Osteoarthritis, magnetic resonance imaging, and biochemical markers: a one year prospective study

From biochemical markers to molecular endotypes of osteoarthritis: a review on validated biomarkers

INTRODUCTION

Osteoarthritis (OA) affects over 500 million people worldwide. OA patients are symptomatically treated, and current therapies exhibit marginal efficacy and frequently carry safety-risks associated with chronic use. No disease-modifying therapies have been approved to date leaving surgical joint replacement as a last resort. To enable effective patient care and successful drug development there is an urgent need to uncover the pathobiological drivers of OA and how these translate into disease endotypes. Endotypes provide a more precise and mechanistic definition of disease subgroups than observable phenotypes, and a panel of tissue- and pathology-specific biochemical markers may uncover treatable endotypes of OA.

AREAS COVERED

We have searched PubMed for full-text articles written in English to provide an in-depth narrative review of a panel of validated biochemical markers utilized for endotyping of OA and their association to key OA pathologies.

EXPERT OPINION

As utilized in IMI-APPROACH and validated in OAI-FNIH, a panel of biochemical markers may uncover disease subgroups and facilitate the enrichment of treatable molecular endotypes for recruitment in therapeutic clinical trials. Understanding the link between biochemical markers and patient-reported outcomes and treatable endotypes that may respond to given therapies will pave the way for new drug development in OA.

Association between osteoarthritis-related serum biochemical markers over 11 years and knee MRI-based imaging biomarkers in middle-aged adults

OBJECTIVE

To describe the associations between osteoarthritis (OA)-related biochemical markers (COMP, MMP-3, HA) and MRI-based imaging biomarkers in middle-aged adults over 10-13 years.

METHODS

Blood serum samples collected during the Childhood Determinants of Adult Health (CDAH)-1 study (year:2004-06; n = 156) and 10-13 year follow-up at CDAH-3 (n = 167) were analysed for COMP, MMP-3, and HA using non-isotopic ELISA. Knee MRI scans obtained during the CDAH-knee study (year:2008-10; n = 313) were assessed for cartilage volume and thickness, subchondral bone area, cartilage defects, and BML.

RESULTS

In a multivariable linear regression model describing the association of baseline biochemical markers with MRI-markers (assessed after 4-years), we found a significant negative association of standardised COMP with medial femorotibial compartment cartilage thickness (β:-0.070; 95%CI:-0.138,-0.001), and standardised MMP-3 with patellar cartilage volume (β:-141.548; 95%CI:-254.917,-28.179) and total bone area (β:-0.729; 95%CI:-1.340,-0.118). In multivariable Tobit regression model, there was a significant association of MRI-markers with biochemical markers (assessed after 6-9 years); a significant negative association of patellar cartilage volume (β:-0.001; 95%CI:-0.002,-0.00004), and total bone area (β:-0.158; 95%CI-0.307,-0.010) with MMP-3, and total cartilage volume (β:-0.001; 95%CI:-0.001,-0.0001) and total bone area (β:-0.373; 95%CI:-0.636,-0.111) with COMP. No significant associations were observed between MRI-based imaging biomarkers and HA.

CONCLUSION

COMP and MMP-3 levels were negatively associated with knee cartilage thickness and volume assessed 4-years later, respectively. Knee cartilage volume and bone area were negatively associated with COMP and MMP-3 levels assessed 6-9 years later. These results suggest that OA-related biochemical markers and MRI-markers are interrelated in early OA.

Comparison of high-resolution magnetic resonance imaging and micro-computed tomography arthrography for in-vivo assessment of cartilage in non-human primate models

Background

Non-human primate (NHP) could be an interesting model for osteoarthritis (OA) longitudinal studies but standard medical imaging protocols are not able to acquire sufficiently high-resolution images to depict the thinner cartilage (compared to human) in an in vivo context. The aim of this study was thus to develop and validate the acquisition protocols for knee joint examination of NHP using magnetic resonance imaging (MRI) at 1.5 T and X-ray micro-computed tomography arthrography (µCTA).

Methods

The first phase of the study focused on developing dedicated in vivo HR-MRI and µCTA protocols for simultaneous acquisitions of both knee joints on NHP. For MR, a dedicated two-channel receiver array coil and acquisition sequence were developed on a 1.5 T Siemens Sonata system and tuned to respect safety issues and reasonable examination time. For µCTA, an experimental setup was devised so as to fulfill similar requirements. The two imaging protocols were used during a longitudinal study so as to confirm that repeated injections of loxaglic acid (contrast agent used for µCTA) didn't induce any bias in cartilage assessment and to compare segmentation results from the two modalities. Lateral and medial cartilage tibial plateaus were assessed using a common image processing protocol leading to a 3D estimation of the cartilage thickness.

Results

From HR-MRI and µCTA images, thickness distributions were extracted allowing for proper evaluation of knee cartilage thickness of the primates. Results obtained in vivo indicated that the µCTA protocol did not induce any bias in the measured cartilage parameters and moreover, segmentation results obtained from the two imaging modalities were consistent.

Conclusions

MR and µCTA are valuable imaging tools for the morphological evaluation of cartilage in NHP models which in turn can be used for OA studies.

Longitudinal changes in tibial and femoral cartilage thickness are associated with baseline ambulatory kinetics and cartilage oligomeric matrix protein (COMP) measures in an asymptomatic aging population

OBJECTIVE

To address the need for early knee osteoarthritis (OA) markers by testing if longitudinal cartilage thickness changes are associated with specific biomechanical and biological measures acquired at a baseline test in asymptomatic aging subjects.

DESIGN

Thirty-eight asymptomatic subjects over age 45 years were studied at baseline and at an average of 7-9 year follow-up. Gait mechanics and knee MRI were measured at baseline and MRI was obtained at follow-up to assess cartilage thickness changes. A subset of the subjects (n = 12) also had serum cartilage oligomeric matrix protein measured at baseline in response to a mechanical stimulus (30-min walk) (mCOMP). Baseline measures, including the knee extension (KEM), flexion (KFM), adduction (KAM) moments and mCOMP, were tested for associations with cartilage thickness changes in specific regions of the knee.

RESULTS

Cartilage change in the full medial femoral condyle (p = 0.005) and external medial femoral region (p = 0.041) was negatively associated with larger early stance peak KEM. Similarly, cartilage change in the full medial femoral region (p = 0.009) and medial femoral external region (p = 0.043) was negatively associated with larger first peak KAM, while cartilage change in the anterior medial tibia was positively associated with larger first peak KAM (p = 0.003). Cartilage change in the anterior medial tibia was also significantly associated (p = 0.011) with mCOMP levels 5.5-h post-activity (percentage of pre-activity levels).

CONCLUSIONS

Interactions found between gait, mechanically-stimulated serum biomarkers, and cartilage thickness in an at-risk aging asymptomatic population suggest the opportunity for early detection of OA with new approaches that bridge across disciplines and scales.

Using the Systems Biology Approach and Molecular Method to Investigate the Role of the Dopaminergic Pathway in Osteoarthritis: A Case Control Study

OBJECTIVE

Osteoarthritis is the most common type of arthritis and one of the leading causes of job loss and motor disabilities. Recently, the involvement of dopaminergic pathways and dopamine receptor genes has been considered in this disease. Therefore, studying and comparing the expression pattern of these receptor genes can lead to a greater understanding of the pathogenesis of this disease.

METHODS

In this research, we used the systems biology approach to investigate the role of the dopaminergic pathway in osteoarthritis. Then the gene expression pattern of dopamine receptor genes was examined in an osteoarthritis patientgroup in comparison with healthy individuals by Real-time PCR method.

RESULTS

The analysis of the transcriptome dataset of osteoarthritis identified some genes in the dopaminergic pathway and the six most important genes in this disease are in the network with a significant relationship to dopamine receptors which differentially expressed compared to health groups. Statistical analysis of the case control study showed a significant difference (P-value<0.05) in DRD1 and DRD2 family in the patients in comparison to healthy individuals.

DISCUSSION

We attained the significant expression pattern of dopamine receptors in the blood of osteoarthritis patients which could be useful to identify new strategies for the diagnosis, management, or treatment of this disease.

Correlation Analysis of C-terminal telopeptide of collagen type II and Interleukin-1β for Early Diagnosis of Knee Osteoarthritis

Objective

To analyze the correlation between the Kellgren–Lawrence (K‐L) score of knee osteoarthritis (KOA) patients with different degrees and their urine concentration of C‐terminal telopeptide of collagen type II (CTX‐II) and interleukin‐1β (IL‐1β), and to further evaluate the diagnostic value of CTX‐II and IL‐1β during the pathological process by producing an experimental osteoarthritis (OA) model in rabbits.

Methods

From 1 January 2017 to 31 December 2018, a total of 34 subjects (7 mild, 9 moderate, 9 severe arthritis patients, and 9 healthy individuals) comprising 16 men and 18 women were included in this study. Patients were diagnosed according to the American College of Rheumatology (ACR) criteria. The urine of all subjects was collected to detect the concentration of CTX‐II and IL‐1β. The rabbits in the KOA group were subjected to protease (control group with saline) injection into the articular cavity of their right knees and immobilization with gypsum. We used radiological and histological examination to identify the KOA model. ELISA was applied to investigate the concentrations of CTX‐II and IL‐1β in urine and serum, and Spearman's rank correlation analysis was used to analyze the correlation.

