Cross-sectional and Longitudinal Associations between Knee Joint Effusion Synovitis and Knee Pain in Older Adults

Sexual dimorphism in peri-articular tissue anatomy - More keys to understanding sex-differences in osteoarthritis?

Objective

Osteoarthritis prevalence differs between women and men; whether this is the result of differences in pre-morbid articular or peri-articular anatomical morphotypes remains enigmatic. Albeit sex within humans cannot be reduced to female/male, this review focusses to the sexual dimorphism of peri-articular tissues, given lack of literature on non-binary subjects.

Methods

Based on a Pubmed search and input from experts, we selected relevant articles based on the authors' judgement of relevance, interest, and quality; no "hard" bibliometric measures were used to evaluate the quality or importance of the work. Emphasis was on clinical studies, with most (imaging) data being available for the knee and thigh.

Results

The literature on sexual dimorphism of peri-articular tissues is reviewed: 1) bone size/shape, 2) subchondral/subarticular bone, 3) synovial membrane and infra-patellar fad-pad (IPFP), 4) muscle/adipose tissue, and 5) peri-articular tissue response to treatment.

Conclusions

Relevant sex-specific differences exist for 3D bone shape and IPFP size, even after normalization to body weight. Presence of effusion- and Hoffa-synovitis is associated with greater risk of incident knee osteoarthritis in overweight women, but not in men. When normalized to bone size, men exhibit greater muscle, and women greater adipose tissue measures relative to the opposite sex. Reduced thigh muscle specific strength is associated with incident knee osteoarthritis and knee replacement in women, but not in men. These observations may explain why women with muscle strength deficits have a poorer prognosis than men with similar deficits. A "one size/sex fits all" approach must be urgently abandoned in osteoarthritis research.

A new injection method for identifying the subpopliteal recess of the knee

The posterolateral region of the knee has a complex and diverse anatomy. Hydrarthrosis of the knee can potentially communicate with other parts of the joint space. The joint fluid distribution reflects anatomical communications between synovial spaces. To observe the continuity between the knee joint cavity and the surrounding bursa, we devised a dissection method with a new injection agent, an eosin-containing congealed liquid that spreads uniformly over the entire space. The purpose of this study was to perform a detailed examination of the subpopliteal recess (SPR) where a bursa connects to the knee joint capsule. We also reported the advantages of this new injection agent compared with conventional materials (latex and epoxy resin). Twenty-two formalin-fixed cadavers (34 knees), two N-vinyl-pyrrolidone (NVP)-fixed cadavers (4 knees), and two cadavers (3 knees) fixed by Thiel's method were used. After filling the knee joint space and SPR with eosin congealed liquid, the specimens were dissected to investigate the morphology of the SPR. In addition, three different types of injection agents were assessed. The SPR extended distally along the popliteus tendon. The SPR length was 22.64 ± 11.38 mm from the upper end of the lateral tibial condyle to the lower end of the depression. The existence of a fabellofibular ligament made the SPR significantly longer, but abrasion of the femoral articular cartilage did not affect the SPR. Furthermore, the relationship between the popliteus muscle and the SPR was classified into three types (types 1-3). Types 2 and 3 in which the SPR extended to the proximal tibiofibular joint may cause instability of the knee joint. The eosin congealed liquid was highly useful in many aspects, such as fluidity and injection workability. The new dissection method with eosin congealed liquid provides insights into the anatomy of the posterior lateral knee, which are useful for radiological diagnoses and clinical treatments.

Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial

Importance

Knee osteoarthritis is disabling, with few effective treatments. Preliminary evidence suggested that krill oil supplementation improved knee pain, but effects on knee osteoarthritis remain unclear.

Objective

To evaluate efficacy of krill oil supplementation, compared with placebo, on knee pain in people with knee osteoarthritis who have significant knee pain and effusion-synovitis.

Design, Setting, and Participants

Multicenter, randomized, double-blind, placebo-controlled clinical trial in 5 Australian cities. Participants with clinical knee osteoarthritis, significant knee pain, and effusion-synovitis on magnetic resonance imaging were enrolled from December 2016 to June 2019; final follow-up occurred on February 7, 2020.

Interventions

Participants were randomized to 2 g/d of krill oil (n = 130) or matching placebo (n = 132) for 24 weeks.

Main Outcomes and Measures

The primary outcome was change in knee pain as assessed by visual analog scale (range, 0-100; 0 indicating least pain; minimum clinically important improvement = 15) over 24 weeks.

Results

Of 262 participants randomized (mean age, 61.6 [SD, 9.6] years; 53% women), 222 (85%) completed the trial. Krill oil did not improve knee pain compared with placebo (mean change in VAS score, -19.9 [krill oil] vs -20.2 [placebo]; between-group mean difference, -0.3; 95% CI, -6.9 to 6.4) over 24 weeks. One or more adverse events was reported by 51% in the krill oil group (67/130) and by 54% in the placebo group (71/132). The most common adverse events were musculoskeletal and connective tissue disorders, which occurred 32 times in the krill oil group and 42 times in the placebo group, including knee pain (n = 10 with krill oil; n = 9 with placebo), lower extremity pain (n = 1 with krill oil; n = 5 with placebo), and hip pain (n = 3 with krill oil; n = 2 with placebo).

Conclusions and Relevance

Among people with knee osteoarthritis who have significant knee pain and effusion-synovitis on magnetic resonance imaging, 2 g/d of daily krill oil supplementation did not improve knee pain over 24 weeks compared with placebo. These findings do not support krill oil for treating knee pain in this population.

Trial Registration

Australian New Zealand Clinical Trials Registry Identifier: ACTRN12616000726459; Universal Trial Number: U1111-1181-7087.

A standardized approach to evaluation and reporting of synovial histopathology in two surgically induced murine models of osteoarthritis

OBJECTIVE

Synovial pathology has been linked to osteoarthritis (OA) pain in patients. Microscopic grading systems for synovial changes in human OA have been described, but a standardized approach for murine models of OA is needed. We sought to develop a reproducible approach and set of minimum recommendations for reporting of synovial histopathology in mouse models of OA.

METHODS

Coronal and sagittal sections from male mouse knee joints subjected to destabilization of medial meniscus (DMM) or partial meniscectomy (PMX) were collected as part of other studies. Stains included Hematoxylin and Eosin (H&E), Toluidine Blue (T-Blue), and Safranin O/Fast Green (Saf-O). Four blinded readers graded pathological features (hyperplasia, cellularity, and fibrosis) at specific anatomic locations. Inter-reader agreement of each feature score was determined.

RESULTS

There was acceptable to very good agreement when using 3-4 individual readers. After DMM and PMX, expected medial predominant changes in hyperplasia and cellularity were observed, with fibrosis noted at 12 weeks post-PMX. Synovial changes were consistent from section to section in the mid-joint area. When comparing stains, H&E and T-blue resulted in better agreement compared to Saf-O stain.

CONCLUSIONS

To account for the pathologic and anatomic variability in synovial pathology and allow for a more standardized evaluation that can be compared across studies, we recommend evaluating a minimum set of 3 pathological features at standardized anatomic areas. Further, we suggest reporting individual feature scores separately before relying on a single summed "synovitis" score. H&E or T-blue are preferred, inter-reader agreement for each feature should be considered.

Diagnostic Accuracy of Ultrasound for Assessment of Synovial Abnormalities Among Patients With Knee Pain: A Meta-Analysis

OBJECTIVE

Synovial abnormalities, which are modifiable treatment targets for knee pain, affect ~25% of adults. Ultrasound is a safe, inexpensive, and easily accessible imaging modality for assessing synovial abnormalities, but its diagnostic accuracy is still controversial. We conducted a meta-analysis by comparing ultrasound with the "reference standard" method, ie, magnetic resonance imaging (MRI), in assessing synovial abnormalities among patients with knee pain.

