Association of obesity and systemic factors with bone marrow lesions at the knee: a systematic review

Bone marrow lesions in osteoarthritis: biomarker or treatment target? A narrative review

Osteoarthritis (OA) is a leading cause of pain, functional impairment, and disability in older adults. However, there are no effective treatments to delay and reverse OA. Magnetic resonance imaging (MRI) can assess structural abnormalities of OA by directly visualizing damage and inflammatory reactions within the tissues and detecting abnormal signals in the subchondral bone marrow region. While some studies have shown that bone marrow lesions (BMLs) are one of the early signs of the development of OA and predict structural and symptomatic progression of OA, others claimed that BMLs are prevalent in the general population and have no role in the progression of OA. In this narrative review, we screened and summarized studies with different designs that evaluated the association of BMLs with joint symptoms and structural abnormalities of OA. We also discussed whether BMLs may serve as an imaging biomarker and a treatment target for OA based on existing clinical trials.

Bone marrow lesions: plugging the holes in our knowledge using animal models

Bone marrow lesions (BMLs), which are early signs of osteoarthritis (OA) that are associated with the presence, onset and severity of pain, represent an emerging imaging biomarker and clinical target. Little is known, however, regarding their early spatial and temporal development, structural relationships or aetiopathogenesis, because of the sparsity of human early OA imaging and paucity of relevant tissue samples. The use of animal models is a logical approach to fill the gaps in our knowledge, and it can be informed by appraising models in which BMLs and closely related subchondral cysts have already been reported, including in spontaneous OA and pain models. The utility of these models in OA research, their relevance to clinical BMLs and practical considerations for their optimal deployment can also inform medical and veterinary clinicians and researchers alike.

Bone marrow lesions in osteoarthritis: From basic science to clinical implications

Osteoarthritis (OA) is the most prevalent musculoskeletal disease characterized by multiple joint structure damages, including articular cartilage, subchondral bone and synovium, resulting in disability and economic burden. Bone marrow lesions (BMLs) are common and important magnetic resonance imaging (MRI) features in OA patients. Basic and clinical research on subchondral BMLs in the pathogenesis of OA has been a hotspot. New evidence shows that subchondral bone degeneration, including BML and angiogenesis, occurs not only at or after cartilage degeneration, but even earlier than cartilage degeneration. Although BMLs are recognized as important biomarkers for OA, their exact roles in the pathogenesis of OA are still unclear, and disputes about the clinical impact and treatment of BMLs remain. This review summarizes the current basic and clinical research progress of BMLs. We particularly focus on molecular pathways, cellular abnormalities and microenvironmental changes of subchondral bone that contributed to the formation of BMLs, and emphasize the crosstalk between subchondral bone and cartilage in OA development. Finally, potential therapeutic strategies targeting BMLs in OA are discussed, which provides novel strategies for OA treatment.

Osteoarthritis Bone Marrow Lesions

Assessment and treatment of Bone Marrow Lesions (BMLs) could ultimately make step changes to the lives of people with osteoarthritis (OA). We here review the imaging and pathological characteristics of OA-BMLs, their differential diagnosis and measurement, and cross-sectional and longitudinal associations with pain and OA structural progression. We discuss how biomechanical and cellular factors may contribute to BML pathogenesis, and how pharmacological and non-pharmacological interventions that target BMLs might reduce pain and OA structural progression. We critically appraise semiquantitative and quantitative methods for assessing BMLs, and their potential utilities for identifying people at risk of symptomatic and structural OA progression, and evaluating treatment responses. New interventions that target OA-BMLs should both confirm their importance, and reduce the unacceptable burden of OA.

Causal Relationships of General and Abdominal Adiposity on Osteoarthritis: A Two-Sample Mendelian Randomization Study

