Magnetic resonance imaging of subchondral bone marrow lesions in association with osteoarthritis

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.

The impact of Yoga on patients with knee osteoarthritis: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

The objective of this review is to conduct a comprehensive and systematic assessment of the efficacy of Yoga as an intervention for knee osteoarthritis (KOA).

METHODS

We searched PubMed, Cochrane Library, Embase, Web of Science, and PEDro as of January 3, 2024. Retrieved a total of 200 articles. Standardised mean differences (SMDs) and 95% confidence intervals (CI) were calculated.

RESULTS

The study included a total of 8 trials and involved 756 KOA patients. The results indicated that compared to the control group, Yoga exercise showed significant improvements in alleviating pain (SMD = -0.92; 95% CI = -1.64 ~ - 0.20; P = 0.01, I2 = 94%), stiffness (SMD = -0.51; 95% CI = -0.91 ~ -0.12; P = 0.01; I2 = 66%) and physical function (SMD = -0.53; 95% CI = -0.89 ~ -0.17; P = 0.004; I2 = 59%) among KOA patients. However, there was no significant improvement observed in terms of activities of activity of daily living (ADL) (SMD = 1.03; 95% CI = -0.01 ~ 2.07; P = 0.05; I2 = 84%), and quality of life (QOL) (SMD = 0.21; 95% CI = -0.33 ~ 0.74; P = 0.44; I2 = 83%) with the practice of Yoga.

CONCLUSIONS

In general, Yoga has been found to be effective in reducing pain and stiffness in KOA patients, it can also improve the physical function of patients. However, there is limited evidence to suggest significant improvements in terms of ADL and QOL.

Bone marrow edema of the knee: a narrative review

Bone marrow edema (BME) is a frequent MRI finding in patients with knee pain. According to the etiology, BME of the knee can be classified into three main categories: ischemic, mechanic, and reactive. The diagnosis may be difficult, because of the specificity of symptoms and the poor radiographic findings. MRI is the gold standard, showing an area of altered signal of the bone with an high signal intensity on fat-suppressed, T2 weighted images, usually in combination with an intermediate or low signal intensity on T1 weighted images. Bone marrow edema tends to be self-limiting and, in most cases, resolves without any consequences in a varying amount of time. However, since it may evolve to complete joint destruction, early diagnosis and correct treatment are crucial to prevent the articular degeneration. Conservative therapy is the first step, with no weight-bearing for 3 to 6 weeks on the affected side, in combination with the administration of anti-inflammatory drugs or painkillers to manage symptoms. In non-responding forms and more advanced stages, minimally invasive preservative surgery can provide significant results, with subchondroplasty and core decompression being the two main procedures available. Knee arthroplasty, both total (TKA) or unicompartmental (UKA), is the only effective option when the degradation of cartilage is diffuse and in patients with subchondral bone collapse.

Evaluation of treatment parameters for focused-extracorporeal shock wave therapy in knee osteoarthritis patients with bone marrow lesions: a pilot study

OBJECTIVES

To evaluate the effect of different dosage parameters of focused-extracorporeal shock wave therapy on pain and physical function in knee osteoarthritis patients with bone marrow lesions. In addition, to investigate pathophysiological changes based on imaging and biomarker measures.

METHODS

Using a single-case experimental design, a total of 12 participants were randomly allocated in 4 equal groups of 3 to receive different dosages of focused-extracorporeal shock wave therapy. Each group received either 4 or 6 sessions of 1500 or 3000 shocks over 4 or 6 weekly sessions. Participants underwent repeated measurements during the baseline, intervention, and post-intervention phases for Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, aggregated locomotor function score and pressure pain threshold. Imaging and inflammatory biomarker outcomes were measured at baseline and 3 months following the intervention.

RESULTS

The group receiving the highest dosage of focused-extracorporeal shock wave therapy showed clinical improvements superior to those of participants in the other 3 groups. Statistically significant changes during the follow-up phase in contrast to baseline measurements for the WOMAC score (Tau-U= -0.88, p < 0.001), aggregated locomotor function score (Tau-U= -0.77, p = 0.002), and pressure pain threshold (Tau-U= 0.54, p = 0.03) were observed. Bone marrow lesion and inflammatory cytokines demonstrated no change.

CONCLUSION

A dose-dependent effect for focused-extracorporeal shock wave therapy on osteoarthritis-related symptoms was suggested. However, these improvements were not associated with changes in the underlying pathophysiological mechanisms.

Triptolide mitigates the inhibition of osteogenesis induced by TNF-α in human periodontal ligament stem cells via the p-IκBα/NF-κB signaling pathway: an in-vitro study

BACKGROUND

Triptolide is a widely utilized natural anti-inflammatory drug in clinical practice. Aim of this study was to evaluate effects of triptolide on hPDLSCs osteogenesis in an inflammatory setting and to investigate underlying mechanisms.

METHODS

Using the tissue block method to obtain hPDLSCs from extracted premolar or third molar. Flow cytometry, osteogenic and adipogenic induction were carried out in order to characterise the features of the cells acquired. hPDLSC proliferative activity was assessed by CCK-8 assay to determine the effect of TNF-α and/or triptolide. The impact of triptolide on the osteogenic differentiation of hPDLSCs was investigated by ALP staining and quantification. Osteogenesis-associated genes and proteins expression level were assessed through PCR and Western blotting assay. Finally, BAY-117,082 was used to study the NF-κB pathway.

RESULTS

In the group treated with TNF-α, there was an elevation in inflammation levels while osteogenic ability and the expression of both osteogenesis-associated genes and proteins decreased. In the group co-treated with TNF-α and triptolide, inflammation levels were reduced and osteogenic ability as well as the expression of both osteogenesis-associated genes and proteins were enhanced. At the end of the experiment, both triptolide and BAY-117,082 exerted similar inhibitory effects on the NF-κB pathway.

CONCLUSION

The osteogenic inhibition of hPDLSCs by TNF-α can be alleviated through triptolide, with the involvement of the p-IκBα/NF-κB pathway in this mechanism.

Bone marrow edema in the acromioclavicular joint after arthroscopic rotator cuff repair

BACKGROUND

Bone marrow edema (BME) in the acromioclavicular joint (ACj) may occur after arthroscopic rotator cuff repair (ARCR), resulting in persistent postoperative ACj pain. We investigated the incidence and clinical characteristics of BME in ACj after ARCR.

METHODS

Patients exhibiting ACj-related symptoms prior to ARCR surgery, no BME in the ACj on MRI, and an ability to undergo 2-year postoperative physical and MRI examinations of the ACj were included. Patients who underwent distal clavicle resection or osteophyte resection below the ACj and those unable to achieve primary repair of the rotator cuff were excluded. MRI evaluation was performed preoperatively and at 3, 6, 12, and 24 months postoperatively. Patients who showed BME in ACj on fat-suppressed T2 MRI at 24 months postoperatively were classified into the BME + group, and those with no BME were classified into the BME- group. Patient background, operation time, Japanese Orthopedic Association (JOA) score, re-tear rate, ACj tenderness, and cross-body adduction test were compared between groups. In addition, we examined the time of occurrence of BME.

