four different physicians. The correlations between scoring of chondropathy (VAS) and radiological articular joint space narrowing, demographic data (sex, age, weight), and disease characteristics (localization, etiology, activity) were studied in 84 outpatients fulfilling the American College of Rheumatology criteria for the diagnosis of osteoarthritis of the knee. The grade and size of the lesions were both correlated with the physician's overall assessment (r = 0.713 and r = 0.816, respectively). These two variables accounted for 72% of the variance of the VAS (multiple regression analysis). Intraobserver reproducibility was better than interobserver reproducibility (CV, 9% and 37%, respectively). There was a strong correlation between the scoring of chondropathy (VAS) and radiological joint space narrowing (r = .646, P < .0001). Moreover, in 17 of 33 patients without radiological joint space narrowing, VAS was > 20 mm. At variance, the body mass index was the single clinical variable found to correlate with the scoring of chondropathy (r = .282, P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Serum keratan sulfate. Quantitative and qualitative comparisons in inflammatory versus noninflammatory arthritides

The concentration of keratan sulfate (KS) epitope was measured in the serum of patients with osteoarthritis (OA) or rheumatoid arthritis (RA) by enzyme-linked immunosorbent assay and compared with that in the serum of patients with primary fibromyalgia syndrome (PFS) and of controls who had no joint disease. By Student's tau-test, the mean serum KS concentrations in OA and RA patients measured with monoclonal antibodies (MAb) 5-D-4 and 2-D-3 were significantly increased over those in the PFS and normal groups; similar findings were observed using a nonparametric test, except that levels in RA patients showed no difference from those in PFS patients and normal subjects. There was no significant correlation between joint scores or disease duration and KS levels in OA or RA patients. Gel filtration of sera revealed mainly large, polydisperse KS-bearing fragments which eluted in a broad profile. KS purified from sera by immunoaffinity chromatography consisted mainly of high-density proteoglycans. Electrophoresis of pooled high-density KS fractions in polyacrylamide-agarose gels followed by Western blotting with MAb 5-D-4 showed diffuse bands with relative mobilities corresponding to large proteoglycans. These findings are consistent with attachment of KS to protein core fragments of various sizes; KS in patient sera is comparable in size with that in normal sera. Elevations of serum KS levels occur in the presence of cartilage degradation, but do not quantitatively define the extent or duration of articular involvement.

Relationship between arthroscopic evidence of cartilage damage and radiographic evidence of joint space narrowing in early osteoarthritis of the knee

We examined the relationship between articular cartilage degeneration, as visualized arthroscopically, and joint space narrowing (JSN) in standing anteroposterior knee radiographs of 161 patients with chronic knee pain. The majority of these patients had radiographic findings of mild osteoarthritis. Twenty-five (33%) of the 76 patients in the series whose radiographs showed tibiofemoral JSN had grossly normal articular cartilage in both tibiofemoral compartments at arthroscopy (false-positive). The specificity of medial JSN for the presence of medial compartment articular cartilage degeneration was 0.61, i.e., only 61% of patients with normal (grade 0) medial compartment cartilage had a normal medial joint space. Of 22 patients with greater than 50% medial JSN, 9 (41%) had normal articular cartilage in the medial compartment at arthroscopy. Of 6 patients with greater than 50% lateral JSN, 3 (50%) had normal lateral compartment articular cartilage at arthroscopy. Among 36 patients with greater than 25% JSN who had neither medial nor lateral compartment articular cartilage degeneration, JSN was associated with articular cartilage degeneration in the patellofemoral compartment in 8 (22%), with meniscus degeneration in 18 (50%), and with both in 8 (22%). Thus, in these patients with chronic knee pain, radiographic evidence of JSN in the tibiofemoral compartment did not permit confident prediction of the status of the articular cartilage.

Glycosaminoglycan concentrations in horse plasma and serum. Differences with other animal species and identification of affecting factors

1. The measured values of acid glycosaminoglycan (GAG) concentration in plasma or in serum show significant differences between trained and untrained horses and among sedentary horses and other animal species (cattle, rabbit, sheep). 2. Diurnal variations in serum GAG levels are reported (cattle), and changes in plasma GAG concentrations after road transport (horses) and in late pregnancy (mares, cows), while sex, age and breed do not affect them.

Cartilage matrix glycoprotein is present in serum in experimental canine osteoarthritis

We have described previously a disulfide-bonded 550,000-D cartilage matrix glycoprotein (CMGP), which is found in normal hyaline cartilage, fibrocartilage, and the vitreous of the eye, and consists of subunits with apparent molecular weights of 130,000 in 4% gels (116,000 in 9% gels). In osteoarthritic cartilage from dogs subjected to transection of the anterior cruciate ligament (ACL), CMGP is cleaved to major immunoreactive fragments with apparent molecular weights of 65,000 and 75,000 after reduction with 2-mercaptoethanol. In the present study, using immunolocation analysis, a monoclonal antibody to CMGP did not react with serum from 8 of 12 dogs before ACL transection but did react with serum from seven of these animals 4 wk after surgery and with serum from 10 dogs at sacrifice, 8-14 wk after ACL transection. Serum from four dogs reacted with the monoclonal antibody before ACL transection. Serum from two dogs was negative at all time points. Immunolocation studies using a polyclonal antiserum to CMGP were performed in seven of these dogs and produced results identical with the monoclonal antibody in four dogs. In contrast, analysis of serial serum samples from three dogs with cartilage atrophy revealed no evidence of CMGP at any time point. These data suggest that CMGP may be a serum marker for osteoarthritis in this canine model.

Gait alterations in dogs after transection of the anterior cruciate ligament

We calculated mean peak vertical forces (MFz) of each limb of 9 adult mongrel dogs before and 2 weeks, 6 weeks, and 12 weeks after left anterior cruciate ligament transection (ACLT). Five additional dogs were studied before and 2 weeks and 6 weeks after sham ACLT. The gaits of 3 dogs that had undergone ACLT 2.5 years previously were also analyzed. Preoperatively, there were no differences in the MFz of the right and left hind limbs of the 9 dogs; we found that each limb exerted approximately 70% of the dog's static body weight on the force plate. Two weeks following ACLT, the MFz of the operated limbs decreased to 25% of the static body weight, while at 6 weeks and 12 weeks after surgery, the MFz generated by the operated limbs rose to about 32% and 37% of static body weight, respectively. No change was noted in the MFz of the contralateral hind limbs. In the 3 dogs that had undergone ACLT 2.5 years earlier, the MFz in the unstable stifle joint was 50% of static body weight. At both 2 weeks and 6 weeks after surgery, the MFz values for all 4 limbs of the animals subjected to sham ACLT were comparable with baseline values. These observations indicate that the osteoarthritic changes seen in the unstable limb are associated with decreased loading of that limb, without increased (compensatory) loading of the contralateral hind limb.