Background: Adiposity is closely related to osteoarthritis, but the causal effects of different types of adiposity on osteoarthritis are indistinct. This study conducted a Mendelian Randomization (MR) analysis for the causal effects of general adiposity and abdominal adiposity on knee osteoarthritis (KOA) and hip osteoarthritis (HOA). Methods: The general adiposity was assessed by body mass index (BMI), while the abdominal adiposity was evaluated with waist circumference (WC), hip circumference (HC), and waist-to-hip ratio (WHR). The data used in this two-sample MR analysis originated from genome-wide association studies (GWAS). Significant (p < 5 × 10−8) and independent (r2 < 0.01) single-nucleotide polymorphisms were selected as instrumental variables for the MR analysis. Subsequently, this study used the inverse variance weighted, weighted median, and other methods for the causal inference, and the results were presented as odds ratios (OR). Moreover, sensitivity analyses were conducted to assess the stability and reliability of the results. Results: The MR results revealed positive causal effects of BMI on KOA (OR: 1.694; 95% CI: from 1.492 to 1.923; p = 3.96 × 10−16) and HOA (OR: 1.412; 95% CI: from 1.196 to 1.666; p = 4.58 × 10−5). Additionally, WC and HC both positively and causally related to KOA (WC: OR: 1.827; 95% CI: from 1.564 to 2.134; p = 2.68 × 10−14; HC: OR: 1.610; 95% CI: from 1.357 to 1.912; p = 5.03 × 10−8) and HOA (WC: OR: 1.491; 95% CI: from 1.254 to 1.772; p = 5.85 × 10−6; HC: OR: 1.439; 95% CI: from 1.205 to 1.719; p = 5.82 × 10−5). However, no causal relationship existed between WHR and obesity. These results were robust according to the sensitivity analyses. Conclusions: This study indicated that both general and abdominal obesity had positive causal effects on knee osteoarthritis and hip osteoarthritis.

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.

Basivertebral Nerve Ablation for the Treatment of Vertebrogenic Pain

Chronic low back pain affects a significant portion of patients worldwide and is a major contributor to patient disability; however, it is a difficult problem to diagnose and treat. The prevailing model of chronic low back pain has presumed to follow a discogenic model, but recent studies have shown a vertebrogenic model that involves the basivertebral nerve (BVN). Radiofrequency ablation of the BVN has emerged as a possible nonsurgical therapy for vertebrogenic low back pain. The objective of this manuscript is to provide a comprehensive review of vertebrogenic pain diagnosis and our current understanding of BVN ablation as treatment.

Horizontal fissuring at the osteochondral interface: a novel and unique pathological feature in patients with obesity-related osteoarthritis

Objectives

Obesity is a well-recognised risk factor for osteoarthritis (OA). Our aim is to characterise body mass index (BMI)-associated pathological changes in the osteochondral unit and determine if obesity is the major causal antecedent of early joint replacement in patients with OA.

Methods

We analysed the correlation between BMI and the age at which patients undergo total knee replacement (TKR) in 41 023 patients from the Australian Orthopaedic Association National Joint Replacement Registry. We then investigated the effect of BMI on pathological changes of the tibia plateau of knee joint in a representative subset of the registry.

Results

57.58% of patients in Australia who had TKR were obese. Patients with overweight, obese class I & II or obese class III received a TKR 1.89, 4.48 and 8.08 years earlier than patients with normal weight, respectively. Microscopic examination revealed that horizontal fissuring at the osteochondral interface was the major pathological feature of obesity-related OA. The frequency of horizontal fissure was strongly associated with increased BMI in the predominant compartment. An increase in one unit of BMI (1 kg/m²) increased the odds of horizontal fissures by 14.7%. 84.4% of the horizontal fissures were attributable to obesity. Reduced cartilage degradation and alteration of subchondral bone microstructure were also associated with increased BMI.

Conclusions

The key pathological feature in OA patients with obesity is horizontal fissuring at the osteochondral unit interface. Obesity is strongly associated with a younger age of first TKR, which may be a result of horizontal fissures.

Psychological distress and health-related quality of life in patients with bone marrow edema syndrome

BACKGROUND

The aim of the study was to investigate psychological distress and health-related quality of life (HrQoL) in patients with bone marrow edema syndrome (BMES) of the hip or knee joint.

METHODS

This retrospective study included patients with the diagnosis BMES treated in the period 2016-2017. As well as analyzing the epidemiological data (age, sex, vascular disease, hypertension, etc.), we used the Hospital Anxiety and Depression Scale (HADS) to document anxiety and depression and the five-level version of the EuroQol Group's EQ-5D instrument (EQ-5D-5L) to assess HrQoL and compared it to historical controls of the healthy population.

RESULTS

The study group comprised 56 patients (26 females, 30 males) with a mean age of 55.8 (range, 15-84) years. HADS: there was no difference between the study and control cohorts in the rates of anxiety (P=0.595) or depression (P=0.241). EQ-5D-5L: the HrQoL was significantly lower in the patients with BMES than in the healthy controls both for parameters of the EQ-5D-5L index and in the various age groups. No difference in HrQoL was seen between BMES of the hip and the knee or among the different radiological stages of BMES.

CONCLUSIONS

The patients with BMES displayed a clear reduction in HrQoL, but this was not associated with psychological distress with regard to significant anxiety and depression. Patients with BMES and a high score for anxiety and depression are at great risk of chronic pain, and we recommend they should receive psychological counseling.