METHODS

PubMed, Embase, and Web of Science were searched from inception to January 7, 2022, to retrieve studies including patients with knee pain for evaluating 1) the diagnostic accuracy of ultrasound versus MRI for synovial abnormalities (synovitis and synovial effusion) and 2) the correlations of synovial abnormalities assessed by ultrasound and MRI. The summary of diagnostic accuracy was analyzed using the bivariate model, and the correlation coefficients were pooled using the random effects model.

RESULTS

Fourteen studies were included, representing a total of 755 patients. The pooled sensitivity, specificity, and area under the curve were 0.88 (95% confidence interval [95% CI] 0.65-0.96), 0.70 (95% CI 0.51-0.84), and 0.81 (95% CI 0.77-0.84) for synovitis and 0.90 (95% CI 0.81-0.95), 0.86 (95% CI 0.77-0.92), and 0.94 (95% CI 0.91-0.96) for synovial effusion, respectively. Strong correlations between ultrasound- and MRI-diagnosed synovitis (r = 0.64, 95% CI 0.56-0.71) and synovial effusion (r = 0.63, 95% CI 0.52-0.73) were observed.

CONCLUSION

Ultrasound demonstrated a promising accuracy in detecting synovial abnormalities among patients with knee pain. The use of ultrasound provides equivalent synovial information to MRI but is less expensive and more accessible. Therefore, it is recommended as an adjuvant for managing patients with knee pain during diagnostic strategy and individualized treatment decision-making.

Predictors of Placebo Response to Local (Intra-Articular) Therapy In Osteoarthritis: An Individual Participant Data Meta-Analysis

OBJECTIVE

We undertook this study to evaluate potential predictors of placebo response with intra-articular (IA) injections for knee/hip osteoarthritis (OA) using individual participant data (IPD) from existing trials.

METHODS

Randomized placebo-controlled trials evaluating IA glucocorticoid or hyaluronic acid published to September 2018 were selected. IPD for disease characteristics and outcome measures were acquired. Potential predictors of placebo response included participant characteristics, pain severity, intervention, and trial design. Placebo response was defined as at least a 20% reduction in baseline pain. Logistic regression models and odds ratios were computed as effect measures to evaluate patient and pain mechanisms and then pooled using a random effects model. Generalized mixed-effect models were applied to intervention and trial characteristics.

RESULTS

Of 56 eligible trials, 6 shared data, and these were combined with the existing 4 OA Trial Bank studies, yielding 10 studies with IPD of 621 placebo participants for analysis. In the total placebo population, at short-term follow-up, the use of local anesthetic and ultrasound guidance were associated with reduced odds of placebo response. At midterm follow-up, mid- to long-term trial duration was associated with increased odds of placebo response, and worse baseline function scores were associated with reduced odds of a placebo response.

CONCLUSION

The administration of local anesthetics or ultrasound guidance may reduce IA placebo response at short-term follow-up. At midterm follow-up, participants with worse baseline function scores may be less likely to respond to IA placebo, and mid- to long-term trial duration may enhance the placebo response. Further studies are required to corroborate these potential predictors of IA placebo response.

Recommendations For a Standardized Approach to Histopathologic Evaluation of Synovial Membrane in Murine Models of Experimental Osteoarthritis

Background

Synovial pathology has been linked to osteoarthritis (OA) pain in patients. Microscopic grading systems for synovial changes in human OA have been described, but a standardized approach for murine models of OA is needed. We sought to develop a reproducible approach and set of minimum recommendations for synovial histopathology in mouse models of OA.

Methods

Coronal and sagittal sections from male mouse knee joints subjected to destabilization of medial meniscus (DMM) or partial meniscectomy (PMX) were collected as part of other studies. Stains included Hematoxylin and Eosin (H&E), Toluidine Blue (T-Blue) and Safranin O/Fast Green (Saf-O). Four blinded readers graded pathological features (hyperplasia, cellularity, and fibrosis) at specific anatomic locations in the medial and lateral compartments. Inter-reader reliability of each feature was determined.

Results

There was acceptable to very good agreement between raters. After DMM, increased hyperplasia and cellularity and a trend towards increased fibrosis were observed 6 weeks after DMM in the medial locations, and persisted up to 16 weeks. In the PMX model, cellularity and hyperplasia were evident in both medial and lateral compartments while fibrotic changes were largely seen on the medial side. Synovial changes were consistent from section to section in the mid-joint area mice. H&E, T-blue, and Saf-O stains resulted in comparable reliability.

Conclusions

To allow for a standard evaluation that can be implemented and compared across labs and studies, we recommend using 3 readers to evaluate a minimum set of 3 pathological features at standardized anatomic areas. Pre-defining areas to be scored, and reliability for each pathologic feature should be considered.

Efficacy and safety of combined Chinese and Western medicine in the treatment of knee osteoarthritis: a prospective, multicenter cohort study

Purpose: To conduct a real-world evaluation of the efficacy and safety of combined Chinese and Western medicine in treating knee osteoarthritis (KOA). Methods: A multicenter, prospective cohort study design was employed, enrolling 450 KOA patients (Kellgren-Lawrence score of 3 or less). The patients were divided into a Western medicine treatment group (WM group) and a combined Western and traditional Chinese medicine treatment group (WM-CM group). A 6-week treatment plan was administered, and follow-up visits occurred at 2 weeks, 4 weeks, and 6 weeks after initiating treatment. The primary outcome indicator was the total Western Ontario and McMaster Universities Arthritis Index (WOMAC) score after 6 weeks of treatment. Secondary outcome indicators included WOMAC subscales for pain, stiffness, and joint function, visual analogue scale (VAS) score, physical component summary (PCS), mental component summary (MCS), and clinical effectiveness. The incidence of drug-related adverse events was used as a safety evaluation indicator. Results: A total of 419 patients were included in the final analysis: 98 in the WM group and 321 in the WM-CM group. The baseline characteristics of the two groups were comparable, except for the incidence of stiffness symptoms and stiffness scores. After 6 weeks of treatment, the WM-CM group exhibited superior results to the WM group in improving the total WOMAC score (24.71 ± 1.38 vs. 16.36 ± 0.62, p < 0.001). The WM-CM group also outperformed the WM group in WOMAC pain and joint function scores, VAS score, PCS score, MCS score, and clinical effectiveness (p < 0.05), which was consistent with the findings of the main evaluation index. Subgroup analysis indicated that the combined Chinese and Western medicine treatment showed more pronounced benefits in patients under 65 years of age and in those with a Kellgren-Lawrence (K-L) classification of 0-I. Throughout the study, no adverse effects were observed in either group. Conclusion: The combination of Chinese and Western medicine demonstrated superiority over Western medicine alone in relieving knee pain symptoms, improving knee function, and enhancing the quality of life for KOA patients with a K-L score of 3 or less. Moreover, the treatment exhibited a good safety profile. Clinical Trial Registration: (https://www.chictr.org.cn/), identifier (ChiCTR1900027175).

Reliability and Validity of Single Axial Slice vs. Multiple Slice Quantitative Measurement of the Volume of Effusion-Synovitis on 3T Knee MRI in Knees with Osteoarthritis

Effusion-synovitis (ES) is recognized as a component of osteoarthritis, creating a need for rapid methods to assess ES on MRI. We describe the development and reliability of an efficient single-slice semi-automated quantitative approach to measure ES. We used two samples from the Osteoarthritis Initiative (OAI): 50 randomly selected OAI participants with radiographic osteoarthritis (i.e., Kellgren–Lawrence (KL) grade 2 or 3) and a subset from the Foundation for the National Institutes of Health Osteoarthritis Biomarker study. An experienced musculoskeletal radiologist trained four non-expert readers to use custom semi-automated software to measure ES on a single axial slice and then read scans blinded to prior assessments. The estimated intraclass correlation coefficient (ICC) for intra-reader reliability of the single-slice ES method in the KL 2–3 sample was 0.96 (95% CI: 0.93, 0.97), and for inter-reader reliability, the ICC was 0.90 (95% CI: 0.87, 0.95). The intra-reader mean absolute difference (MAD) was 35 mm3 (95% CI: 28, 44), and the inter-reader MAD was 61 mm3 (95% CI: 48, 76). Our single-slice quantitative knee ES measurement offers a reliable, valid, and efficient surrogate for multi-slice quantitative and semi-quantitative assessment.