Results

There was no significant difference in the mean ages and body mass index (BMI) between groups. The mean ages of mild, moderate, and severe arthritis patients and healthy individuals were 54.29 ± 5.76, 58.44 ± 6.44, 59.89 ± 6.75, and 56.67 ± 4.18 years, respectively. The mean BMI of mild, moderate, and severe arthritis patients and healthy individuals were 23.59 ± 1.56, 23.57 ± 2.06, 24.46 ± 1.64, and 23.42 ± 1.35 kg/m², respectively. The Kellgren–Lawrence (K‐L) score was higher with the aggravation of KOA. The K‐L scores of mild, moderate, and severe KOA patients were 1.14 ± 0.38, 2.56 ± 0.53, and 3.63 ± 0.52, respectively. The KOA symptoms of patients became more severe, with not only increased K‐L scores but also elevated concentrations of CTX‐II and IL‐1β. Moreover, there was a positive correlation between CTX‐II and IL‐1β of all subjects (r = 0.974, P < 0.001), between K‐L score and urine concentration of CTX‐II (r = 0.900, P < 0.001), and between K‐L score and IL‐1β (r = 0.813, P < 0.001) of all subjects. Both were significantly increased in KOA group rabbits at all time points after surgery. The serum concentration of CTX‐II and IL‐1β was elevated as early as in the 2nd week (3.69 and 4.25 times) and reached a peak (5.41 and 7.23 times) in the 4th week after surgery. Then, until 12 weeks after surgery, the CTX‐II and IL‐1β concentrations in the KOA group were slightly reduced and remained around 4.5 and 6.3 times that in the control group. Moreover, there was a positive correlation between the serum concentration of IL‐1β and CTX‐II (r = 0.967, P < 0.001).

Conclusion

CTX‐II and IL‐1β, which were significantly increased during the process of KOA, can be used as biomolecular markers to provide guidelines for early diagnosis and treatment of KOA.

Difference in Articular Degeneration Depending on the Type of Sport

Objective  To determine whether type-II collagen degradation is determined by the type of sport. Carboxy-terminal telepoptide of type-II collagen (CTX-II), a serum biomarker of collagen degradation, was measured in athletes who play different sports, and was compared with matched controls.

Methods  The sample size consisted of 70 female participants aged between 18 and 25 years, 15 of whom were members of a soccer team, 10 of a futsal (a variant of association football played on a hard court) team, 10 of a handball team, 18 of a volleyball team, and 7 of a swimming team. A total of 9 age- and sex-matched individuals with sedentary lifestyles were included in the control group. 3-mL blood samples were collected from each participant, and they were analyzed using an enzyme-linked immunosorbent assay (ELISA).

Results  A comparison of the CTX-II concentrations of the players of different sports with those of the control group resulted in the following p -values: volleyball ( p  = 0.21); soccer ( p  = 0.91); handball ( p  = 0.13); futsal ( p  = 0.02); and swimming ( p  = 0.0015). Therefore, in the investigated population, futsal represented the highest risk for type-II collagen degradation and, consequently, for articular cartilage degradation, whereas swimming was a protective factor for the articular cartilage. No statistically significant difference was found in the body mass index among the groups.

Conclusion   Futsal players are exposed to greater articular degradation, while swimmers exhibited less cartilage degradation compared with the control group in the study population, suggesting that strengthening the periarticular muscles and aerobic exercise in low-load environments has a positive effect on the articular cartilage.

CTX-II and YKL-40 in early diagnosis and treatment evaluation of osteoarthritis

This study investigated the value of C-terminal telopeptides of collagen type II (CTX-II) and YKL-40 in early diagnosis and treatment evaluation of osteoarthritis (OA). A total of 90 patients with OA diagnosed and treated in The First Affiliated Hospital, Guangzhou Medical University from March 2015 to January 2018 were selected as the study group. At the same time, 50 healthy elderly were included as the control group. The study group was divided into three subgroups including group A (29 cases, 500 mg glucosamine sulfate), group B (29 cases, 50 mg diacerein) and group C (32 cases, 500 mg glucosamine sulfate and 50 mg diacerein). Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was used to assess the severity and treatment of arthritis. Enzyme-linked immunosorbent assay was used to measure the concentration of CTX-II and YKL-40 in serum. WOMAC scores in the study A, B and C groups were significantly higher than those in the control group (P<0.001). Serum CTX-II and YKL-40 concentrations were higher in the study group than in the control group (P<0.001). Sensitivity of serum CTX-II combined with YKL-40 in the diagnosis of OA was 90% and the specificity was 78%. CTX-II and YKL-40 levels in different Kellgren Lawrence (K-L) grades were significantly different (P<0.001), and increased with the increase of K-L grade. Concentrations of serum CTX-II and YKL-40 before treatment in the study group was positively correlated with WOMAC score (P<0.001). At 3, 6 and 9 weeks after the beginning of treatment, serum concentrations of CTX-II and YKL-40 decreased significantly (P<0.001). At 3 weeks of treatment, CTX-II was positively correlated with YKL-40 concentration and WOMAC score (r=0.406, P<0.001; r=0.430, P<0.001); CTX-II was positively correlated with YKL-40 concentration and WOMAC score at 6 weeks of treatment (r=0.350, P<0.001; r=0.358, P<0.001); CTX-II was positively correlated with YKL-40 concentration and WOMAC score at 9 weeks after treatment (r=0.370, P<0.001; r=0.394, P<0.001). Combined detection of serum CTX-II and YKL-40 can improve the sensitivity of early OA diagnosis, and it has an important diagnostic value for early OA patients. Therefore, it can be used as a biological indicator for early OA diagnosis, severity assessment, and evaluation of treatment effects.

Associations between molecular biomarkers and MR-based cartilage composition and knee joint morphology: data from the Osteoarthritis Initiative

OBJECTIVE

The purpose of this study was to assess the associations between serum/urine biomarkers for osteoarthritis and magnetic resonance (MR) imaging measures of cartilage composition and joint structure (cartilage, meniscus, and bone marrow), using MR imaging data from the Osteoarthritis Initiative (OAI).

DESIGN

141 subjects with Kellgren Lawrence (KL) grades 0-3 in the right knee and with available serum/urine biomarker assays were selected from the OAI. Cartilage magnetic resonance imaging (MRI) T2 measurements were performed in the medial femur, lateral femur, medial tibia, lateral tibia, and patella compartments. Compartment-specific knee morphologic grading [whole-organ magnetic resonance imaging score (WORMS)] in the cartilage, meniscus, and bone marrow was also performed. We focused on associations of serum hyaluronan (sHA), serum cartilage oligomeric matrix protein (sCOMP), serum matrix metalloproteinase-3 (sMMP3), and Urine Carboxy-Terminal Telepeptides of Type II Collagen (uCtX-II)) with MRI parameters (T2, WORMS), assessed using partial correlations adjusted for age, gender, body mass index (BMI), KL grade in both knees, and diabetes status.

RESULTS

Higher levels of sHA, sMMP3 and sCOMP were correlated (P < 0.05) with T2 of the lateral femur (r = 0.18 to 0.32) and lateral tibia (r = 0.17 to 0.23), and with average T2 of all knee regions (r = 0.23). uCTXII was correlated with patellar T2 (r = 0.19, P = 0.04). Among the morphologic measures, sHA and sMMP3 was positively correlated (r = 0.17 to 0.21, P < 0.05) with meniscal damage.

CONCLUSIONS

This study suggests weak, but statistically significant, correlations between serum biomarkers of OA (sHA, sCOMP, and sMMP3) and MRI T2 measures of cartilage extra-cellular matrix degeneration.

Cartilage oligomeric protein, matrix metalloproteinase-3, and Coll2-1 as serum biomarkers in knee osteoarthritis: a cross-sectional study

Biochemical markers reflecting joint remodeling in osteoarthritis (OA) are a promising diagnostic tool. The aim of this study was to investigate serum levels of candidate biomarkers in subjects with and without knee OA and assess their correlation with clinical parameters and knee structural damage. 56 patients with primary knee OA and 31 healthy controls participated in this study. Patients were separated into two groups: isolated knee OA and generalized OA. Clinical parameters were obtained by validated self-reported questionnaires and a visual analogue scale. Serum levels of cartilage oligomeric protein (COMP), matrix metalloproteinase-3 (MMP-3), and Coll2-1 were quantified by enzyme-linked immunosorbent assay. Knee structural damage was determined by plain X-ray and 1.5 T magnetic resonance imaging (MRI), using Kellgren-Lawrence (KL) grading scale and Whole-Organ Magnetic Resonance Imaging Score (WORMS), respectively. Compared to controls, patients had significantly higher median serum COMP (985 vs. 625 ng/ml; p < 0.001) and MMP-3 (36.85 vs. 22.10 ng/ml; p = 0.003) levels. Patients with radiographic evidence of KLII/III knee OA had greater median COMP levels than KLI patients (1095 vs. 720 ng/ml; p = 0.001). In the generalized OA group, mean MMP-3 levels were higher than in the isolated knee OA group (30.40 vs. 55.13 ng/ml; p < 0.001). COMP correlated positively with WORMS (r _s = 0.454, p < 0.001) and MMP-3 (r _s = 0.337, p = 0.003). Cut-off values for serum COMP and MMP-3 were determined. We observed higher serum COMP and MMP-3 levels in knee OA patients compared to controls. COMP may reflect knee structural damage, while MMP-3-OA "generalization".

Meta-analysis of urinary C-terminal telopeptide of type II collagen as a biomarker in osteoarthritis diagnosis

Objective

This study aims to discover that the urinary C-terminal telopeptide of type II collagen (uCTX-II) levels differ between osteoarthritis (OA) patients and healthy individuals (controls). According to this difference, we may conclude that uCTX-II can be a biomarker for OA diagnosis.