Surgical Treatment of Insufficiency Fractures of the Knee

Bone marrow lesions (BMLs) in the knee represent focal edema caused by subchondral bone attrition and microfractures to the trabecular bone. These lesions are poor prognostic indicators for several orthopaedic procedures but also have been associated with the progression of osteoarthritis. Current research is aimed at treating BMLs with the intent to improve the overall structural integrity of the subchondral bone and delay the need for arthroplasty. The injection of calcium phosphate bone substitute has been proposed to treat BMLs because animal models have shown its potential to stimulate bone repair. This technical note describes the key steps involved in performing percutaneous fixation of BMLs with a hard-setting bone substitute, as well as associated pearls and pitfalls. Although continued research with prospective comparative cohorts and long-term follow-up is needed to determine the efficacy of this procedure, this intervention holds promise in delaying the need for total knee replacement in the arthritic patient with a focal lesion.

Association between metabolic syndrome and knee structural change on MRI

Objective

To examine the association of metabolic syndrome (MetS) and its components with knee cartilage volume loss and bone marrow lesion (BML) change.

Methods

Longitudinal data on 435 participants from a population-based cohort study were analysed. Blood pressure, glucose, triglycerides and high-density lipoprotein (HDL) were collected. MetS was defined based on the National Cholesterol Education Program–Adult Treatment Panel III criteria. MRI of the right knee was performed to measure cartilage volume and BML. Radiographic knee OA was assessed by X-ray and graded using the Altman atlas for osteophytes and joint space narrowing.

Results

Thirty-two percent of participants had MetS and 60% had radiographic knee OA. In multivariable analysis, the following were independently associated with medial tibial cartilage volume loss: MetS, β = −0.30%; central obesity, β = −0.26%; and low HDL, β = −0.25% per annum. MetS, hypertriglyceridaemia and low HDL were also associated with higher risk of BML size increase in the medial compartment (MetS: relative risk 1.72, 95% CI 1.22, 2.43; hypertriglyceridaemia: relative risk 1.43, 95% CI 1.01, 2.02; low HDL: relative risk 1.67, 95% CI 1.18, 2.36). After further adjustment for central obesity or BMI, MetS and low HDL remained statistically significant for medial tibial cartilage volume loss and BML size increase. The number of components of MetS correlated with greater cartilage volume loss and BML size increase (both P for trend <0.05). There were no statistically significant associations in the lateral compartment.

Conclusion

MetS and low HDL are associated with medial compartment cartilage volume loss and BML size increase, suggesting that targeting these factors has the potential to prevent or slow knee structural change.

Establishing outcome measures in early knee osteoarthritis

The classification and monitoring of individuals with early knee osteoarthritis (OA) are important considerations for the design and evaluation of therapeutic interventions and require the identification of appropriate outcome measures. Potential outcome domains to assess for early OA include patient-reported outcomes (such as pain, function and quality of life), features of clinical examination (such as joint line tenderness and crepitus), objective measures of physical function, levels of physical activity, features of imaging modalities (such as of magnetic resonance imaging) and biochemical markers in body fluid. Patient characteristics such as adiposity and biomechanics of the knee could also have relevance to the assessment of early OA. Importantly, research is needed to enable the selection of outcome measures that are feasible, reliable and validated in individuals at risk of knee OA or with early knee OA. In this Perspectives article, potential outcome measures for early symptomatic knee OA are discussed, including those measures that could be of use in clinical practice and/or the research setting.

Effects of long-term exercise therapy on knee joint structure in people with knee osteoarthritis: A systematic review and meta-analysis

OBJECTIVE

To investigate effects of long-term exercise therapy for people with knee osteoarthritis (OA) on radiographic disease severity and cartilage integrity (primary outcomes) as well as severity of bone marrow lesions (BMLs), synovitis and/or effusion (secondary outcomes).

METHODS

We sourced randomized controlled trials in people with clinical and/or radiographic OA investigating the effect of land-based exercise therapy of > 6 months on radiographic disease severity and magnetic resonance imaging outcomes of cartilage integrity (morphology or composition) as well as BML, synovitis and/or effusion severity, when compared to no exercise. Two independent reviewers extracted data and assessed risk of bias. Random-effects meta-analysis was used to pool standardised mean differences (SMD) (95% confidence intervals (CI)) or odds ratios (OR) (95% CI) and estimate heterogeneity (I², %). Quality of the pooled body of evidence was rated implementing the GRADE approach. Studies unsuitable for meta-analysis were summarized in a best-evidence synthesis.