Efficacy and safety of GLucocorticoid injections into InfrapaTellar faT pad in patients with knee ostEoarthRitiS: protocol for the GLITTERS randomized controlled trial

BACKGROUND

Knee osteoarthritis (OA) is a prevalent disabling disorder that involves changes in articular cartilage damage, subchondral bone remodeling, synovitis, and abnormal infrapatellar fat pad (IPFP). Due to the complicated etiology and numerous phenotypes of knee OA, limited improvement is achieved for treatments among knee OA patients with different phenotypes. Inflammatory OA phenotype is a typical knee OA phenotype, and individualized treatment targeting inflammation is a promising way to obtain an optimal therapeutic effect for people with inflammatory knee OA phenotype. Glucocorticoid is a traditional anti-inflammatory drug for knee OA, and intra-articular glucocorticoid injections are recommended clinically. However, emerging evidence has shown that repeated intra-articular glucocorticoid injections in the long term would induce cartilage loss. IPFP and its adjacent synovium are considered as the main source of inflammation in knee OA. This GLITTERS trial aims to investigate if a glucocorticoid injection into the IPFP is effective and safe over 12 weeks among knee OA patients with an inflammatory phenotype.

METHODS

GLITTERS is a multicenter, double-blinded, randomized, and placebo-controlled clinical trial among knee OA patients with both Hoffa-synovitis and effusion-synovitis. Sixty participants will be allocated randomly and equally to either the glucocorticoid group or the control group. Each group will receive an injection of glucocorticoid or saline into the IPFP with an intra-articular hyaluronic acid injection as a background treatment at baseline and be followed at 4, 8, and 12 weeks. The primary outcomes will be changes in knee pain on a visual analog scale and effusion-synovitis volume measured on magnetic resonance imaging (MRI). The secondary outcomes will be changes in the total score of Western Ontario and McMaster Universities Osteoarthritis Index score, MRI-detected Hoffa-synovitis score, quality of life, pain medication use, IPFP volume, and the incidence of adverse reactions. Data analyses based on the intention-to-treat principle will include mixed-effects regressions, Wilcoxon rank-sum tests, and chi-square tests (or Fisher's exact test).

DISCUSSION

GLITTERS may provide high-quality evidence for the efficacy and safety of ultrasound-guided glucocorticoid injections into IPFP among people with inflammatory knee OA in a short term. The results of this trial are expected to provide a reliable reference for a longer-term risk-benefit profile of this treatment in the future.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05291650. Registered on 23 March 2022.

Effusion detected by ultrasonography and overweight may predict the risk of knee osteoarthritis in females with early knee osteoarthritis: a retrospective analysis of Iwaki cohort data

BACKGROUND

Knee osteoarthritis (OA) has enormous medical and socioeconomic burdens, which early diagnosis and intervention can reduce. We investigated the influence of knee effusion on the progression of knee OA in patients with early knee OA.

METHODS

A total of 404 participants without radiographic knee OA were assessed from a 3-year longitudinal analysis. Participants were classified into non-OA and early knee OA groups. The effusion area (mm²) was quantified using ultrasonography. Receiver operating characteristic and logistic regression analyses were performed.

RESULTS

At the 3-year follow-up, 114 of 349 knees (32%) had progressed from non-OA and 32 of 55 knees (58%) had progressed from early knee OA to radiographic knee OA. Logistic regression analysis showed that female sex (odds ratio [OR] 3.36, 95% confidence interval [CIs] 2.98-5.42), early knee OA (OR 2.02, 95% CI 1.08-3.75), body mass index (OR 1.11, 95% CI 1.02-1.19), and effusion area (OR 1.01, 95% CI 1.01-1.02) were significantly correlated with knee OA progression. Women who were overweight (body mass index ≥ 25 kg/m²) with more severe effusion had a higher risk of OA progression (area under the curve = 0.691, OR = 6.00) compared to those not overweight (area under the curve = 0.568, OR = 1.91).

CONCLUSION

Knee effusion may be an indicator of the progression of early-stage knee OA.

Study protocol for a randomised controlled trial of diacerein versus placebo to treat knee osteoarthritis with effusion-synovitis (DICKENS)

Background

There is an unmet need for treatments for knee osteoarthritis (OA). Effusion-synovitis is a common inflammatory phenotype of knee OA and predicts knee pain and structural degradation. Anti-inflammatory therapies, such as diacerein, may be effective for this phenotype. While diacerein is recommended for alleviating pain in OA patients, evidence for its effectiveness is inconsistent, possibly because studies have not targeted patients with an inflammatory phenotype. Therefore, we will conduct a multi-centre, randomised, placebo-controlled double-blind trial to determine the effect of diacerein on changes in knee pain and effusion-synovitis over 24 weeks in patients with knee OA and magnetic resonance imaging (MRI)-defined effusion-synovitis.

Methods

We will recruit 260 patients with clinical knee OA, significant knee pain, and MRI-detected effusion-synovitis in Hobart, Melbourne, Adelaide, and Perth, Australia. They will be randomly allocated to receive either diacerein (50mg twice daily) or identical placebo for 24 weeks. MRI of the study knee will be performed at screening and after 24 weeks of intervention. The primary outcome is improvement in knee pain at 24 weeks as assessed by a 100-mm visual analogue scale (VAS). Secondary outcomes include improvement in volumetric (ml) and semi-quantitative (Whole-Organ Magnetic Resonance Imaging Score, 0–3) measurements of effusion-synovitis using MRI over 24 weeks, and improvement in knee pain (VAS) at 4, 8, 12, 16, and 20 weeks. Intention-to-treat analyses of primary and secondary outcomes will be performed as the primary analyses. Per protocol analyses will be performed as the secondary analyses.

Discussion

This study will provide high-quality evidence to determine whether diacerein improves pain, changes disease trajectory, and slows disease progression in OA patients with effusion-synovitis. If diacerein proves effective, this has the potential to significantly benefit the substantial proportion (up to 60%) of knee OA patients with an inflammatory phenotype.

Trial registration

Australian and New Zealand Clinical Trial Registry ACTRN12618001656224. Registered on 08 October 2018.

Synovitis mediates the association between bone marrow lesions and knee pain in osteoarthritis: data from the Foundation for the National Institute of Health (FNIH) Osteoarthritis Biomarkers Consortium

OBJECTIVES

Although subchondral bone marrow lesions (BMLs) and synovitis have been well acknowledged as important sources of pain in knee osteoarthritis (KOA), it is unclear if synovitis plays the mediating role in the relationship between BMLs and knee pain.

METHODS

We analyzed 600 subjects with magnetic resonance imaging (MRI) in the Foundation for National Institutes of Health Osteoarthritis Biomarkers Consortium (FNIH) cohort at baseline and 24-month. BMLs and synovitis were measured according to the MRI Osteoarthritis Knee Score (MOAKS) scoring system. BMLs were scored in five subregions. A summary synovitis score of effusion and Hoffa-synovitis was calculated. Knee pain was evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Linear regression models were applied to analyze the natural direct effect (NDE) of BMLs and synovitis with knee pain, respectively, and natural indirect effect (NIE) mediated by synovitis.

RESULTS

590 participants (58.8% females, with a mean age of 61.5) were included in the present analyses. For NDE, knee pain was cross-sectionally associated with medial femorotibial BMLs (β = 0.23, 95% CI: 0.09, 0.38) and synovitis (β = 0.40, 95% CI: 0.20, 0.60). Longitudinal associations retained significant [medial femorotibial BMLs (β = 0.37, 95% CI: 0.21, 0.53); synovitis (β = 0.72, 95% CI: 0.45, 0.99)]. In the NIE analyses, synovitis mediated the association between medial femorotibial BML and knee pain at baseline (β = 0.051, 95% CI: 0.01, 0.09) and over 24 months (β = 0.079, 95% CI: 0.023, 0.15), with the mediating proportion of 17.8% and 22.4%, respectively.

