Developments in the clinical understanding of osteoarthritis

The repeatability of T2 relaxation time measurement of human knee articular cartilage

OBJECTIVES

To assess short- and long-term repeatability of T2 relaxation time measurements of the knee articular cartilage.

MATERIALS AND METHODS

The right knees of nine asymptomatic volunteers (age 30-38 years, five male, four female) were imaged at 1.5 T in three sessions 1 and 2 weeks apart. To observe short-term repeatability, the measurements were repeated three times within one of the three imaging sessions for each volunteer. T2 relaxation time was mapped using a multi-slice multi-echo spin echo sequence in axial and sagittal planes. Cartilage was manually segmented and repeatability, as measured by root-mean-square coefficient of variation (CVRMS) was evaluated both for the entire bulk cartilage of each joint surface in the slice and separately for each region of interest (ROI) at different topographical locations and separately for the superficial and deep half of each ROI.

RESULTS

For bulk T2, the long-term repeatability was 3.2, 5.4, and 3.7%, and the short-term reproducibility was 3.9, 3.9, and 3.4% for bulk femoral, tibial, and patellar cartilage, respectively. There were no significant differences between long-term and short-term repeatability in superficial or deep cartilage when comparing CVRMS values (p = 0.338 and 0.700, respectively). For individual ROIs, the repeatability varied between 2.5 and 22.2% depending on the topographical location.

CONCLUSION

The current results show mostly good repeatability. However, there were remarkable variations of T2 between bulk cartilage and different ROIs, bulk cartilage showing better repeatability. With careful patient positioning T2 can be accurately determined for different cartilage surfaces.

Macrophage-specific metalloelastase (MMP-12) immunoexpression in the osteochondral unit in osteoarthritis correlates with BMI and disease severity

BACKGROUND

Metalloproteinase 12 (MMP-12) is induced in chondrocytes during fetal development and malignant transformation.

OBJECTIVES

The aim of our study is to examine the expression of MMP-12 in the cartilage and the subchondral bone of patients with osteoarthritis (OA) and to correlate its expression with disease severity and anthropometric characteristics.

METHODS

Overall, 60 sections from 20 patients with idiopathic OA, were examined for the immunolocalization of MMP-12. As controls, we used the femoral heads of 4 patients treated with seniarthroplasty after fracture. Demographic characteristics and Body Mass Index (BMI) were calculated for all subjects.

RESULTS

Specimens were divided into four groups based on the Mankin histological severity score. The immunohistochemical study showed MMP-12 expression in the cartilage and subchonral bone of OA patients, while there was no expression in normal controls. At the moderate OA changes (Mankin score: 6-7), MMP-12 was detected mainly at the matrix of fibrocartilage tissue. During disease progression, MMP-12 was expressed at the sides of the cartilage and bone erosion and in the bone cysts. Furthermore, it was traced in the osteocytes of the subchondral bone. Osteoblast-like cells and bone lining cells express MMP-12 during the stage of severe OA (Mankin: ≥8). Osteoclasts expressing MMP-12 were also detected in the group of severe OA. Interestingly, MMP-12 expression was positively correlated with the age and the BMI of OA patients.

CONCLUSION

The increased expression of MMP-12 in the bone-cartilage unit of OA patients suggests a possible role in OA pathogenesis and progression.

LEVEL OF EVIDENCE

III, prospective comparative study.

Cartilage regeneration for treatment of osteoarthritis: a paradigm for nonsurgical intervention

Osteoarthritis (OA) is associated with articular cartilage abnormalities and affects people of older age: preventative or therapeutic treatment measures for OA and related articular cartilage disorders remain challenging. In this perspective review, we have integrated multiple biological, morphological, developmental, stem cell and homeostasis concepts of articular cartilage to develop a paradigm for cartilage regeneration. OA is conceptually defined as an injury of cartilage that initiates chondrocyte activation, expression of proteases and growth factor release from the matrix. This regenerative process results in the local activation of inflammatory response genes in cartilage without migration of inflammatory cells or angiogenesis. The end results are catabolic and anabolic responses, and it is the balance between these two outcomes that controls remodelling of the matrix and regeneration. A tantalizing clinical clue for cartilage regrowth in OA joints has been observed in surgically created joint distraction. We hypothesize that cartilage growth in these distracted joints may have a biological connection with the size of organs and regeneration. Therefore we propose a novel, practical and nonsurgical intervention to validate the role of distraction in cartilage regeneration in OA. The approach permits normal wake-up activity while during sleep; the index knee is subjected to distraction with a pull traction device. Comparison of follow-up magnetic resonance imaging (MRI) at 3 and 6 months of therapy to those taken before therapy will provide much-needed objective evidence for the use of this mode of therapy for OA. We suggest that the paradigm presented here merits investigation for treatment of OA in knee joints.