RESULTS

A total of 345 ARCRs were performed during the study period. After the exclusion of 114 shoulders, the remaining 231 shoulders were included in this study. There were 208 cases in the BME- group and 23 cases in the BME + group. The incidence of BME was 9.96 %. Although the JOA scores of both groups showed a significant improvement postoperatively compared to preoperatively, there was no significant difference between the two groups. In terms of re-tear, there was 1 case in the BME + group and 7 in the BME- group. Positive ACj tenderness and cross-body adduction test were significantly higher in the BME + group (P < 0.001). BME occurred in 6 cases at 3 months, 9 cases at 6 months, and 8 cases at 1 year postoperatively. None of the patients developed BME at more than 1 year postoperatively. BME was observed on MRI in all cases at 2 years postoperatively.

CONCLUSIONS

The rate of occurrence of BME in the ACj after ARCR was 9.96 %. Patients with BME were significantly more likely to have ACj tenderness and positive cross-body adduction test. BME in the ACj often occurs within 6 months to 1 year after ARCR of small-to-medium rotator cuff tears, suggesting a relationship with postoperative functional improvement of the shoulder joint. The ACj should be considered as a potential site of persistent pain after ARCR for small-to-medium rotator cuff tears.

Bone marrow edema of the hip: a narrative review

Bone marrow edema (BME) of the hip is a radiological-clinical condition with symptoms ranging from asymptomatic to severe, and it is characterized by increased interstitial fluid within the bone marrow, usually at the femur. Depending on the etiology it can be classified as primary or secondary. The primary cause of BME is unknown, while the secondary forms include traumatic, degenerative, inflammatory, vascular, infectious, metabolic, iatrogenic, and neoplastic etiologies. BME could be classified as reversible or progressive. Reversible forms include transient BME syndrome and regional migratory BME syndrome. Progressive forms include avascular necrosis of the femoral head (AVNH), subchondral insufficiency fracture, and hip degenerative arthritis. The diagnosis can be difficult, because at the beginning, the outbreak of hip pain, typically acute and disabling without any prior trauma or exceptional physical activity, is poorly supported by radiographic findings. MRI is the gold standard, and it shows an area of intermediate signal on T1-weighted MRI scans and a high signal on T2-weighted scans, usually lacking sharps margins. In the reversible form, BME is typically self-limiting, and it can be managed conservatively by means of pharmacological and physical therapy. Surgery is generally required for progressive forms in patients who failed non-operative treatment, and it ranges from femoral head and neck core decompression to total hip arthroplasty.

Bone Remodeling in Osteoarthritis-Biological and Radiological Aspects

Among available papers published on the given subject over the last century, various terms have been used as synonyms for one, now generally accepted-osteoarthritis, in some countries called "wear and tear" or "overload arthritis". The opsolent terms-hypertrophic arthritis, degenerative arthritis, arthritis deformans and osteoarthrosis-sought to highlight the dominant clinical signs of this ubiquitous, polymorph disease of the whole osteochondral unit, which by incidence and prevalence represents one of the leading chronic conditions that cause long-term pain and incapacity for work. Numerous in vitro and in vivo research resulted in broadened acknowledgments about osteoarthritis pathophysiology and pathology on both histological and cellular levels. However, the cause of osteoarthritis is still unknown and is currently the subject of a hypothesis. In this paper, we provide a review of recent findings on biological phenomena taking place in bone tissue during osteoarthritis to the extent useful for clinical practice. Choosing a proper radiological approach is a conditio sine qua non to the early diagnosis of this entity.

Debate: Intra-articular steroid injections for osteoarthritis - harmful or helpful?☆,☆☆

Intra-articular corticosteroids injections are a widely used treatment for pain from symptomatic osteoarthritis. Systematic reviews show that the treatment effect is modest compared with intra-articular saline (often considered as placebo) and lasts for 2-4 weeks on average. Potentially as a consequence of limited therapeutic duration, repeated injections are often given up to 4 injections annually. In this context of repeat injections, recent evidence has emerged that intra-articular corticosteroids might be associated with more MRI-assessed quantitative cartilage thickness loss than saline injections. Guidelines vary in the recommendation for use of intra-articular corticosteroids. Given the frequency with which intra-articular corticosteroids injections are used, the size and scale of the population with osteoarthritis, it is critical to fully understand the benefits and drawbacks of intra-articular corticosteroids injections. That is the focus of this debate article.

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.

Tissue Integration of Calcium Phosphate Compound after Subchondroplasty: 4-Year Follow-Up in a 76-Year-Old Female Patient

Subchondroplasty is a new minimally invasive surgical technique developed to treat bone marrow lesions (BML) and early osteoarthritis (OA). During the procedure, engineered calcium phosphate compound (CPC) is injected. It is claimed by the manufacturer that during the healing process, the CPC is replaced with new bone. The purpose of this study was to verify the replacement of CPC with new bone after subchondroplasty for the first time in humans. A 76-year old woman was referred for resistant medial knee pain. Standing radiographs showed varus knee OA and magnetic resonance imaging (MRI) revealed BML. She was treated with subchondroplasty of medial femoral condyle. Excellent relief of pain was achieved after procedure. Afterwards, the pain worsened, the radiographs confirmed the OA progression and the patient was treated with a total knee arthroplasty (TKA) 4 years after primary procedure. The resected bone was examined histologically and with micro-computed tomography (CT). Histologically, bone trabeculae of subcortical bone were embedded in the amorphous mass. However, no signs of CPC resorption and/or bone replacement have been found with micro-CT. In short term, excellent pain relief could be expected after the subchondroplasty procedure. However, there was no replacement of CPC with bone and the technique probably did not influence the natural process of knee OA.

Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage Values in Hips With Bone Marrow Lesions

OBJECTIVE

Bone marrow lesions (BMLs) are associated with painful and progressive osteoarthritis (OA). Quantitative magnetic resonance imaging (MRI) has been used to study early cartilage degeneration in knees with BML, but similar work has not been done in hips. The purpose of this study was to compare mean delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) relaxation values (T1Gd) in hips with BML to hips without BML in a population-based study. Reduced T1Gd suggests depleted glycosaminoglycan. Our hypothesis was that mean T1Gd is lower in hips with BML compared to hips without BML.

METHODS

Study participants (n = 128) were recruited from a cross-sectional population-based study of people ages 20-49 years with and without hip pain. dGEMRIC and proton density (PD)-weighted MRI scans of 1 hip from each participant were used for this analysis. BMLs were identified from PD-weighted fat-suppressed images. We applied a sampling-weighted linear regression model to determine the association of the presence of BMLs with mean cartilage T1Gd (significance: P < 0.05). The model was adjusted for age, sex, body mass index (BMI), hip pain, cam/pincer deformity, and physical activity.

RESULTS

Thirty-two (25%) of the 128 participants had at least 1 BML. Subjects with at least 1 BML, compared to those without, had similar weighted characteristics of age, BMI, physical activity levels, and frequency of hip pain. Mean T1Gd was 75.25 msec lower (95% confidence interval -149.69, -0.81; P = 0.048) (9%) in the BML compared to the no-BML group.

CONCLUSION

Our results suggest that hips with BMLs are associated with hip cartilage degeneration early in the OA disease process.

Case report: Electroacupuncture for acute pain flare-up of knee osteoarthritis

Acute pain flare-up of knee osteoarthritis (KOA) is a common disease in orthopedics and is mainly treated with analgesic drugs. Patients usually refuse to take western medicines orally owing to gastrointestinal side effects or unsatisfactory treatment results. We report the case of a 69-year-old woman who had an acute pain flare-up of right KOA induced by long-distance walking. As the patient refused medication, we used electroacupuncture (EA) to relieve her symptoms. EA with a 2-Hz frequency and a 1–2-mA intensity had an analgesic effect on the acute pain flare-up of KOA. After 12 weeks of EA intervention, the bone marrow edema-like lesions (BMLs) improved significantly, as depicted on magnetic resonance imaging of the knee joint. However, more powerful evidence is needed to understand the mechanism of the EA technique that alleviates BMLs of KOA.