CONCLUSION

Synovitis partially mediates the association between medial femorotibial BMLs and knee pain.

Association between Markers of Synovial Inflammation, Matrix Turnover and Symptoms in Knee Osteoarthritis: A Cross-Sectional Study

To investigate the association between markers of synovial inflammation and matrix turnover (MRI-based and serum biomarkers) and knee symptoms in established knee osteoarthritis (KOA). This cross-sectional study utilised data from a randomised, multicentre placebo-controlled trial (UK-VIDEO) of vitamin D therapy in symptomatic KOA. Data on serum biomarkers, type III collagen degradation (C3M), metabolite of C-reactive protein (CRPM) and cartilage oligomeric matrix protein (COMP), were available at baseline whilst contrast-enhanced (CE) MRI data were acquired in a subsample at baseline and annually. Knee symptoms were assessed using WOMAC at all visits. We examined the cross-sectional association between knee symptoms and three MRI-based and three serum markers of synovitis and matrix turnover, respectively. A total of 447 participants were included in the serum and 136 participants in the MRI analyses. MRI-defined medial perimeniscal synovitis was positively associated with knee pain and, suprapatellar and medial perimeniscal synovitis with knee function in multivariate analysis. We observed a statistically significant, negative association between a higher concentration of serum C3M and CRPM and knee pain, respectively. Furthermore, the highest CRPM quartile was negatively associated with knee function. Our findings suggest that, in established painful radiographic KOA, MRI-defined medial perimeniscal and suprapatellar synovitis were positively associated with knee symptoms. Serum-based C3M and CRPM markers were negatively associated with knee symptoms. Pain fluctuations are common in KOA and a better understanding of the relationship between markers of synovitis and matrix turnover and knee symptoms would facilitate a more accurate assessment of temporal changes in disease progression.

Association between changes in knee load and effusion-synovitis: evidence of mechano-inflammation in knee osteoarthritis using high tibial osteotomy as a model

OBJECTIVE

Although mechanically-induced inflammation is an appealing explanation linking different etiologic factors in osteoarthritis (OA), clinical research investigating changes in both biomechanics and joint inflammation is limited. The purpose of this study was to evaluate the association between change in surrogate measures of knee load and knee effusion-synovitis in patients with medial compartment knee OA undergoing high tibial osteotomy (HTO).

METHODS

Thirty-six patients with medial compartment knee OA and varus alignment underwent 3D gait analysis and 3T magnetic resonance imaging (MRI) preoperatively and 1 year after medial opening wedge HTO. Primary outcome measures were the change in the external knee adduction moment impulse during walking and change in knee suprapatellar effusion-synovitis volume manually segmented on MRI by one blinded assessor.

RESULTS

Mean (SD) knee adduction moment impulse [24.0 (6.5) Nm•s] and knee effusion-synovitis volume [8976.7 (8016.9) mm³] suggested substantial preoperative medial knee load and inflammation. 1-year postoperative changes in knee adduction moment impulse [-10.1 Nm•s (95%CI: -12.7, -7.4)], and knee effusion-synovitis volume [-1856 mm³ (95%CI: -3830, 117)] were positively correlated [r = 0.60 (95% CI 0.34, 0.78)]. Simple linear regression suggested a 448 mm³ (95%CI: 241, 656) reduction in knee effusion-synovitis volume per 1 Nm•s reduction in knee adduction moment impulse. Change in knee adduction moment impulse explained 36% (R² = 0.36) of the variance of change in knee effusion-synovitis volume.

CONCLUSIONS

Reduction in medial knee load is positively associated with reduction in knee inflammation after HTO, suggesting the phenomenon of mechano-inflammation in patients with knee OA.

Association of subchondral bone marrow lesion localization with weight-bearing pain in people with knee osteoarthritis: data from the Osteoarthritis Initiative

Background

Subchondral bone marrow lesions (BMLs) detected on MRI in knee osteoarthritis (OA) are associated with knee pain. The prevalence and progression of subchondral BMLs are increased by mechanical knee load. However, associations of subchondral BML location with weight-bearing knee pain are currently unknown. In this study, we aim to demonstrate associations of subchondral BML location and size with weight-bearing knee pain in knee OA.

Methods

We analyzed 1412 and 582 varus knees from cross-sectional and longitudinal Osteoarthritis Initiative datasets, respectively. BML scores were semi-quantitatively analyzed with the MRI Osteoarthritis Knee Score for 4 subchondral regions (median and lateral femorotibial, medial and lateral patellofemoral) and subspinous region. Weight-bearing and non-weight-bearing pain scores were derived from WOMAC pain items. Correlation and negative binomial regression models were used for analysis of associations between the BML scores and pain at baseline and changes in the BML scores and changes in pain after 24-month follow-up.

Results

Greater BML scores at medial femorotibial and lateral patellofemoral compartments were associated with greater weight-bearing pain scores, and statistical significance was retained after adjusting for BML scores at the other 4 joint compartments and other OA features, as well as for non-weight-bearing pain, age, sex, and body mass index (BMI) (medial femorotibial; B = 0.08, p = 0.02. patellofemoral; B = 0.13, p = 0.01). Subanalysis revealed that greater medial femorotibial BML scores were associated with greater pain on walking and standing (B = 0.11, p = 0.01, and B = 0.10, p = 0.04, respectively). Lateral patellofemoral BML scores were associated with pain on climbing, respectively (B = 0.14, p = 0.02). Increases or decreases over 24 months in BML score in the medial femorotibial compartment were significantly associated with increases or decreases in weight-bearing pain severity after adjusting for non-weight-bearing pain, age, sex, baseline weight-bearing pain, BMI, and BML at the other 4 joint compartments (B = 0.10, p = 0.01).

Conclusions

Subchondral BML size at the medial femorotibial joint compartment was specifically associated with the severity and the change in weight-bearing pain, independent of non-weight-bearing pain, in knee OA. Specific associations of weight-bearing pain with subchondral BMLs in weight-bearing compartments of the knee indicate that BMLs in subchondral bone contribute to biomechanically induced OA pain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02422-0.

Obese and overweight individuals have greater knee synovial inflammation and associated structural and cartilage compositional degeneration: data from the osteoarthritis initiative

OBJECTIVE

This work aims to study (i) the relationship between body mass index (BMI) and knee synovial inflammation using non-contrast-enhanced MRI and (ii) the association of synovial inflammation versus degenerative abnormalities and pain.

MATERIALS AND METHODS

Subjects with risk for and mild to moderate radiographic osteoarthritis were selected from the Osteoarthritis Initiative. Subjects were grouped into three BMI categories with 87 subjects per group: normal weight (BMI, 20-24.9 kg/m²), overweight (BMI, 25-29.9 kg/m²), and obese (BMI, ≥ 30 kg/m²), frequency matched for age, sex, race, Kellgren-Lawrence grade, and history of knee surgery and injury. Semi-quantitative synovial inflammation imaging biomarkers were obtained including effusion-synovitis, size and intensity of infrapatellar fat pad signal abnormality, and synovial proliferation score. Cartilage composition was measured using T₂ relaxation time and structural abnormalities using the whole-organ magnetic resonance imaging score (WORMS). The Western Ontario and McMasters (WOMAC) Osteoarthritis Index was used for pain assessment. Intra- and inter-reader reproducibility was assessed by kappa values.

RESULTS

Overweight and obese groups had higher prevalence and severity of all synovial inflammatory markers (p ≤ 0.03). Positive associations were found between synovial inflammation imaging biomarkers and average T₂ values, WORMS maximum scores and total WOMAC pain scores (p < 0.05). Intra- and inter-reader kappa values for imaging biomarkers were high (0.76-1.00 and 0.60-0.94, respectively).