Musculoskeletal Pain, Self-reported Physical Function, and Quality of Life in the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) Cohort

IMPORTANCE

Obesity is associated with chronic musculoskeletal pain and is a risk factor for disability and osteoarthritis.

OBJECTIVES

To describe the prevalence, sites, and intensity of musculoskeletal pain in adolescents with severe obesity; to evaluate associations between musculoskeletal pain and self-reported physical function as well as weight-related quality of life; and to evaluate the association between musculoskeletal pain and high-sensitivity C-reactive protein level.

DESIGN, SETTING, AND PARTICIPANTS

Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) is a prospective, observational study that collects standardized data on adolescents undergoing weight loss surgery at 5 US centers. We examined baseline data from this cohort between February 28, 2007, and December 30, 2011. We excluded adolescents with Blount disease and slipped capital femoral epiphyses. A total of 233 participants were included in these analyses.

MAIN OUTCOMES AND MEASURES

We assessed musculoskeletal pain and pain intensity of the lower back, hips, knees, and ankles/feet using the visual analog scale, categorizing musculoskeletal pain into lower back pain, lower extremity (hips, knees, and feet/ankles combined) pain, and no pain. We assessed self-reported physical function status with the Health Assessment Questionnaire Disability Index and assessed weight-related quality of life with the Impact of Weight on Quality of Life-Kids measure. We adjusted for sex, race, age at surgery, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), and clinical depressive symptoms in regression analyses.

RESULTS

Among the 233 participants, the mean (SD) age at surgery was 17.1 (1.56) years and the median BMI was 50.4. Participants were predominantly female (77%), white (73%), and non-Hispanic (93%). Among the participants, 49% had poor functional status and 76% had musculoskeletal pain. Lower back pain was prevalent (63%), followed by ankle/foot (53%), knee (49%), and hip (31%) pain; 26% had pain at all 4 sites. In adjusted analyses, compared with pain-free participants, those reporting lower extremity pain had greater odds of having poor physical function according to scores on the Health Assessment Questionnaire Disability Index (odds ratio = 2.82; 95% CI, 1.35 to 5.88; P < .01). Compared with pain-free participants, those reporting lower extremity pain had significantly lower Impact of Weight on Quality of Life-Kids total scores (β = -9.42; 95% CI, -14.15 to -4.69; P < .01) and physical comfort scores (β = -17.29; 95% CI, -23.32 to -11.25; P < .01). After adjustment, no significant relationship was observed between musculoskeletal pain and high-sensitivity C-reactive protein level.

CONCLUSIONS AND RELEVANCE

Adolescents with severe obesity have musculoskeletal pain that limits their physical function and quality of life. Longitudinal follow-up will reveal whether weight loss surgery reverses pain and physical functional limitations and improves quality of life.

Potential role of age, sex, body mass index and pain to identify patients with knee osteoarthritis

AIM

To evaluate the potential role of age, sex, body mass index (BMI), radiographic features and pain in knee osteoarthritis (OA) case ascertainment.

METHODS

A cross-sectional study was performed using information from the EPIPorto cohort; social, demographic, behavioral and clinical data was obtained. Pain was assessed using a pain frequency score (regarding ever having knee pain, pain in the last year, in the last 6 months and in the last month). Knee radiographs were classified using the Kellgren-Lawrence scale (0-4). Path analysis was used to assess the plausibility of the causal assumptions and a classification tree to identify characteristics that could improve the identification of patients with radiographic OA.

RESULTS

Higher age and higher BMI were associated with higher radiographic score, but sex had no statistical association. Females, higher age, higher BMI and higher radiographic score were statistically associated with higher pain scores. For both genders, the classification tree estimated age as the first variable to identify individuals with knee radiographic features. In females older than 56 years, pain frequency score is the second discriminator characteristic, followed by age (> 65 years) and (BMI > 30 kg/m² ). Higher pain frequency and BMI > 29 kg/m² were relevant for identifying OA in men with ages between 43.5 and 55.5 years.

CONCLUSIONS

Age, BMI and pain frequency are independently associated with radiographic OA and the use of information on these characteristics can improve the identification of patients with knee OA. Beyond age, pain complaints are particularly relevant but the level of pain is different by sex.