Metformin alleviates osteoarthritis in mice by inhibiting chondrocyte ferroptosis and improving subchondral osteosclerosis and angiogenesis

BACKGROUND

Osteoarthritis (OA) is the most common musculoskeletal disease, and it has a complex pathology and unknown pathogenesis. Chondrocyte ferroptosis is closely associated with the development of OA. As a common drug administered for the treatment of type 2 diabetes, metformin (Met) is known to inhibit the development of ferroptosis. However, its therapeutic effect in OA remains unknown. The present study aimed to explore the effects of Met on cartilage and subchondral bone in a mouse OA model and to explore the potential underlying mechanisms.

METHODS

A mouse OA model was induced using destabilization of the medial meniscus (DMM) surgery, chondrocyte ferroptosis was induced using an intra-articular injection of Erastin, and Met (200 mg/kg/day) was intragastrically administered for 8 weeks after surgery. H&E and Safranin O‑fast green staining were used to evaluate cartilage degeneration, and μ‑computed tomography was used to evaluate changes in subchondral bone microarchitecture. Moreover, immunohistochemical staining was performed to detect mechanistic metalloproteinases 13, type II collagen, glutathione peroxidase 4, acyl-CoA synthetase long-chain family member 4, solute carrier family 7 member 11 and p53. Runt-associated transcription factor 2 and CD31 were detected using immunofluorescent staining.

RESULTS

Met protected articular cartilage and reversed the abnormal expression of ferroptosis-related proteins in the chondrocytes of DMM mice. Moreover, intra-articular injection of Erastin induced ferroptosis in mouse chondrocytes, and Met eliminated the ferroptosis effects induced by Erastin and protected articular cartilage. In addition, the results of the present study demonstrated that Met alleviated the microstructural changes of subchondral osteosclerosis and reduced heterotypic angiogenesis in DMM mice.

CONCLUSION

Met alleviates the pathological changes of OA by inhibiting ferroptosis in OA chondrocytes, alleviating subchondral sclerosis and reducing abnormal angiogenesis in subchondral bone in advanced OA.

A novel approach to studying early knee osteoarthritis illustrates that bilateral medial tibiofemoral osteoarthritis is a heritable phenotype: an offspring study

To assess the potential of studying offspring of people with and without knee osteoarthritis to understand the risk factors and heritability for knee osteoarthritis. We selected two groups of Osteoarthritis Initiative (OAI) participants from one clinical site: (1) participants with bilateral radiographic medial tibiofemoral osteoarthritis and (2) those without tibiofemoral osteoarthritis. We then invited biological offspring ≥ 18 years old to complete an online survey that inquired about osteoarthritis risk factors and symptoms. Among the survey respondents, we recruited ten offspring of members from each group for a clinic visit with bilateral knee posterior-anterior radiographs and magnetic resonance imaging of the right knee. We established contact with 269/413 (65%) eligible OAI participants. Most (227/269, 84%) had ≥ 1 eligible biological offspring, and 213 (94%) were willing to share information about the new family study with their offspring. Our survey was completed by 188 offspring from 110 OAI participants: mean age of 43.0 (10.4) years, mean body mass index of 23.7 (5.9) kg/m², 65% female. Offspring obesity (OR = 2.7, 95% CI 1.0-7.3), hypertension (OR = 3.7, 95% CI 1.2-11.3), and Heberden's nodes (OR = 3.6, 95% CI 1.0-13.2) were associated with parental osteoarthritis status; however, adjusted models were not statistically significant. Radiographic tibiofemoral osteoarthritis (16/18 knees vs. 2/20 knees) and meniscal abnormalities (7/9 vs. 2/10 index knees) were more common among offspring with parental osteoarthritis status than not. We established the potential of a novel offspring study design within the OAI, and our results are consistent with bilateral radiographic medial tibiofemoral osteoarthritis being a heritable phenotype of osteoarthritis.

Bone Marrow Edema: Overview of Etiology and Treatment Strategies

➤

Bone marrow edema (BME) is a nonspecific but relevant finding, usually indicating the presence of an underlying pathology.

➤

The gold standard technique for detecting BME is magnetic resonance imaging (MRI), as it allows for a correct diagnosis to be made, which is extremely important given the heterogeneity of BME-related diseases.

➤

Depending on the severity of painful symptomatology and the MRI evidence, different treatment strategies can be followed: physical modalities, pharmacological options, and surgical therapy.

Subchondral insufficiency fracture of the knee: review of current concepts and radiological differential diagnoses

Subchondral insufficiency fracture of the knee (SIFK) is a common cause of knee joint pain in older adults. SIFK is a type of stress fracture that occurs when repetitive and excessive stress is applied to the subchondral bone. If the fracture does not heal, the lesion develops into osteonecrosis and results in osteochondral collapse, requiring surgical management. Because of these clinical features, SIFK was initially termed "spontaneous osteonecrosis of the knee (SONK)" in the pre-MRI era. SONK is now categorized as an advanced SIFK lesion in the spectrum of this disease, and some authors believe the term "SONK" is a misnomer. MRI plays a significant role in the early diagnosis of SIFK. A subchondral T2 hypointense line of the affected condyle with extended bone marrow edema-like signal intensity are characteristic findings on MRI. The large lesion size and the presence of osteochondral collapse on imaging are associated with an increased risk of osteoarthritis. However, bone marrow edema-like signal intensity and osteochondral collapse alone are not specific to SIFK, and other osteochondral lesions, including avascular necrosis, osteochondral dissecans, and osteoarthritis should be considered. Chondral lesions and meniscal abnormalities, including posterior root tears, are also found in many patients with SIFK, and they are considered to be related to the development of SIFK. We review the clinical and imaging findings, including the anatomy and terminology history of SIFK, as well as its differential diagnoses. Radiologists should be familiar with these imaging features and clinical presentations for appropriate management.

Injectable Amniotic Membrane/Umbilical Cord Particulate for Knee Osteoarthritis: A Prospective, Single-Center Pilot Study

OBJECTIVE

To evaluate the short-term safety and effectiveness of amniotic membrane/umbilical cord particulate (AMUC) in managing pain in patients with various severities of knee osteoarthritis (OA).

DESIGN

Single-center, prospective, investigator-initiated pilot study.

SETTING

Private practice.

SUBJECTS

A total of 20 knee OA patients aged ≥18 years were enrolled with pain >40 mm, as determined by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)-A.

METHODS

Patients received an ultrasound-guided, intra-articular injection of 50 mg of AMUC particulate reconstituted in 2 mL of preservative-free saline. All patients were then monitored at six weeks, 12 weeks, and 24 weeks postinjection. Patients who did not show >30% reduction in pain received a second injection of AMUC at six weeks. WOMAC, Patient Global Assessment, medication usage, and magnetic resonance imaging (MRI) were assessed.

RESULTS

Knee OA pain significantly decreased from 74.3 ± 17.2 at baseline to 45.0 ± 25.4 at six weeks (P < 0.01), 35.4 ± 26.6 at 12 weeks (P < 0.001), and 37.4 ± 26.7 at 24 weeks (P < 0.001). This pain reduction was associated with a significant improvement in physical function (WOMAC-C) at all time points (P < 0.05) and stiffness (WOMAC-B) at 12 weeks (P = 0.01). Eleven patients received a second injection, which was significantly correlated with body mass index >30 kg/m2 (P = 0.025). MRI evaluation of the overall population revealed an improvement in the severity of bone marrow lesions in seven patients. No adverse events were observed.