CONCLUSION

Being overweight or obese was significantly associated with a greater prevalence and severity of synovial inflammation imaging biomarkers. Substantial reproducibility and high correlation with knee structural, cartilage compositional degeneration, and WOMAC pain scores validate the synovial inflammation biomarkers used in this study.

Efficacy and predictive factors of response to intra-articular corticosteroids in knee osteoarthritis

In knee osteoarthritis (KOA), synovial inflammation is linked with pain, swelling and structural abnormalities. Intra-articular corticosteroids (IACS) have been considered for pain relief in subjects who are non-responders to standard therapy. However, the results vary across different studies. This review aims to determine efficacy of IACS in KOA by review of the existing data.

In several randomized controlled trials (RCTs), meta-analyses and uncontrolled studies a single IACS resulted in pain relief from 1 to a few weeks. In a few studies repeated IACS every three months provided a longer duration of pain relief and functional improvement in a proportion of patients. Baseline synovitis was predictor of treatment response in some but not all studies.

Based upon the existing data, IACS provides a short-term pain relief in a proportion of patients. Given, anti-inflammatory properties of IACS, it is likely to be more effective in subgroups of KOA who display inflammatory phenotype.

Effectiveness of Curcuma longa Extract for the Treatment of Symptoms and Effusion-Synovitis of Knee Osteoarthritis : A Randomized Trial

BACKGROUND

Current pharmacologic therapies for patients with osteoarthritis are suboptimal.

OBJECTIVE

To determine the efficacy of Curcuma longa extract (CL) for reducing knee symptoms and effusion-synovitis in patients with symptomatic knee osteoarthritis and knee effusion-synovitis.

DESIGN

Randomized, double-blind, placebo-controlled trial. (Australian New Zealand Clinical Trials Registry: ACTRN12618000080224).

SETTING

Single-center study with patients from southern Tasmania, Australia.

PARTICIPANTS

70 participants with symptomatic knee osteoarthritis and ultrasonography-defined effusion-synovitis.

INTERVENTION

2 capsules of CL (n = 36) or matched placebo (n = 34) per day for 12 weeks.

MEASUREMENTS

The 2 primary outcomes were changes in knee pain on a visual analogue scale (VAS) and effusion-synovitis volume on magnetic resonance imaging (MRI). The key secondary outcomes were change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and cartilage composition values. Outcomes were assessed over 12 weeks.

RESULTS

CL improved VAS pain compared with placebo by -9.1 mm (95% CI, -17.8 to -0.4 mm [P = 0.039]) but did not change effusion-synovitis volume (3.2 mL [CI, -0.3 to 6.8 mL]). CL also improved WOMAC knee pain (-47.2 mm [CI, -81.2 to -13.2 mm]; P = 0.006) but not lateral femoral cartilage T2 relaxation time (-0.4 ms [CI, -1.1 to 0.3 ms]). The incidence of adverse events was similar in the CL (n = 14 [39%]) and placebo (n = 18 [53%]) groups (P = 0.16); 2 events in the CL group and 5 in the placebo group may have been treatment related.

LIMITATION

Modest sample size and short duration.

CONCLUSION

CL was more effective than placebo for knee pain but did not affect knee effusion-synovitis or cartilage composition. Multicenter trials with larger sample sizes are needed to assess the clinical significance of these findings.

PRIMARY FUNDING SOURCE

University of Tasmania and Natural Remedies Private Limited.

Efficacy and Safety of Ultrasound-Guided Radiofrequency Treatment for Chronic Pain in Patients with Knee Osteoarthritis: A Systematic Review and Meta-Analysis

Background

Knee osteoarthritis (KOA) is a common degenerative disease associated with joint dysfunction and pain. Ultrasound-guided radiofrequency (RF) may be a promising therapy in the treatment of chronic pain for KOA patients.

Objective

To evaluate the efficacy and safety of ultrasound-guided RF treatment for chronic pain in patients with KOA.

Design

A systematic review was conducted, and a meta-analysis was carried out when possible. Setting. We examined the studies evaluating the clinical efficiency of ultrasound-guided RF on chronic pain in KOA population.

Method

A systematic review for the efficacy and safety of ultrasound-guided RF treatment for pain management of KOA patients was carried out in PubMed, EMBASE, Cochrane Library, Web of Science, Wanfang Data, and China National Knowledge Infrastructure (CNKI) from the date of inception to February 2020, and a meta-analysis was conducted. The primary outcomes of pain intensity (visual analogue scale or numerical rating scale) and knee function [the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)] were evaluated from baseline to various follow-up times by random-effects model. Heterogeneity was assessed by I ² statistic and the potential sources of heterogeneity by subgroup and metaregression analyses, respectively.

Results

Eight publications with 256 patients were included in the meta-analysis. RF could relieve pain with -4.196 of pooled mean difference and improve knee function by decreasing 23.155 points in WOMAC. Three patients had ecchymosis, two with hypoesthesia and one with numbness after the procedure, and improved within 6 months. Furthermore, study design and treatment target were the sources of heterogeneity by subgroup and metaregression analyses, accounting for 37% and 74% of variances, respectively. Target of genicular nerve achieved better pain relief than intra-articular or sciatic nerve. Sensitivity analysis showed that removal of any single study was unlikely to overturn the findings. Limitations. There were some limitations in the study. Firstly, the small number of relevant studies limited the confidence level of the meta-analysis. Also, the significant heterogeneity may not be explained due to the limited data. Secondly, the direct comparison of two different guidance methods (ultrasound vs. fluoroscopy) for RF therapy is lacking. In addition, the outcomes were blindly assessed in the meta-analysis from all studies according to evaluation of bias, which could affect the reality of the data. Finally, most of the studies only provided short follow-up times, so we could not analyze the long-term effectiveness of ultrasound-guided RF in the treatment of patients with KOA.

Conclusions

Ultrasonography is an effective, safe, nonradiative, and easily applicable guidance method for RF in pain relief and functional improvement in KOA patients.

Comparison of radiographic and MRI osteoarthritis definitions and their combination for prediction of tibial cartilage loss, knee symptoms and total knee replacement: a longitudinal study

OBJECTIVE

To describe the value of radiographic- and magnetic resonance imaging (MRI)-defined tibiofemoral osteoarthritis (ROA and MRI-OA, respectively) and in combination for predicting tibial cartilage loss, knee pain and disability and total knee replacement (TKR) in a population-based cohort.

DESIGN

A radiograph and 1.5T MRI of the right knee was performed. ROA and MRI-OA at baseline were defined according to the Osteoarthritis Research Society International atlas and a published Delphi exercise, respectively. Tibial cartilage volume was measured over 2.6 and 10.7 years. Knee pain and disability were assessed at baseline, 2.6, 5.1 and 10.7 years. Right-sided TKRs were assessed over 13.5 years.

RESULTS

Of 574 participants (mean 62 years, 49% female), 8% had ROA alone, 15% had MRI-OA alone, 13% had both ROA and MRI-OA. Having ROA (vs. no ROA) and MRI-OA (vs. no MRI-OA) predicted greater tibial cartilage loss over 2.6 years (-75.9 and -86.4 mm³/year) and higher risk of TKR over 13.5 years (Risk Ratio [RR]: 15.0 and 10.9). Only MRI-OA predicted tibial cartilage loss over 10.7 years (-7.1 mm³/year) and only ROA predicted onset and progression of knee symptoms (RR: 1.32-1.88). In participants with both MRI-OA and ROA, tibial cartilage loss was the greatest (over 2.6 years: -116.1 mm³/year; over 10.7 years: -11.2 mm³/year), and the onset and progression of knee symptoms (RR: 1.75-2.89) and risk of TKR (RR: 50.9) were the highest.

CONCLUSIONS

The Delphi definition of MRI-OA is not superior to ROA for predicting structural or symptomatic OA progression but, combining MRI-OA and ROA has much stronger predictive validity.

The bulge sign - a simple physical examination for identifying progressive knee osteoarthritis: data from the Osteoarthritis Initiative

OBJECTIVE

To examine whether the presence of bulge sign or patellar tap was associated with frequent knee pain, progression of radiographic OA (ROA) and total knee replacement (TKR).