RESULTS

Meta-analysis showed moderate quality evidence of no treatment effect on tibiofemoral radiographic disease severity ((SMD) 95% (CI): 0.06 (-0.07, 0.20), I²= 0%) and low-quality evidence of no effect on tibiofemoral cartilage morphology (SMD (95%): 0.06 (-0.20, 0.36), I²= 0%). Low quality evidence revealed no treatment effect on the odds of change in synovitis ((OR) (95% CI): 0.90 (0.51,1.60), I²= 0%) and effusion ((OR (95% CI): 0.88 (0.64, 1.20), I²= 0%), but greater odds of tibiofemoral BMLs worsening (OR (95% CI): 1.90 (1.11, 3.26), I²= 0%). In best-evidence synthesis, limited evidence was found for changes in patellar cartilage composition following exercise in women with mild knee OA compared to no exercise, but not for tibiofemoral cartilage.

CONCLUSION

Long-term exercise therapy did not change tibiofemoral radiographic disease severity, cartilage morphology or synovitis/effusion, but may slightly increase the likelihood for increased BML severity. Overall, meta-analysis findings were limited in directness and precision and restricted to relatively imprecise effect estimates in people who were obese on average. Limited evidence suggested some protective effects on patellar cartilage composition.

Subchondroplasty for the treatment of post-traumatic bone marrow lesions of the medial femoral condyle in a pre-clinical canine model

This study characterizes long-term outcomes associated with subchondroplasty (SCP) treatment for impact-induced subchondral bone marrow lesions (BML) using a validated pre-clinical canine model. With IACUC approval, purpose-bred research hounds (n = 16) underwent arthroscopic impact injury (40N) to both medial femoral condyles. At 3 months, functional assessments, arthroscopy, and MRI were performed and knees (n = 32) were randomly assigned to SCP (3 ml fluoroscopically guided percutaneous injection of AccuFill BSM into BML bone defects) or sham injection (Control). Dogs were assessed at 3, 6, 12, and 24 months after treatment using functional assessments, radiographic evaluation, arthroscopy, and MRI. Dogs were humanely euthanatized at 3, 6, 12, or 24 months after treatment for gross, microCT, and histologic assessments. All knees had focal articular cartilage defects with associated subchondral BMLs, as well as clinical dysfunction, 3 months after injury. At the 3 and 6 months, SCP knees showed more functional impairment than Control knees, however, these differences were not statistically significant. At 1- and 2-year post-treatment, function in SCP knees was better than in Control knees with range of motion being significantly (p < 0.05) better for SCP. Radiographic, arthroscopic, MRI, gross, microCT, and histologic findings matched the functional assessments well with Control being associated with better results at the two early time points and SCP being associated with better results at 1 and 2 years. Clinical significance: SCP treatment using calcium phosphate bone void filler was associated with an initial increase in pain and dysfunction followed by symptomatic benefits for up to 2 years after treatment for post-traumatic femoral condyle BMLs in a preclinical canine model. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2709-2717, 2018.

Association of childhood adiposity measures with adulthood knee cartilage defects and bone marrow lesions: a 25-year cohort study

OBJECTIVE

To describe the associations between childhood adiposity measures and adulthood knee cartilage defects and bone marrow lesions (BMLs) measured 25 years later.

METHODS

327 participants from the Australian Schools Health and Fitness Survey (ASHFS) of 1985 (aged 7-15 years) were followed up 25 years later (aged 31-41 years). Childhood measures (weight, height and skinfolds) were collected in 1985. Body mass index (BMI), overweight status and fat mass were calculated. Participants underwent 1.5 T knee magnetic resonance imaging (MRI) during 2008-2010, and cartilage defects and BMLs were scored from knee MRI scans. Log binomial regressions were used to examine the associations.

RESULTS

Among 327 participants (47.1% females), 21 (6.4%) were overweight in childhood. Childhood adiposity measures were associated with the increased risk of adulthood patellar cartilage defects (Weight relative risk (RR) 1.05/kg, 95% confidence interval (CI) 1.01-1.09; BMI 1.10/kg/m², 1.01-1.19; Overweight 2.22/yes, 1.21-4.08; fat mass 1.11/kg, 1.01-1.22), but not tibiofemoral cartilage defects. Childhood adiposity measures were not significantly associated with adulthood knee BMLs except for the association between childhood overweight status and adulthood patellar BMLs (RR 2.87/yes, 95% CI 1.10-7.53). These significant associations persisted after adjustment for corresponding adulthood adiposity measure.