CONCLUSIONS

AMUC particulate injection relieved pain and improved physical function in patients with symptomatic knee OA.

Setting up distinctive outcome measures for each osteoarthritis phenotype

Osteoarthritis (OA) is an evolving chronic joint disease with a huge global impact. Given the intricate nature of the etiopathogenesis and subsequent high heterogeneity in the clinical course of OA, it is crucial to discriminate between etiopathogenic endotypes and clinical phenotypes, especially in the early stages of the disease. In this sense, we propose that an OA phenotype should be properly assessed with a set of outcome measures including those specifically related to the main underlying pathophysiological mechanisms. Thus, each OA phenotype can be related to different and clinically meaningful outcomes. OA phenotyping would lead to an adequate patient stratification in well-designed clinical trials and the discovery of precise therapeutic approaches. A significant effort will be required in this field in light of inconclusive results of clinical trials of tissue-targeting agents for the treatment of OA.

A global bibliometric and visualized analysis in the status and trends of subchondral bone research

BACKGROUND

Structural and functional changes in subchondral bone have been recognized as a key factor in the development of related disease, and subchondral bone may be a new target for the treatment of osteoarthritis. The purpose of our present study is to investigate the global status and trends of subchondral bone research.

METHOD

Publications related to the studies of subchondral bone from 1993 to 2018 were retrieved from the Science Citation Index-Expanded Web of Science database. The data source was studied and indexed by using bibliometric methodology. For visualized study, bibliographic coupling analysis, co-authorship analysis, co-citation analysis, co-occurrence analysis and the analysis of publication trends in subchondral bone research were conducted by VOS viewer and GraphPadPrism 5 software.

RESULTS

A total of 4780 publications were included. There is an increasing trend of the relative research interests and number of publications per year globally. The cumulative number of publications about subchondral bone research followed the logistic growth model (Equation is included in full-text article.). The USA made the highest contributions to the global research with the most citations, the highest H-index, and the most total link strength, while Denmark had the highest average citation per item. The journal Osteoarthritis and Cartilage had the largest publication number. Boston University is the most contributive institution. Studies could be divided into 4 clusters: "Mechanism research", "Animal study", "Clinical study" and "Pathological features". Less efforts were put into clinical study.

CONCLUSION

The number of publications about subchondral bone research would be increasing in the next years based on the current global trends. Attention should be drawn to the latest popular research, including "Mesenchymal stem-cells", "Autologous chondrocyte implantation", "Microfracture" and "Pain". Therefore, more and more efforts will be put into mechanism research on subchondral bone, which may inspire new clinical treatments for osteoarthritis and other related diseases based on subchondral bone.

The simultaneous analysis of mesenchymal stem cells and early osteocytes accumulation in osteoarthritic femoral head sclerotic bone

OBJECTIVE

OA subchondral bone is a key target for therapy development. Osteocytes, the most abundant bone cell, critically regulate bone formation and resorption. Their progenitors, mesenchymal stem cells (MSCs), display altered behaviour in osteoarthritic subchondral bone. This study investigated the relationships between native osteocytes and native MSCs in osteoarthritic femoral heads.

METHODS

To avoid culture manipulations, a bone treatment procedure was developed to simultaneously obtain pure osteocyte-enriched fragments and matched native CD45-CD271+ MSCs. Gene expression in osteocytes and MSCs was compared between healthy and OA bone and selected molecules were examined by immunohistochemistry in relation to OA tissue pathology. Cell sorting and standard trilineage differentiation assays were employed to test OA MSC functionality.

RESULTS

Native osteocyte enrichment was confirmed histologically and by higher-level osteocyte maturation transcripts expression, compared with purified MSCs. Compared with healthy bone, native OA osteocytes expressed 9- and 4-fold more early/embedding osteocyte molecules E11 and MMP14, and 6-fold more osteoprotegerin (P<0.01). CD271+ MSCs accumulated in the regions of bone sclerosis (9-fold, P<0.0001) in close juxtaposition to trabeculae densely populated with morphologically immature E11-positive osteocytes (medians of 76% vs 15% in non-sclerotic areas, P<0.0001), and osteoblasts. Gene expression of OA MSCs indicated their bone formation bias, with retained multipotentiality following culture-expansion.

CONCLUSIONS

In human late-stage OA, osteogenically-committed MSCs and adjacent immature osteocytes exhibit a marked accumulation in sclerotic areas. This hitherto unappreciated MSC-early osteocyte axis could be key to understanding bone abnormalities in OA and represents a potential target for novel therapy development in early disease.

Exploration of New Contrasts, Targets, and MR Imaging and Spectroscopy Techniques for Neuromuscular Disease - A Workshop Report of Working Group 3 of the Biomedicine and Molecular Biosciences COST Action BM1304 MYO-MRI

Neuromuscular diseases are characterized by progressive muscle degeneration and muscle weakness resulting in functional disabilities. While each of these diseases is individually rare, they are common as a group, and a large majority lacks effective treatment with fully market approved drugs. Magnetic resonance imaging and spectroscopy techniques (MRI and MRS) are showing increasing promise as an outcome measure in clinical trials for these diseases. In 2013, the European Union funded the COST (co-operation in science and technology) action BM1304 called MYO-MRI (www.myo-mri.eu), with the overall aim to advance novel MRI and MRS techniques for both diagnosis and quantitative monitoring of neuromuscular diseases through sharing of expertise and data, joint development of protocols, opportunities for young researchers and creation of an online atlas of muscle MRI and MRS. In this report, the topics that were discussed in the framework of working group 3, which had the objective to: Explore new contrasts, new targets and new imaging techniques for NMD are described. The report is written by the scientists who attended the meetings and presented their data. An overview is given on the different contrasts that MRI can generate and their application, clinical needs and desired readouts, and emerging methods.

Blood and urinary collagen markers in osteoarthritis: markers of tissue turnover and disease activity

Introduction: The need for diagnostic markers in osteoarthritis (OA) is acute and immediate, as sensitive and precise tools that monitor disease activity and treatment response are lacking. Collagens - types I, II, and III - are the skeleton of the extracellular matrix of joint tissues. Joint collagens are generally turned over at a low rate, but the balance between formation and degradation is disturbed, leading to the loss of, for example, cartilage.Areas covered: We discuss the markers reflecting collagen turnover and provide examples of how they have been applied in OA research, as well as how we believe these should be used in the future. We have searched PubMed for full-text articles written in English using different combinations of the following terms: OA, biomarker, and collagen. The result is a narrative review that gives examples from the literature.Expert opinion: Collagen markers show promise, as they are direct measures of tissue balance. Until now, collagen markers have mainly been tested in observational cohorts, which may provide insights into the association between the candidate marker and clinical variables; however, these do not advance the development of qualified markers that can be used for drug development or in clinical practice.