METHODS

This study included 4344 Osteoarthritis Initiative participants examined at baseline for bulge sign and/or patellar tap. The clinical signs were categorized as no (none at baseline and 2 years), resolved (present at baseline only), developed (present at 2 years only) and persistent (present at both time points). Frequent knee pain and progression of ROA over 4 years and TKR over 6 years were assessed. Binary logistic regression was used to examine the associations.

RESULTS

A total of 12.7% of participants had bulge sign only, 2.0% had patellar tap only and 3.3% had both. A positive baseline bulge sign was associated with an increased risk of frequent knee pain [OR 1.31 (95% CI 1.04, 1.64), P = 0.02] and TKR [OR 1.47 (95% CI 1.06, 2.05), P = 0.02]. Developed bulge sign was associated with an increased risk of frequent knee pain [OR 1.75 (95% CI 1.34, 2.29), P < 0.001] and progressive ROA [OR 1.67 (95% CI 1.11, 2.51), P = 0.01]. Persistent bulge sign was associated with an increased risk of frequent knee pain [OR 1.60 (95% CI 1.09, 2.35), P = 0.02], progressive ROA [OR 1.84 (95% CI 1.01, 3.33), P = 0.045] and TKR [OR 2.13 (95% CI 1.23, 3.68), P = 0.007]. Patellar tap was not examined for its association with joint outcomes due to its low prevalence.

CONCLUSION

The presence of bulge sign identifies individuals at increased risk of frequent knee pain, progression of ROA and TKR. This provides clinicians with a quick, simple, inexpensive method for identifying those at higher risk of progressive knee OA who should be targeted for therapy.

Risk factors and the natural history of accelerated knee osteoarthritis: a narrative review

BACKGROUND

Osteoarthritis is generally a slowly progressive disorder. However, at least 1 in 7 people with incident knee osteoarthritis develop an abrupt progression to advanced-stage radiographic disease, many within 12 months. We summarize what is known - primarily based on findings from the Osteoarthritis Initiative - about the risk factors and natural history of accelerated knee osteoarthritis (AKOA) - defined as a transition from no radiographic knee osteoarthritis to advanced-stage disease < 4 years - and put these findings in context with typical osteoarthritis (slowly progressing disease), aging, prior case reports/series, and relevant animal models. Risk factors in the 2 to 4 years before radiographic manifestation of AKOA (onset) include older age, higher body mass index, altered joint alignment, contralateral osteoarthritis, greater pre-radiographic disease burden (structural, symptoms, and function), or low fasting glucose. One to 2 years before AKOA onset people often exhibit rapid articular cartilage loss, larger bone marrow lesions and effusion-synovitis, more meniscal pathology, slower chair-stand or walking pace, and increased global impact of arthritis than adults with typical knee osteoarthritis. Increased joint symptoms predispose a person to new joint trauma, which for someone who develops AKOA is often characterized by a destabilizing meniscal tear (e.g., radial or root tear). One in 7 people with AKOA onset subsequently receive a knee replacement during a 9-year period. The median time from any increase in radiographic severity to knee replacement is only 2.3 years. Despite some similarities, AKOA is different than other rapidly progressive arthropathies and collapsing these phenomena together or extracting results from one type of osteoarthritis to another should be avoided until further research comparing these types of osteoarthritis is conducted. Animal models that induce meniscal damage in the presence of other risk factors or create an incongruent distribution of loading on joints create an accelerated form of osteoarthritis compared to other models and may offer insights into AKOA.

CONCLUSION

Accelerated knee osteoarthritis is unique from typical knee osteoarthritis. The incidence of AKOA in the Osteoarthritis Initiative and Chingford Study is substantial. AKOA needs to be taken into account and studied in epidemiologic studies and clinical trials.

KARAOKE: Krill oil versus placebo in the treatment of knee osteoarthritis: protocol for a randomised controlled trial

BACKGROUND

Knee osteoarthritis (OA) is a common and important cause of pain and disability, but interventions aimed at modifying structures visible on imaging have been disappointing. While OA affects the whole joint, synovitis and effusion have been recognised as having a role in the pathogenesis of OA. Krill oil reduces knee pain and systemic inflammation and could be used for targeting inflammatory mechanisms of OA.

METHODS/DESIGN

We will recruit 260 patients with clinical knee OA, significant knee pain and effusion-synovitis present on MRI in five Australian cities (Hobart, Melbourne, Sydney, Adelaide and Perth). These patients will be randomly allocated to the two arms of the study, receiving 2 g/day krill oil or inert placebo daily for 6 months. MRI of the study knee will be performed at screening and after 6 months. Knee symptoms, function and MRI structural abnormalities will be assessed using validated methods. Safety data will be recorded. Primary outcomes are absolute change in knee pain (assessed by visual analog score) and change in size of knee effusion-synovitis over 24 weeks. Secondary outcomes include improvement in knee pain over 4, 8, 12, 16 and 20 weeks. The primary analyses will be intention-to-treat analyses of primary and secondary outcomes. Per protocol analyses adjusting for missing data and for treatment compliance will be performed as the secondary analyses.

DISCUSSION

This study will provide high-quality evidence to assess whether krill oil 2 g/day reduces pain and effusion-synovitis size in older adults with clinical knee OA and knee effusion-synovitis. If krill oil is effective and confirmed to be safe, we will provide compelling evidence that krill oil improves pain and function, changes disease trajectory and slows disease progression in OA. Given the lack of approved therapies for slowing disease progression in OA, and moderate cost of krill oil, these findings will be readily translated into clinical practice.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, ACTRN12616000726459. Registered on 02 June 2016. Universal Trial Number (UTN) U1111-1181-7087.

Knee effusion volume assessed by magnetic resonance imaging and progression of knee osteoarthritis: data from the Osteoarthritis Initiative

Objective

To examine whether baseline knee joint effusion volume and the change in effusion volume over 1 year are associated with cartilage volume loss, progression of radiographic OA (ROA) over 4 years and risk of total knee replacement over 6 years.

Methods

This study included 4115 Osteoarthritis Initiative participants with knee joint effusion volume quantified by MRI at baseline. The change in effusion volume over 1 year was assessed. Cartilage volume loss and progression of ROA over 4 years were assessed using MRI and X-ray and total knee replacement over 6 years was assessed. Multiple linear regression and binary logistic regression were used for data analyses.

Results

Baseline knee effusion volume (per 5 ml) was positively associated with a loss of medial and lateral cartilage volume [regression coefficient 0.13%/year (95% CI 0.10, 0.17) and 0.13%/year (95% CI 0.10, 0.16), respectively, both P < 0.001], progression of ROA [odds ratio (OR) 1.28 (95% CI 1.20, 1.37), P < 0.001], and risk of knee replacement [OR 1.12 (95% CI 1.05, 1.20), P = 0.001]. A 5 ml increase in knee effusion volume over 1 year was positively associated with medial cartilage volume loss [regression coefficient 0.09%/year (95% CI 0.04, 0.15), P = 0.001], progression of ROA [OR 1.21 (95% CI 1.11, 1.33), P < 0.001] and risk of knee replacement [OR 1.24 (95% CI 1.12, 1.37), P < 0.001].

Conclusions

Knee joint effusion volume assessed from MRI provides a continuous and sensitive measure that was associated with cartilage volume loss, progression of ROA and risk of total knee replacement. It may provide a method to identify individuals with an inflammatory OA phenotype who are at higher risk of disease progression.

Degenerative Meniscal Tears and High Tibial Osteotomy: Do Current Treatment Algorithms Need to Be Realigned?

Degenerative medial meniscal tears (DMMTs) are a common feature of early knee osteoarthritis (OA). Varus alignment is a strong risk factor for medial compartment knee OA and its progression. We propose that high tibial osteotomy (HTO) should be considered much earlier in the treatment algorithm for patients presenting with recurring medial knee pain, varus alignment, and DMMT, absent of radiographic OA. We provide rationale for investigating HTO as a disease-modifying intervention for secondary prevention in knee OA, and present case examples as low-level proof of principle. Finally, caveats and challenges are discussed along with proposed future research.

