Change in MRI-detected subchondral bone marrow lesions is associated with cartilage loss: the MOST Study. A longitudinal multicentre study of knee osteoarthritis

Factors associated with trajectories of bone marrow lesions over 4 years: data from the Osteoarthritis Initiative

OBJECTIVE

To identify bone marrow lesion (BML) trajectories over 4 years and their demographic and structural predictors in middle-aged and older adults with or at increased risk of knee osteoarthritis (OA).

METHODS

A total of 614 participants (mean age 61 years, 62% female) from the Osteoarthritis Initiative cohort (OAI) were included. BMLs in 15 anatomical locations of the knee were measured annually from baseline to 4 years using the Magnetic Resonance Imaging Osteoarthritis Knee Score (MOAKS) method. BML trajectories were determined using latent class mixed models (LCMMs). Multinomial logistic regression was used to examine baseline characteristics that predicted BML trajectories.

RESULTS

Three distinct BML trajectories were identified: "Mild-stable BMLs" (25.9%), "Moderate-stable BMLs" (66.4%), and "Rapid-rise BMLs" (7.7%). Compared to the "Mild-stable BMLs" trajectory, current smokers were more likely to be in the "Moderate-stable BMLs" (odds ratio [OR] 2.089, P < 0.001) and "Rapid-rise" (OR 2.462, P < 0.001) trajectories. Moreover, female sex and meniscal tears were associated with an increased risk of being in the "Rapid-rise BMLs" trajectory (OR 2.023 to 2.504, P < 0.05). Participants who had higher education levels and drank more alcohol were more likely to be in the "Rapid-rise BMLs" trajectory (OR 1.624 to 3.178, P < 0.05) and less likely to be in the "Moderate-stable BMLs" trajectory (OR 0.668 to 0.674, P < 0.05).

CONCLUSIONS

During the 4-year follow-up, most participants had relatively stable BMLs, few had enlarged BMLs, and no trajectory of decreased BMLs was identified. Sociodemographic factors, lifestyle, and knee structural pathology play roles in predicting distinct BML trajectories.

Bone marrow lesion and 5-year incident joint surgery in patients with knee osteoarthritis: a retrospective cohort study

BACKGROUND

It is beneficial for society to discover the risk factors associated with surgery and to carry out some early interventions for patients with these risk factors. Few studies specifically explored the relationship between bone marrow lesions (BMLs) and long-term incident joint surgery.

OBJECTIVE

To investigate the association between BML severity observed in knee osteoarthritis (OA) patients' first MRI examination and incident knee surgery within 5 years. Additionally, to assess the predictive value of BMLs for the incident knee surgery.

DESIGN

Retrospective cohort study.

METHODS

We identified patients diagnosed with knee OA and treated at our institution between January 2015 and January 2018, and retrieved their baseline clinical data and first MRI examination films from the information system. Next, we proceeded to determine the Max BML grades, BML burden grades and Presence BML grades for the medial, lateral, patellofemoral, and total compartments, respectively. Multi-variable logistic regression models examined the association of the BML grades with 5-year incident knee surgery. Positive and negative predictive values (PPVs and NPVs) were determined for BML grades referring to 5-year incident knee surgery.

RESULTS

Totally, 1011 participants (knees) were found eligible to form the study population. Within the 5 years, surgery was performed on 74 knees. Max BML grade 2 and grade 3 of medial, patellofemoral and total compartments were strongly and significantly associated with incident surgery. None of the BML grades from lateral compartment was associated with incident surgery. The PPV was low and NPV was high for BMLs.

CONCLUSIONS

BMLs found in the first MRI examination were associated with 5-year incident joint surgery, except for those allocated in lateral compartments. The high NPVs imply that patients without BMLs have a low risk of requiring surgery within 5 years.

Automatic Segmentation of Bone Marrow Lesions on MRI Using a Deep Learning Method

Bone marrow lesion (BML) volume is a potential biomarker of knee osteoarthritis (KOA) as it is associated with cartilage degeneration and pain. However, segmenting and quantifying the BML volume is challenging due to the small size, low contrast, and various positions where the BML may occur. It is also time-consuming to delineate BMLs manually. In this paper, we proposed a fully automatic segmentation method for BMLs without requiring human intervention. The model takes intermediate weighted fat-suppressed (IWFS) magnetic resonance (MR) images as input, and the output BML masks are evaluated using both regular 2D Dice similarity coefficient (DSC) of the slice-level area metric and 3D DSC of the subject-level volume metric. On a dataset with 300 subjects, each subject has a sequence of 36 IWFS MR images approximately. We randomly separated the dataset into training, validation, and testing sets with a 70%/15%/15% split at the subject level. Since not every subject or image has a BML, we excluded the images without a BML in each subset. The ground truth of the BML was labeled by trained medical staff using a semi-automatic tool. Compared with the ground truth, the proposed segmentation method achieved a Pearson's correlation coefficient of 0.98 between the manually measured volumes and automatically segmented volumes, a 2D DSC of 0.68, and a 3D DSC of 0.60 on the testing set. Although the DSC result is not high, the high correlation of 0.98 indicates that the automatically measured BML volume is strongly correlated with the manually measured BML volume, which shows the potential to use the proposed method as an automatic measurement tool for the BML biomarker to facilitate the assessment of knee OA progression.

Molecular pathogenesis of OA pain: Past, present, and future

OBJECTIVE

To provide a historical perspective and narrative review on research into the molecular pathogenesis of osteoarthritis pain.

DESIGN

PubMed databases were searched for combinations of "osteoarthritis", "pain" and "animal models" for papers that represented key phases in the history of osteoarthritis pain discovery research including epidemiology, pathology, imaging, preclinical modeling and clinical trials.

RESULTS

The possible anatomical sources of osteoarthritis pain were identified over 50 years ago, but relatively slow progress has been made in understanding the apparent disconnect between structural changes captured by radiography and symptom severity. Translationally relevant animal models of osteoarthritis have aided in our understanding of the structural and molecular drivers of osteoarthritis pain, including molecules such as nerve growth factor and C-C motif chemokine ligand 2. Events leading to persistent osteoarthritis pain appear to involve a two-step process involving changes in joint innervation, including neo-innervation of the articular cartilage, as well as sensitization at the level of the joint, dorsal root ganglion and central nervous system.

CONCLUSIONS

There remains a great need for the development of treatments to reduce osteoarthritis pain in patients. Harnessing all that we have learned over the past several decades is helping us to appreciate the important interaction between structural disease and pain, and this is likely to facilitate development of new disease modifying therapies in the future.

Modern low-field MRI

This narrative review explores recent advancements and applications of modern low-field (≤ 1 Tesla) magnetic resonance imaging (MRI) in musculoskeletal radiology. Historically, high-field MRI systems (1.5 T and 3 T) have been the standard in clinical practice due to superior image resolution and signal-to-noise ratio. However, recent technological advancements in low-field MRI offer promising avenues for musculoskeletal imaging. General principles of low-field MRI systems are being introduced, highlighting their strengths and limitations compared to high-field counterparts. Emphasis is placed on advancements in hardware design, including novel magnet configurations, gradient systems, and radiofrequency coils, which have improved image quality and reduced susceptibility artifacts particularly in musculoskeletal imaging. Different clinical applications of modern low-field MRI in musculoskeletal radiology are being discussed. The diagnostic performance of low-field MRI in diagnosing various musculoskeletal pathologies, such as ligament and tendon injuries, osteoarthritis, and cartilage lesions, is being presented. Moreover, the discussion encompasses the cost-effectiveness and accessibility of low-field MRI systems, making them viable options for imaging centers with limited resources or specific patient populations. From a scientific standpoint, the amount of available data regarding musculoskeletal imaging at low-field strengths is limited and often several decades old. This review will give an insight to the existing literature and summarize our own experiences with a modern low-field MRI system over the last 3 years. In conclusion, the narrative review highlights the potential clinical utility, challenges, and future directions of modern low-field MRI, offering valuable insights for radiologists and healthcare professionals seeking to leverage these advancements in their practice.

Imaging Biomarkers of Osteoarthritis

Currently no disease-modifying osteoarthritis drug has been approved for the treatment of osteoarthritis (OA) that can reverse, hold, or slow the progression of structural damage of OA-affected joints. The reasons for failure are manifold and include the heterogeneity of structural disease of the OA joint at trial inclusion, and the sensitivity of biomarkers used to measure a potential treatment effect.This article discusses the role and potential of different imaging biomarkers in OA research. We review the current role of radiography, as well as advances in quantitative three-dimensional morphological cartilage assessment and semiquantitative whole-organ assessment of OA. Although magnetic resonance imaging has evolved as the leading imaging method in OA research, recent developments in computed tomography are also discussed briefly. Finally, we address the experience from the Foundation for the National Institutes of Health Biomarker Consortium biomarker qualification study and the future role of artificial intelligence.

Association of biochemical markers with bone marrow lesion changes on imaging-data from the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium

BACKGROUND

To assess the prognostic value of short-term change in biochemical markers as it relates to bone marrow lesions (BMLs) on MRI in knee osteoarthritis (OA) over 24 months and, furthermore, to assess the relationship between biochemical markers involved with tissue turnover and inflammation and BMLs on MRI.