Methods

We searched MEDLINE and EMBASE databases updated to 2014 to find literature on OA biomarkers. We retrieved the publications that met the required criterion. Literature quality was assessed according to the Newcastle-Ottawa Scale. Publication bias was assessed by Begg's test and Egger's test with the software STATA version 12.0. The weighted mean difference (WMD) was calculated, and the subgroup analysis was completed using STATA 12.0.

Results

Six publications were included in our analysis. The WMD for OA patients versus the controls was 83.05, which was within the 95% confidence interval. For subgroup analysis, the WMD of patients with severe OA was 119.92, whereas that of patients with mild OA was 28.07.

Conclusions

uCTX-II levels were higher in OA patients than in controls, subgroup analysis revealed that the uCTX-II levels rised with the OA severity, the heterogeneity originated from different levels of OA severity, These results showed that uCTX-II would be a promising clinical biomarker in OA diagnosis.

Daily oral consumption of hydrolyzed type 1 collagen is chondroprotective and anti-inflammatory in murine posttraumatic osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease for which there are no disease modifying therapies. Thus, strategies that offer chondroprotective or regenerative capability represent a critical unmet need. Recently, oral consumption of a hydrolyzed type 1 collagen (hCol1) preparation has been reported to reduce pain in human OA and support a positive influence on chondrocyte function. To evaluate the tissue and cellular basis for these effects, we examined the impact of orally administered hCol1 in a model of posttraumatic OA (PTOA). In addition to standard chow, male C57BL/6J mice were provided a daily oral dietary supplement of hCol1 and a meniscal-ligamentous injury was induced on the right knee. At various time points post-injury, hydroxyproline (hProline) assays were performed on blood samples to confirm hCol1 delivery, and joints were harvested for tissue and molecular analyses were performed, including histomorphometry, OARSI and synovial scoring, immunohistochemistry and mRNA expression studies. Confirming ingestion of the supplements, serum hProline levels were elevated in experimental mice administered hCol1. In the hCol1 supplemented mice, chondroprotective effects were observed in injured knee joints, with dose-dependent increases in cartilage area, chondrocyte number and proteoglycan matrix at 3 and 12 weeks post-injury. Preservation of cartilage and increased chondrocyte numbers correlated with reductions in MMP13 protein levels and apoptosis, respectively. Supplemented mice also displayed reduced synovial hyperplasia that paralleled a reduction in Tnf mRNA, suggesting an anti-inflammatory effect. These findings establish that in the context of murine knee PTOA, daily oral consumption of hCol1 is chondroprotective, anti-apoptotic in articular chondrocytes, and anti-inflammatory. While the underlying mechanism driving these effects is yet to be determined, these findings provide the first tissue and cellular level information explaining the already published evidence of symptom relief supported by hCol1 in human knee OA. These results suggest that oral consumption of hCol1 is disease modifying in the context of PTOA.

Effect of mud compress therapy on cartilage destruction detected by CTX-II in patients with knee osteoarthritis

BACKGROUND/OBJECTIVE

The aim of this study is to investigate the effect of mud compress (MC) therapy compared to hot pack (HP) therapy on cartilage destruction and subchondral bone alterations detected by urine levels of C telopeptide fragment of collagen type-II (uCTX-II) in patients with knee osteoarthritis (OA).

METHODS

Fifty-nine patients between 49-74 years of age with bilateral knee OA divided into 2 groups. Twenty-five patients (16 females, 9 males) and 34 patients (22 females, 13 males) were given HP versus local natural organic and mineral-rich MC therapy respectively for 2 weeks as a total of 12 sessions. uCTX-II, Visual Analog Scale (VAS), 15 m walking time, Western Ontario and McMaster Universities multifunctional (WOMAC) index were measured at baseline, after-treatment and 3 months after treatment.

RESULTS

uCTX-II level did not show any difference between the two groups, however it decreased significantly in MC and HP groups 3 months after treatment (p< 0.017). WOMAC stiffness sore was significantly lower in MC group 3 months after treatment (p< 0.05). Both MC and HP therapies lowered VAS, WOMAC total and subscores significantly up to 3 months (p< 0.017).

CONCLUSIONS

HP and MC therapies for OA of knee are not superior to one another with respect to the level of uCTX-II. MC may probably decrease the ongoing cartilage destruction and related subchonral bone interactions earlier compared to HP treatment in patients with knee OA as evidenced by decreased uCTX-II levels after-treatment.

Using 7.0T MRI T2 mapping to detect early changes of the cartilage matrix caused by immobilization in a rabbit model of immobilization-induced osteoarthritis

OBJECTIVE

The goal of this study was to detect early changes in the cartilage matrix caused by immobilization in a rabbit model of immobilization-induced osteoarthritis (OA) by T2 mapping with 7.0T MRI.

MATERIALS AND METHODS

Left knee joints of 28 mature rabbits were immobilized at 180° of extension with orthopedic casting tape for 1, 2, or 3weeks (n=7 rabbits each). No immobilization was performed in the control group (n=7 rabbits). T2 mapping was performed after 1, 2, and 3weeks. Osteochondral specimens harvested from the trochlea groove (TG) and medial femoral condyle (MFC) were subjected to histologic, immunohistochemical, and microscopic evaluation, followed by biochemical assays for water, glycosaminoglycan (GAG), and collagen. The ability of T2 mapping to reveal changes in the cartilage matrix was further assessed.

RESULTS

Rabbits demonstrated elevated T2 values (9.9% in TG, 10.6% in MFC), a dulled cartilage surface, reduced Safranin-O staining, and decreased GAG content (14.2% in TG and MFC) after 2weeks, with cartilage surface softening, irregularity, and markedly reduced GAG content by 3weeks. T2 values were correlated positively with water (r=0.836 in TG, r=0.821 in MFC) and negatively with GAG content (r=-0.945 in TG, r=-0.957 in MFC), but had no discernible relationship with collagen content (r=-0.196 in TG, r=-0.213 in MFC).

CONCLUSIONS

7.0T MRI T2 mapping can be used to detect early changes of the cartilage matrix caused by immobilization in an immobilization-induced OA model.

Analysis on the serum levels of the biomarker CTX-II in professional indoor soccer players over the course of one season

Objective

The aim of this study was to analyze the blood serum levels of CTX-II in professional indoor soccer players, at three different times during one season: at the start of the pre-season, four months later (a time that marks the middle of the season) and at the end of the season.

Methods

Fourteen male soccer players of mean age 19 years were included. Blood samples of 3 mL were collected from each individual. The samples were analyzed by means of Elisa tests.

Results

There was a significant increase in the serum level of CTX-II in the indoor soccer players, from the beginning to the end of the season (p < 0.01).

Conclusion

These data suggest that joint degradation had occurred in these soccer players, by the end of this period. It is evident that further studies are needed, with methodological rigor, so as to make an effective contribution toward precise elucidation of the etiology of this osteoarthritis and its relationship with the biomarkers, as a tool for early diagnosis.

Association of adipokines and joint biomarkers with cartilage-modifying effects of weight loss in obese subjects

OBJECTIVES

To determine (1) the effects of weight loss in obese subjects on six adipokines and joint biomarkers; and (2) the relationship between changes in these markers with changes in cartilage outcomes.

DESIGN

Plasma levels of adiponectin, leptin, IL-6, COMP, MMP-3 and urine levels of CTX-II were measured at baseline and 12 months from 75 obese subjects enrolled in two weight-loss programs. Magnetic resonance imaging (MRI) was used to assess cartilage volume and thickness. Associations between weight loss, cartilage outcomes and markers were adjusted for age, gender, baseline BMI, presence of clinical knee OA, with and without weight loss percent.

RESULTS

Mean weight loss was 13.0 ± 9.5%. Greater weight loss percentage was associated with an increase in adiponectin (β = 0.019, 95% CI 0.012 to 0.026,) and a decrease in leptin (β = -1.09, 95% CI -1.37 to -0.82). Multiple regression analysis saw an increase in adiponectin associated with reduced loss of medial tibial cartilage volume (β = 14.4, CI 2.6 to 26.3) and medial femoral cartilage volume (β = 18.1, 95% CI 4.4 to 31.8). Decrease in leptin was associated with reduced loss of medial femoral volume (β = -4.1, 95% CI -6.8 to -1.4) and lateral femoral volume (β = -1.8, 95% CI -3.7 to 0.0). When weight loss percent was included in the model, only the relationships between COMP and cartilage volume remained statistically significant.

CONCLUSIONS

Adiponectin and leptin may be associated with cartilage loss. Further work will determine the relative contributions of metabolic and mechanical factors in the obesity-related joint changes.

Systemic biochemical markers of joint metabolism and inflammation in relation to radiographic parameters and pain of the knee: data from CHECK, a cohort of early-osteoarthritis subjects

OBJECTIVE

To investigate associations of biochemical markers of joint metabolism and inflammation with minimum joint space width (JSW) and osteophyte area (OP area) of knees showing no or doubtful radiographic osteoarthritis (OA) and to investigate whether these differed between painful and non-painful knees.

DESIGN

Serum (s-) and urinary (u-) levels of the cartilage markers uCTX-II, sCOMP, sPIIANP, and sCS846, bone markers uCTX-I, uNTX-I, sPINP, and sOC, synovial markers sPIIINP and sHA, and inflammation markers hsCRP and erythrocyte sedimentation rate (ESR) were assessed in subjects from CHECK (Cohort Hip and Cohort Knee) demonstrating Kellgren and Lawrence grade ≤1 OA on knee radiographs. Minimum JSW and OP area of these knees were quantified in detail using Knee Images Digital Analysis (KIDA).