Automatic segmentation of high- and low-field knee MRIs using knee image quantification with data from the osteoarthritis initiative

Clinical studies including thousands of magnetic resonance imaging (MRI) scans offer potential for pathogenesis research in osteoarthritis. However, comprehensive quantification of all bone, cartilage, and meniscus compartments is challenging. We propose a segmentation framework for fully automatic segmentation of knee MRI. The framework combines multiatlas rigid registration with voxel classification and was trained on manual segmentations with varying configurations of bones, cartilages, and menisci. The validation included high- and low-field knee MRI cohorts from the Center for Clinical and Basic Research, the osteoarthritis initiative (QAI), and the segmentation of knee images10 (SKI10) challenge. In total, 1907 knee MRIs were segmented during the evaluation. No segmentations were excluded. Our resulting OAI cartilage volume scores are available upon request. The precision and accuracy performances matched manual reader re-segmentation well. The cartilage volume scan-rescan precision was 4.9% (RMS CV). The Dice volume overlaps in the medial/lateral tibial/femoral cartilage compartments were 0.80 to 0.87. The correlations with volumes from independent methods were between 0.90 and 0.96 on the OAI scans. Thus, the framework demonstrated precision and accuracy comparable to manual segmentations. Finally, our method placed second for cartilage segmentation in the SKI10 challenge. The comprehensive validation suggested that automatic segmentation is appropriate for cohorts with thousands of scans.

Association between polymorphisms in the estrogen receptor alpha gene and osteoarthritis susceptibility: a meta-analysis

Background

Osteoarthritis (OA) is a common chronic disease of the joints. Genetic factors may play a role in its development, and polymorphisms in the estrogen receptor alpha gene (ERα) have been associated with OA. However, previous studies into this relationship have reported inconsistent results, so we aimed to systematically review the association between ERα polymorphisms and OA susceptibility.

Methods

We conducted a comprehensive literature search of Ovid MEDLINE, EMBASE, CBM, and PubMed databases, and Google scholar, and identified 11 eligible studies that examined the association between ERα polymorphisms and OA susceptibility. We carried out a meta-analysis of these studies based on ERα XbaI (rs9340799) and PvuII (rs2234693) genotypes.

Results

Seventeen comparisons involving 10 European and seven Asian populations of 5,325 OA patients and 10,834 controls were included in the study. The ERα XbaI polymorphism were significantly associated with OA in Europeans (AA vs. AG + GG: OR = 1.17, 95% confidence interval (CI) = 1.02–1.34, P = 0.03; AG vs. AA + GG: OR = 0.86, 95% CI = 0.75–0.99, P = 0.04) but not in Asian populations. No association was found between OA and the ERα PvuII polymorphism in any population (C vs. T, OR = 0.98, 95% CI = 0.93–1.03, P = 0.37; CC vs. TT + CT, OR = 0.97, 95% CI = 0.89–1.06, P = 0.55; CT vs. CC + TT, OR = 0.99, 95% CI = 0.92–1.06, P = 0.75; TT vs. CC + CT, OR = 1.01, 95% CI =0.92–1.12, P = 0.79).

Conclusions

This study suggested that there may be a weak relationship between the ERα XbaI polymorphism and OA in Europeans but not Asians, and that the ERα PvuII polymorphism was not associated with OA in either population. However, large well-designed studies are necessary to confirm these results in more homogeneous populations.

The safety and efficacy of an enzyme combination in managing knee osteoarthritis pain in adults: a randomized, double-blind, placebo-controlled trial

This randomized, double-blind, placebo-controlled, and comparator-controlled trial evaluated the safety and efficacy of an enzyme combination, as Wobenzym, in adults with moderate-to-severe osteoarthritis (OA) of the knee. Adults (n = 150) received Wobenzym, diclofenac (a nonsteroidal anti-inflammatory drug, NSAID), or placebo for 12 weeks. Improvement in pain scores (Lequesne Functional Index) did not differ between subjects treated with Wobenzym or diclofenac, and both treatment groups improved compared to placebo (P < 0.05). Reduction in total WOMAC scores (secondary outcome measure) did not differ between Wobenzym and diclofenac, although only diclofenac emerged as different from placebo (P < 0.05). The median number of rescue medication (paracetamol) tablets consumed was less in the Wobenzym group compared to placebo (P < 0.05), while there was no difference between diclofenac and placebo. Adverse events were similar in frequency in Wobenzym and placebo groups (7.2% and 9.1% of subjects, resp.) and higher in diclofenac group (15.6%). Wobenzym is comparable to the NSAID diclofenac in relieving pain and increasing function in adults with moderate-to-severe painful knee OA and reduces reliance on analgesic medication. Wobenzym is associated with fewer adverse events and, therefore, may be appropriate for long-term use.

Green tea polyphenol treatment is chondroprotective, anti-inflammatory and palliative in a mouse post-traumatic osteoarthritis model

Introduction

Epigallocatechin 3-gallate (EGCG), a polyphenol present in green tea, was shown to exert chondroprotective effects in vitro. In this study, we used a posttraumatic osteoarthritis (OA) mouse model to test whether EGCG could slow the progression of OA and relieve OA-associated pain.