Accelerated Knee Osteoarthritis Is Characterized by Destabilizing Meniscal Tears and Preradiographic Structural Disease Burden

OBJECTIVE

To determine whether accelerated knee osteoarthritis (KOA) is preceded by, and characterized over time by, destabilizing meniscal tears or other pathologic changes.

METHODS

We selected 3 sex-matched groups of subjects from the first 48 months of the Osteoarthritis Initiative, comprising adults who had a knee without KOA (Kellgren/Lawrence [K/L] radiographic grade <2) at baseline. Subjects in the accelerated KOA group developed KOA of K/L grade ≥3, those with typical KOA showed increased K/L radiographic scores, and those with no KOA had the same K/L grade over time. An index visit was the visit when the radiographic criteria for accelerated KOA and typical KOA were met (the no KOA group was matched to the accelerated KOA group). The observation period was up to 2 years before and after an index visit. Radiologists reviewed magnetic resonance (MR) images of the index knee and identified destabilizing meniscal tears (root tears, radial tears, complex tears), miscellaneous pathologic features (acute ligamentous or tendinous injuries, attrition, subchondral insufficiency fractures, other incidental findings), and meniscal damage in >2 of 6 regions (3 regions per meniscus: anterior horn, body, posterior horn). In addition, bone marrow lesions (BMLs) and cartilage damage on MR images were quantified. Linear mixed regression models were performed to analyze the results.

RESULTS

At 1 year before the index visit, >75% of adults with accelerated KOA had meniscal damage in ≥2 regions (odds ratio 3.19 [95% confidence interval 1.70-5.97] versus adults with typical KOA). By the index visit, meniscal damage in ≥2 regions was ubiquitous in adults with accelerated KOA, including 42% of subjects having evidence of a destabilizing meniscal tear (versus 14% of subjects with typical KOA). These changes corresponded to findings of larger BMLs and greater cartilage loss in the accelerated KOA group.

CONCLUSION

Accelerated KOA is characterized by destabilizing meniscal tears in a knee compromised by meniscal damage in >2 regions, and also characterized by the presence of large BMLs and greater cartilage loss.

Patellar tendon enthesis abnormalities and their association with knee pain and structural abnormalities in older adults

OBJECTIVE

To describe associations between presence of patellar tendon enthesis (PTE) abnormalities and symptoms, structural abnormalities, and total knee replacement (TKR) in older adult cohort.

METHODS

PTE abnormalities (presence of abnormal bone signal and/or bone erosion), were measured on T2-weighted magnetic resonance (MR) images at baseline in 961 community-dwelling older adults. Knee pain and function limitation were assessed using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Bone marrow lesions (BMLs), cartilage volume and defects score, and infrapatellar fat pad (IPFP) area were measured using validated methods. Incidence of TKR was determined by data linkage.

RESULTS

Participants with abnormal PTE bone signal and/or erosion was 20%. Cross-sectionally, presence of PTE abnormalities was associated with greater pain intensity while going up and down stairs (β = 0.22 (95% confidence interval (CI); 0.03, 0.41)), greater risk of femoral BMLs (RR = 1.46 (1.12, 1.90)) and worse tibial cartilage defects score (RR = 1.70 (1.16, 2.47), and smaller IPFP area (β = -0.27 (-0.47, -0.06) cm²), after adjustment of confounders. Longitudinally, presence of baseline PTE abnormalities was associated with a deleterious increase in tibial BML size (RR = 1.52 (1.12, 2.05)) over 10.7 years but not symptoms, other structural changes, or TKR.

CONCLUSION

PTE abnormalities are common in older adults. Presence of cross-sectional but not longitudinal associations suggests they are commonly co-exist with other knee structural abnormalities but may not play a major role in symptom development or structural change, excepting tibial BMLs.

The Diagnosis and Therapy of Degenerative Knee Joint Disease: Expert Consensus from the Chinese Pain Medicine Panel

At present, there are many constantly updated guidelines and consensuses on the diagnosis and treatment of osteoarthritis both at home and abroad. The recommendations established using methods of evidence-based medicine has experienced strict research on controlling bias and promoting reproduction rate. As a result, the previous evidence was reevaluated, and a lot of changes were provoked in the diagnosis and treatment concept of osteoarthritis. However, several methods not recommended by foreign guidelines are still in use in the current clinical practice in China. On the one hand, Chinese experts have not reached extensive consensus on whether it is necessary to make changes according to foreign guidelines. On the other hand, almost all the current relevant guidelines are on osteoarthritis, but the lesions around knee joints which, as a whole, bear the largest weight in human body, cannot be ignored. For this purpose, Chinese Association for the Study of Pain (CASP) organized some leading experts to formulate this Chinese Pain Specialist Consensus on the diagnosis and treatment of degenerative knee osteoarthritis (DKOA) in combination with the guidelines in foreign countries and the expert experience of clinical practice in China. The consensus, which includes the definition, pathophysiology, epidemiology, clinical manifestation, diagnostic criteria, and treatments of DKOA, is intended to be used by first-line doctors, including pain physicians to manage patients with DKOA.

The importance of synovial inflammation in osteoarthritis: current evidence from imaging assessments and clinical trials

Synovial abnormalities have been observed at multiple stages of osteoarthritis (OA). Increasing evidence suggests that it may play an important role in the OA pathological process. Many assessment systems using magnetic resonance imaging (MRI) and ultrasound have been established to detect synovial inflammation in OA. These have been used to inform the current investigation of OA disease phenotypes and progression and can be utilised in the future for clinical trials developing potential treatments. This narrative review aims to illustrate the importance of synovial tissue in OA and provide an overview of imaging assessments and possible therapies targeting synovial abnormalities.

Associations between MRI-detected early osteophytes and knee structure in older adults: a population-based cohort study

OBJECTIVES

To describe prevalence of osteophytes (OPs) detected only by magnetic resonance imaging (MRI) but not by standard X-ray in older adults and to evaluate longitudinal associations with knee structural changes.

METHODS

837 participants were randomly selected from the local community and had MRI scans to assess knee OPs and other structures. OPs detected only by MRI but not by standard X-ray were defined as MRI-detected early OPs (MRI-OPs for short). OPs detected by both MRI and X-ray were defined as established-OPs.

RESULTS

The prevalence of MRI-OPs was 50% while the prevalence of established-OPs was 10% and no-OPs was 40% at total tibiofemoral (TF) compartment at baseline. Compared with no-OPs, participants with MRI-OPs had greater risks of increased cartilage defects in all TF compartments (RR 1.37, 95%CI 1.07-1.74) and bone marrow lesions (BMLs) only in medial TF compartment (RR 1.49, 95%CI 1.06-2.11), after adjustment for age, sex, BMI, cartilage defects, BMLs and/or joint space narrowing; participants with established-OPs had greater cartilage volume loss at total (β -2.02, 95%CI -3.86, -0.17) and lateral tibial sites (β -5.63, 95%CI -9.93, -1.32), greater risks of increased cartilage defects in total (RR 1.66, 95%CI 1.15-2.40) and medial TF compartments (RR 1.49, 95%CI 1.20-1.69) and BMLs in all TF compartments (RR 1.88, 95%CI 1.22-2.89), after adjustment for covariates.

CONCLUSION

MRI-OPs were associated with changes in knee structures, and the associations were similar but not as prominent as those for established-OPs. These suggest MRI-OPs may have a role to play in knee early-stage osteoarthritic progression.

Is synovitis detected on non-contrast-enhanced magnetic resonance imaging associated with serum biomarkers and clinical signs of effusion? Data from the Osteoarthritis Initiative

OBJECTIVES

To determine the relationship between synovitis detected on non-contrast-enhanced (non-CE) magnetic resonance imaging (MRI), biochemical markers of inflammation, and clinical assessment of effusion in people with knee osteoarthritis (OA).