METHODS

Data from the Foundation for the National Institutes of Health OA Biomarkers Consortium within the Osteoarthritis Initiative (n = 600) was analyzed. BMLs were measured according to the MRI Osteoarthritis Knee Score (MOAKS) system (0-3), in 15 knee subregions. Serum and urinary biochemical markers assessed were as follows: serum C-terminal crosslinked telopeptide of type I collagen (CTX-I), serum crosslinked N-telopeptide of type I collagen (NTX-I), urinary CTX-Iα and CTX-Iβ, urinary NTX-I, urinary C-terminal cross-linked telopeptide of type II collagen (CTX-II), serum matrix metalloproteinase (MMP)-degraded type I, II, and III collagen (C1M, C2M, C3M), serum high sensitivity propeptide of type IIb collagen (hsPRO-C2), and matrix metalloproteinase-generated neoepitope of C-reactive protein (CRPM). The association between change in biochemical markers over 12 months and BMLs over 24 months was examined using regression models adjusted for covariates. The relationship between C1M, C2M, C3M, hsPRO-C2, and CRPM and BMLs at baseline and over 24 months was examined.

RESULTS

Increases in serum CTX-I and urinary CTX-Iβ over 12 months were associated with increased odds of changes in the number of subregions affected by any BML at 24 months. Increase in hsPRO-C2 was associated with decreased odds of worsening in the number of subregions affected by any BML over 24 months. C1M and C3M were associated with BMLs affected at baseline.

CONCLUSIONS

Short-term changes in serum CTX-I, hsPRO-C2, and urinary CTX-Iβ hold the potential to be prognostic of BML progression on MRI. The association of C1M and C3M with baseline BMLs on MRI warrants further investigation.

Exploring the Potential of Lateral Wedge Insoles in Alleviating Bone Marrow Lesions in End-Stage Knee Osteoarthritis: A Preliminary Case Report

The efficacy of lateral wedge insoles (LWIs) in patients with end-stage knee osteoarthritis (OA) is unclear. A 43-year-old male underwent two anterior cruciate ligament reconstructions in his right knee and was later diagnosed with end-stage knee OA. An LWI combining arch support with a lateral heel wedge was fabricated for this patient and used over 12 months. As a result, after 12 months, the bone marrow lesion (BML), as measured by the magnetic resonance imaging Osteoarthritis Knee Score (MOAKS), was downgraded from grade 2 to grade 1. The use of LWI in a patient with end-stage knee OA showed lower co-contraction ratios in knee muscles even after 12 months. The results provide preliminary evidence suggesting the use of LWI in patients with end-stage knee OA has potential benefits for reducing BML.

Greater medial proximal tibial slope is associated with bone marrow lesions in middle-aged women with early knee osteoarthritis

BACKGROUND

Bone marrow lesion (BML) is an important magnetic resonance finding (MRI) finding that predicts knee osteoarthritis. The purpose of this study was to investigate the influence of proximal tibial morphology on BML, including the spreading root sign (SRS), in women without radiographic knee osteoarthritis (OA). It was hypothesized that varus alignment and a greater posterior tibial slopes (PTS) are associated with BML.

MATERIALS AND METHODS

A total of 359 female volunteers without knee OA who were participants in the Iwaki Health Promotion Project in 2017 or 2019 were enrolled. Participants were divided into the non-OA and early knee OA (EKOA) groups based on the Luyten's classification criteria. The presence of pathological cartilage lesions, BMLs, attritions, meniscal lesions and effusions was scored on T2-weighted fat-suppressed magnetic resonance imaging (MRI) according to the Whole-Organ MRI Scoring system. The medial proximal tibial angle (MPTA) and medial and lateral PTS (MPTS and LPTS, respectively) were measured. Regression and receiver operating characteristic (ROC) analyses were performed to reveal the relationship between BMLs and proximal tibial morphological parameters.

RESULTS

Of the 359 participants, 54 (15%) were classified as having EKOA. The prevalence of cartilage lesions, BMLs, attritions, meniscal lesions and effusions was higher in the EKOA group than in the non-OA group. The two groups had no significant difference in the proximal tibial parameters. Regression analysis revealed that age and a smaller MPTA were associated with BML in both groups. Attrition (p = 0.029) and the MPTS (p = 0.025) were positively associated with BML in the EKOA group.

CONCLUSION

The prevalence of BMLs was higher in women with EKOA and correlated with the varus and greater posterior slopes in those without radiographic knee OA.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Structural phenotypes of knee osteoarthritis: potential clinical and research relevance

A joint contains many different tissues that can exhibit pathological changes, providing many potential targets for treatment. Researchers are increasingly suggesting that osteoarthritis (OA) comprises several phenotypes or subpopulations. Consequently, a treatment for OA that targets only one pathophysiologic abnormality is unlikely to be similarly efficacious in preventing or delaying the progression of all the different phenotypes of structural OA. Five structural phenotypes have been proposed, namely the inflammatory, meniscus-cartilage, subchondral bone, and atrophic and hypertrophic phenotypes. The inflammatory phenotype is characterized by marked synovitis and/or joint effusion, while the meniscus-cartilage phenotype exhibits severe meniscal and cartilage damage. Large bone marrow lesions characterize the subchondral bone phenotype. The hypertrophic and atrophic OA phenotype are defined based on the presence large osteophytes or absence of any osteophytes, respectively, in the presence of concomitant cartilage damage. Limitations of the concept of structural phenotyping are that they are not mutually exclusive and that more than one phenotype may be present. It must be acknowledged that a wide range of views exist on how best to operationalize the concept of structural OA phenotypes and that the concept of structural phenotypic characterization is still in its infancy. Structural phenotypic stratification, however, may result in more targeted trial populations with successful outcomes and practitioners need to be aware of the heterogeneity of the disease to personalize their treatment recommendations for an individual patient. Radiologists should be able to define a joint at risk for progression based on the predominant phenotype present at different disease stages.

Imaging of knee osteoarthritis: a review of multimodal diagnostic approach

Knee osteoarthritis (KOA) is a common chronic condition among the elderly population that significantly affects the quality of life. Imaging is crucial in the diagnosis, evaluation, and management of KOA. This manuscript reviews the various imaging modalities available until now, with a little focus on the recent developments with Artificial Intelligence. Currently, radiography is the first-line imaging modality recommended for the diagnosis of KOA, owing to its wide availability, affordability, and ability to provide a clear view of bony components of the knee. Although radiography is useful in assessing joint space narrowing (JSN), osteophytes and subchondral sclerosis, it has limited effectiveness in detecting early cartilage damage, soft tissue abnormalities and synovial inflammation. Ultrasound is a safe and affordable imaging technique that can provide information on cartilage thickness, synovial fluid, JSN and osteophytes, though its ability to evaluate deep structures such as subchondral bone is limited. Magnetic resonance imaging (MRI) represents the optimal imaging modality to assess soft tissue structures. New MRI techniques are able to detect early cartilage damage measuring the T1ρ and T2 relaxation time of knee cartilage. Delayed gadolinium-enhanced MRI of cartilage, by injecting a contrast agent to enhance the visibility of the cartilage on MRI scans, can provide information about its integrity. Despite these techniques can provide valuable information about the biochemical composition of knee cartilage and can help detect early signs of osteoarthritis (OA), they may not be widely available. Computed tomography (CT) has restricted utility in evaluating OA; nonetheless, weight-bearing CT imaging, using the joint space mapping technique, exhibits potential in quantifying knee joint space width and detecting structural joint ailments. PET-MRI is a hybrid imaging technique able to combine morphological information on bone and soft tissue alterations with the biochemical changes, but more research is needed to justify its high cost and time involved. The new tools of artificial intelligence, including machine learning models, can assist in detecting patterns and correlations in KOA that may be useful in the diagnosis, grading, predicting the need for arthroplasty, and improving surgical accuracy.

Comprehensive analysis on subchondral bone marrow lesions of human osteoarthritis by integrating bulk and single-cell transcriptomes

OBJECTIVE

This study aims to demonstrate the cellular composition and underlying mechanisms in subchondral bone marrow lesions (BMLs) of knee osteoarthritis (OA).

METHODS

BMLs were assessed by MRI Osteoarthritis Knee Score (MOAKS)≥2. Bulk RNA-sequencing (bulk-seq) and BML-specific differentially expressed genes (DEGs) analysis were performed among subchondral bone samples (including OA-BML=3, paired OA-NBML=3; non-OA=3). The hub genes of BMLs were identified by verifying in independent datasets and multiple bioinformatic analyses. To further estimate cell-type composition of subchondral bone, we utilized two newly developed deconvolution algorithms (MuSiC, MCP-counter) in transcriptomic datasets, based on signatures from open-accessed single-cell RNA sequencing (scRNA-seq). Finally, competing endogenous RNA (ceRNA) and transcription factor (TF) networks were constructed through multiple predictive databases, and validated by public non-coding RNA profiles.

RESULTS

A total of 86 BML-specific DEGs (up 79, down 7) were identified. IL11 and VCAN were identified as core hub genes. The "has-miR-424-5p/lncRNA PVT1" was determined as crucial network, targeting IL11 and VCAN, respectively. More importantly, two deconvolution algorithms produced approximate estimations of cell-type composition, and the cluster of heterotopic-chondrocyte was discovered abundant in BMLs, and positively correlated with the expression of hub genes.

CONCLUSION

IL11 and VCAN were identified as the core hub genes of BMLs, and their molecular networks were determined as well. We profiled the characteristics of subchondral bone at single-cell level and determined that the heterotopic-chondrocyte was abundant in BMLs and was closely linked to IL11 and VCAN. Our study may provide new insights into the microenvironment and pathological molecular mechanism of BMLs, and could lead to novel therapeutic strategies.

Lower bone mineral density can be a risk for an enlarging bone marrow lesion: A longitudinal cohort study of Japanese women without radiographic knee osteoarthritis

OBJECTIVES

The aim is to elucidate the relationship between bone mineral density (BMD) at baseline and the change of bone marrow lesion (BML) during a 2-year follow-up (2YFU) period.