Methods

C57BL/6 mice were subjected to surgical destabilization of the medial meniscus (DMM) or sham surgery. EGCG (25 mg/kg) or vehicle control was administered daily for 4 or 8 weeks by intraperitoneal injection starting on the day of surgery. OA severity was evaluated using Safranin O staining and Osteoarthritis Research Society International (OARSI) scores, as well as by immunohistochemical analysis to detect cleaved aggrecan and type II collagen and expression of proteolytic enzymes matrix metalloproteinase 13 (MMP-13) and A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5). Real-time PCR was performed to characterize the expression of genes critical for articular cartilage homeostasis. During the course of the experiments, tactile sensitivity testing (von Frey test) and open-field assays were used to evaluate pain behaviors associated with OA, and expression of pain expression markers and inflammatory cytokines in the dorsal root ganglion (DRG) was determined by real-time PCR.

Results

Four and eight weeks after DMM surgery, the cartilage in EGCG-treated mice exhibited less Safranin O loss and cartilage erosion, as well as lower OARSI scores compared to vehicle-treated controls, which was associated with reduced staining for aggrecan and type II collagen cleavage epitopes, and reduced staining for MMP-13 and ADAMTS5 in the articular cartilage. Articular cartilage in the EGCG-treated mice also exhibited reduced levels of Mmp1, Mmp3, Mmp8, Mmp13,Adamts5, interleukin 1 beta (Il1b) and tumor necrosis factor alpha (Tnfa) mRNA and elevated gene expression of the MMP regulator Cbp/p300 interacting transactivator 2 (Cited2). Compared to vehicle controls, mice treated with EGCG exhibited reduced OA-associated pain, as indicated by higher locomotor behavior (that is, distance traveled). Moreover, expression of the chemokine receptor Ccr2 and proinflammatory cytokines Il1b and Tnfa in the DRG were significantly reduced to levels similar to those of sham-operated animals.

Conclusions

This study provides the first evidence in an OA animal model that EGCG significantly slows OA disease progression and exerts a palliative effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0508-y) contains supplementary material, which is available to authorized users.

Intraarticular sprifermin (recombinant human fibroblast growth factor 18) in knee osteoarthritis: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate the efficacy and safety of intraarticular sprifermin (recombinant human fibroblast growth factor 18) in the treatment of symptomatic knee osteoarthritis (OA).

METHODS

The study was a randomized, double-blind, placebo-controlled, proof-of-concept trial. Intraarticular sprifermin was evaluated at doses of 10 μg, 30 μg, and 100 μg. The primary efficacy end point was change in central medial femorotibial compartment cartilage thickness at 6 months and 12 months as determined using quantitative magnetic resonance imaging (qMRI). The primary safety end points were nature, incidence, and severity of local and systemic treatment-emergent adverse events (AEs) and acute inflammatory reactions, as well as results of laboratory assessments. Secondary end points included changes in total and compartment femorotibial cartilage thickness and volume as assessed by qMRI, changes in joint space width (JSW) seen on radiographs, and pain scores on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

RESULTS

One hundred ninety-two patients were randomized and evaluated for safety, 180 completed the trial, and 168 were evaluated for the primary efficacy end point. We found no statistically significant dose response in change in central medial femorotibial compartment cartilage thickness. Sprifermin was associated with statistically significant, dose-dependent reductions in loss of total and lateral femorotibial cartilage thickness and volume and in JSW narrowing in the lateral femorotibial compartment. All groups had improved WOMAC pain scores, with statistically significantly less improvement at 12 months in patients receiving the 100-μg dose of sprifermin as compared with those receiving placebo. There was no significant difference in serious AEs, treatment-emergent AEs, or acute inflammatory reactions between sprifermin and placebo groups.

CONCLUSION

No statistically significant relationship between treatment group and reduction in central medial femorotibial compartment cartilage thickness was observed; however, prespecified structural secondary end points showed statistically significant dose-dependent reductions after sprifermin treatment. Sprifermin was not associated with any local or systemic safety concerns.

Therapeutic effect of irradiation of magnetic infrared laser on osteoarthritis rat model

Osteoarthritis (OA) is a degenerative joint disease caused by articular cartilage loss. Many complementary and alternative medicines for OA have been reported so far, but the effectiveness is controversial. Previously, we have shown anti-inflammatory effects of low level laser therapy with static magnetic field, magnetic infrared laser (MIL), in various animal models. Therefore, the beneficial effects were examined in OA rat model. Rats were divided by six groups; no treatment controls of sham and OA model, three MIL treatment groups of OA model at 6.65, 2.66 and 1.33 J cm(-2), and Diclofenac group of OA model with 2 mg kg(-1) diclofenac sodium. The OA control exhibited typical symptoms of OA, but 4-week MIL treatment improved the functional movement of knee joint with reduced edematous changes. In addition, cartilage GAGs were detected more in all MIL treatment groups than OA control. It suggests that 4-week MIL irradiation has dose-dependent anti-inflammatory and chondroprotective effects on OA. Histopathological analyses revealed that MIL treatment inhibits the cartilage degradation and enhances chondrocyte proliferation. The fact that MIL has an additional potential for the cartilage formation and no adverse effects can be regarded as great advantages for OA treatment. These suggest that MIL can be useful for OA treatment.