RESULTS

uCTX-II levels showed negative associations with minimum JSW and positive associations with OP area. sCOMP and sHA levels showed positive associations with OP area, but not with minimum JSW. uCTX-I and uNTX-I levels showed negative associations with minimum JSW and OP area. Associations of biochemical marker levels with minimum JSW were similar between painful and non-painful knees, associations of uCTX-II, sCOMP, and sHA with OP area were only observed in painful knees.

CONCLUSIONS

In these subjects with no or doubtful radiographic knee OA, uCTX-II might not only reflect articular cartilage degradation but also endochondral ossification in osteophytes. Furthermore, sCOMP and sHA relate to osteophytes, maybe because synovitis drives osteophyte development. High bone turnover may aggravate articular cartilage loss. Metabolic activity in osteophytes and synovial tissue, but not in articular cartilage may be related to knee pain.

Osteoarthritis-related biomarkers following anterior cruciate ligament injury and reconstruction: a systematic review

OBJECTIVE

There is an increased risk of developing knee osteoarthritis (OA) following anterior cruciate ligament (ACL) injury. Biomarkers may provide diagnostic, prognostic, or burden of disease indicators of OA before radiographic changes become apparent. Unfortunately, there has been no systematic review to clarify which biomarkers may be most informative following injury. Therefore, this review critically investigated existing studies of OA-related biomarkers in ACL-deficient (ACL-D) and reconstructed (ACL-R) patients to summarize the current evidence and identify knowledge gaps.

DESIGN

A systematic review of the literature in Web of Science and PubMed databases (1960-June 2014) was performed. All English-language case-control and longitudinal studies assessing OA-related biomarkers in ACL-D and ACL-R patients were considered. Data regarding biomarker changes over time within ACL-D and ACL-R patients as well as differences in ACL-D/ACL-R patients compared with a control group were extracted from pertinent studies.

RESULTS

A descriptive summary of 20 included studies was produced. In ACL-D patients compared with controls, synovial fluid biomarkers indicated elevated collagen turnover, while the inflammatory cytokine response was inconclusive. In ACL-R patients, serum concentrations indicated decreased collagen breakdown, but urine concentrations were indicative of greater collagen breakdown when compared to controls. Compared to preoperative values, the overall inflammatory cytokine response measured with synovial fluid biomarkers increased while plasma biomarkers did not change following reconstruction.

CONCLUSION

Patients with ACL-D or ACL-R have altered biomarkers indicative of OA. More research with standardized reporting is needed to effectively determine which biomarkers are the most indicative for OA development and progression following ACL injury.

Hyaluronan molecular weight distribution is associated with the risk of knee osteoarthritis progression

OBJECTIVE

We investigated the relationship between the molecular weight (MW) distribution of hyaluronan (HA) in synovial fluid (SF) and risk of knee osteoarthritis (OA) progression.

METHODS

HA MW was analyzed for 65 baseline knee SFs. At 3-year follow-up, knees were scored for change in joint space narrowing (JSN), osteophyte (OST) progression, or occurrence of total knee arthroplasty (TKA). HA MW distribution was analyzed using agarose gel electrophoresis (AGE), and its relationship to OA progression was evaluated using logistic regression. The association between HA MW and self-reported baseline knee pain was analyzed using Pearson's correlation coefficients.

RESULTS

Knee OA was categorized as non-progressing (OST-/JSN-, 26 knees, 40%), or progressing based on OST (OST+/JSN-, 24 knees, 37%), OST and JSN (OST+/JSN+, 7 knees, 11%) or total knee arthroplasty (TKA, 8 knees, 12%). The MW distribution of HA in baseline SFs was significantly associated with the odds of OA progression, particularly for index knees. After adjusting for age, gender, BMI, baseline X-ray grade and pain, each increase of one percentage point in %HA below 1 million significantly increased the odds of JSN (odds ratios (OR) = 1.45, 95% CI 1.02-2.07), TKA or JSN (OR = 1.24, 95%CI 1.01-1.53) and the odds of any progression (OR = 1.16, 95% CI 1.01-1.32). HA MW distribution significantly correlated with pain.

CONCLUSION

These data suggest that the odds of knee OA progression increases as HA MW distribution shifts lower and highlight the value of reporting MW distribution rather than just average MW values for HA.

Imaging of cartilage and bone: promises and pitfalls in clinical trials of osteoarthritis

Imaging in clinical trials is used to evaluate subject eligibility, and/or efficacy of intervention, supporting decision making in drug development by ascertaining treatment effects on joint structure. This review focusses on imaging of bone and cartilage in clinical trials of (knee) osteoarthritis. We narratively review the full-text literature on imaging of bone and cartilage, adding primary experience in the implementation of imaging methods in clinical trials. Aims and constraints of applying imaging in clinical trials are outlined. The specific uses of semi-quantitative and quantitative imaging biomarkers of bone and cartilage in osteoarthritis trials are summarized, focusing on radiography and magnetic resonance imaging (MRI). Studies having compared both imaging methodologies directly and those having established a relationship between imaging biomarkers and clinical outcomes are highlighted. To make this review of practical use, recommendations are provided as to which imaging protocols are ideal for capturing specific aspects of bone and cartilage tissue, and pitfalls in their usage are highlighted. Further, the longitudinal sensitivity to change, of different imaging methods is reported for various patient strata. From these power calculations can be accomplished, provided the strength of the treatment effect is known. In conclusion, current imaging methodologies provide powerful tools for scoring and measuring morphological and compositional aspects of most articular tissues, capturing longitudinal change with reasonable to excellent sensitivity. When employed properly, imaging has tremendous potential for ascertaining treatment effects on various joint structures, potentially over shorter time scales than required for demonstrating effects on clinical outcomes.

Association between urinary C-telopeptide fragments of type II collagen and knee structure in middle-aged women without clinical knee disease

OBJECTIVE

There is evidence for an association between levels of urinary C-telopeptide fragments of type II collagen (uCTX-II) and risk of knee osteoarthritis (OA). The aim of this cohort study was to examine the association between uCTX-II levels and knee cartilage and bone changes in middle-aged women without clinical knee disease.

DESIGN

140 women, aged 40-67 years, with no significant knee pain, knee injury or any forms of arthritis, underwent knee magnetic resonance imaging (MRI) at baseline and 2 years later. Cartilage volume, cartilage defects, tibial plateau bone area and bone marrow lesions (BMLs) were measured using validated methods. Baseline uCTX-II was measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

For every one unit (natural logarithm transformed) increase in baseline uCTX-II level, there was an increase in the prevalence of medial tibiofemoral cartilage defects (Odds ratio (OR) 4.36, 95% confidence interval (CI) 1.58-12.04), medial (80.2 mm(2), 95% CI 9.3-151.1) and lateral (86.0 mm(2), 95% CI 33.3-138.7) tibial plateau bone area, and the prevalence of lateral tibiofemoral BMLs (OR 10.62, 95% CI 1.82-61.85). Baseline uCTX-II levels were not significantly associated with baseline tibial cartilage volume or changes in knee cartilage volume or defects or bone area over 2 years, although there was a trend for the deterioration of medial tibiofemoral BMLs (P = 0.06).

CONCLUSION

In middle-aged women without clinical knee disease, higher uCTX-II levels were associated with early detrimental structural changes at the knee (cartilage defects, tibial bone expansion and BMLs) at baseline but not over 2 years. Further work will be needed to determine its sensitivity to change and whether it predicts disease progression over longer time periods.

Effect of oral glucosamine on joint structure in individuals with chronic knee pain: a randomized, placebo-controlled clinical trial

OBJECTIVE

To determine the short-term efficacy of oral glucosamine supplementation by evaluating structural lesions in the knee joints, as assessed using 3T magnetic resonance imaging (MRI).

METHODS

This study was designed as a randomized, double-blind, placebo-controlled trial. Recruitment was performed via mass mailings and an arthritis registry in southwestern Pennsylvania. In total, 201 participants with mild-to-moderate pain in one or both knees, as defined by a Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score ≥25 and ≤100, were enrolled. Of these subjects, 69.2% had a Kellgren/Lawrence grade ≥2 in at least 1 knee. Participants received 24 weeks of treatment with 1,500 mg glucosamine hydrochloride in beverage form or a placebo beverage. The primary outcome was decreased worsening of cartilage damage on 3T MRI of both knees, assessed according to a validated scoring system, the Whole-Organ MRI Score (WORMS). Secondary outcomes included change in bone marrow lesion (BML) scores in all knees and change in excretion of urinary C-terminal crosslinking telopeptide of type II collagen (CTX-II).

RESULTS

The adjusted odds ratio (OR) for the likelihood of decreased cartilage damage over 24 weeks in any WORMS-scored subregion of the knee in the glucosamine treatment group compared to the control group was 0.938 (95% confidence interval [95% CI] 0.528, 1.666). Compared to subjects treated with glucosamine, control subjects showed more improvement in BMLs (adjusted OR 0.537, 95% CI 0.291, 0.990) but no difference in worsening BMLs (adjusted OR 0.691, 95% CI 0.410, 1.166) over 24 weeks. There was no indication that treatment with glucosamine decreased the excretion of urinary CTX-II (β = -0.10, 95% CI -0.21, 0.002).