METHODS

Seventy-eight female participants (mean age: 54.9 ± 9.6 years) without radiographic knee osteoarthritis were eligible. Based on right-knee magnetic resonance imaging, maximum BML area (BMLa) was calculated by tracing the BML border. The change in BMLa was defined using the following formula: [2YFU] - [Baseline] = ΔBMLa. Positive ΔBMLa was defined as enlarged; negative ΔBMLa was defined as regressed. Dual-energy X-ray absorptiometry was performed to measure the BMD of distal radius. Young adult mean [YAM (%)] of the BMD was used for statistical analysis. Linear regression analysis was conducted with ΔBMLa as the dependent variable and YAM as the independent variable. Receiver operating characteristic curve and logistic regression analyses were conducted for YAM to predict the prevalence of BML enlargement or regression.

RESULTS

Twenty-six (33.3%) patients had enlarged BMLa, 12 (15.4%) participants showed regressing BMLa, and 40 (51.3%) patients remained stable. YAM was negatively associated with ΔBMLa (β: - 0.375, P = 0.046). The best predictor of BML enlargement risk was 85% (odds ratio: 8.383, P = 0.025).

CONCLUSIONS

Lower BMD could predict BML enlargement during a 2YFU period.

Comparative validation of the knee inflammation MRI scoring system and the MRI osteoarthritis knee score for semi-quantitative assessment of bone marrow lesions and synovitis-effusion in osteoarthritis: an international multi-reader exercise

Background

Bone marrow lesions (BMLs) and synovitis on magnetic resonance imaging (MRI) are associated with symptoms and predict degeneration of articular cartilage in osteoarthritis (OA). Validated methods for their semiquantitative assessment on MRI are available, but they all have similar scoring designs and questionable sensitivity to change. New scoring methods with completely different designs need to be developed and compared to existing methods.

Objectives

To compare the performance of new web-based versions of the Knee Inflammation MRI Scoring System (KIMRISS) with the MRI OA Knee Score (MOAKS) for quantification of BMLs and synovitis-effusion (S-E).

Design

Retrospective follow-up cohort.

Methods

We designed web-based overlays outlining regions in the knee that are scored for BML in MOAKS and KIMRISS. For KIMRISS, both BML and S-E are scored on consecutive sagittal slices. The performance of these methods was compared in an international reading exercise of 8 readers evaluating 60 pairs of scans conducted 1 year apart from cases recruited to the OA Initiative (OAI) cohort. Interobserver reliability for baseline status and baseline to 1 year change in BML and S-E was assessed by intra-class correlation coefficient (ICC) and smallest detectable change (SDC). Feasibility was assessed using the System Usability Scale (SUS).

Results

Mean change in BML and S-E was minimal over 1 year. Pre-specified targets for acceptable reliability (ICC ⩾ 0.80 and ⩾ 0.70 for status and change scores, respectively) were achieved more frequently for KIMRISS for both BML and synovitis. Mean (95% CI) ICC for change in BML was 0.88 (0.83-0.92) and 0.69 (0.60-0.78) for KIMRISS and MOAKS, respectively. KIMRISS mean SUS usability score was 85.7 and at the 95th centile of ranking for usability versus a score of 55.4 and 20th centile for MOAKS.

Conclusion

KIMRISS had superior performance metrics to MOAKS for quantification of BML and S-E. Both methods should be further compared in trials of new therapies for OA.

Re-thinking osteoarthritis pathogenesis: what can we learn (and what do we need to unlearn) from mouse models about the mechanisms involved in disease development

Efforts to develop effective disease-modifying drugs to treat osteoarthritis have so far proved unsuccessful with a number of promising drug candidates from pre-clinical studies failing to show efficacy in clinical trials. It is therefore timely to re-evaluate our current understanding of osteoarthritis pathogenesis and the similarities and differences in disease development between commonly used pre-clinical mouse models and human patients. There is substantial heterogeneity between patients presenting with osteoarthritis and mounting evidence that the pathways involved in osteoarthritis (e.g. Wnt signalling) differ between patient sub-groups. There is also emerging evidence that the pathways involved in osteoarthritis differ between the STR/ort mouse model (the most extensively studied mouse model of spontaneously occurring osteoarthritis) and injury-induced osteoarthritis mouse models. For instance, while canonical Wnt signalling is upregulated in the synovium and cartilage at an early stage of disease in injury-induced osteoarthritis mouse models, this does not appear to be the case in the STR/ort mouse. Such findings may prove insightful for understanding the heterogeneity in mechanisms involved in osteoarthritis pathogenesis in human disease. However, it is important to recognise that there are differences between mice and humans in osteoarthritis pathogenesis. A much more extensive array of pathological changes are evident in osteoarthritic joints in individual mice with osteoarthritis compared to individual patients. There are also specified differences in the pathways involved in disease development. For instance, although increased TGF-β signalling is implicated in osteoarthritis development in both mouse models of osteoarthritis and human disease, in mice, this is mainly mediated through TGF-β3 whereas in humans, it is through TGF-β1. Studies in other tissues have shown TGF-β1 is more potent than TGF-β3 in inducing the switch to SMAD1/5 signalling that occurs in osteoarthritic cartilage and that TGF-β1 and TGF-β3 have opposing effects on fibrosis. It is therefore possible that the relative contribution of TGF-β signalling to joint pathology in osteoarthritis differs between murine models and humans. Understanding the similarities and differences in osteoarthritis pathogenesis between mouse models and humans is critical for understanding the translational potential of findings from pre-clinical studies.

5-Year progression prediction of endplate defects: Utilizing the EDPP-Flow convolutional neural network based on unbalanced data

Background

Lumbar disc degeneration (LDD) is considered as one of the main causes of low back pain. For clinical diagnosis of LDD, magnetic resonance imaging (MRI) is commonly used. Schmorl's node, high intensity zone (HIZ), Modic changes, and other MRI biomarkers of intervertebral disc (IVD) degeneration are also associated with low back pain. However, the progression and natural history of these features are unclear and there is limited predictive capacity with MRI.

Purpose

We aim to establish and validate a deep learning pipeline, EDPP-Flow, for the 5-year progression prediction of Schmorl's node, HIZ, and Modic changes, based on clinical MRIs.

Materials and methods

An MRI dataset developed on 1152 volunteers was used in this study. For each volunteer, two MRI scans, at baseline and 5-year follow-up, were collected and pathology labels were annotated as present or absent (with/without pathology) by two specialists with over 10 years of clinical experience. Our pipeline contained the published MRI-SegFlow and state-of-the-art convolutional neural network for progression prediction of endplate defects. The label distribution of the dataset is unbalanced, where the number of present samples was much smaller than absent samples. The resampling and data augmentation strategies were adopted to increase the number of present samples in the training process and balance the influence of different samples on the model, which can improve the prediction accuracy.

Results

Our pipeline achieved high weighted accuracy, sensitivity, and specificity for progression prediction of Schmorl's node (89.46 ± 3.71%, 89.19 ± 2.70%, 89.72 ± 2.42%), HIZ (91.75 ± 2.48%, 93.07 ± 3.96%, 90.43 ± 2.51%), and Modic changes (87.51 ± 2.23%, 87.93 ± 1.72%, 87.10 ± 1.99%), on the unbalanced dataset (present sample's percentages of the 3 pathologies above were 4.3%, 11.7%, and 6.7%).

Conclusion

We developed and validated a deep learning pipeline, for the progression prediction of endplate defects, which showed high prediction accuracy on unbalanced data. The method has significant potential for clinical implementation.

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.

Advances in Mesenchymal Stem Cell Therapy for Osteoarthritis: From Preclinical and Clinical Perspectives

The prevalence of osteoarthritis (OA), a degenerative disorder of joints, has substantially increased in recent years. Its key pathogenic hallmarks include articular cartilage destruction, synovium inflammation, and bone remodeling. However, treatment outcomes are unsatisfactory. Until recently, common therapy methods, such as analgesic and anti-inflammatory treatments, were aimed to treat symptoms that cannot be radically cured. Mesenchymal stem cells (MSCs), i.e., mesoderm non-hematopoietic cells separated from bone marrow, adipose tissue, umbilical cord blood, etc., have been intensively explored as an emerging technique for the treatment of OA over the last few decades. According to existing research, MSCs may limit cartilage degradation in OA by interfering with cellular immunity and secreting a number of active chemicals. This study aimed to examine the potential mechanism of MSCs in the treatment of OA and conduct a thorough review of both preclinical and clinical data.

Experimental models of bone marrow lesions in ovine femoral condyles

OBJECTIVE

To develop an in vivo experimental model for bone marrow lesions (BMLs) in ovine femorotibial joints.

STUDY DESIGN

Randomized, prospective experimental study.

ANIMALS

Eighteen healthy, skeletally-mature Dorper cross ewes.

METHODS

One medial femoral condyle was penetrated with a 1.1 mm pin, and the contralateral medial femoral condyle was treated with transcutaneous extracorporeal shockwave (ESW) at 0.39 ± 0.04 mJ/mm² . Clinical examination, magnetic resonance imaging (MRI), computed tomography (CT), and histopathological analyses were used to detect and characterize the development and progression of BMLs in the medial femoral condyle at 4, 8, and 12 weeks post-surgery.

RESULTS

Pin penetration induced a BML detected on MRI within 2 weeks and lasted at least 12 weeks. BMLs were not observed in ESW-treated condyles. Histologically, BMLs were characterized by hemorrhage and inflammatory cellular infiltrate, and progressed to more dense fibrous tissue over time. Pathological changes were not observed in the articular cartilage overlying the region of BMLs.

CONCLUSIONS

Direct, focal trauma to all layers of the osteochondral unit was sufficient to create an experimentally-induced BML which persisted for at least 90 days. The protocol used for ESW in this study did not induce BMLs.

CLINICAL SIGNIFICANCE

Experimental induction of BMLs is possible and mimicked naturally occurring disease states. Volumetric imaging is a sensitive method for characterization of the dynamic nature of these lesions.