Intraarticular Ligament Degeneration Is Interrelated with Cartilage and Bone Destruction in Osteoarthritis

Osteoarthritis (OA) induces inflammation and degeneration of all joint components including cartilage, joint capsule, bone and bone marrow, and ligaments. Particularly intraarticular ligaments, which connect the articulating bones such as the anterior cruciate ligament (ACL) and meniscotibial ligaments, fixing the fibrocartilaginous menisci to the tibial bone, are prone to the inflamed joint milieu in OA. However, the pathogenesis of ligament degeneration on the cellular level, most likely triggered by OA associated inflammation, remains poorly understood. Hence, this review sheds light into the intimate interrelation between ligament degeneration, synovitis, joint cartilage degradation, and dysbalanced subchondral bone remodeling. Various features of ligament degeneration accompanying joint cartilage degradation have been reported including chondroid metaplasia, cyst formation, heterotopic ossification, and mucoid and fatty degenerations. The entheses of ligaments, fixing ligaments to the subchondral bone, possibly influence the localization of subchondral bone lesions. The transforming growth factor (TGF)β/bone morphogenetic (BMP) pathway could present a link between degeneration of the osteochondral unit and ligaments with misrouted stem cell differentiation as one likely reason for ligament degeneration, but less studied pathways such as complement activation could also contribute to inflammation. Facilitation of OA progression by changed biomechanics of degenerated ligaments should be addressed in more detail in the future.

Musculoskeletal ultrasound in symptomatic thumb-base osteoarthritis: clinical, functional, radiological and muscle strength associations

Background

Thumb-base osteoarthritis (OA) is a common cause of pain and disability This study aimed to investigate the associations of musculoskeletal ultrasound OA pathologies with the extent of pain, function, radiographic scores, and muscle strength in symptomatic thumb-base osteoarthritis.

Methods

This is a cross-sectional study of an ongoing clinical trial with eligibility criteria including thumb-base pain on Visual Analogue Scale (VAS) ≥40 (0 to 100 mm), Functional Index for Hand OA (FIHOA) ≥ 6 (0 to 30) and Kellgren Lawrence (KL) grade ≥ 2. The most symptomatic side was scanned to measure synovitis and osteophyte severity using a 0–3 semi-quantitative score, power Doppler and erosion in binary score. A linear regression model was used for associations of ultrasound findings with VAS pain, FIHOA and hand grip and pinch strength tests after adjusting for age, gender, body mass index, disease duration and KL grade as appropriate. For correlation of ultrasound features with KL grade, OARSI ((Osteoarthritis Research Society International) osteophyte and JSN scores, Eaton grades, Spearman coefficients were calculated, and a significant test defined as a p-value less than 0.05.

Results

The study included 93 participants (mean age of 67.04 years, 78.5% females). Presence of power Doppler has a significant association with VAS pain [adjusted β coefficient = 11.29, P = 0.02] while other ultrasound pathologies revealed no significant associations with all clinical outcomes.

In comparison to radiograph, ultrasonographic osteophyte score was significantly associated with KL grade [r_s = 0.44 (P < 0.001)], OARSI osteophyte grade [r_s = 0.35 (P = 0.001)], OARSI JSN grade [r_s = 0.43 (P < 0.001)] and Eaton grade [r_s = 0.30 (P < 0.01)]. Ultrasonographic erosion was significantly related with radiographic erosion [r_s = − 0.49 (P = 0.001)].

Conclusion

From a clinical perspective the significant relationship of power Doppler with pain severity in thumb base OA suggests this might be a useful tool in understanding pain aetiology. It is important to recognise that power Doppler activity was only detected in 14% of the study so this might be an important subgroup of persons to monitor more closely.

Trial registration

Registered at Australian New Zealand Clinical Trials Registry (ANZCTR), http://www.anzctr.org.au/, ACTRN12616000353493.

Knee pain as a predictor of structural progression over 4 years: data from the Osteoarthritis Initiative, a prospective cohort study

Background

There is evidence that knee pain not only is a consequence of structural deterioration in osteoarthritis (OA) but also contributes to structural progression. Clarifying this is important because targeting the factors related to knee pain may offer a clinical approach for slowing the progression of knee OA. The aim of this study was to examine whether knee pain over 1 year predicted cartilage volume loss, incidence and progression of radiographic osteoarthritis (ROA) over 4 years.

Methods

Osteoarthritis Initiative participants with no ROA (Kellgren-Lawrence grade ≤ 1) (n = 2120) and with ROA (Kellgren-Lawrence grade > 2) (n = 2249) were examined. Knee pain was assessed at baseline and 1 year using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Knee pain patterns were categorised as no pain (WOMAC pain < 5 at baseline and 1 year), fluctuating pain (WOMAC pain > 5 at either time point) and persistent pain (WOMAC pain > 5 at both time points). Cartilage volume, incidence and progression of ROA were assessed using magnetic resonance imaging and x-rays at baseline and 4-years.

Results

In both non-ROA and ROA, greater baseline WOMAC knee pain score was associated with increased medial and lateral cartilage volume loss (p ≤ 0.001), incidence (OR 1.07, 95% CI 1.01–1.13) and progression (OR 1.07, 95% CI 1.03–1.10) of ROA. Non-ROA and ROA participants with fluctuating and persistent knee pain had increased cartilage volume loss compared with those with no pain (p for trend ≤ 0.01). Non-ROA participants with fluctuating knee pain had increased risk of incident ROA (OR 1.62, 95% CI 1.04–2.54), corresponding to a number needed to harm of 19.5. In ROA the risk of progressive ROA increased in participants with persistent knee pain (OR 1.82, 95% CI 1.28–2.60), corresponding to a number needed to harm of 9.6.

Conclusions

Knee pain over 1 year predicted accelerated cartilage volume loss and increased risk of incident and progressive ROA. Early management of knee pain and controlling knee pain over time by targeting the underlying mechanisms may be important for preserving knee structure and reducing the burden of knee OA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1751-4) contains supplementary material, which is available to authorized users.

The Importance of Subchondral Bone in the Pathophysiology of Osteoarthritis

Subchondral bone plays a critical role in the pathogenesis of osteochondral disease across veterinary species. The subchondral bone is highly adaptable, with the ability to model and remodel in response to loading stresses experienced by the joint. Repetitive stress injuries within the joint can result in primary or secondary pathologic lesions within the subchondral bone, which have been recognized to contribute to the development and progression of osteoarthritis. Recent advances in diagnostic imaging, particularly volumetric imaging modalities have facilitated earlier identification of subchondral bone disease. Despite these advancements, limitations in our knowledge about subchondral bone makes treatment and prevention of these conditions challenging. The purpose of this report is to review our current understanding of subchondral bone and its relationship to osteoarthritis across veterinary species, with a specific focus in the research that has been performed in horses. It can be concluded that our current understanding of subchondral bone is advancing, and future experimental, clinical and pathologic studies will provide additional insight about subchondral bone and its relationship to joint disease.