METHOD

We examined data from the OA Biomarkers Consortium within the Osteoarthritis Initiative (n = 600). Non-CE MRIs were semi-quantitatively scored (grades 0-3) for severity of Hoffa synovitis and effusion synovitis. Serum (s) matrix metalloproteinase-3 (sMMP-3), hyaluronic acid (sHA), and nitrated epitope of the α-helical region of type II collagen (sColl2-1NO2) were quantified. The bulge and patellar tap clinical tests were performed at baseline and performance characteristics were assessed for the detection of effusion synovitis on MRI. Multinomial logistic regression adjusted for covariates was used to assess the association between biochemical and imaging markers at baseline and over 12 and 24 months.

RESULTS

At baseline, sHA and sMMP-3 were associated with moderate to large (score ≥ 2, n = 117) effusion synovitis, with odds ratio = 1.35 and 1.30 per 1 standard deviation in biochemical markers (95% confidence intervals 1.07, 1.71 and 1.00, 1.69), c-statistics 0.640 and 0.626, respectively. The c-statistics for the presence of Hoffa synovitis (score ≥ 2) were 0.693, 0.694, and 0.694 for sHA, sMMP-3, and sColl2-1NO2, respectively. There was no significant association between biochemical markers (baseline and 12 and 24 month time-integrated concentrations) and changes in MRI markers. The bulge and patellar tap signs were 22.0% and 4.3% sensitive and 88.8% and 94.8% specific, respectively, for detecting effusion synovitis (score ≥ 1) on MRI.

CONCLUSIONS

sHA and sMMP-3 were modestly associated with effusion synovitis at baseline. Clinical signs of effusion are insensitive but highly specific for the presence of any effusion synovitis on non-CE MRI.

Associations Between Knee Effusion-synovitis and Joint Structural Changes in Patients with Knee Osteoarthritis

Objective.

To describe the associations between effusion-synovitis and joint structural abnormalities in patients with knee osteoarthritis (OA) over 24 months.

Methods.

A posthoc analysis using data from a randomized controlled trial in 413 patients with symptomatic OA (aged 63 ± 7 yrs, 208 women). Knee effusion-synovitis volume and score, cartilage defects, cartilage volume, and bone marrow lesions (BML) were assessed using magnetic resonance imaging. Joint space narrowing (JSN) and osteophytes were assessed using radiograph. Least significant change criterion was used to define change in effusion-synovitis volume. Knee symptoms were assessed by Western Ontario and McMaster University OA Index. Multivariable linear/logistic regression and multilevel generalized mixed-effects models were used in longitudinal analyses.

Results.

Total effusion-synovitis volume increased modestly from baseline (8.0 ± 8.5 ml) to followup (9.0 ± 10.5 ml). Baseline BML, cartilage defect, JSN, and osteophyte scores were positively associated with change in effusion-synovitis volume (p < 0.05). Baseline cartilage defects and JSN were also associated with change in effusion-synovitis score (p < 0.05). However, neither baseline effusion-synovitis score nor volume consistently predicted change in the above structures except cartilage volume. In the mixed-effects models, knee effusion-synovitis was positively associated with BML (volume: β = 1.19 ml/grade; score: OR = 1.75/grade) and cartilage defects (volume: β = 1.87 ml/grade; score: OR = 2.22/grade), while negatively associated with cartilage volume loss. Change in effusion-synovitis volume was positively correlated with changes in knee pain and stiffness scores (p < 0.05).

Conclusion.

Knee cartilage and subchondral bone abnormalities predicted change in effusion-synovitis, but effusion-synovitis did not predict knee structural changes. These findings suggest that synovial inflammation is likely the result of joint structural abnormalities in established OA. ClinicalTrials.gov identifier: NCT01176344. Australian New Zealand Clinical Trials Registry: ACTRN12610000495022.

Reduced Osteoarthritis Severity in Aged Mice With Deletion of Macrophage Migration Inhibitory Factor

OBJECTIVE

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that is elevated in the serum and synovial fluid of patients with osteoarthritis (OA). This study was undertaken to investigate the potential role of MIF in OA in human joint tissues and in vivo in mice with age-related and surgically induced OA.

METHODS

MIF in conditioned media from human chondrocytes and meniscal cells and from cartilage explants was measured by enzyme-linked immunosorbent assay. The severity of OA was analyzed histologically in male wild-type and MIF^-/- mice at 12 and 22 months of age and following destabilization of the medial meniscus (DMM) surgery in 12-week-old MIF^-/- mice as well as in wild-type mice treated with a neutralizing MIF antibody. Synovial hyperplasia was graded in S100A8-immunostained histologic sections. Bone morphometric parameters were measured by micro-computed tomography.

RESULTS

Human OA chondrocytes secreted 3-fold higher levels of MIF than normal chondrocytes, while normal and OA meniscal cells produced equivalent amounts. Compared to age- and strain-matched controls, the cartilage, bone, and synovium in older adult mice with MIF deletion were protected against changes of naturally occurring age-related OA. No protection against DMM-induced OA was seen in young adult MIF^-/- mice or in wild-type mice treated with anti-MIF. Increased bone density in 8-week-old mice with MIF deletion was not maintained at 12 months.

CONCLUSION

These results demonstrate a differential mechanism in the pathogenesis of naturally occurring age-related OA compared to injury-induced OA. The inhibition of MIF may represent a novel therapeutic target in the reduction of the severity of age-related OA.

Synovitis in osteoarthritis: current understanding with therapeutic implications

Modern concepts of osteoarthritis (OA) have been forever changed by modern imaging phenotypes demonstrating complex and multi-tissue pathologies involving cartilage, subchondral bone and (increasingly recognized) inflammation of the synovium. The synovium may show significant changes, even before visible cartilage degeneration has occurred, with infiltration of mononuclear cells, thickening of the synovial lining layer and production of inflammatory cytokines. The combination of sensitive imaging modalities and tissue examination has confirmed a high prevalence of synovial inflammation in all stages of OA, with a number of studies demonstrating that synovitis is related to pain, poor function and may even be an independent driver of radiographic OA onset and structural progression. Treating key aspects of synovial inflammation therefore holds great promise for analgesia and also for structure modification. This article will review current knowledge on the prevalence of synovitis in OA and its role in symptoms and structural progression, and explore lessons learnt from targeting synovitis therapeutically.

Osteoarthritis year in review 2016: imaging

PURPOSE

The current narrative review covers original research related to imaging in osteoarthritis (OA) in humans published in English between April 1st 2015 and March 31st 2016, in peer reviewed journals available in Medline via PubMed (http://www.ncbi.nlm.nih.gov/pubmed/).

METHODS

Relevant studies in humans, subjectively decided by the authors, contributing significantly to the OA imaging field, were selected from an extensive Medline search using the terms "Osteoarthritis" in combination with "MRI", "Imaging", "Radiography", "X-rays", "Ultrasound", "Computed tomography", "Nuclear medicine", "PET-CT", "PET-MRI", "Scintigraphy", "SPECT". Publications were sorted according to relevance for the OA imaging research community with an emphasis on high impact special interest journals using the software for systematic reviews www.covidence.org.

RESULTS

An overview of newly published studies compared to studies reported previous years is presented, followed by a review of selected imaging studies of primarily knee, hip and hand OA focussing on (1) results for detection of OA and OA-related pathology (2) studies dealing with treatments and (3) studies focussing on prognosis of disease progression or joint replacement. A record high number of 1420 articles were published, among others, of new technologies and tools for improved morphological and pathophysiological understanding of OA-related changes in joints. Also, imaging data were presented of monitoring treatment effect and prognosis of OA progression, primarily using established radiographic, magnetic resonance imaging (MRI), and ultrasound (US) methods.

CONCLUSION

Imaging continues to play an important role in OA research, where several exciting new technologies and computer aided analysis methods are emerging to complement the conventional imaging approaches.