Qualitative and Quantitative Evaluation of Morpho-Metabolic Changes in Bone Cartilage Complex of Knee Joint in Osteoarthritis Using Simultaneous 18F-NaF PET/MRI—A Pilot Study

Background Articular cartilage (AC) loss and deterioration, as well as bone remodeling, are all symptoms of osteoarthritis (OA). As a result, an ideal imaging technique for researching OA is required, which must be sensitive to both soft tissue and bone health.

Objective The aim of this study was to assess the potential of simultaneous 18F sodium fluoride (18F-NaF) positron emission tomography/magnetic resonance imaging (PET/MRI) to identify as well as classify osseous metabolic abnormalities in knee OA and to see if degenerative changes in the cartilage and bone on MRI might be correlated with subchondral 18F-NaF uptake on PET.

Methods Sixteen (32 knees) volunteers with no past history of knee injury, with or without pain, were enrolled for the research from January to July 2021. The images of both knees were taken utilizing an molecular magnetic resonance (mMR) body matrix coil on a simultaneous PET/MRI biograph mMR. The acquisition was conducted after 45 minutes of intravenous infusion of 18F-NaF 185–370 MBq (5–10 mCi) over one PET bed for 40 minutes, while MRI sequences were performed simultaneously.

Results All pathologies showed significantly higher maximum standardized uptake value (SUVmax) than the background. Thirty-four subchondral magic spots were identified on 18F-NaF PET without any structural alteration on MRI. Bone marrow lesions (BMLs) and osteophytes with higher MRI osteoarthritis knee score (MOAKS) score showed higher 18F-NaF uptake (grade1˂grade2˂grade3). BMLs had corresponding AC degeneration. There was discordance between grade 1 osteophytes (86.6%), sclerosis (53.7%) and grade 1 BML in cruciate ligament insertion site (91.66%); they did not have high uptake of 18F-NaF. In case of cartilage, there was significant difference between AC grades and average subchondral SUVmax and T2* relaxometry (grade0˂grade1˂grade2˂grade3˂grade4). BMLs are much more metabolically active than other pathologies, while sclerosis is the least. We also found that the subchondral uptake was statistically increased in the areas of pathology:

Conclusion 18F-NaF PET/MRI was able to detect knee abnormalities unseen on MRI alone and simultaneously assessed metabolic and structural markers of knee OA across multiple tissues in the joint. Thus, it is a promising tool for detection of early metabolic changes in OA.

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.

Carboplasty, a Simple Tibial Marrow Technique for Knee Osteoarthritis: A Placebo-Controlled Randomized Trial

Background

Carboplasty is a new minimally invasive technique for knee osteoarthritis (OA) that consists of injecting tibial marrow aspirate into the bone-cartilage interface as well as intra-articularly.

Purpose

To compare the clinical and imaging outcomes, as well as the safety, of carboplasty for symptomatic knee OA in a placebo-controlled trial.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

The authors conducted a randomized controlled trial to compare carboplasty with placebo for the treatment of symptomatic knee OA. Patients who had failed medical treatment and had bone edema on magnetic resonance imaging (MRI) were randomized in a 1:1 ratio to carboplasty or placebo. The primary outcome of the study was the Numeric Pain Rating Scale (NPRS) for the knee at 1 year (scores range from 0 to 10, with a higher score indicating worse pain). Secondary outcomes were the Knee injury and Osteoarthritis Outcome Score (KOOS), treatment responder rate (based on achieving the minimal clinically important difference of the NPRS), MRI bone edema reduction, and treatment safety.

Results

In total, 50 patients (25 carboplasty vs 25 placebo) were enrolled and followed up with for an average of 18 months (range, 14-24 months). The average NPRS at baseline decreased from 7.1 ± 0.9 to 2.9 ± 2.1 (P < .001) at 1 year in the carboplasty group and from 7.7 ± 0.9 to 4.9 ± 2.2 (P < .001) in the placebo group. On average, patients after carboplasty improved 60% from their initial NPRS, and patients after placebo improved 37% (P = .003). Patients had a statistically significantly greater improvement from baseline in all KOOS subscales in the carboplasty group compared with the placebo group (P < .001). The responder rates were 96% for carboplasty and 76% for placebo (P = .098). Bone edema was reduced in 72% of patients in the carboplasty group and 44% of patients in the placebo group (P = .045). Neither group had adverse events related to treatment.

Conclusion

Carboplasty resulted in greater pain reduction, a significantly greater improvement in all KOOS subscales, and a similar safety profile compared with placebo in patients with symptomatic knee OA and bone edema.

Registration

ISRCTN69838191 (ISRCT Registry).

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.

Mesenchymal stem cells for subchondral bone marrow lesions: From bench to bedside

Subchondral bone marrow lesions (BMLs) are areas of disease within subchondral bone that appear as T1 hypointense and T2 hyperintense ill-defined areas of bone marrow on magnetic resonance imaging. The most common bone marrow lesions include subchondral lesions related to osteoarthritis, osteochondral defects, and avascular necrosis. Emerging therapies include autologous biologic therapeutics, in particular mesenchymal stem cells (MSCs), to maintain and improve cartilage health; MSCs have become a potential treatment option for BMLs given the unmet need for disease modification. Active areas in the preclinical research of bone marrow lesions include the paracrine function of MSCs in pathways of angiogenesis and inflammation, and the use of bioactive scaffolds to optimize the environment for implanted MSCs by facilitating chondrogenesis and higher bone volumes. A review of the clinical data demonstrates improvements in pain and functional outcomes when patients with knee osteoarthritis were treated with MSCs, suggesting that BM-MSCs can be a safe and effective treatment for patients with painful knee osteoarthritis with or without bone marrow lesions. Preliminary data examining MSCs in osteochondral defects suggest they can be beneficial as a subchondral injection alone, or as a surgical augmentation. In patients with hip avascular necrosis, those with earlier stage disease have improved outcomes when core decompression is augmented with MSCs, whereas patients in later stages post-collapse have equivalent outcomes with or without MSC treatment. While the evidence for the use of MSCs in conditions with associated bone marrow lesions seems promising, there remains a need for continued investigation into this treatment as a viable treatment option.

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Common BMLs include osteoarthritis, osteochondral defects, and avascular necrosis.

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Patients with knee osteoarthritis treated with MSCs show improved pain and function.

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MSCs used as subchondral injection or surgical augmentation in osteochondral defects

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Improved outcomes of early hip avascular necrosis after core decompression with MSCs

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Additional preclinical and clinical evidence of MSCs as treatment for BMLs is needed.

Endothelial PDGF-BB/PDGFR-β signaling promotes osteoarthritis by enhancing angiogenesis-dependent abnormal subchondral bone formation

The mechanisms that coordinate the shift from joint homeostasis to osteoarthritis (OA) remain unknown. No pharmacological intervention can currently prevent the progression of osteoarthritis. Accumulating evidence has shown that subchondral bone deterioration is a primary trigger for overlying cartilage degeneration. We previously found that H-type vessels modulate aberrant subchondral bone formation during the pathogenesis of OA. However, the mechanism responsible for the elevation of H-type vessels in OA is still unclear. Here, we found that PDGFR-β expression, predominantly in the CD31^hiEmcn^hi endothelium, was substantially elevated in subchondral bones from OA patients and rodent OA models. A mouse model of OA with deletion of PDGFR-β in endothelial cells (ECs) exhibited fewer H-type vessels, ameliorated subchondral bone deterioration and alleviated overlying cartilage degeneration. Endothelial PDGFR-β promotes angiogenesis through the formation of the PDGFR-β/talin1/FAK complex. Notably, endothelium-specific inhibition of PDGFR-β by local injection of AAV9 in subchondral bone effectively attenuated the pathogenesis of OA compared with that of the vehicle-treated controls. Based on the results from this study, targeting PDGFR-β is a novel and promising approach for the prevention or early treatment of OA.

Transient Hip Osteoporosis: Etiopathogenetic, Clinical, and Imaging Approach

Transient Hip Osteoporosis (THO) is a relatively rare, benign, and usually self-limiting disease caused by bone marrow edema, depicted on MRI. It presents with sudden onset of pain or may be asymptomatic. Given the poor coverage of this subject in the relevant international literature and the lack of sufficient understanding of the aetiopathogenic mechanisms underlying this condition, no established diagnostic guidelines are available, leading to frequent under- or overdiagnosis. Therefore, great care should be taken to provide a correct differential diagnosis in order to achieve proper treatment. The international literature from 1990 to 2020 was searched in the PubMed and Google Scholar databases. The keywords: bone marrow edema, transient osteoporosis, osteonecrosis, and aetiopathogenesis were used, and original studies and review articles in English and Greek language were retrieved. Based on evidence provided in the current literature, this article offers a definition and describes in a concise and comprehensive manner the aetiopathogenesis, symptomatology, imaging findings, and differential diagnosis of the disease, in order to provide physicians with a sound knowledge of the condition, necessary to their clinical practice.

Heterogeneity of cartilage damage in Kellgren and Lawrence grade 2 and 3 knees: the MOST study

OBJECTIVE

Eligibility for clinical trials in osteoarthritis (OA) is usually limited to Kellgren-Lawrence (KL) grades 2 and 3 knees. Our aim was to describe the prevalence and severity of cartilage damage in KL 2 and 3 knees by compartment and articular subregion.

DESIGN

The Multicenter Osteoarthritis (MOST) study is a cohort study of individuals with or at risk for knee OA. All baseline MRIs with radiographic disease severity KL2 and 3 were included. Knee MRIs were read for cartilage damage in 14 subregions. We determined the frequencies of no, any and widespread full-thickness cartilage damage by knee compartment, and the prevalence of any cartilage damage in 14 articular subregions.