CONCLUSION

Childhood adiposity measures were associated with the increased risk of adulthood patellar cartilage defects and, to a lesser extent, BMLs, independent of adulthood adiposity measures. These results suggest that adiposity in childhood has long-term effects on patellar structural abnormalities in young adults.

Bone matrix microdamage and vascular changes characterize bone marrow lesions in the subchondral bone of knee osteoarthritis

INTRODUCTION

Bone marrow lesions (BMLs) in the subchondral bone in osteoarthritis (OA) are suggested to be multifactorial, although the pathogenic mechanisms are unknown. Bone metabolism and cardiovascular risk factors associate with BML in epidemiologic studies. However, there are no studies at the tissue level investigating the relationship between these processes and BML. The aim of this study was to investigate the relationship between BMLs in the tibial plateau (TP) of knee OA and bone matrix microdamage, osteocyte density and vascular changes.

METHODS

TP were obtained from 73 patients at total knee replacement surgery and BMLs were identified ex vivo in TP tissue using MRI. Comparator 'No BML' tissue was from matched anatomical sites to the BMLs. Quantitative assessment was made of subchondral bone microdamage, bone resorption indices, osteocyte cellularity, and vascular features.

RESULTS

Several key parameters were different between BML and No BML tissue. These included increased microcrack burden (p = .01, p = .0001), which associated positively with bone resorption and negatively with cartilage volume, and greater osteocyte numerical density (p = .02, p = .01), in the subchondral bone plate and subchondral trabeculae, respectively. The marrow tissue within BML zones contained increased arteriolar density (p = .04, p = .0006), and altered vascular characteristics, in particular increased wall thickness (p = .007) and wall:lumen ratio (wall thickness over internal lumen area) (p = .001), compared with No BML bone.

CONCLUSIONS

Increased bone matrix microdamage and altered vasculature in the subchondral bone of BMLs is consistent with overloading and vascular contributions to the formation of these lesions. Given the important role of BMLs in knee OA, these contributing factors offer potential targets for the treatment and prevention of knee OA.

Prevalence of and risk factors for Modic change in patients with symptomatic cervical spondylosis: an observational study

Background

The aim of this study was to assess the prevalence of cervical Modic change (MC) in patients with cervical spondylosis and to develop a better understanding of the possible risk factors for the prevalence of MC.

Methods

Between January 2014 and April 2017, patients with cervical spondylosis were included in our study. All patients underwent magnetic resonance imaging (MRI) to evaluate the presence of MC. The MC was classified into three types according to the Modic classification. Potential risk factors were collected from demographic data, lifestyle variables, laboratory tests, and radiographic images. Both univariate and multivariate analysis were used to detect factors associated with MC. We further compared several variables related to fat metabolism between patients with Type 1 and Type 2 MC.

Results

The prevalence of MC in patients with cervical spondylosis was 9.24%. The MC was most frequent at C5–6, followed by C6–7, C4–5, and C3–4. The proportion of Type 1 MC in patients with neck pain was significantly higher than that in patients without neck pain (46.2% vs 13.6%, P=0.027). However, none of the variables associated with fat metabolism showed a significant difference between Type 1 and Type 2 MC. Multivariate logistic analysis showed that age ≥55 years (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.22–2.98) and body mass index (BMI) ≥25 kg/m² (OR, 2.41; 95% CI, 1.62–3.59) were two significant independent factors that are associated with cervical MC in patients with cervical spondylosis (P<0.05).

Conclusion

It appears that advanced age and high BMI were two factors that may be responsible for cervical MC. Type 1 MC is associated with the prevalence of neck pain. However, we cannot confirm that Type 2 MC is correlated with fat metabolism.

Pathobiology of Modic changes

PURPOSE

Low back pain (LBP) is the most disabling condition worldwide. Although LBP relates to different spinal pathologies, vertebral bone marrow lesions visualized as Modic changes on MRI have a high specificity for discogenic LBP. This review summarizes the pathobiology of Modic changes and suggests a disease model.

METHODS

Non-systematic literature review.