Efficacy and safety of plasma rich in growth factors intra-articular infiltrations in the treatment of knee osteoarthritis

PURPOSE

The goal of this study was to systematically review the efficacy and safety of plasma rich in growth factors (PRGF) as a treatment for reducing symptoms in patients with knee osteoarthritis.

METHODS

A comprehensive and systematic literature search was conducted for PRGF treatment of knee osteoarthritis following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All the studies had to include a PRGF group and a control group. Pre- and post-treatment measures of joint pain, reduced function, and stiffness were evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index, Knee Injury and Osteoarthritis Outcome Score, International Knee Documentation Committee score, Lequesne index, or number of Outcome Measures for Rheumatology Committee and Osteoarthritis Research Society International Standing Committee for Clinical Trials Response Criteria Initiative (OMERACT-OARSI) responders, with a follow-up period of at least 4 weeks. An assessment of both the quality and risk of bias of the studies was conducted.

RESULTS

The literature search yielded 91 citations, but only 5 were eligible publications that met the inclusion criteria (2 randomized controlled trials, 2 prospective studies, and 1 retrospective analysis). Two studies were rated as having a low risk of bias whereas 3 had a high risk. In both randomized controlled trials, it was observed that after 6 months of treatment, the number of patients with a pain reduction of more than 50% was significantly higher in the PRGF group. In 2 other studies, the patients treated with PRGF showed a significant pain reduction compared with the control group. The remaining variables (Western Ontario and McMaster Universities Osteoarthritis Index scale for pain, function, and stiffness; Lequesne index; Knee Injury and Osteoarthritis Outcome Score scale; and number of OMERACT-OARSI responders) showed a statistically significant superiority of the group treated with PRGF.

CONCLUSIONS

The current clinical evidence suggests that PRGF intra-articular infiltrations in patients with knee osteoarthritis reduce pain and therefore are clinically efficacious in osteoarthritis treatment.

LEVEL OF EVIDENCE

Level III, systematic review of Level I, II, and III studies.

Association of single nucleotide polymorphisms in ADAM12 gene with susceptibility to knee osteoarthritis: a case-control study in a Chinese Han population

OBJECTIVE

Genetic factors play an important role in osteoarthritis (OA) etiology and ADAM12 gene polymorphisms may be involved. This study tried to examine the single-nucleotide polymorphisms (SNPs) of ADAM12 for their association with knee OA susceptibility in a Chinese Han population.

METHODS

The rs3740199, rs1871054, rs1278279, and rs1044122 SNPs in ADAM12 gene were genotyped in 152 subjects who were diagnosed as knee osteoarthritis and in 179 healthy controls.

RESULTS

Rs1871054 was found to be significantly associated with increased risk of OA (C vs. T, OR 1.802 (1.308 to 2.483), P < 0.0001) after adjustment of age, gender, and BMI. For other SNPs, no statistically significant associations with OA were found.

CONCLUSION

In conclusion, our data demonstrated the ADAM12 rs1871054 variant was found to be significantly associated with increased OA susceptibility in a Chinese Han population.

Altered expression of circulating microRNA in plasma of patients with primary osteoarthritis and in silico analysis of their pathways

Objective

To analyze a set of circulating microRNA (miRNA) in plasma from patients with primary Osteoarthritis (OA) and describe the biological significance of altered miRNA in OA based on an in silico analysis of their target genes.

Methods

miRNA expression was analyzed using TaqMan Low Density Arrays and independent assays. The search for potential messenger RNA (mRNA) targets of the differentially expressed miRNA was performed by means of the miRWalk and miRecords database; we conducted the biological relevance of the predicted miRNA targets by pathway analysis with the Reactome and DAVID databases.

Results

We measured the expression of 380 miRNA in OA; 12 miRNA were overexpressed under the OA condition (p value, ≤0.05; fold change, >2). These results were validated by the detection of some selected miRNA by quantitative PCR (qPCR). In silico analysis showed that target messenger RNA (mRNA) were potentially regulated by these miRNA, including genes such as SMAD1, IL-1B, COL3A, VEGFA, and FGFR1, important in chondrocyte maintenance and differentiation. Some metabolic pathways affected by the miRNA: mRNA ratio are signaling Bone morphogenetic proteins (BMP), Platelet-derived growth factor (PDGF), and Nerve growth factor (NGF), these latter two involved in the process of pain.