RESULTS

665 knees from 665 participants were included (mean age 63.8 ± 7.9 years, 66.5% women). 372 knees were KL2 and 293 knees were KL3. There was no cartilage damage in 78 (21.0%) medial tibio-femoral joint (TFJ), 157 (42.2%) lateral TFJ and 62 (16.7%) patello-femoral joint (PFJ) compartments of KL2 knees, and 17 (5.8%), 115 (39.3%) and 35 (12.0%) compartments, respectively, of KL3 knees. There was widespread full-thickness damage in 94 (25.3%) medial TFJ, 36 (9.7%) lateral TFJ and 176 (47.3%) PFJ compartments of KL2 knees, and 217 (74.1%), 70 (23.9%) and 104 (35.5%) compartments, respectively, of KL3 knees. The subregions most likely to have any damage were central medial femur (80.5%), medial patella (69.8%) and central medial tibia (69.9).

CONCLUSIONS

KL2 and KL3 knees vary greatly in cartilage morphology. Heterogeneity in the prevalence, severity and location of cartilage damage in in KL2 and 3 knees should be considered when planning disease modifying trials for knee OA.

The osteoarthritis bone score (OABS): a new histological scoring system for the characterisation of bone marrow lesions in osteoarthritis

OBJECTIVES

Bone marrow lesions (BMLs) are associated with pain in osteoarthritis (OA), but histological scores for OA focus on cartilage pathology. We developed a new scoring system, the Osteoarthritis Bone Score (OABS), to characterise OA-related BMLs.

METHODS

BML/non-BML tissues identified by Magnetic Resonance Imaging (MRI) in 10 knee OA subjects were harvested at total knee replacement (TKR). Osteochondral tissue from a further 140 TKR and 23 post-mortem (PM) cases was assessed. Histological features distinguishing MRI-defined BML/non-BML tissues on qualitative analysis were classified as present (0) or absent (1), summated for the OABS, validated by Rasch analysis and sensitivity to distinguish between sample groups. Immunohistochemistry for PGP9.5 assessed innervation.

RESULTS

Subchondral characteristics associated with BML tissues were cysts, fibrosis, hypervascularity, cartilage islands, trabecular thickening, loss of tidemark integrity and inflammatory cell infiltration. PGP9.5 immunoreactive perivascular nerves were associated with BMLs. OABS performed well as a measurement tool, displayed good reliability (Cronbach alpha = 0.68), had a 2-factor structure (trabecular/non-trabecular), with moderate correlation between the two factors (r = 0.56, 95% CI 0.46, 0.65). OABS scores were higher in TKR than PM cases with chondropathy, median difference 1.5 (95% CI -2, 0). OABS and Mankin scores similarly distinguished TKR from non-OA controls, but only OABS was higher in BML than non-BML tissues, median difference -4 (95% CI -5 to -2).

CONCLUSIONS

OABS identifies and validly quantifies histopathological changes associated with OA BMLs. Histopathology underlying BMLs may represent 2 inter-related pathological processes affecting trabecular/non-trabecular structures. Increased vascularity/perivascular innervation in BMLs might contribute to pain.

PGE2 activates EP4 in subchondral bone osteoclasts to regulate osteoarthritis

Prostaglandin E2 (PGE2), a major cyclooxygenase-2 (COX-2) product, is highly secreted by the osteoblast lineage in the subchondral bone tissue of osteoarthritis (OA) patients. However, NSAIDs, including COX-2 inhibitors, have severe side effects during OA treatment. Therefore, the identification of novel drug targets of PGE2 signaling in OA progression is urgently needed. Osteoclasts play a critical role in subchondral bone homeostasis and OA-related pain. However, the mechanisms by which PGE2 regulates osteoclast function and subsequently subchondral bone homeostasis are largely unknown. Here, we show that PGE2 acts via EP4 receptors on osteoclasts during the progression of OA and OA-related pain. Our data show that while PGE2 mediates migration and osteoclastogenesis via its EP2 and EP4 receptors, tissue-specific knockout of only the EP4 receptor in osteoclasts (EP4^LysM) reduced disease progression and osteophyte formation in a murine model of OA. Furthermore, OA-related pain was alleviated in the EP4^LysM mice, with reduced Netrin-1 secretion and CGRP-positive sensory innervation of the subchondral bone. The expression of platelet-derived growth factor-BB (PDGF-BB) was also lower in the EP4^LysM mice, which resulted in reduced type H blood vessel formation in subchondral bone. Importantly, we identified a novel potent EP4 antagonist, HL-43, which showed in vitro and in vivo effects consistent with those observed in the EP4^LysM mice. Finally, we showed that the Gαs/PI3K/AKT/MAPK signaling pathway is downstream of EP4 activation via PGE2 in osteoclasts. Together, our data demonstrate that PGE2/EP4 signaling in osteoclasts mediates angiogenesis and sensory neuron innervation in subchondral bone, promoting OA progression and pain, and that inhibition of EP4 with HL-43 has therapeutic potential in OA.

Percussion test: description and diagnostic accuracy of a new manual test for bone marrow edema of the knee

Background

Prompt diagnosis of bone marrow lesion (BML) is difficult but critical for correct treatment. Magnetic resonance imaging is the gold standard, although expensive and time consuming. Simple and reliable clinical test for BML detection is lacking. Aim of the study is to describe a new manual clinical test called Percussion Test (PT) and to statistically determine its diagnostic accuracy in BML, compared to MRI imaging.

Methods

After evaluation of the inclusion and exclusion criteria, 218 consecutive patients with unilateral knee pain and age comprised between 18 and 80 years old were enrolled in our observational prospective study. Informed consent was obtained for each patient. After medical history collection, PT was performed by a single operator as described. MRI was performed in the affected knee to detect the presence of BML. Coherence in PT and MRI assessment was evaluated in each quadrant of the knee via contingency tables, as sensitivity, specificity, NPV, PPV and diagnostic accuracy were calculated.

Results

No correlation with a positive PT was demonstrated for the covariables gender (p = 0.156), age (p = 0.272) and BMI (p = 0.639).

PT showed a sensitivity ranging from 60.6 (40.6–80.6) to 79.5 (63.0–96.0) and a specificity ranging from 85.7 (80.0–91.5) to 96.0 (93.1–98.9) depending on knee quadrant. Diagnostic accuracy ranged from 81.6 (75.9–86.6) to 89.4 (84.6–93.2), and p-value was < 0.00001 in a chi-squared analysis for all quadrants.

Conclusions

PT showed sensitivity and specificity values that are comparable with other clinical tests routinely adopted in clinical practice. In the absence of other reliable clinical test, PT has the potential to become a useful bedside tool in the diagnosis and management of BMLs.

Cartilage Biomarkers Coll2-1 and Coll2-1NO2 Are Associated with Knee OA MRI Features and Are Helpful in Identifying Patients at Risk of Disease Worsening

OBJECTIVE

To assess the cross-sectional association between serum levels of Coll2-1 and Coll2-1NO2, two cartilage degradation biomarkers; the burden of magnetic resonance imaging (MRI) features and clinical outcomes; and to evaluate the predictive value of these biomarkers on progression.

DESIGN

A total of 121 subjects with knee osteoarthritis (OA) were followed during 1 year with pain, function, and MRI assessment (PRODIGE study). Type II collagen-specific biomarker Coll2-1 and its nitrated form Coll2-1NO2 were directly measured in serum using immunoassays at baseline and after 3-, 6-, and 12-month follow-up.

RESULTS

Serum Coll2-1 and Coll2-1NO2 were correlated with several baseline knee features quantified with Whole-Organ Magnetic Resonance Imaging Score (WORMS). Coll2-1 was significantly correlated with periarticular cysts/bursitis (ρ = 0.29, P < 0.01), subarticular bone attrition (ρ = 0.25, P = 0.01), subarticular cysts (ρ = 0.24, P = 0.02), and articular cartilage integrity (ρ = 0.23, P = 0.03) WORMS subscores for the whole joint as well as with the medial femorotibial joint sum score (ρ = 0.26, P = 0.01) and medial femorotibial joint cartilage (ρ = 0.23, P = 0.02). Coll2-1NO2 correlated with WORMS total score (ρ = 0.23, P = 0.02), WORMS scores in the patellofemoral (ρ = 0.23, P = 0.02) and medial femorotibial compartments (ρ = 0.21, P = 0.03), with osteophytes scores (ρ = 0.27, P < 0.01), subarticular cysts (ρ = 0.24, P = 0.019), and intraarticular loose bodies (ρ = 0.27, P = 0.007). Baseline Coll2-1NO2 was higher in subjects with a pain worsening (426.4 pg/mL [278.04-566.95]) as compared to non-progressors (306.84 pg/mL [200.37-427.84]) over 1 year (AUC = 0.655, P = 0.015).

CONCLUSION

Serum cartilage biomarkers Coll2-1 and Coll2-1NO2 are associated with several knee OA features quantified with WORMS. Our study also shows that the baseline value of Coll2-1NO2 is positively associated with pain worsening.