RESULTS

Chemical and mechanical stimulation of nociceptors adjacent to damaged endplates are likely a source of pain. Modic changes are adjacent to a degenerated intervertebral disc and have three generally interconvertible types suggesting that the different Modic change types represent different stages of the same pathological process, which is characterized by inflammation, high bone turnover, and fibrosis. A disease model is suggested where disc/endplate damage and the persistence of an inflammatory stimulus (i.e., occult discitis or autoimmune response against disc material) create predisposing conditions. The risk to develop Modic changes likely depends on the inflammatory potential of the disc and the capacity of the bone marrow to respond to it. Bone marrow lesions in osteoarthritic knee joints share many characteristics with Modic changes adjacent to degenerated discs and suggest that damage-associated molecular patterns and marrow fat metabolism are important pathogenetic factors. There is no consensus on the ideal therapy. Non-surgical treatment approaches including intradiscal steroid injections, anti-TNF-α antibody, antibiotics, and bisphosphonates have some demonstrated efficacy in mostly non-replicated clinical studies in reducing Modic changes in the short term, but with unknown long-term benefits. New diagnostic tools and animal models are required to improve painful Modic change identification and classification, and to clarify the pathogenesis.

CONCLUSION

Modic changes are likely to be more than just a coincidental imaging finding in LBP patients and rather represent an underlying pathology that should be a target for therapy.

Prevention of Incident Knee Osteoarthritis by Moderate Weight Loss in Overweight and Obese Females

OBJECTIVE

This study evaluated the effect of moderate weight loss on the incidence of knee osteoarthritis (OA) in middle-aged overweight and obese women, without clinical and radiologic knee OA at baseline.

METHODS

A total of 353 women (87%) with followup data available were selected from the Prevention of Knee Osteoarthritis in Overweight Females study, which evaluated the preventive effect of a diet and exercise intervention and of oral glucosamine sulfate on the incidence of knee OA. This was an exploratory proof-of-concept analysis, which compared the incidence of knee OA between women who reached the clinically relevant weight loss target of 5 kg or 5% of body weight after 30 months and those who did not reach this target.

RESULTS

The weight loss group showed a significantly lower incidence of knee OA according to the primary outcome measure, which was composed of the American College of Rheumatology criteria (clinical and radiographic), Kellgren/Lawrence grade ≥2, and joint space narrowing ≥1.0 mm (15% versus 20%; odds ratio 0.5, 95% confidence interval 0.3-0.9). Moreover, the weight loss also positively affected several health measures, such as blood glucose level, body fat percentage, and blood pressure.

CONCLUSION

A reduction of ≥5 kg or 5% of body weight over a 30-month period reduces the risk for the onset of radiographic knee OA in middle-aged overweight and obese women. Because of the slow progression of the disease, a longer followup period will be necessary before the number of prevented cases of knee OA by moderate weight loss becomes clinically more relevant.

Longitudinal analysis of cartilage T2 relaxation times and joint degeneration in African American and Caucasian American women over an observation period of 6 years - data from the Osteoarthritis Initiative

OBJECTIVES

To investigate the change in cartilage T2 values and structural degeneration in knee joints over 72 months in women of African American (AA) vs Caucasian American (CA) ethnicity.

METHODS

Knee 3T magnetic resonance imaging (MRIs) from baseline, 24, 48 and 72 months visits of 100 AA and 100 CA women from the Osteoarthritis Initiative (OAI) were assessed for cartilage T2 values and whole-organ magnetic resonance imaging (WORMS) score. Subjects were pair-matched by age, body mass index (BMI), Kellgren-Lawrence (KL) score, clinical site and subcohort within the OAI. We compared the rate of change in whole knee cartilage T2 values and WORMS cartilage, bone marrow edema pattern (BMEP) and meniscus scores between the two ethnic groups using mixed random effects models.

RESULTS

At 24 and 48 months 60 subjects and at 72 months 45 subjects per group were available for analysis resulting in 38 complete pairs with data of all time points. Compared to CA, cartilage T2 values in AA increased at a significantly faster rate at baseline (AA: 0.45 ms/y, CA: 0.35 ms/y, P = 0.029) and averaged over 6 years (AA: 0.36 ms/y, CA: 0.27 ms/y, P = 0.039) with changes in both groups reaching a plateau by 48 months. Cartilage, meniscus and BMEP scores tended to increase in both groups during follow up, but rates of change did not differ by ethnicity.

CONCLUSION

Cartilage T2 values increased faster over 72 months in AA than CA, however changes in WORMS cartilage, meniscus and BMEP scores did not differ. T2 values may be able to distinguish ethnicity-related differences of cartilage degeneration at an early stage before differences in structural joint degeneration appear.

Differences in MRI features between two different osteoarthritis subpopulations: data from the Osteoarthritis Initiative

OBJECTIVE

To investigate differences in MRI features between two etiologically distinct subtypes of knee osteoarthritis (OA): one group with metabolic syndrome and one lean group with frequent physical activity.