CONCLUSION

The results of this short-term study provide no evidence of structural benefits (i.e., improvements in MRI morphologic features or urinary CTX-II excretion) from glucosamine supplementation in individuals with chronic knee pain.

How to define responders in osteoarthritis

BACKGROUND

Osteoarthritis is a clinical syndrome of failure of the joint accompanied by varying degrees of joint pain, functional limitation, and reduced quality of life due to deterioration of articular cartilage and involvement of other joint structures.

SCOPE

Regulatory agencies require relevant clinical benefit on symptoms and structure modification for registration of a new therapy as a disease-modifying osteoarthritis drug (DMOAD). An international Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) and International Osteoporosis Foundation was convened to explore the current burden of osteoarthritis, review current regulatory guidelines for the conduct of clinical trials, and examine the concept of responder analyses for improving drug evaluation in osteoarthritis.

FINDINGS

The ESCEO considers that the major challenges in DMOAD development are the absence of a precise definition of the disease, particularly in the early stages, and the lack of consensus on how to detect structural changes and link them to clinically meaningful endpoints. Responder criteria should help identify progression of disease and be clinically meaningful. The ideal criterion should be sensitive to change over time and should predict disease progression and outcomes such as joint replacement.

CONCLUSION

The ESCEO considers that, for knee osteoarthritis, clinical trial data indicate that radiographic joint space narrowing >0.5 mm over 2 or 3 years might be a reliable surrogate measure for total joint replacement. On-going research using techniques such as magnetic resonance imaging and biochemical markers may allow the identification of these patients earlier in the disease process.

Diagnostic and prognostic value of bone biomarkers in progressive knee osteoarthritis: a 6-year follow-up study in middle-aged subjects

OBJECTIVE

To determine the value of bone markers in early-stage progressive knee osteoarthritis (OA), a population-based cohort of middle-aged subjects with chronic knee complaints was followed over 6 years (two consecutive two 3-year periods).

METHODS

Tibiofemoral (TF) and patellofemoral (PF) radiographs were graded in 128 subjects (mean age at baseline 45 ± 6.2 years) in 2002, 2005 and 2008. Bone formation was assessed by the serum concentration of procollagen type I amino-terminal propeptide (sPINP); bone resorption by the level of the C-terminal cross-linked telopeptides of type I collagen (sCTx-I); and bone mineralization by the values of osteocalcin (sOC) by electrochemiluminescence immunoassay. A novel marker of bone resorption, urinary osteocalcin midfragments (uMidOC), was assayed using enzyme linked immunosorbent assay (ELISA).

RESULTS

Several diagnostic associations were found between the bone markers (PINP, OC, MidOC) and progressive OA expressed by TF osteophytosis. The increasing output of MidOC demonstrated several-fold higher risk for progressive TF osteophytosis [odds ratio (OR) 5.32; 95% confidence interval (CI) 1.41-20.06, P = 0.014] than other bone markers. The values of PINP had prognostic value for subsequent more severely expressed knee OA progression [r(s) = 0.460, P = 0.005].

CONCLUSIONS

Bone metabolism is activated in early-stage knee OA. OA progression was preceded by the enhanced bone formation (by PINP) and accompanied by the activation of bone formation (by PINP), non-collagenous bone resorption (by MidOC), as well as by changes in mineralization (by OC). All three bone markers had diagnostic value, and one of them, PINP, had also a predictive value for knee OA progression, especially for progressive osteophytosis.

Individual magnetic resonance imaging and radiographic features of knee osteoarthritis in subjects with unilateral knee pain: the health, aging, and body composition study

OBJECTIVE

Strong associations between radiographic features of knee osteoarthritis (OA) and pain have been demonstrated in persons with unilateral knee symptoms. This study was undertaken to compare radiographic and magnetic resonance imaging (MRI) features of knee OA and assess their ability to discriminate between painful and nonpainful knees in persons with unilateral symptoms.

METHODS

The study population included 283 individuals ages 70-79 years with unilateral knee pain who were enrolled in the Health, Aging, and Body Composition Study, a study of weight-related diseases and mobility. Radiographs of both knees were read for Kellgren/Lawrence (K/L) grade and individual radiographic features, and 1.5T MRIs were assessed using the Whole-Organ Magnetic Resonance Imaging Score. The association between structural features and pain was assessed using a within-person case-control design and conditional logistic regression. Receiver operating characteristic (ROC) analysis was then used to test the discriminatory performance of structural features.

RESULTS

In conditional logistic analyses, knee pain was significantly associated with both radiographic features (any joint space narrowing grade ≥ 1) (odds ratio 3.20 [95% confidence interval 1.79-5.71]) and MRI features (any cartilage defect scored ≥ 2) (odds ratio 3.67 [95% confidence interval 1.49-9.04]). However, in most subjects, MRI revealed osteophytes and cartilage and bone marrow lesions in both knees, and using ROC analysis, no individual structural feature discriminated well between painful and nonpainful knees. The best-performing MRI feature (synovitis/effusion) was not significantly more informative than K/L grade ≥ 2 (P = 0.42).

CONCLUSION

In persons with unilateral knee pain, MRI and radiographic features were associated with knee pain, confirming that structural abnormalities in the knee have an important role in the etiology of pain. However, no single MRI or radiographic finding performed well in discriminating between painful and nonpainful knees. Further work is needed to examine how structural and nonstructural factors influence knee pain.

Urinary CTX-II concentrations are elevated and associated with knee pain and function in subjects with ACL reconstruction

OBJECTIVE

Post-traumatic knee osteoarthritis (OA) is prevalent after anterior cruciate ligament reconstruction (ACLR). Biomarkers that identify individuals likely to develop OA, especially symptomatic OA, can help target preventative and therapeutic strategies. This study examined the magnitude and change over time in urinary CTX-II (uCTX-II) concentrations shortly after ACL reconstruction, and, secondarily, the associations with knee pain and function.

DESIGN

Subjects were 28 patients with ACLR and 28 age- and sex-matched controls (CNTRL). Testing was conducted at four time points spaced 4 weeks apart (4, 8, 12 and 16 weeks post-operative in ACLR). Measures included demographics, urine samples, Numeric Pain Rating Scale (NPRS) and International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). uCTX-II concentrations were determined with competitive enzyme-linked immunosorbent assay (ELISA). uCTX-II concentrations at each time point in ACLR were compared to the mean concentration over time in CNTRL, with and without adjustment for body mass index (BMI). Changes over time in each measure and correlations between the slopes of change were examined.

RESULTS

uCTX-II concentrations were significantly higher in ACLR than CNTRL through 16 weeks post-operative when adjusted for BMI. In ACLR, uCTX-II concentrations significantly decreased over time, and the slope was associated with NPRS (r = 0.406, P = 0.039) and IKDC-SKF (r = -0.402, P = 0.034) slopes.

CONCLUSION

uCTX-II concentrations shortly after ACLR were elevated compared to CNTRL and declined over time. Decreasing uCTX-II concentrations were associated with decreasing knee pain and improving function. uCTX-II may have a role as a prognostic marker following ACLR and warrants further investigation.

A relationship between mechanically-induced changes in serum cartilage oligomeric matrix protein (COMP) and changes in cartilage thickness after 5 years

OBJECTIVE

To evaluate the hypothesis that a mechanical stimulus (30-min walk) will produce a change in serum concentrations of cartilage oligomeric matrix protein (COMP) that is associated with cartilage thickness changes on magnetic resonance imaging (MRI).

METHODS

Serum COMP concentrations were measured by enzyme-linked immunosorbent assay in 17 patients (11 females, age: 59.0±9.2 years) with medial compartment knee osteoarthritis (OA) at study entry immediately before, immediately after, 3.5 h, and 5.5 h after a 30-min walking activity. Cartilage thickness changes in the medial femur and medial tibia were determined from MR images taken at study entry and at 5-year follow-up. Relationships between changes in cartilage thickness and COMP levels, with post-activity concentrations expressed as a percentage of pre-activity levels, were assessed by the calculation of Pearson correlation coefficients and by multiple linear regression analysis, with adjustments for age, sex, and body mass index (BMI).

RESULTS

Changes in COMP levels 3.5 h and 5.5 h post-activity were correlated with changes in cartilage thickness in the medial femur and tibia at the 5-year follow-up. The results were strengthened after analyses were adjusted for age, sex, and BMI. Neither baseline pre-activity COMP levels nor changes in COMP levels immediately post-activity were correlated with cartilage thickness changes.

CONCLUSIONS

The results of this study support the hypothesis that a change in COMP concentration induced by a mechanical stimulus is associated with cartilage thinning at 5 years. Mechanically-induced changes in mechano-sensitive biomarkers should be further explored in the context of stimulus-response models to improve the ability to assess OA progression.

Biological markers in osteoarthritis

Osteoarthritis (OA) is considered as a chronic disease with a long "silent" period. The diagnosis is generally based on clinical symptoms and radiographic changes. However X-ray has a poor sensitivity and a relatively large precision error that does not allow an early detection of OA or the monitoring of joint damage progression. The limitations of the tools that are currently available for OA assessment have been the impetus to identify specific biological markers that reflect quantitative and dynamic variations in joint remodeling. Research has focused on the structural components of cartilage matrix, especially type II collagen degradation markers. In spite of a significant increase of some markers in individuals with early stage of OA, the large overlap with control subjects indicates that the current biomarkers used alone have limited diagnostic potential. However, the combination of specific markers seems to improve the prediction of disease progression at the individual level. Several types of treatment have been investigated but the lack of medications with definitively demonstrated chondroprotective activity has limited the assessment of the potential role of biomarkers for monitoring patients' responses to the treatment of OA. In this review, we will use the BIPED classification that appeared in 2006 for OA markers to describe the potential usage of a given marker [5]. This article is part of a Special Issue entitled "Osteoarthritis".