Betaine Attenuates Osteoarthritis by Inhibiting Osteoclastogenesis and Angiogenesis in Subchondral Bone

Osteoarthritis (OA) is the most common type of arthritis with no effective therapy. Subchondral bone and overlying articular cartilage are closely associated and function as “osteo-chondral unit” in the joint. Abnormal mechanical load leads to activated osteoclast activity and increased bone resorption in the subchondral bone, which is implicated in the onset of OA pathogenesis. Thus, inhibiting subchondral bone osteoclast activation could prevent OA onset. Betaine, isolated from the Lycii Radicis Cortex (LRC), has been demonstrated to exert anti-inflammatory, antifibrotic and antiangiogenic properties. Here, we evaluated the effects of betaine on anterior cruciate ligament transection (ACLT)-induced OA mice. We observed that betaine decreased the number of matrix metalloproteinase 13 (MMP-13)-positive and collagen X (Col X)-positive cells, prevented articular cartilage proteoglycan loss and lowered the OARSI score. Betaine decreased the thickness of calcified cartilage and increased the expression level of lubricin. Moreover, betaine normalized uncoupled subchondral bone remodeling as defined by lowered trabecular pattern factor (Tb.pf) and increased subchondral bone plate thickness (SBP). Additionally, aberrant angiogenesis in subchondral bone was blunted by betaine treatment. Mechanistically, we demonstrated that betaine suppressed osteoclastogenesis in vitro by inhibiting reactive oxygen species (ROS) production and subsequent mitogen-activated protein kinase (MAPK) signaling. These data demonstrated that betaine attenuated OA progression by inhibiting hyperactivated osteoclastogenesis and maintaining microarchitecture in subchondral bone.

Improvement of clinical and radiological outcomes of root repair patients with advanced articular cartilage degeneration and osteoarthritis

PURPOSE

The main purpose of this study was to investigate clinical and radiological outcomes of medial meniscus posterior root tear (MMPRT) repair in knees with advanced articular cartilage degeneration and osteoarthritis compared to those with minimal degenerative change.

METHODS

Thirty-three knees underwent MMPRT repair using an arthroscopic pullout repair tibial tunnel technique. Clinical scores including Lysholm Score, International Knee Documentation Committee (IKDC) Score and Knee injury and Osteoarthritis Outcome (KOOS) Score were collected preoperatively and sequentially at 6 months, 12 months and mean final follow-up of 39.4 months. Kellgren-Lawrence (K-L) osteoarthritis grade, Outerbridge classification of cartilage degeneration and the presence of bone marrow oedema on MRI were also evaluated.

RESULTS

All clinical scores improved at final follow-up for knees with K-L grade ≥ 2 osteoarthritis (p < 0.001), with no significant difference compared to K-L 0/1. Patients with Outerbridge class 3/4 cartilage degeneration also reported improvements in clinical scores, albeit lower than those with class 2 degeneration (p < 0.05). During recovery, the majority of patients reported clinical improvements by 6 months, and six patients further improved by at least 15 points in IKDC score between 6 and 12 months. Osteoarthritis progressed in 10 of 31 knees (32%), with an overall mean pre-operative K-L grade of 1.6 ± 0.9 compared to 2.0 ± 0.9 at final follow-up (n.s.). No knees progressed to K-L 4 or underwent re-operation. Pre-operative bone marrow oedema was present in 17 knees (52%), all of which had signal localised to the medial tibia or femur. Oedema had resolved in all but 5 knees post-operatively (p < 0.01).

CONCLUSION

Arthroscopic repair of medial meniscus posterior root tears is associated with improved outcomes in knees with advanced cartilage degeneration and osteoarthritis. Meaningful improvements in clinical outcomes can be achieved beyond 6 months, thus success of the operation is best determined at the 12-month mark. Oedema signal significantly improved post-operatively, however a relatively high proportion of knees had K-L progression.

LEVEL OF EVIDENCE

IV - Case Series.

Assessment of bone marrow oedema-like lesions using MRI in patellofemoral knee osteoarthritis: comparison of different MRI pulse sequences

OBJECTIVE

To compare bone marrow oedema-like lesion (BML) volume in subjects with symptomatic patellofemoral (PF) knee osteoarthritis (OA) using four different MRI sequences and to determine reliability of BML volume assessment using these sequences and their correlation with pain.

METHODS

76 males and females (mean age 55.8 years) with symptomatic patellofemoral knee OA had 1.5 T MRI scans. PD fat suppressed (FS), STIR, contrast-enhanced (CE) T1W FS, and 3D T1W fast field echo (FFE) sequences were obtained. All sequences were assessed by one reader, including repeat assessment of 15 knees using manual segmentation and the measurements were compared. We used random-effects panel linear regression to look for differences in the log-transformed BML volume (due to positive skew in the BML volume distribution) between sequences and to determine associations between BML volumes and knee pain.

RESULTS

58 subjects had PF BMLs present on at least one sequence. Median BML volume measured using T1W FFE sequence was significantly smaller (224.7 mm3, interquartile range [IQR] 82.50-607.95) than the other three sequences. BML volume was greatest on the CE sequence (1129.8 mm3, IQR 467.28-3166.02). Compared to CE sequence, BML volumes were slightly lower when assessed using PDFS (proportional difference = 0.79; 95% confidence interval [CI] 0.62, 1.01) and STIR sequences (proportional difference = 0.85; 95% CI 0.67, 1.08). There were strong correlations between BML volume on PDFS, STIR, and CE T1W FS sequences (ρs = 0.98). Correlations were lower between these three sequences and T1W FFE (ρs = 0.80-0.81). Intraclass correlation coefficients were excellent for proton density fat-suppressed, short-tau inversion recovery, and CE T1W FS sequences (0.991-0.995), while the ICC for T1W FFE was good at 0.88. We found no significant association between BML volumes assessed using any of the sequences and knee pain.

CONCLUSION

T1W FFE sequences were less reliable and measured considerably smaller BML volume compared to other sequences. BML volume was larger when assessed using the contrast enhanced T1W FS though not statistically significantly different from BMLs when assessed using PDFS and STIR sequences.

ADVANCES IN KNOWLEDGE

This is the first study to assess BMLs by four different MRI pulse sequences on the same data set, including different fluid sensitive sequences and gradient echo type sequence.

Relationship between abnormalities detected by magnetic resonance imaging and knee symptoms in early knee osteoarthritis

We investigated the prevalence of magnetic resonance imaging (MRI) findings and their relationship with knee symptoms in women without radiographic evidence of knee osteoarthritis (KOA). This cross-sectional cohort study included 359 Japanese women without radiographic evidence of KOA (Kellgren‒Lawrence grade < 2). All participants underwent T2-weighted fat-suppressed MRI of their knees. Structural abnormalities (cartilage damage, bone marrow lesions [BMLs], subchondral cysts, bone attrition, osteophytes, meniscal lesions, and synovitis) were scored according to the whole-organ MRI score method. Knee symptoms were evaluated using the Knee Injury and Osteoarthritis Outcome Score. Participants were divided into early and non-KOA groups based on early KOA classification criteria. Logistic regression analysis was performed to evaluate the relationship between MRI abnormalities and knee symptoms. Cartilage damage was the most common abnormality (43.5%). The prevalences of cartilage damage, BMLs, subchondral cysts, bone attrition, meniscal lesions, and synovitis were higher in patients with early KOA than in those without. Synovitis (odds ratio [OR] 2.254, P = 0.002) and meniscal lesions (OR 1.479, P = 0.031) were positively associated with the presence of early KOA. Synovitis was most strongly associated with knee pain and might be a therapeutic target in patients with early KOA.

Age-related alterations and senescence of mesenchymal stromal cells: Implications for regenerative treatments of bones and joints

The most common clinical manifestations of age-related musculoskeletal degeneration are osteoarthritis and osteoporosis, and these represent an enormous burden on modern society. Mesenchymal stromal cells (MSCs) have pivotal roles in musculoskeletal tissue development. In adult organisms, MSCs retain their ability to regenerate tissues following bone fractures, articular cartilage injuries, and other traumatic injuries of connective tissue. However, their remarkable regenerative ability appears to be impaired through aging, and in particular in age-related diseases of bones and joints. Here, we review age-related alterations of MSCs in musculoskeletal tissues, and address the underlying mechanisms of aging and senescence of MSCs. Furthermore, we focus on the properties of MSCs in osteoarthritis and osteoporosis, and how their changes contribute to onset and progression of these disorders. Finally, we consider current treatments that exploit the enormous potential of MSCs for tissue regeneration, as well as for innovative cell-free extracellular-vesicle-based and anti-aging treatment approaches.

Intra-Articular Injections of Platelet-Rich Plasma, Adipose Mesenchymal Stem Cells, and Bone Marrow Mesenchymal Stem Cells Associated With Better Outcomes Than Hyaluronic Acid and Saline in Knee Osteoarthritis: A Systematic Review and Network Meta-analysis

PURPOSE

To perform a network meta-analysis to evaluate clinical efficacy and treatment-related adverse events (AEs) of intra-articular hyaluronic acid (HA), leukocyte-poor platelet-rich plasma (LP-PRP), leukocyte-rich platelet-rich plasma (LR-PRP), bone marrow mesenchymal stem cells (BM-MSCs), adipose mesenchymal stem cells (AD-MSCs), and saline (placebo) during 6 and 12 months of follow-up.

METHODS

Six databases were searched for randomized controlled trials. Outcome assessment included the visual analog scale (VAS) score, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) pain subscore, WOMAC score, International Knee Documentation Committee (IKDC) subjective score, and treatment-related AEs. Main inclusion criteria were at least one of the aforementioned outcome measurements, a minimum follow-up period of 5 months, and >80% patient follow-up. Treatments combined with the use of other operations or drugs were excluded.