METHODS

We included two groups of 50 subjects of the Osteoarthritis Initiative (OAI) incidence subcohort, with KL ≥ 2 in at least one knee at 48 months follow-up. Inclusion criteria for the metabolic syndrome group were a body mass index (BMI) ≥ 30 kg/m(2) and two out of three of the following criteria: hypertension (RR > 130/85 mm Hg or hypertension medication), insulin resistance (high blood sugar or diabetic medication) or dyslipidemia (lipid lowering medication). Inclusion criteria for the active lean group were a BMI < 25 kg/m(2) and a Physical Activity Scale for the Elderly (PASE) score ≥ 2. MRI scans were scored using MR Imaging Osteoarthritis Knee Score (MOAKS). Differences in MOAKS items between groups were tested using generalized linear models adjusted for sex and age.

RESULTS

Scores for cartilage damage were significantly higher in the patella, trochlea and lateral femur in the metabolic syndrome group. Osteophyte scores were higher for all compartments in the metabolic syndrome group, though only significant for the patella, trochlea and medial tibia. Hoffa synovitis was significantly more prevalent in the active lean group while prepatellar bursa signal was more prevalent in the metabolic syndrome group.

CONCLUSION

Metabolic OA and OA related to physical activity showed differences in MRI features, depending on knee compartment. These results show that different etiological processes in knee OA can lead to differences in structural degradation.

Correlates of knee bone marrow lesions in younger adults

Background

Subchondral bone marrow lesions (BMLs) play a key role in the pathogenesis of osteoarthritis (OA) and are associated with pain and structural progression in knee OA. However, little is known about clinical significance and determinants of BMLs of the knee joint in younger adults. We aimed to describe the prevalence and environmental (physical activity), structural (cartilage defects, meniscal lesions) and clinical (pain, stiffness, physical dysfunction) correlates of BMLs in younger adults and to determine whether cholesterol levels measured 5 years prior were associated with current BMLs in young adults.

Methods

Subjects broadly representative of the Australian young adult population (n = 328, aged 31–41 years, female 48.7 %) underwent T1- and proton density-weighted fat-suppressed magnetic resonance imaging (MRI) in their dominant knee. BMLs, cartilage defects, meniscal lesions and cartilage volume were measured. Knee pain was assessed by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and physical activity was measured by the International Physical Activity Questionnaire (IPAQ). Cholesterol levels including high-density lipoprotein (HDL) were assessed 5 years prior to MRI.

Results

The overall prevalence of BML was 17 % (grade 1: 10.7 %, grade 2: 4.3 %, grade 3: 1.8 %). BML was positively associated with increasing age and previous knee injury but not body mass index. Moderate physical activity (prevalence ratio (PR):0.93, 95 % CI: 0.87, 0.99) and HDL cholesterol (PR:0.36, 95 % CI: 0.15, 0.87) were negatively associated with BML, while vigorous activity (PR:1.02, 95 % CI: 1.01, 1.03) was positively associated with medial tibiofemoral BMLs. BMLs were associated with more severe total WOMAC knee pain (>5 vs ≤5, PR:1.05, 95 % CI: 1.02, 1.09) and WOMAC dysfunction (PR:1.75, 95 % CI: 1.07, 2.89), total knee cartilage defects (PR:2.65, 95 % CI: 1.47, 4.80) and total meniscal lesion score (PR:1.92, 95 % CI: 1.13, 3.28).

Conclusions

BMLs in young adults are associated with knee symptoms and knee structural lesions. Moderate physical activity and HDL cholesterol are beneficially associated with BMLs; in contrast, vigorous physical activity is weakly but positively associated with medial tibiofemoral BMLs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-0938-9) contains supplementary material, which is available to authorized users.

Evaluation of acute and chronic MRI features of sacroiliitis in asymptomatic primary hyperparathyroid patients