Conclusions

We identified 12 miRNA in the plasma of patients with primary OA. Specific miRNA that are altered in the disease could be released into plasma, either due to cartilage damage or to an inherent cellular mechanism. Several miRNA could regulate genes and pathways related with development of the disease; eight of these circulating miRNA are described, to our knowledge, for first time in OA.

Neuropathic pain in osteoarthritis: a review of pathophysiological mechanisms and implications for treatment

OBJECTIVES

Osteoarthritis (OA) is the leading cause of musculoskeletal pain and functional disability worldwide, affecting a growing number of individuals in the western society. Despite various conservative and interventional treatment approaches, the overall management of the condition is problematic, and pain-the major clinical problem of the disease-remains sub-optimally controlled. The objectives of this review are to present the pathophysiologic mechanisms underlying the complexity of pain in OA and to discuss the challenges for new treatment strategies aiming to translate experimental findings into daily clinical practice.

METHODS

A narrative literature review of studies investigating the existence of a neuropathic component in OA pain was conducted. We searched PubMed, Embase and Scopus for English language publications. A hand-search of reference lists of relevant studies was also performed.

RESULTS

Recent advances have shed additional light on the pathophysiology of osteoarthritic pain, highlighting the contribution of central pain pathways together with the sensitisation of peripheral joint receptors and changes of the nociceptive process induced by local joint inflammation and structural bone tissue changes. Thus, a neuropathic pain component may be predominant in individuals with minor joint changes but with high levels of pain refractory to analgesic treatment, providing an alternative explanation for osteoarthritic pain perception.

CONCLUSION

A growing amount of evidence suggests that the pain in OA has a neuropathic component in some patients. The deeper understanding of multiple mechanisms of OA pain has led to the use of centrally acting medicines that may have a benefit on alleviating osteoarthritic pain. The ineffective pain management and the increasing rates of disability associated with OA mandate for change in our treatment paradigm.

Occupational physical loading tasks and knee osteoarthritis: a review of the evidence

Purpose : To perform a systematic review with best evidence synthesis examining the literature on the relationship between occupational loading tasks and knee osteoarthritis (OA).

METHODS

Two databases were searched to identify articles published between 1946 and April, 2011. Eligible studies were those that (1) included adults reporting on their employment history; (2) measured individuals' exposure to work-related activities with heavy loading in the knee joint; and (3) identified presence of knee OA (determined by X-ray), cartilage defects associated with knee OA (identified by magnetic resonance imaging), or joint replacement surgery.

RESULTS

A total of 32 articles from 31 studies met the inclusion criteria. We found moderate evidence that combined heavy lifting and kneeling is a risk factor for knee OA, with odds ratios (OR) varying from 1.8 to 7.9, and limited evidence for heavy lifting (OR=1.4-7.3), kneeling (OR=1.5-6.9), stair climbing (OR=1.6-5.1), and occupational groups (OR=1.4-4.7) as risk factors. When examined by sex, moderate level evidence of knee OA was found in men; however, the evidence in women was limited.

CONCLUSIONS

Further high-quality prospective studies are warranted to provide further evidence on the role of occupational loading tasks in knee OA, particularly in women.

Future directions for the management of pain in osteoarthritis

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

The future of osteoarthritis therapeutics: targeted pharmacological therapy

Osteoarthritis (OA) is one of the most common forms of degenerative joint disease and a major cause of pain and disability affecting the aging population. It is estimated that more than 20 million Americans and 35 to 40 million Europeans suffer from OA. Analgesics and non-steroidal anti-inflammatory drugs (NSAIDs) are the only therapeutic treatment options for OA. Effective pharmacotherapy for OA, capable of restoring the original structure and function of damaged cartilage and other synovial tissue, is urgently needed, and research into such disease-modifying osteoarthritis drugs (DMOADs) is in progress. This is the first of three reviews focusing on OA therapeutics. This paper provides an overview of current research into potential structure-modifying drugs and more appropriately targeted pharmacological therapy. The challenges and opportunities in this area of research and development are reviewed, covering the most up-to-date initiatives, trends, and topics.