RESULTS

Forty-three studies meeting the eligibility criteria were included. At 6 months, VAS scores and WOMAC pain subscores showed that AD-MSCs were the best treatment option (surface under the cumulative ranking curve [SUCRA] = 96.7%, SUCRA = 85.3%, respectively). According to WOMAC scores and subjective IKDC scores, LP-PRP was the most effective treatment (SUCRA = 86.0%, SUCRA = 80.5%, respectively). At 12 months, only AD-MSCs were associated with improved VAS scores compared with the placebo (weighted mean difference [WMD] = -20.93, 95% credibility interval [CrI], -41.71 to -0.78). Both LP-PRP and AD-MSCs were more beneficial than the placebo for improving WOMAC pain subscores (WMD = -30.08; 95% CrI, -53.59 to -6.25; WMD = -34.85; 95% CrI, -68.03 to -4.86, respectively). For WOMAC scores, LP-PRP and LR-PRP were significantly associated with improved WOMAC scores compared with the placebo after sensitivity analysis was performed (WMD = -35.26; 95% CrI, -64.99 to -6.01; WMD = -38.69; 95% CrI, -76.21 to -2.76). LP-PRP exhibited relatively better efficacy in improving subjective IKDC scores than the placebo (WMD = 13.67; 95% CrI, 4.05-23.39). Regarding safety, all treatments except for LP-PRP (relative risk = 1.83; 95% CrI, 0.89-4.64) increased treatment-related AEs compared with the placebo.

CONCLUSIONS

Based on the results of current research findings, during 6 months of follow-up, AD-MSCs relieved pain the best; LP-PRP was most effective for functional improvement. During the 12-month follow-up, both AD-MSCs and LP-PRP showed potential clinical pain relief effects; functional improvement was achieved with LP-PRP. Unfortunately, AD-MSC/LP-PRP functional comparisons were only based on WOMAC scores due to missing IKDC scores. BM-MSCs seem to have potentially beneficial effects, but the wide credibility interval makes it impossible to draw a well-supported conclusion. HA viscosupplementation clinical efficacy was lower than that of biological agents during follow-up, which may be related to the properties of the drugs. Considering the evaluation of treatment-related AEs, LP-PRP is the most advisable choice; although the AEs of these treatments are not serious, they may affect treatment compliance and satisfaction.

LEVEL OF EVIDENCE

Level II, meta-analysis of Level I and II studies.

The association between change in bone marrow lesion size and change in tibiofemoral cartilage volume and knee symptoms

OBJECTIVE

To describe the association between change in subchondral bone marrow lesions (BMLs) and change in tibiofemoral cartilage volume and knee symptoms in patients with symptomatic knee OA.

METHODS

In total, 251 participants (mean 61.7 years, 51% female) were included. Tibiofemoral cartilage volume was measured at baseline and 24 months, and BML size at baseline, 6 and 24 months. Knee pain and function scores were evaluated at baseline, 6 and 24 months. Change in total and compartment-specific BML size was categorized according to the Least Significance Criterion. Linear mixed-effects models were used to evaluate the associations of change in BMLs over 6 and 24 months with change in cartilage volume over 24 months and knee symptoms over 6 and 24 months.

RESULTS

Total BML size enlarged in 26% of participants, regressed in 31% and remained stable in 43% over 24 months. Compared with stable BMLs in the same compartment, enlarging BMLs over 24 months were associated with greater cartilage loss (difference: -53.0mm3, 95% CI: -100.0, -6.0), and regressing BMLs were not significantly associated with reduced cartilage loss (difference: 32.4mm3, 95% CI: -8.6, 73.3) over 24 months. Neither enlargement nor regression of total BML size over 6 and 24 months was associated with change in knee pain and function over the same time intervals.

CONCLUSIONS

In subjects with symptomatic knee osteoarthritis and BMLs, enlarging BMLs may lead to greater cartilage loss but regressing lesions are not associated with reduced cartilage loss while neither is associated with change in knee symptoms.

Inhibition of SDF-1/CXCR4 Axis to Alleviate Abnormal Bone Formation and Angiogenesis Could Improve the Subchondral Bone Microenvironment in Osteoarthritis

The pathogenesis of the osteoarthritis (OA) is complex. Abnormal subchondral bone metabolism is an important cause of this disease. Further understanding on the pathology of the subchondral bone in OA may provide a new therapy. This research is about to investigate the role of SDF-1 in the subchondral bone during the pathological process of OA. In vitro, Transwell was used to test the migratory ability of bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs). Western blot presented the protein level after SDF-1 treatment in BMSCs and HUVESs. Alizarin red was used to assess the ability of osteogenic differentiation. To inhibit SDF-1 signaling pathway in vivo, AMD3100 (SDF-1 receptor blocker) was continuously delivered via miniosmotic pump for 4 weeks in mice after performing anterior cruciate ligament transaction surgery. Micro-CT, histology staining, immunofluorescence, immunohistochemistry, and TRAP staining were used to assess the role of SDF-1 on osteogenesis and angiogenesis in the subchondral bone. Our results showed that SDF-1 could recruit BMSCs, activate the p-ERK pathway, and enhance osteogenic differentiation. SDF-1 promoted the ability of proliferation, migration and tube formation of HUVECs by activating the ERK and AKT signaling pathways. In an animal study, inhibition of SDF-1/CXCR4 axis could significantly reduce subchondral osteogenesis differentiation and H-type vessel formation. Furthermore, the AMD3100-treated group showed less cartilage destruction and bone resorption. Our research shows that SDF-1 alters the microenvironment of the subchondral bone by promoting osteoid islet formation and abnormal H-type angiogenesis in the subchondral bone, resulting in articular cartilage degeneration.

Peripheral pain mechanisms in osteoarthritis

There is a well-established historical observation that structural joint damage by plain X-ray correlates poorly with symptomatic disease in osteoarthritis (OA). This is often attributed to the inability to visualise soft-tissue pathology within the joint and the recognition of heterogeneous patient factors that drive central pain sensitisation. A major issue is the relative paucity of mechanistic studies in which molecular pathogenesis of pain is interrogated in relation to tissue pathology. Nonetheless, in recent years, three broad approaches have been deployed to attempt to address this: correlative clinical studies of peripheral and central pain outcomes using magnetic resonance imaging, where soft-tissue processes can be visualised; molecular studies on tissue from patients with OA; and careful molecular interrogation of preclinical models of OA across the disease time course. Studies have taken advantage of established clinical molecular targets such as nerve growth factor. Not only is the regulation of nerve growth factor within the joint being used to explore the relationship between tissue pathology and the origins of pain in OA, but it also provides a core model on which other molecules present within the joint can modulate the pain response. In this narrative review, how molecular and pathological tissue change relates to joint pain in OA will be discussed. Finally, a model for how tissue damage may lead to pain over the disease course will be proposed.

RNA Sequencing Reveals Interacting Key Determinants of Osteoarthritis Acting in Subchondral Bone and Articular Cartilage: Identification of IL11 and CHADL as Attractive Treatment Targets

OBJECTIVE

To identify key determinants of the interactive pathophysiologic processes in subchondral bone and cartilage in osteoarthritis (OA).

METHODS

We performed RNA sequencing on macroscopically preserved and lesional OA subchondral bone from patients in the Research Arthritis and Articular Cartilage study who underwent joint replacement surgery due to OA (n = 24 sample pairs: 6 hips and 18 knees). Unsupervised hierarchical clustering and differential expression analyses were conducted. Results were combined with data on previously identified differentially expressed genes in cartilage (partly overlapping samples) as well as data on recently identified OA risk genes.

RESULTS

We identified 1,569 genes that were significantly differentially expressed between lesional and preserved subchondral bone, including CNTNAP2 (fold change [FC] 2.4, false discovery rate [FDR] 3.36 × 10^-5 ) and STMN2 (FC 9.6, FDR 2.36 × 10^-3 ). Among these 1,569 genes, 305 were also differentially expressed, and with the same direction of effect, in cartilage, including the recently recognized OA susceptibility genes IL11 and CHADL. Upon differential expression analysis with stratification for joint site, we identified 509 genes that were exclusively differentially expressed in subchondral bone of the knee, including KLF11 and WNT4. These genes that were differentially expressed exclusively in the knee were enriched for involvement in epigenetic processes, characterized by, e.g., HIST1H3J and HIST1H3H.

CONCLUSION

IL11 and CHADL were among the most consistently differentially expressed genes OA pathophysiology-related genes in both bone and cartilage. As these genes were recently also identified as robust OA risk genes, they classify as attractive therapeutic targets acting on 2 OA-relevant tissues.

Long-term Effect of a Single Subcritical Knee Injury: Increasing the Risk of Anterior Cruciate Ligament Rupture and Osteoarthritis

BACKGROUND

Rupture of the anterior cruciate ligament (ACL) is a well-known risk factor for the development of posttraumatic osteoarthritis (PTOA), but patients with the "same injury" can have vastly different trajectories for the onset and progression of disease. Minor subcritical injuries preceding the critical injury event may drive this disparity through preexisting tissue pathologies and sensory changes.

PURPOSE

To investigate the role of subcritical injury on ACL rupture risk and PTOA through the evaluation of pain behaviors, joint mechanics, and tissue structural change in a mouse model of knee injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten-week-old male C57BL/6J mice were allocated to naïve control and subcritical knee injury groups. Injury was induced by a single mechanical compression to the right hindlimb, and mice were evaluated using joint histopathology, anteroposterior joint biomechanics, pain behaviors (mechanical allodynia and hindlimb weightbearing), and isolated ACL tensile testing to failure at 1, 2, 4, or 8 weeks after injury.

RESULTS

Subcritical knee injury produced focal osteochondral lesions in the patellofemoral and lateral tibiofemoral compartments with no resolution for the duration of the study (8 weeks). These lesions were characterized by focal loss of proteoglycan staining, cartilage structural change, chondrocyte pathology, microcracks, and osteocyte cell loss. Injury also resulted in the rapid onset of allodynia (at 1 week), which persisted over time and reduced ACL failure load (P = .006; mean ± SD, 7.91 ± 2.01 N vs 9.37 ± 1.01 N in naïve controls at 8 weeks after injury), accompanied by evidence of ACL remodeling at the femoral enthesis.

CONCLUSION

The present study in mice establishes a direct effect of a single subcritical knee injury on the development of specific joint tissue pathologies (osteochondral lesions and progressive weakening of the ACL) and allodynic sensitization. These findings demonstrate a predisposition for secondary critical injuries (eg, ACL rupture) and an increased risk of PTOA onset and progression (structurally and symptomatically).