Osteochondral Lesions of the Knee: Differentiating the Most Common Entities at MRI

Several pathologic conditions may manifest as an osteochondral lesion of the knee that consists of a localized abnormality involving subchondral marrow, subchondral bone, and articular cartilage. Although understanding of these conditions has evolved substantially with the use of high-spatial-resolution MRI and histologic correlation, it is impeded by inconsistent terminology and ambiguous abbreviations. Common entities include acute traumatic osteochondral injuries, subchondral insufficiency fracture, so-called spontaneous osteonecrosis of the knee, avascular necrosis, osteochondritis dissecans, and localized osteochondral abnormalities in osteoarthritis. Patient demographics, the clinical presentation, and the role of trauma are critical for differential diagnosis. A localized osteochondral defect can be created acutely or can develop as an end result of several chronic conditions. MRI features that aid in diagnosis include the location and extent of bone marrow edema, the presence of a fracture line, a hypointense area immediately subjacent to the subchondral bone plate, and deformity of the subchondral bone plate. These findings are essential in diagnosis of acute traumatic injuries, subchondral insufficiency fracture, and its potentially irreversible form, spontaneous osteonecrosis of the knee. If the lesion consists of a subchondral region demarcated from the surrounding bone, the demarcation should be examined for completeness and the presence of a "double-line sign" that is seen in avascular necrosis or findings of instability, which are important for proper evaluation of osteochondritis dissecans. Subchondral bone plate collapse, demonstrated by the presence of a depression or a fluid-filled cleft, can be seen in advanced stages of both avascular necrosis and subchondral insufficiency fracture, indicating irreversibility. Once the diagnosis is established, it is important to report pertinent MRI findings that may guide treatment of each condition. ^©RSNA, 2018 An earlier incorrect version of this article appeared online. This article was corrected on August 23, 2018.

Comparison of T2 Relaxation Values in Subtalar Cartilage between Patients with Lateral Instability of the Ankle Joint and Healthy Volunteers

PURPOSE

To evaluate the difference between T2 relaxation values of the subtalar cartilage in lateral ankle instability patients and healthy volunteers.

MATERIALS AND METHODS

This institutional review board-approved study included 27 preoperative magnetic resonance imaging (MRI) examinations of 26 patients who underwent Broström operations. Data of previously enrolled healthy volunteers (12 volunteers, 13 MRIs) were used as controls. Two radiologists independently measured T2 values in eight posterior subtalar joint cartilage compartments: central calcaneus anterior (CCA) and posterior (CCP), central talus anterior (CTA) and posterior (CTP), lateral calcaneus anterior (LCA) and posterior (LCP), and lateral talus anterior (LTA) and posterior (LTP). Patient and control values were compared using linear regression analysis. Inter- and intraobserver agreement was calculated.

RESULTS

Mean T2 values were significantly higher in the patient group in all measurements of subtalar joint cartilage compartments (p < 0.05) except that in LTP (p = 0.085) measured by reviewer 1. Both inter- and intraobserver agreements were excellent.

CONCLUSIONS

The T2 relaxation values of the subtalar cartilage were significantly higher in lateral ankle instability patients compared with those of controls.

KEY POINTS

• Subtalar cartilage T2 values are increased in patients with lateral ankle instability. • This trend was demonstrated regardless of the presence of talar dome cartilage lesions. • Inter-and intraobserver agreements were excellent (intraclass coefficient range, 0.765-0.951) in subtalar cartilage T2 mapping.

Inflammation and glucose homeostasis are associated with specific structural features among adults without knee osteoarthritis: a cross-sectional study from the osteoarthritis initiative

Background

Greater age and body mass index are strong risk factors for osteoarthritis (OA). Older and overweight individuals may be more susceptible to OA because these factors alter tissue turnover in menisci, articular cartilage, and bone via altered glucose homeostasis and inflammation. Understanding the role of inflammation and glucose homeostasis on structural features of early-stage OA may help identify therapeutic targets to delay or prevent the onset of OA among subsets of adults with these features. We examined if serum concentrations of glucose homeostasis (glucose, glycated serum protein [GSP]) or inflammation (C-reactive protein [CRP]) were associated with prevalent knee bone marrow lesions (BMLs) or effusion among adults without knee OA.

Methods

We conducted a cross-sectional study using baseline data from the Osteoarthritis Initiative. We selected participants who had no radiographic knee OA but were at high risk for knee OA. Blinded staff conducted assays for CRP, GSP, and glucose. Readers segmented BML volume and effusion using semi-automated programs. Our outcomes were prevalent BML (knee with a BML volume > 1 cm³) and effusion (knee with an effusion volume > 7.5 cm³). We used logistic regression models with CRP, GSP, or glucose concentrations as the predictors. We adjusted for age, sex, body mass index (BMI), and Physical Activity Scale for the Elderly (PASE) scores.

Results

We included 343 participants: mean age = 59 ± 9 years, BMI = 27.9 ± 4.5 kg/m², PASE score = 171 ± 82, and 64% female. Only CRP was associated with BML prevalence (odds ratio [OR] = 1.43, 95% confidence interval [CI] = 1.09 to 1.87). For effusion, we found an interaction between BMI and CRP: only among adults with a BMI <25 kg/m² was there a significant trend towards a positive association between CRP and effusion (OR = 1.40, 95% CI = 1.00 to 1.97). We detected a U-shaped relationship between GSP and effusion prevalence. Fasting glucose levels were not significantly associated with the presence of baseline effusion or BML.

Conclusions

Among individuals without knee OA, CRP may be related to the presence of BMLs and effusion among normal weight individuals. Abnormal GSP may be associated with effusion. Future studies should explore whether inflammation and glucose homeostasis are predictive of symptomatic knee OA.

An in vivo model of a mechanically-induced bone marrow lesion

Bone marrow lesions (BMLs) are radiologic abnormalities in magnetic resonance images of subchondral bone that are correlated with osteoarthritis. Little is known about the physiologic processes within a BML, although BMLs are associated with mechanical stress, bone tissue microdamage and increased bone remodeling. Here we establish a rabbit model to study the pathophysiology of BMLs. We hypothesized that in vivo loads that generate microdamage in cancellous bone would also create BMLs and increase bone remodeling. In vivo cyclic loading (0.2-2.0 MPa in compression for 10,000 cycles at 2 Hz) was applied to epiphyseal cancellous bone in the distal femurs of New Zealand white rabbits (n=3, right limb loaded, left limb controls experienced surgery but no loading). Magnetic resonance images were collected using short tau inversion recovery (STIR) and T1 weighted sequences at 1 and 2 weeks after surgery/loading and histological analysis of the BML was performed after euthanasia to examine tissue microdamage and remodeling. Loaded limbs displayed BMLs while control limbs showed only a small BML-like signal caused by surgery. Histological analysis of the BML at 2 weeks after loading showed increased tissue microdamage (p=0.03) and bone resorption (p=0.01) as compared to controls. The model described here displays the hallmarks of load-induced BMLs, supporting the use of the model to examine changes in bone during the development, progression and treatment of BMLs.

Hip Inflammation MRI Scoring System (HIMRISS) to predict response to hyaluronic acid injection in hip osteoarthritis

OBJECTIVE

To assess predictors of response, according to hip MRI inflammatory scoring system (HIMRISS), in a sample of patients with hip osteoarthritis (OA) treated by hyaluronic acid (HA) injection.

METHOD

Sixty patients with hip OA were included. Clinical outcomes were assessed at baseline and three months after HA injection by WOMAC. On hip MRI performed before HA injection, bone marrow lesion (BML) and synovitis were assessed by HIMRISS by four readers. The inter-reader reliability of HIMRISS was for HIMRISS total, acetabular BML, femoral BML and synovitis-effusion respectively 0.86, 0.64, 0.83 and 0.78. Associations between MRI features and clinical data were assessed. Logistic regression (univariate and multivariate) was used to explore associations between MRI features and response to HA injection, according to WOMAC50 response at three months.