Association of single nucleotide polymorphisms in estrogen receptor alpha gene with susceptibility to knee osteoarthritis: a case-control study in a Chinese Han population

Osteoarthritis (OA) is the most prevalent form of arthritis and its multifactorial nature has been increasingly recognized. Genetic factors play an important role in OA etiology and estrogen receptor alpha (ESR1) gene polymorphisms may be involved. This study tried to explore whether the ESR1 gene single nucleotide polymorphisms (SNPs) were associated with primary knee OA in the Chinese Han population. Two SNPs, rs2234693 and rs9340799, were genotyped in 469 cases and 522 controls. Rs2234693 was associated with knee OA in the dominant genetic model (TT + TC versus CC) (P = 0.025) and a higher T allele frequency existed (P = 0.047) among females. The combined genotype (TT + TC) (P = 0.025) and T allele (P = 0.016) were related with mild knee OA only. For rs9340799, A allele was associated with knee OA in all subjects (P = 0.031) and females (P = 0.046). Statistical differences were detected in the dominant genetic model (AA + AG versus GG) among females (P = 0.030). The combined genotype (AA + AG) (P = 0.036) and A allele (P = 0.039) were merely correlated with mild knee OA. ESR1 gene is considerably associated with knee OA etiology in the Chinese Han population.

Selective lateral muscle activation in moderate medial knee osteoarthritis subjects does not unload medial knee condyle

There is some debate in the literature regarding the role of quadriceps-hamstrings co-contraction in the onset and progression of knee osteoarthritis. Does co-contraction during walking increase knee contact loads, thereby causing knee osteoarthritis, or might it be a compensatory mechanism to unload the medial tibial condyle? We used a detailed musculoskeletal model of the lower limb to test the hypothesis that selective activation of lateral hamstrings and quadriceps, in conjunction with inhibited medial gastrocnemius, can actually reduce the joint contact force on the medial compartment of the knee, independent of changes in kinematics or external forces. "Baseline" joint loads were computed for eight subjects with moderate medial knee osteoarthritis (OA) during level walking, using static optimization to resolve the system of muscle forces for each subject's scaled model. Holding all external loads and kinematics constant, each subject's model was then perturbed to represent non-optimal "OA-type" activation based on mean differences detected between electromyograms (EMG) of control and osteoarthritis subjects. Knee joint contact forces were greater for the "OA-type" than the "Baseline" distribution of muscle forces, particularly during early stance. The early-stance increase in medial contact load due to the "OA-type" perturbation could implicate this selective activation strategy as a cause of knee osteoarthritis. However, the largest increase in the contact load was found at the lateral condyle, and the "OA-type" lateral activation strategy did not increase the overall (greater of the first or second) medial peak contact load. While "OA-type" selective activation of lateral muscles does not appear to reduce the medial knee contact load, it could allow subjects to increase knee joint stiffness without any further increase to the peak medial contact load.

Quadriceps strengthening exercises are effective in improving pain, function and quality of life in patients with osteoarthritis of the knee

Objective

The purpose of this research was to verify the effectiveness of an eight-week quadriceps strengthening program on pain, function and quality of life of patients with knee osteoarthritis.

Methods

A hundred patients were randomized into two groups: 1- Exercise Group (ExG) and 2- Orientation Group. The Timed Up and Go (TUG) test, the Numerical Rating Scale (NRS) and the Short Form-36 were used for the assessment.

Results

Eighty-one patients completed the survey. According to the intention to treat (ITT) analysis, there was statistically significant difference in ExG compared to OG in all the variables assessed.

Conclusion

The program quadriceps strengthening exercises applied in this randomized clinical trial was effective in improving pain, function and quality of life of patients with knee osteoarthritis. Level of Evidence I, Randomized Clinical Trial.

Towards a mechanism-based approach to pain management in osteoarthritis

Pain is the defining symptom of osteoarthritis (OA), yet available treatment options, of which NSAIDs are the most common, provide inadequate pain relief and are associated with serious health risks when used long term. Chronic pain pathways are subject to complex levels of control and modulation, both in the periphery and in the central nervous system. Ongoing clinical and basic research is uncovering how these pathways operate in OA. Indeed, clinical investigation into the types of pain associated with progressive OA, the presence of central sensitization, the correlation with structural changes in the joint, and the efficacy of novel analgesics affords new insights into the pathophysiology of OA pain. Moreover, studies in disease-specific animal models enable the unravelling of the cellular and molecular pathways involved. We expect that increased understanding of the mechanisms by which chronic OA-associated pain is generated and maintained will offer opportunities for targeting and improving the safety of analgesia. In addition, using clinical and genetic approaches, it might become possible to identify subsets of patients with pain of different pathophysiology, thus enabling a tailored approach to pain management.