CLINICAL RELEVANCE

Subcritical knee injuries are a common occurrence and, based on this study, can cause persistent sensory and structural change. These findings have important implications for the understanding of risk factors of ACL injury and subsequent PTOA, particularly with regard to prevention and management strategies following an often underreported event.

The effect of exercise therapy on inflammatory activity assessed by MRI in knee osteoarthritis: Secondary outcomes from a randomized controlled trial

OBJECTIVE

This study investigated the effect of exercise therapy on inflammatory activity in synovitis and bone marrow lesions (BMLs) assessed by magnetic resonance imaging (MRI) in patients with knee OA.

METHODS

60 patients with knee OA were randomized 1:1 to 12 weeks of supervised exercise therapy 3 times/week (ET) or a no-attention control group (CG). Synovitis and BMLs were assessed with static MRI with and without contrast and with dynamic contrast enhanced MRI (DCE-MRI). DCE-MRI data was quantified using pixel-by-pixel methodology based on analysis of signal intensity curves. Pain was assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS). Analyses of covariance were used assessing group differences in changes from baseline to week 12.

RESULTS

33 patients adhered to the protocol and had valid MRI and KOOS data (ET, n = 16, CG, n = 17). Statistically significant and clinically relevant group difference in favour of ET was seen in KOOS pain change (-11.7 points, 95%CI: -20.1 to -3.4). There were statistically significant group differences in DCE-MRI assessed synovitis in the anterior synovium with unchanged inflammatory activity in the ET group compared to the CG. There were no group differences in BMLs and static MRI.

CONCLUSION

Inflammatory activity was unchanged, and pain was reduced in patients with knee OA adhering to 12 weeks of exercise therapy compared to a no-attention control group. The reduction in pain was not explained by changes in inflammatory activity. Overall, the results suggest that exercise is not harmful in knee OA. ClinicalTrials.gov number: NCT01545258.

Arthroscopic procedures could delay the need for a subsequent knee arthroplasty in older patients with end-stage osteoarthritis

BACKGROUND/OBJECTIVE

Arthroscopic surgery in knee osteoarthritis is controversial with many studies refuting its efficacy in recent literature. This study aims to evaluate the mean duration to knee arthroplasty, and the effect of microfracture on the need for subsequent knee arthroplasty in patients above the age of 55 undergoing arthroscopic procedures for osteoarthritis.

METHODS

One hundred and nine consecutive patients with diagnosed osteoarthritis who underwent arthroscopic surgery performed from January 2000 to December 2012 on patients aged 55 years and above by a single surgeon were reviewed retrospectively. Demographic data, age at operation, comorbidities, perioperative details and information of subsequent total knee arthroplasty were collected and analysed.

RESULTS

There were 38 males and 71 females in our study group. The group was predominantly Chinese (51.38%), with hypertension and hyperlipidaemia being the most common comorbidities, each affecting 57.8% of our study cohort. All patients had a preoperative radiograph and a magnetic resonance imaging confirming the diagnosis of osteoarthritis associated with meniscal tears. Fifty-eight knees underwent microfracture along with arthroscopic meniscectomy. The mean follow-up duration was 127.5 months (10.5 years, range: 67-212 months). Twenty three patients (20.91%) underwent knee arthroplasties subsequently, with the mean duration to arthroplasty being 65.0 months (5.5 years, range: 7-166 months). The odds ratio of avoiding knee arthroplasty with microfracture was 1.03 (95% CI = 0.410-2.581).

CONCLUSION

Arthroscopic procedures could possibly delay the need for subsequent knee arthroplasty for approximately 65 months in older patients with osteoarthritis. However, microfracture does not affect the duration between therapeutic arthroscopy and subsequent arthroplasty. Our long-term retrospective study provides an additional step in the understanding of the impact of arthroscopic procedures and a prospective case-control study would be an ideal follow-up to fully justify the application of arthroscopic procedures to delay knee arthroplasty.

Osteo-core Plasty: A Minimally Invasive Approach for Subchondral Bone Marrow Lesions of the Knee

"Bone marrow lesion" (BML) is a common term used to describe the presence of fluid in the bone marrow. Although various pathologies can cause BMLs seen on magnetic resonance imaging, in this Technical Note we focus on treating the lesions associated with osteoarthritis in the knee joint. The role of the subchondral bone in transferring loads within the knee joint, as well as in cartilage homeostasis, is well established. In addition, cartilage and subchondral bone are increasingly considered as an osteochondral unit, rather than as 2 separate structures. Knee osteoarthritis, along with insufficiency fracture, is one of the main indications for the treatment of painful BMLs. Nowadays, there is a growing interest in this field, and new approaches are being developed. Our technique can be defined as a surgical procedure aimed directly at pathology within the subchondral bone and is named "osteo-core plasty." It consists of 2 parts: The first is decompression of bone marrow to decrease intraosseous pressure, and the second is administration of bone marrow aspirate concentrate for better healing potential and bone autograft to deliver supportive tissue. It should be noted that the cause of BMLs must be known before this kind of treatment is performed.

Bone Marrow Edema, Clinical Significance, and Treatment Options: A Review

Bone marrow edema (BME) is a descriptive term used to describe high-signal intensity changes detected on magnetic resonance fluid-sensitive sequences that could be attributed to a number of underlying pathologies. Regardless of the cause, physiologic remodeling of the subchondral bone can be limited because of ongoing joint forces, increased focalization of stress, and reduced healing capacity of the subchondral bone. BME is a known prognostic factor associated with pain, dysfunction, and progressive cartilage damage. This review summarizes the current known causes of BMEs, theories related to histopathological changes, and current treatment options including novel biologic surgical options.

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.

Ruboxistaurin maintains the bone mass of subchondral bone for blunting osteoarthritis progression by inhibition of osteoclastogenesis and bone resorption activity

Osteoarthritis (OA) is a common degenerative disease with a series of changes occurring in aging cartilage, such as increased oxidative stress, decreased markers of healthy cartilage and alterations in the autophagy pathway. And increasing evidence indicates that osteoarthritis affects the whole joint, including both cartilage and subchondral bone. The agents that can effectively suppress chondrocyte degradation and subchondral bone deterioration are crucial for the prevention and treatment of OA. Ruboxistaurin (RU), an orally active protein kinase C inhibitor, can reduce macrophage adhesion to endothelial cells and relieve the local inflammation when applicating in diabetes and kinds of aging-related vasculopathy, which were realized by its effects on decreasing inflammatory cytokines' expression and increasing cell anti-oxidative stress ability. However, whether ruboxistaurin protects against OA remains unknown. In this study, we investigated the therapeutic effects of ruboxistaurin in an anterior cruciate ligament transection (ACLT)-induced OA model by preventing the bone mass loss of subchondral bone. We found that ruboxistaurin can effectively alleviate ACLT-induced osteoarthritis, as demonstrated by the phenomenon of correcting pathological bone loss caused by osteoclasts overactivated in the early stage of osteoarthritis and protecting against articular cartilage degeneration. Moreover, we found that ruboxistaurin inhibited osteoclast formation and resorption activity by suppressing the expressions of osteoclast-related genes and (PKCδ/MAPKs) signaling cascade. Taken together, these results show that ruboxistaurin may be a potential therapeutic agent for rescuing abnormal subchondral bone deterioration and cartilage degradation in OA and reverses the vicious cycle related to osteoarthritis.

Talar Avascular Necrosis After Calcium Phosphate Injection Treatment of Talar Bone Marrow Lesions: A Report of 2 Cases

CASE

We report on 2 patients who developed avascular necrosis (AVN) of the talus and poor patient outcomes after undergoing calcium phosphate injection into talar dome bone marrow lesions.

CONCLUSION

Subchondroplasty, defined as calcium phosphate injection for the treatment of articular bone marrow edema, is a recently described procedure for use in the ankle joint. In our opinion, the limited available research is of poor quality and describes equivocal improvement in patient symptoms after this procedure. Given the debilitating outcomes and extensive AVN we observed in 2 patients, we strongly advise caution in the use of this procedure in the talus.

Clinical effect of intramuscular calcitonin compared with oral celecoxib in the treatment of knee bone marrow lesions: a retrospective study

BACKGROUND

Bone marrow lesions (BMLs) are a common finding in patients with osteoarthritis (OA), which are predictors of progression and pain related to cartilage damage in OA. The objective of the present research was to compare the short-term clinical effect of intramuscular calcitonin and oral celecoxib in treating knee BMLs.

PATIENTS AND METHODS

Between January 2016 and December 2018, the medical records of patients with knee BMLs treated by intramuscular calcitonin or oral celecoxib were reviewed. Visual analog scale (VAS) and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) were used to assess knee pain and function, respectively. BMLs were assessed by MRI scans and were scored by the modified Whole-Organ MRI Score (WORMS). The safety of these two medications was also evaluated.

RESULTS

A total of 123 eligible patients who received calcitonin treatment (n = 66) or celecoxib treatment (n = 57) were included. All patients were followed up clinically and radiographically for 3 months. The VAS and WOMAC scores were lower statistically in calcitonin group than celecoxib group at 4-week and 3-month follow-up. For BMLs, the WORMS scores in the calcitonin group were significantly lower than the celecoxib group. Besides, statistically higher MRI improvement rates were found in the calcitonin group compared with the celecoxib group at 4-week follow-up (21.21% vs. 7.01%; P = 0.039) and 3-month follow-up (37.88% vs. 15.79%; P = 0.006).

CONCLUSION

Intramuscular calcitonin 50 IU once daily demonstrated a better short-term effect for knee BML patients compared with oral celecoxib 200 mg twice per day.