RESULTS

In total, 45.5% of patients met WOMAC50 response. Five adverse events were reported. At baseline, WOMAC function correlated significantly to HIMRISS synovitis-effusion (r=0.27, P=0.03). In univariate analysis, BML femoral according to binary assessment (P=0.025), HIMRISS BML femoral (P=0.0038), HIMRISS BML acetabular (P=0.042), HIMRISS total (P=0.0092) were associated negatively with WOMAC50 response. In multivariate analysis, adjusted for age and BMI, HIMRISS femoral BML (P=0.02) and HIMRISS total (P=0.016) were negatively associated with response. At a HIMRISS threshold of<15, 82% of patients were responders, with specificity SP=0.97, sensitivity SN=0.39, and positive and negative predictive values of 0.91 and 0.64, respectively.

CONCLUSION

HIMRISS is reliable for total scores and sub-domains. It permits identification of responders to HA injection in hip OA patients.

Mesenchymal Stem Cell Alterations in Bone Marrow Lesions in Patients With Hip Osteoarthritis

Objective

In patients with osteoarthritis (OA), bone marrow lesions (BMLs) are intimately linked to disease progression. We hypothesized that aberrant multipotential stromal cell (also known as mesenchymal stem cell [MSC]) responses within bone tissue contributes to BML pathophysiology. The aim of this study was to investigate BML and non‐BML native subchondral bone MSCs for numeric, topographic, in vitro functional, and gene expression differences.

Methods

Ex vivo 3T magnetic resonance imaging (MRI) of the femoral heads of 20 patients with hip OA was performed. MRI‐determined BML and non‐BML regions were excised and enzymatically treated to extract cells and quantify MSCs using flow cytometry and colony‐forming unit–fibroblast (CFU‐F) assay. Immunohistochemical analysis was performed to determine in vivo CD271+ MSC distribution. Culture‐expanded CD271+ cells were analyzed for tripotentiality and gene expression.

Results

BML regions were associated with greater trabecular bone area and cartilage damage compared with non‐BML regions. The proportion of CD45−CD271+ MSCs was higher in BML regions compared with non‐BML regions (median difference 5.6‐fold; P < 0.001); the CFU‐F assay showed a similar trend (median difference 4.3‐fold; P = 0.013). Immunohistochemistry revealed CD271+ cell accumulation in bone adjacent to cartilage defects and areas of osteochondral angiogenesis. BML MSCs had lower proliferation and mineralization capacities in vitro and altered expression of TNFSF11/RANKL and CXCR4/stromal cell–derived factor 1 receptor. OA MSCs showed up‐regulated transcripts for CXCR1 and CCR6 compared with MSCs derived from healthy or osteoporotic bone.

Conclusion

This study is the first to show numeric and topographic alterations in native MSCs in the diseased bone of patients with hip OA. Given the associated functional perturbation of MSCs, these data suggest that subchondral bone MSC manipulation may be an OA treatment target.

New Therapeutic Targets for Osteoarthritis Pain

Osteoarthritis (OA), the most common form of arthritis, causes pain and disability, as well as emotional distress. While total joint replacement is one of the most effective treatments available for improving the quality of life in people with severe OA, it is not suitable for all patients and all joints. Current pharmacological analgesics have limited efficacy, and their use is often restricted by adverse events. Medications that might reduce pain by slowing or preventing structural disease remain elusive. Our increasing understanding of the complex mechanisms that underlie OA pain offers a wide range of potential new treatment targets. New drugs for OA pain might come from repurposing those developed for other conditions, as well as novel compounds targeting pain mechanisms specific to the joint. Here we discuss the mechanisms of OA pain and its therapeutic implications. We explore evolving treatment modalities, including combination treatment. We review recent research and patents pointing to future OA therapies. We discuss the potential for biomarkers to facilitate drug development and targeting.

Effect of Intra-articular Triamcinolone vs Saline on Knee Cartilage Volume and Pain in Patients With Knee Osteoarthritis: A Randomized Clinical Trial

IMPORTANCE

Synovitis is common and is associated with progression of structural characteristics of knee osteoarthritis. Intra-articular corticosteroids could reduce cartilage damage associated with synovitis but might have adverse effects on cartilage and periarticular bone.

OBJECTIVE

To determine the effects of intra-articular injection of 40 mg of triamcinolone acetonide every 3 months on progression of cartilage loss and knee pain.

DESIGN, SETTING, AND PARTICIPANTS

Two-year, randomized, placebo-controlled, double-blind trial of intra-articular triamcinolone vs saline for symptomatic knee osteoarthritis with ultrasonic features of synovitis in 140 patients. Mixed-effects regression models with a random intercept were used to analyze the longitudinal repeated outcome measures. Patients fulfilling the American College of Rheumatology criteria for symptomatic knee osteoarthritis, Kellgren-Lawrence grades 2 or 3, were enrolled at Tufts Medical Center beginning February 11, 2013; all patients completed the study by January 1, 2015.

INTERVENTIONS

Intra-articular triamcinolone (n = 70) or saline (n = 70) every 12 weeks for 2 years.

MAIN OUTCOMES AND MEASURES

Annual knee magnetic resonance imaging for quantitative evaluation of cartilage volume (minimal clinically important difference not yet defined), and Western Ontario and McMaster Universities Osteoarthritis index collected every 3 months (Likert pain subscale range, 0 [no pain] to 20 [extreme pain]; minimal clinically important improvement, 3.94).

RESULTS

Among 140 randomized patients (mean age, 58 [SD, 8] years, 75 women [54%]), 119 (85%) completed the study. Intra-articular triamcinolone resulted in significantly greater cartilage volume loss than did saline for a mean change in index compartment cartilage thickness of -0.21 mm vs -0.10 mm (between-group difference, -0.11 mm; 95% CI, -0.20 to -0.03 mm); and no significant difference in pain (-1.2 vs -1.9; between-group difference, -0.6; 95% CI, -1.6 to 0.3). The saline group had 3 treatment-related adverse events compared with 5 in the triamcinolone group and had a small increase in hemoglobin A1c levels (between-group difference, -0.2%; 95% CI, -0.5% to -0.007%).

CONCLUSIONS AND RELEVANCE

Among patients with symptomatic knee osteoarthritis, 2 years of intra-articular triamcinolone, compared with intra-articular saline, resulted in significantly greater cartilage volume loss and no significant difference in knee pain. These findings do not support this treatment for patients with symptomatic knee osteoarthritis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01230424.

Basic science of osteoarthritis

Osteoarthritis (OA) is a prevalent, disabling disorder of the joints that affects a large population worldwide and for which there is no definitive cure. This review provides critical insights into the basic knowledge on OA that may lead to innovative end efficient new therapeutic regimens. While degradation of the articular cartilage is the hallmark of OA, with altered interactions between chondrocytes and compounds of the extracellular matrix, the subchondral bone has been also described as a key component of the disease, involving specific pathomechanisms controlling its initiation and progression. The identification of such events (and thus of possible targets for therapy) has been made possible by the availability of a number of animal models that aim at reproducing the human pathology, in particular large models of high tibial osteotomy (HTO). From a therapeutic point of view, mesenchymal stem cells (MSCs) represent a promising option for the treatment of OA and may be used concomitantly with functional substitutes integrating scaffolds and drugs/growth factors in tissue engineering setups. Altogether, these advances in the fundamental and experimental knowledge on OA may allow for the generation of improved, adapted therapeutic regimens to treat human OA.

Assessment of subchondral bone marrow lesions in knee osteoarthritis by MRI: a comparison of fluid sensitive and contrast enhanced sequences

Background

Bone marrow lesions (BMLs) in knee osteoarthritis (OA) can be assessed using fluid sensitive and contrast enhanced sequences. The association between BMLs and symptoms has been investigated in several studies but only using fluid sensitive sequences. Our aims were to assess BMLs by contrast enhanced MRI sequences in comparison with a fluid sensitive STIR sequence using two different segmentation methods and to analyze the association between the MR findings and disability and pain.