The value of cartilage biomarkers in progressive knee osteoarthritis: cross-sectional and 6-year follow-up study in middle-aged subjects

To determine the possible diagnostic and prognostic value of cartilage biomarkers in early-stage progressive and nonprogressive knee osteoarthritis (OA) in a population-based cohort of middle-aged subjects with chronic knee pain. Design tibiofemoral (TF) and patellofemoral (PF) radiographs were graded in 128 subjects (mean age at baseline, 45 ± 6.2 years) in 2002, 2005, and 2008. Cartilage degradation was assessed by urinary C-telopeptide fragments of type II collagen (uCTx-II), synthesis by serum type II A procollagen N-terminal propeptide (sPIIANP), and articular tissue turnover in general by cartilage oligomeric matrix protein (sCOMP). Several diagnostic associations were found between all studied biomarkers and progressive osteophytosis. COMP and CTx-II had a predictive value for subsequent progressive osteophytosis in multiple knee compartments and in case of CTx-II-also for progressive JSN. Over the first 3 years (2002-2005), significant associations were observed between COMP and progressive osteophytosis, whereas 3 years later (2005-2008) between CTx-II and progressive JSN. Thus, the associations between cartilage markers (COMP, CTx-II) and progression of radiographic OA features--osteophytes and JSN--were different between 2002-2005 and 2005-2008. Logistic regression revealed that for every unit increase in COMP level, there was 33 % higher risk for TF osteophyte progression. During early-stage OA, the presence and progression of osteophytosis is accompanied by increased level of cartilage biomarkers. This is the first study to demonstrate biochemical differences over the course of knee OA, illustrating a phasic nonpersistent character of OA with periods of progression and stabilization.

Potential plasma biomarkers for progression of knee osteoarthritis using glycoproteomic analysis coupled with a 2D-LC-MALDI system

Background

Although osteoarthritis (OA) is a highly prevalent joint disease, to date, no reliable biomarkers have been found for the disease. In this study, we attempted to identify factors the amounts of which significantly change in association with the progression of knee OA.

Methods

A total of 68 subjects with primary knee OA were enrolled in the study. These subjects were followed up over an 18-month period, and plasma and serum samples were obtained together with knee radiographs every 6 months, i.e., 0, 6, 12 and 18 months after the enrollment. Progressors and non-progressors were determined from the changes on radiographs, and plasma samples from those subjects were subjected to N-glycoproteomic 2D-LC-MALDI analysis. MS peaks were identified, and intensities for respective peaks were compared between the progressors and non-progressors to find the peak intensities of which differed significantly between the two groups of subjects. Proteins represented by the chosen peaks were identified by MS/MS analysis. Expression of the identified proteins was evaluated in synovial tissues from 10 OA knee joints by in situ hybridization, western blotting analysis and ELISA.

Results

Among the subjects involved in the study, 3 subjects were determined to be progressors, and 6 plasma and serum samples from these subjects were subjected to the analysis together with another 6 samples from the non-progressors. More than 3000 MS peaks were identified by N-glycoproteomic 2D-LC-MALDI analysis. Among them, 4 peaks were found to have significantly different peak intensities between the progressors and non-progressors. MS/MS analysis revealed that these peaks represented clusterin, hemopexin, alpha-1 acid glycoprotein-2, and macrophage stimulating protein, respectively. The expression of these genes in OA synovium was confirmed by in situ hybridization, and for clusterin and hemopexin, by western blotting analysis and ELISA as well.

Conclusions

In this study, 4 potential biomarkers were identified as potential prognostic markers for knee OA through N-glycoproteomic analysis. To the best of our knowledge, this is the first report for the use of glycoproteomic technology in exploring potential biomarkers for knee OA.

Acute joint pathology and synovial inflammation is associated with increased intra-articular fracture severity in the mouse knee

OBJECTIVE

Post-traumatic arthritis is a frequent cause of disability and occurs most commonly and predictably after articular fracture. The objective of this investigation was to examine the effect of fracture severity on acute joint pathology in a novel murine model of intra-articular fracture.

DESIGN

Low and high energy articular fractures (n=25 per group) of the tibial plateau were created in adult male C57BL/6 mice. The acute effect of articular fracture severity on synovial inflammation, bone morphology, liberated fracture area, cartilage pathology, chondrocyte viability, and systemic cytokines and biomarkers levels was assessed at 0, 1, 3, 5, and 7 days post-fracture.

RESULTS

Increasing intra-articular fracture severity was associated with greater acute pathology in the synovium and bone compared to control limbs, including increased global synovitis and reduced periarticular bone density and thickness. Applied fracture energy was significantly correlated with degree of liberated cortical bone surface area, indicating greater comminution. Serum concentrations of hyaluronic acid (HA) were significantly increased 1 day post-fracture. While articular fracture significantly reduced chondrocyte viability, there was no relationship between fracture severity and chondrocyte viability, cartilage degeneration, or systemic levels of cytokines and biomarkers.

CONCLUSIONS

This study demonstrates that articular fracture is associated with a loss of chondrocyte viability and increased levels of systemic biomarkers, and that increased intra-articular fracture severity is associated with increased acute joint pathology in a variety of joint tissues, including synovial inflammation, cortical comminution, and bone morphology. Further characterization of the early events following articular fracture could aid in the treatment of post-traumatic arthritis.

Systematic review of the concurrent and predictive validity of MRI biomarkers in OA

OBJECTIVE

To summarize literature on the concurrent and predictive validity of MRI-based measures of osteoarthritis (OA) structural change.

METHODS

An online literature search was conducted of the OVID, EMBASE, CINAHL, PsychInfo and Cochrane databases of articles published up to the time of the search, April 2009. 1338 abstracts obtained with this search were preliminarily screened for relevance by two reviewers. Of these, 243 were selected for data extraction for this analysis on validity as well as separate reviews on discriminate validity and diagnostic performance. Of these 142 manuscripts included data pertinent to concurrent validity and 61 manuscripts for the predictive validity review. For this analysis we extracted data on criterion (concurrent and predictive) validity from both longitudinal and cross-sectional studies for all synovial joint tissues as it relates to MRI measurement in OA.

RESULTS

Concurrent validity of MRI in OA has been examined compared to symptoms, radiography, histology/pathology, arthroscopy, CT, and alignment. The relation of bone marrow lesions, synovitis and effusion to pain was moderate to strong. There was a weak or no relation of cartilage morphology or meniscal tears to pain. The relation of cartilage morphology to radiographic OA and radiographic joint space was inconsistent. There was a higher frequency of meniscal tears, synovitis and other features in persons with radiographic OA. The relation of cartilage to other constructs including histology and arthroscopy was stronger. Predictive validity of MRI in OA has been examined for ability to predict total knee replacement (TKR), change in symptoms, radiographic progression as well as MRI progression. Quantitative cartilage volume change and presence of cartilage defects or bone marrow lesions are potential predictors of TKR.

CONCLUSION

MRI has inherent strengths and unique advantages in its ability to visualize multiple individual tissue pathologies relating to pain and also predict clinical outcome. The complex disease of OA which involves an array of tissue abnormalities is best imaged using this imaging tool.

[Inflammation in knee osteoarthrosis--cause of aggravation]

INTRODUCTION

Knee osteoarthrosis is a degenerative disease which induces intense trouble.

MATERIAL AND METHODS

The aim of the study was the parallel analysis of clinical and ultrasound examination in patients diagnosed with knee osteoarthrosis. A group of 88 patients underwent the clinical examination and the outflow and size of flexion were determined, the intensity of pain was assessed by the patient's mark on VAS, the functional ability by HAQ index, and the size of effusion and synovitis by arthrosonography.

RESULTS

The minimal outflow was diagnosed in 34.1% of patients, medium in 22.7%, and significant in 4.5%. Synovitis was evident in 67% of patients, 17.0% had nodular, 30.7% diffuse and 19.3% nodular-diffuse type. Effusion was observed in 75% of patients. The average size of synovitis in suprapatellar recess (SR) in the patients with significant, medium and lateral outflow was 6.68 (2.93-10.04) mm (p = 0.000), 1.57 (0-5.53) mm (p = 0.006) and 6.18 (3.44-7.10) mm (p = 0.000), respectively. The grade of pain on VAS was the highest in patients with significant outflow 70 (60-95) (p = 0.014), effusion 60 (50-80) (p = 0.024) and nodular type of synovitis 70 (50-90) (p = 0.029). There was a significant correlation on VAS in the positive direction with the size of effusion (r = 0.238, p = 0.025) and synovitis in LR (r = 0.215, p = 0.044), HAQ index (r = 0.502, p = 0.000), and in the negative direction with the size of flexion (r = -0.346, p = 0.001). The average size of flexion in the patients with significant outflow was 90 (82.5-90) degrees (p = 0.000), HAQ index 1.99 (1.49-2.30) (p = 0.078). HAQ index depended on effusion in LR in the positive direction (p = 0.014).

DISCUSSION AND CONCLUSION

Clinically significant outflow is shown by arthrosonography as the biggest in SR, moderate and minimal only in LR. Moderate or significant outflow, effusion and nodular type of synovitis lead to intensive pain. Patients with bigger functional disability had intense pain, significant outflow in LR and significantly limited motions.