Asymptomatic primary hyperparathyroidism (PHPT) is characterized with autonomous overproduction of parathyroid hormone without signs or symptoms associated with hyperparathyroidism. Before symptoms become obvious, PHPT may affect structures like sacroiliac joints, which consist of bone. So, in the asymptomatic PHPT patients, structural and inflammatory changes in sacroiliac joints may lead to confusion during diagnosis workup of axial spondyloarthropathy. In this study, we evaluated active and chronic sacroiliac magnetic resonance imaging (MRI) changes relevant to sacroiliitis in the patients with asymptomatic PHPT and interpreted bone marrow edema within the scope of Assessment of SpondyloArthritis International Society-Outcome Measures in Rheumatology Clinical Trials (ASAS-OMERACT) criteria. Forty-nine patients with asymptomatic PHPT, 26 patients with newly diagnosed axial spondyloarthropathy (SpA), and 37 healthy controls were enrolled. All subjects were evaluated by sacroiliac MRI for four active (bone marrow edema, enthesitis, capsulitis, and synovitis) and four chronic (subchondral sclerosis, subchondral/periarticular erosions, periarticular fat deposition, and bony bridges/ankylosis) lesions relevant to sacroiliitis. Bone marrow edema compatible with ASAS-OMERACT active sacroiliitis criteria in sacroiliac MRI was fulfilled by 16.3 % (8/49) of the asymptomatic PHPT patients which was similar with controls but statistically lower than axial SpA. Moreover, asymptomatic PHPT patients and controls were similar for other chronic or active MRI findings. Also, we detected lower frequency of all other MRI findings, except enthesis, in asymptomatic PHPT patients according to axial SpA. Acute inflammatory including bone marrow edema fulfilling ASAS-OMERACT active sacroiliitis criteria and chronic structural sacroiliac lesions relevant to sacroiliitis in MRI were detected in asymptomatic PHPT similar frequency with controls but as expected, lower than axial SpA. But, these findings could not be attributed to excessive secretion of parathyroid hormone.

State of the evidence

PURPOSE OF REVIEW

This review focuses on recent studies of osteoarthritis epidemiology, including research on prevalence, incidence, and a broad array of potential risk factors at the person level and joint level.

RECENT FINDINGS

Studies continue to illustrate the high impact of osteoarthritis worldwide, with increasing incidence. Person-level risk factors with strong evidence regarding osteoarthritis incidence and/or progression include age, sex, socioeconomic status, family history, and obesity. Joint-level risk factors with strong evidence for incident osteoarthritis risk include injury and occupational joint loading; the associations of injury and joint alignment with osteoarthritis progression are compelling. Moderate levels of physical activity have not been linked to increased osteoarthritis risk. Some topics of high recent interest or emerging evidence for association with osteoarthritis include metabolic pathways, vitamins, joint shape, bone density, limb length inequality, muscle strength and mass, and early structural damage.

SUMMARY

Osteoarthritis is a complex, multifactorial disease, and there is still much to learn regarding mechanisms underlying incidence and progression. However, there are several known modifiable and preventable risk factors, including obesity and joint injury; efforts to mitigate these risks can help to lessen the impact of osteoarthritis.

Factors associated with arthrogenous muscle inhibition in patellofemoral osteoarthritis

OBJECTIVES

Arthrogenous muscle inhibition (AMI) is thought to contribute to quadriceps weakness in knee osteoarthritis (OA), but its relationship with structural changes of bone marrow lesions (BMLs), capsular distension and pain is unclear. This study's objective was to investigate the factors associated with AMI in subjects with symptomatic patellofemoral joint OA (PFJOA).

DESIGN

126 Subjects with predominant PFJOA were assessed for pain by the visual analogue scale (VAS) for a nominated aggravating activity. Their more symptomatic knee underwent a magnetic resonance imaging (MRI) scan which was used to assess BMLs and synovitis which were scored using the Whole Organ MRI score (WORMS). Quadriceps AMI was measured by calculating the activation deficit and quadriceps strength assessed by isometric maximum voluntary contraction. Multiple linear regressions were used to assess factors associated with AMI.

RESULTS

We studied 124 subjects [mean age 55.5 (SD 7.5); 57.14% female]. In regression analyses, higher levels of AMI were significantly associated with more severe knee pain and with lower BML score.

CONCLUSION

Quadriceps AMI in knee OA is associated with severity of knee pain and surprisingly with lower BML scores.

Future directions for the management of pain in osteoarthritis

Osteoarthritis (OA) is the predominant form of arthritis worldwide, resulting in a high degree of functional impairment and reduced quality of life owing to chronic pain. To date, there are no treatments that are known to modify disease progression of OA in the long term. Current treatments are largely based on the modulation of pain, including NSAIDs, opiates and, more recently, centrally acting pharmacotherapies to avert pain. This review will focus on the rationale for new avenues in pain modulation, including inhibition with anti-NGF antibodies and centrally acting analgesics. The authors also consider the potential for structure modification in cartilage/bone using growth factors and stem cell therapies. The possible mismatch between structural change and pain perception will also be discussed, introducing recent techniques that may assist in improved patient phenotyping of pain subsets in OA. Such developments could help further stratify subgroups and treatments for people with OA in future.