Methods

Twenty-two patients (mean age 61 years, range 41–79 years) with medial femoro-tibial knee OA obtained MRI and filled out a WOMAC questionnaire at baseline and follow-up (median interval of 334 days). STIR, dynamic contrast enhanced-MRI (DCE-MRI) and fat saturated T1 post-contrast (T1 CE FS) MRI sequences were obtained. All STIR and T1 CE FS sequences were assessed independently by two readers for STIR-BMLs and contrast enhancing areas of BMLs (CEA-BMLs) using manual segmentation and computer assisted segmentation, and the measurements were compared. DCE-MRIs were assessed for the relative distribution of voxels with an inflammatory enhancement pattern, N_voxel, in the bone marrow. All findings were compared to WOMAC scores, including pain and overall symptoms, and changes from baseline to follow-up were analyzed.

Results

The average volume of CEA-BML was smaller than the STIR-BML volume by manual segmentation. The opposite was found for computer assisted segmentation where the average CEA-BML volume was larger than the STIR-BML volume. The contradictory finding by computer assisted segmentation was partly caused by a number of outliers with an apparent generally increased signal intensity in the anterior parts of the femoral condyle and tibial plateau causing an overestimation of the CEA-BML volume.

Both CEA-BML, STIR-BML and N_voxel were significantly correlated with symptoms and to a similar degree. A significant reduction in total WOMAC score was seen at follow-up, but no significant changes were observed for either CEA-BML, STIR-BML or N_voxel.

Conclusions

Neither the degree nor the volume of contrast enhancement in BMLs seems to add any clinical information compared to BMLs visualized by fluid sensitive sequences. Manual segmentation may be needed to obtain valid CEA-BML measurements.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1336-9) contains supplementary material, which is available to authorized users.

Bone marrow lesions in hip osteoarthritis are characterized by increased bone turnover and enhanced angiogenesis

OBJECTIVE

Bone marrow lesions (BML), previously denoted bone marrow edema, are detected as water signals by magnetic resonance imaging (MRI). Previous histologic studies were unable to demonstrate any edematous changes at the tissue level. Therefore, our aim was to investigate the underlying biological mechanisms of the water signal in MRI scans of bone affected by BML.

METHODS

Tetracycline labeling in addition to water sensitive MRI scans of 30 patients planned for total hip replacement surgery was undertaken. Twenty-one femoral heads revealed BML on MRI, while nine were negative and used as controls (CON). Guided by the MRI images cylindrical biopsies were extracted from areas with BML in the femoral heads. Tissue sections from the biopsies were subjected to histomorphometric image analyses of the cancellous bone envelope.

RESULTS

Patients with BML exhibited an average 40- and 18-fold increase of bone formation rate and mineralizing surface, respectively. Additionally, samples with BML demonstrated 2-fold reduction of marrow fat and 28-fold increase of woven bone. Immunohistochemical analysis showed a 4-fold increase of angiogenesis markers CD31 and von Willebrand Factor (vWF) in the BML-group compared to CON.

CONCLUSION

This study indicates that BML are characterized by increased bone turnover, vascularity and angiogenesis in keeping with it being a reparatory process. Thus, the water signal, which is the hallmark of BML on MRI, is most probably reflecting increased tissue vascularity accompanying increased remodeling activity.

Subchondroplasty: What the Radiologist Needs to Know

OBJECTIVE

Subchondroplasty is a novel minimally invasive procedure that is used to treat painful bone marrow lesions in patients with knee osteoarthritis or insufficiency fractures. The objective of this article is to describe the surgical technique and the pre- and postoperative imaging findings of a small case series acquired at a single center.

CONCLUSION

The radiologist should be familiar with the anticipated postoperative imaging appearances after subchondroplasty and the potential complications.

Bone repair with skeletal stem cells: rationale, progress to date and clinical application

Bone marrow (BM) contains stem cells for both hematopoietic and nonhematopoietic lineages. Hematopoietic stem cells enable hematopoiesis to occur in a controlled manner in order to accurately compensate for the loss of short- as well as long-lived mature blood cells. The physiological role of nonhematopoietic BM stem cells, often referred to as multipotential stromal cells or skeletal stem cells (SSCs), is less understood. According to an authoritative current opinion, the main function of SSCs is to give rise to cartilage, bone, marrow fat and hematopoiesis-supportive stroma, in a specific sequence during embryonic and postnatal development. This review outlines recent advances in the understanding of origins and homeostatic functions of SSCs in vivo and highlights current and future SSC-based treatments for skeletal and joint disorders.

Subchondral bone and osteoarthritis

PURPOSE OF REVIEW

Increasing evidence show that bone is a key factor in the development of osteoarthritis. This article reviews the latest results of basic and clinical research on the role of the subchondral bone in osteoarthritis.

RECENT FINDINGS

Early changes in the subchondral bone can predict subsequent symptoms or disease structural progression. New tools may help clinicians to stratify different osteoarthritis phenotypes with regards to bone remodeling status.

SUMMARY

The involvement of bone in osteoarthritis has long been thought to be secondary to cartilage damage as an adaptation of the joint. Recent clinical studies with MRI have demonstrated that bone changes could be observed in early stages of the disease, even preceding cartilage lesions. Moreover, there is clear evidence of an association between subchondral bone mineral density and osteoarthritis. The level of bone remodeling plays a critical role under mechanical loading conditions as demonstrated by consistent experimental studies. Yet new clinical biomarkers are being developed to assess the bone phenotype of osteoarthritic patients. This stratification strategy is likely to better identify groups of patients who would benefit from bone-acting drugs to decrease disease progression and improve pain and disability.

Scan-rescan precision of subchondral bone curvature maps from routine 3D DESS water excitation sequences: Data from the Osteoarthritis Initiative

BACKGROUND

Subchondral bone (SCB) undergoes changes in the shape of the articulating bone surfaces and is currently recognized as a key target in osteoarthritis (OA) treatment. The aim of this study was to present an automated system that determines the curvature of the SCB regions of the knee and to evaluate its cross-sectional and longitudinal scan-rescan precision

METHODS

Six subjects with OA and six control subjects were selected from the Osteoarthritis Initiative (OAI) pilot study database. As per OAI protocol, these subjects underwent 3T MRI at baseline and every twelve months thereafter, including a 3D DESS WE sequence. We analyzed the baseline and twenty-four month images. Each subject was scanned twice at these visits, thus generating scan-rescan information. Images were segmented with an automated multi-atlas framework platform and then 3D renderings of the bone structure were created from the segmentations. Curvature maps were extracted from the 3D renderings and morphed into a reference atlas to determine precision, to generate population statistics, and to visualize cross-sectional and longitudinal curvature changes.

RESULTS

The baseline scan-rescan root mean square error values ranged from 0.006mm(-1) to 0.013mm(-1), and from 0.007mm(-1) to 0.018mm(-1) for the SCB of the femur and the tibia, respectively. The standardized response of the mean of the longitudinal changes in curvature in these regions ranged from -0.09 to 0.02 and from -0.016 to 0.015, respectively.

CONCLUSION

The fully automated system produces accurate and precise curvature maps of femoral and tibial SCB, and will provide a valuable tool for the analysis of the curvature changes of articulating bone surfaces during the course of knee OA.