Cartilage oligomeric matrix protein - inflammation biomarker in knee osteoarthritis

Chondrocytes and synovial cells synthesize Cartilage Oligomeric Matrix Protein (COMP) when activated by proinflammatory cytokines. The aim of this study was to analyze and compare ultrasound parameters of joint inflammation, effusion and synovitis with the levels of COMP in the serum of patients with primary osteoarthritis. Ultrasound was done and the concentration of COMP (ng/mL was examined in 88 patients. 75% of patients had effusion (size 10.13±4.35 mm), 62.5% had effusion in lateral recessus (LR), 28.4% (size 8.53±2.27 mm) in suprapatelar (SR), and 27.3% (size 11.38±4.44 mm) in medial (MR). 67% of patients had synovitis size 4.84±3.57 mm in SR, 3.15±1.86 mm in MR; and 6.09±2.80 mm in LR. 17.0% of patients had nodular type of synovitis, 30.7% had diffusive, and 19.3% nodular - diffusive. There was a significant link between the size of synovitis and effusion in SR (r = 0.966, p = 0.000), MR (r = 0.812, p = 0.009) and LR (r = 0.886, p = 0.003). The median of COMP concentration was 54 (44.5-58) ng/mL in patients without effusion. In those with effusion it was 57 (48.75-64.25) ng/mL (p = 0.030). Without synovitis it was 52 (45.5-58) ng/mL, with synovitis 58 (50-66) ng/mL, (p = 0.006), diffusion type synovitis 60 (50-67) ng/mL, nodular 57 (50-62) ng/mL, nodular-diffusion 54 (44.5-66.5) ng/mL (p = 0.014). With longer osteophytes the median of COMP was 56 (48-64) ng/mL, with shorter osteophytes 55 (46.5-59) ng/mL (p = 0.000). Cartilage oligomeric matrix protein has a moderate significance in the assessment of disturbance of the metabolism of synovial and cartilage tissue in patients with knee osteoarthritis (sensitivity = 59%; specificity = 50%; cut off = 53.5 ng/mL).

Biochemical markers in the diagnosis of chondral defects following anterior cruciate ligament insufficiency

PURPOSE

The aim of this study was to determine the value of systemic biochemical markers of bone turnover-urine levels of cross-linked C-terminal telopeptide I (uCTX-I), urinary C-terminal telopeptide II (uCTX-II) and serum cartilage oligomeric matrix protein (sCOMP)-in the diagnosis of chondral defects after anterior cruciate ligament (ACL) rupture. Thirty-eight patients with previous ACL rupture were included.

METHODS

Magnetic resonance imaging (MRI) of the injured and the intact knee joint was performed with volumetric measurement of volume and area of cartilage (VC/AC), area of subchondral bone (cAB), and area of subchondral bone denuded and eroded (dAB). Biochemical markers were measured using commercially available enzyme-linked immunoassays.

RESULTS

MRI-based volumetric cartilage measurement showed significant differences between the injured and the intact knees. uCTX-I, sCOMP and in parts uCTX-II correlated well with MRI parameters. CTX-I showed a significant correlation with VC and AC of the whole knee joint.

CONCLUSIONS

The results suggest that uCTX-I, uCTX-II and sCOMP could identify patients with focal cartilage lesions from an early stage of osteoarthritis of the knee.

Knee osteoarthritis, knee joint pain and aging in relation to increasing serum hyaluronan level in the Japanese population

OBJECTIVE

To investigate relationship between serum hyaluronan (HA) level and the presence and severity of radiographic knee osteoarthritis (OA) as well as degree of knee pain in Japanese population.

DESIGN

A total of 616 volunteers participated in this study. Based on the Kellgren-Lawrence (K-L) grade, participants were radiographically classified into three groups: Normal (K-L grade 0 or 1), Moderate (grade 2) and Severe (grade 3 or 4). The degree of knee pain was quantified by visual analogue scale (VAS) and Knee injury and Osteoarthritis Outcome Score (KOOS) Pain. Serum HA levels were compared among the Normal, Moderate and Severe groups, and the relationship between serum HA level and the severity of knee OA was analyzed after age, sex and body mass index (BMI) were adjusted. In addition, the correlation between serum HA level and the degree of knee pain was analyzed in each group.

RESULTS

Regarding relationship between serum HA level and the severity of radiographic knee OA, serum HA levels of the Moderate and Severe groups were significantly higher than in the Normal group (P<0.001). Furthermore, serum HA level correlated with the severity of radiographic knee OA (r=0.289, P<0.001) after adjusting for age, sex and BMI. Serum HA level correlated with VAS of knee pain and/or KOOS Pain in the Normal and Moderate groups.

CONCLUSION

Serum HA level has the potential to be useful for the diagnosis of the presence and severity of knee OA.

Quantitative cartilage imaging in knee osteoarthritis

Quantitative measures of cartilage morphology (i.e., thickness) represent potentially powerful surrogate endpoints in osteoarthritis (OA). These can be used to identify risk factors of structural disease progression and can facilitate the clinical efficacy testing of structure modifying drugs in OA. This paper focuses on quantitative imaging of articular cartilage morphology in the knee, and will specifically deal with different cartilage morphology outcome variables and regions of interest, the relative performance and relationship between cartilage morphology measures, reference values for MRI-based knee cartilage morphometry, imaging protocols for measurement of cartilage morphology (including those used in the Osteoarthritis Initiative), sensitivity to change observed in knee OA, spatial patterns of cartilage loss as derived by subregional analysis, comparison of MRI changes with radiographic changes, risk factors of MRI-based cartilage loss in knee OA, the correlation of MRI-based cartilage loss with clinical outcomes, treatment response in knee OA, and future directions of the field.

Aggrecan and cartilage oligomeric matrix protein in serum and synovial fluid of patients with knee osteoarthritis

Aggrecan and cartilage oligomeric matrix protein (COMP) which are important degradation products of articular cartilage may be promising diagnostic markers in serum and/or synovial fluid for diagnosis of knee osteoarthritis (OA). Our objective was to measure serum and synovial fluid levels of aggrecan and COMP in patients with OA of the knee joint to find out if they could be of diagnostic value in OA and if their levels correlate with the clinical and radiological manifestations of the disease. Sixty-six patients suffering from primary knee OA with effusion (26 males and 40 females) were studied. Twenty individuals (six males and 14 females) with recent traumatic knee effusion matched for age and sex were chosen to serve as a control group. All subjects had thorough clinical and radiological (X-ray and MRI) evaluation. Aggrecan and COMP in serum and synovial fluid were measured by ELISA. Serum and synovial fluid aggrecan and COMP levels were significantly higher than the control. Serum and synovial fluid aggrecan and COMP levels were positively correlated with age, body mass index, disease duration, plain X-ray and MRI scores. In OA, serum and synovial fluid aggrecan and COMP levels are elevated and represent useful markers in the diagnosis. Moreover, these elevated levels positively correlated with radiological joint damage but not with clinical disease parameters. These markers have the potential to be used for monitoring articular cartilage destruction and response to different therapeutic modalities.

Serum and urinary biochemical markers for knee and hip-osteoarthritis: a systematic review applying the consensus BIPED criteria

CONTEXT

Molecules that are released into biological fluids during matrix metabolism of articular cartilage, subchondral bone, and synovial tissue could serve as biochemical markers of the process of osteoarthritis (OA). Unfortunately, actual breakthroughs in the biochemical OA marker field are limited so far.

OBJECTIVE

By reviewing the status of commercially available biochemical OA markers according to the "Burden of disease, Investigative, Prognostic, Efficacy of intervention, and Diagnostic" ("BIPED") classification, future use of this "BIPED" classification is encouraged and more efficient biochemical OA marker research stimulated.

DATA SOURCES

Three electronic databases [PubMed, Scopus, EMBASE (1997-May 2009)] were searched for publications on blood and urinary biochemical markers in human primary knee and hip-OA.

STUDY SELECTION

Stepwise selection of original English publications describing human studies on blood or urinary biochemical markers in primary knee or hip-OA was performed. Selected articles were fully read to determine whether biochemical markers were investigated on performance within any of the "BIPED" categories. Eighty-four relevant publications were identified.

DATA EXTRACTION

Data from relevant publications were tabulated according to the "BIPED" classification. Individual analyses within a publication were summarized in general "BIPED" scores.

DATA SYNTHESIS

An uneven distribution of scores on biochemical marker performance and heterogeneity among the publications complicated direct comparison of individual biochemical markers. Comparison of categories of biochemical markers was therefore performed instead. In general, biochemical markers of cartilage degradation were investigated most extensively and performed well in comparison with other categories of biochemical markers. Biochemical markers of bone metabolism performed less adequately. Biochemical markers of synovial tissue metabolism were not investigated extensively, but performed quite well.

CONCLUSIONS

Specific biochemical markers and categories of biochemical markers as well as their nature, origin and metabolism, need further investigation. International standardization of future investigations should be pursued to obtain more high-quality, homogenous data on the full spectrum of biochemical OA markers.

Targeting subchondral bone for treating osteoarthritis: what is the evidence?

Over the past few decades, significant progress has been made with respect to new concepts about the pathogenesis of osteoarthritis (OA). This article summarises some of the knowledge we have today on the involvement of the subchondral bone in OA. It provides substantial evidence that changes in the metabolism of the subchondral bone are an integral part of the OA disease process and that these alterations are not merely secondary manifestations, but are part of a more active component of the disease. Thus, a strong rationale exists for therapeutic approaches that target subchondral bone resorption and/or formation, and data evaluating the drugs targeting bone remodelling raise the hope that new treatment options for OA may become available.

Markers of Bone Formation and Resorption Identify Subgroups of Patients with Clinical Knee Osteoarthritis Who Have Reduced Rates of Cartilage Loss

Objective.

To determine whether serum markers of bone formation and resorption, used individually or in combination, can be used to identify subgroups who lose cartilage volume at different rates over 2 years within a knee osteoarthritis (OA) population.

Methods.

Changes in cartilage volume over 2 years were measured in 117 subjects with knee OA using magnetic resonance imaging. We examined relationships between change in cartilage volume and baseline serum markers of bone formation [intact N-terminal propeptide of type I procollagen (PINP) and osteocalcin] and resorption [N-telopeptide of type I collagen (NTX-I), C-telopeptide of type I collagen (CTX-I), and C-telopeptide of type I collagen (ICTP).

Results.

The baseline markers of bone formation, PINP and osteocalcin (p = 0.02, p = 0.01, respectively), and the baseline markers of bone resorption, CTX-I and NTX-I (p = 0.02 for both), were significantly associated with reduced cartilage loss. There were no significant associations between baseline ratios of bone formation to resorption markers and cartilage loss. However, when subjects were divided into subgroups with high or low bone formation markers (based on levels of marker ≥ mean or < mean for the population, respectively), in the subgroup with high PINP there was a significant association between increasing bone resorption markers CTX-I and NTX-I and reduced cartilage loss (p = 0.02, p = 0.001, respectively). Similarly, in the subgroup with high osteocalcin, there was a significant association between increasing CTX-I and NTX-I and reduced cartilage loss (p = 0.02, p = 0.003, respectively). In contrast, in subgroups with low bone formation markers, no significant associations were obtained between markers of bone resorption and cartilage loss.

Conclusion.

Overall, the results suggest that higher bone remodeling (i.e., higher serum levels of bone formation and resorption) is associated with reduced cartilage loss. Considering markers of bone formation and resorption together, it is possible to identify subgroups within the OA population who have reduced rates of cartilage loss.

First qualification study of serum biomarkers as indicators of total body burden of osteoarthritis

Background

Osteoarthritis (OA) is a debilitating chronic multijoint disease of global proportions. OA presence and severity is usually documented by x-ray imaging but whole body imaging is impractical due to radiation exposure, time and cost. Systemic (serum or urine) biomarkers offer a potential alternative method of quantifying total body burden of disease but no OA-related biomarker has ever been stringently qualified to determine the feasibility of this approach. The goal of this study was to evaluate the ability of three OA-related biomarkers to predict various forms or subspecies of OA and total body burden of disease.

Methodology/Principal Findings

Female participants (461) with clinical hand OA underwent radiography of hands, hips, knees and lumbar spine; x-rays were comprehensively scored for OA features of osteophyte and joint space narrowing. Three OA-related biomarkers, serum hyaluronan (sHA), cartilage oligomeric matrix protein (sCOMP), and urinary C-telopeptide of type II collagen (uCTX2), were measured by ELISA. sHA, sCOMP and uCTX2 correlated positively with total osteophyte burden in models accounting for demographics (age, weight, height): R² = 0.60, R² = 0.47, R² = 0.51 (all p<10⁻⁶); sCOMP correlated negatively with total joint space narrowing burden: R² = 0.69 (p<10⁻⁶). Biomarkers and demographics predicted 35–38% of variance in total burden of OA (total joint space narrowing or osteophyte). Joint size did not determine the contribution to the systemic biomarker concentration. Biomarker correlation with disease in the lumbar spine resembled that in the rest of the skeleton.

Conclusions/Significance

We have suspected that the correlation of systemic biomarkers with disease has been hampered by the inability to fully phenotype the burden of OA in a patient. These results confirm the hypothesis, revealed upon adequate patient phenotyping, that systemic joint tissue concentrations of several biomarkers can be quantitative indicators of specific subspecies of OA and of total body burden of disease.

Effect of exercise and osteochondral injury on synovial fluid and serum concentrations of carboxy-terminal telopeptide fragments of type II collagen in racehorses

OBJECTIVE

To investigate the effects of exercise and osteochondral injury on concentrations of carboxy-terminal telopeptide fragments of type II collagen (CTX-II) in synovial fluid (SF) and serum of Thoroughbred racehorses and to compare findings with radiographic and arthroscopic scores of joint injury severity.

ANIMALS

78 Thoroughbreds with (n = 38) and without (40) osteochondral injury.

PROCEDURES

Serum and metacarpophalangeal or carpal joint SF samples were collected from noninjured horses before and at the end of 5 to 6 months of race training (pre- and postexercise samples, respectively) and from horses with osteochondral injury (1 joint assessed/horse). Synovial fluid and serum CTX-II concentrations were determined by use of an ELISA. Radiographic and arthroscopic scores of joint injury severity were determined for the injured horses.

RESULTS

The CTX-II concentrations in SF and SF:serum CTX-II ratio were significantly higher for horses with joint injuries, compared with pre- and postexercise findings in noninjured horses. Serum CTX-II concentrations in postexercise and injured-horse samples were significantly lower than values in pre-exercise samples. On the basis of serum and SF CTX-II concentrations and SF:serum CTX-II ratio, 64% to 93% of serum and SF samples were correctly classified into their appropriate group (pre-exercise, postexercise, or injured-joint samples). In horses with joint injuries, arthroscopic scores were positively correlated with radiographic scores, but neither score correlated with SF or serum CTX-II concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that serum and SF CTX-II concentrations and SF:serum CTX-II ratio may be used to detect cartilage degradation in horses with joint injury.

Radiographic assessment of the femorotibial joint of the CCLT rabbit experimental model of osteoarthritis

Background

The purposes of the study were to determine the relevance and validity of in vivo non-invasive radiographic assessment of the CCLT (Cranial Cruciate Ligament Transection) rabbit model of osteoarthritis (OA) and to estimate the pertinence, reliability and reproducibility of a radiographic OA (ROA) grading scale and associated radiographic atlas.

Methods

In vivo non-invasive extended non weight-bearing radiography of the rabbit femorotibial joint was standardized. Two hundred and fifty radiographs from control and CCLT rabbits up to five months after surgery were reviewed by three readers. They subsequently constructed an original semi-quantitative grading scale as well as an illustrative atlas of individual ROA feature for the medial compartment. To measure agreements, five readers independently scored the same radiographic sample using this atlas and three of them performed a second reading. To evaluate the pertinence of the ROA grading scale, ROA results were compared with gross examination in forty operated and ten control rabbits.

Results

Radiographic osteophytes of medial femoral condyles and medial tibial condyles were scored on a four point scale and dichotomously for osteophytes of medial fabella. Medial joint space width was scored as normal, reduced or absent. Each ROA features was well correlated with gross examination (p < 0.001). ICCs of each ROA features demonstrated excellent agreement between readers and within reading. Global ROA score gave the highest ICCs value for between (ICC 0.93; CI 0.90-0.96) and within (ICC ranged from 0.94 to 0.96) observer agreements. Among all individual ROA features, medial joint space width scoring gave the highest overall reliability and reproducibility and was correlated with both meniscal and cartilage macroscopic lesions (r_s = 0.68 and r_s = 0.58, p < 0.001 respectively). Radiographic osteophytes of the medial femoral condyle gave the lowest agreements while being well correlated with the macroscopic osteophytes (r_s = 0.64, p < 0.001).

Conclusion

Non-invasive in vivo radiography of the rabbit femorotibial joint is feasible, relevant and allows a reproducible grading of experimentally induced OA lesion. The radiographic grading scale and atlas presented could be used as a template for in vivo non invasive grading of ROA in preclinical studies and could allow future comparisons between studies.

Whole-body bone scintigraphy provides a measure of the total-body burden of osteoarthritis for the purpose of systemic biomarker validation

OBJECTIVE

To evaluate the association of serum and synovial fluid cartilage oligomeric matrix protein (COMP) with systemic and local measures of osteoarthritis (OA) activity by bone scintigraphy.

METHODS

Samples of serum and knee joint synovial fluid (275 knees) were obtained from 159 patients with symptomatic OA of at least 1 knee. Bone scintigraphy using (99m)Tc-labeled methylene diphosphonate was performed, and early-phase knee scans and late-phase whole-body bone scans of 15 additional joint sites were scored semiquantitatively. To control for within-subject correlations of knee data, generalized linear modeling was used in the correlation of the bone scan scores with the COMP levels. Principal components analysis was used to explore the contribution of each joint site to the variance in serum COMP levels.

RESULTS

The correlation between synovial fluid and serum COMP levels was significant (r = 0.206, P = 0.006). Synovial fluid COMP levels correlated most strongly with the early-phase knee bone scan scores (P = 0.0003), even after adjustment for OA severity according to the late-phase bone scan scores (P = 0.015), as well as synovial fluid volumes (P < 0.0001). Serum COMP levels correlated with the total-body bone scan scores (r = 0.188, P = 0.018) and with a factor composed of the bone scan scores in the shoulders, spine, lateral knees, and sacroiliac joints (P = 0.0004).

CONCLUSION

Synovial fluid COMP levels correlated strongly with 2 indicators of knee joint inflammation: early-phase bone scintigraphic findings and synovial fluid volume. Serum COMP levels correlated with total-body joint disease severity as determined by late-phase bone scintigraphy, supporting the hypothesis that whole-body bone scintigraphy is a means of quantifying the total-body burden of OA for systemic biomarker validation.