Effects of neuromuscular electrical stimulation combined with exercises versus an exercise program on the pain and the function in patients with knee osteoarthritis: a randomized controlled trial

Objectives. To investigate the effect of 8 weeks of NMES + Ex (neuromuscular electrical stimulation combined with exercises) on pain and functional improvement in patients with knee osteoarthritis (OA) compared to exercise (Ex) alone. Design. Randomized controlled trial. Setting. A specialty outpatient clinic. Participants. Patients (N = 100; women = 86, men = 14; age range, 50–75 years) with knee OA. Interventions. Participants were randomly assigned to NMES + Ex or Ex group. Outcome Measures. Numerical Rating Scale 0 to 10 (NRS) and the Timed Up and Go (TUG) test were the primary outcomes. The secondary outcomes used were the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Results. Following the interventions, a statistically significant improvement in both groups was observed in all outcomes assessed. For the comparison between the groups, no statistically significant difference was found between the NMES + Ex and the Ex groups in NRS (P = 0.52), TUG test (P = 0.12), and aspects of WOMAC: pain (P = 0.26), function (P = 0.23), and stiffness (P = 0.63). Conclusion. The addition of NMES to exercise did not improve the outcomes assessed in knee OA patients. This study was registered at the Australian Clinical Trials Registry (ACTRN012607000357459).

The innervation of synovium of human osteoarthritic joints in comparison with normal rat and sheep synovium

OBJECTIVE

To study whether osteoarthritis (OA) in the knee is associated with a change of the innervation pattern in the synovial layer.

DESIGN

In synovial tissue from the normal knee joint of rat and sheep we studied the presence of vessels and of nerve fibres using transmission electron microscopy and immunohistochemistry. Synovial material was also obtained from patients who underwent total knee replacement surgery. This material was examined for inflammatory changes, and the presence of vessels and nerve fibres was assessed.

RESULTS

The synovium in the parapatellar region of the normal knee joint of rat and sheep exhibited a dense capillary and neuronal network. It was entered by calcitonin gene-related peptide containing sensory fibres and tyrosine hydroxylase-positive sympathetic nerve fibres. Synovial material from patients with knee OA exhibited different degrees of inflammation. Synovial material without inflammation exhibited a similar vascular and neuronal network as the normal knee joint from rat and sheep. However, in synovium with inflammatory changes we found a significant decrease of nerve fibres in depth ranges close to the synovial lining layer depending on the degree of inflammation whereas deeper regions were less affected.

CONCLUSIONS

Inflammatory changes in the synovium of OA joints are associated with a massive destruction of the capillary and neuronal network which is present in normal synovium. Due to the disappearance of the sensory fibres it is unlikely that OA pain is initiated directly in the synovium. The loss of normally innervated vascularisation may have multiple consequences for the physiological functions of the synovium.

Defining the content of an opportunistic osteoarthritis consultation with primary health care professionals: a Delphi consensus study

OBJECTIVE

To define the core content for an opportunistic consultation between a health care professional (HCP) and a patient with osteoarthritis (OA) in primary care.

METHODS

An ideas generation round and a 2-round Delphi postal consensus study allowed participants to rank the importance of tasks for an opportunistic consultation. The study was conducted with a lay group (n = 18) and 3 groups of HCPs (n = 30 for general practitioners, n = 19 for practice nurses, and n = 37 for allied health professionals).

RESULTS

The ideas generation round formulated 35 consultation tasks. There was a 50% response rate to the 2-round postal exercise (n = 52). Consensus was reached on 12 tasks for an opportunistic OA consultation using a >80% level of agreement across all groups. Three of these consultation tasks were defined at 100%. The 3 tasks were questions asked by the HCP about how things are going with the condition, the type and amount of pain the patient has, and whether the patient is taking regular analgesia.

CONCLUSION

In a Delphi study to define the content of an opportunistic primary care OA consultation, 12 consultation tasks provided the content of a comprehensive consultation. Three of these tasks with 100% agreement could be adopted in any multidisciplinary consultation for OA in primary care. Inquiring about the condition, the type and amount of pain the patient has, and whether analgesia is being taken forms a core set of questions that are considered important by both lay and health professional groups in an opportunistic consultation.

A hexadecylamide derivative of hyaluronan (HYMOVIS®) has superior beneficial effects on human osteoarthritic chondrocytes and synoviocytes than unmodified hyaluronan

Background

Intra-articular hyaluronan (HA) injection provides symptomatic benefit in the treatment of osteoarthritis (OA). Previously we found superior beneficial effects in a large animal OA model of a hexadecylamide derivative compared with unmodified HA of the same initial molecular weight. The current study sought to define possible molecular mechanisms whereby this enhanced relief of symptoms was occurring.

Methods

Chondrocytes and synovial fibroblasts were isolated from tissues of patients undergoing arthroplasty for knee OA. Monolayer cultures of cells were treated with 0, 0.5, 1.0 or 1.5 mg/mL of unmodified HA (500–730 kDa) or a hexadecylamide derivative of HA of the same initial molecular weight (HYADD4®-G; HYMOVIS®) simultaneously or 1 hour before incubation with interleukin (IL)-1beta (2 ng/mL). Cultures were terminated 15 or 30 minutes later (chondrocytes and synovial fibroblasts, respectively) for quantitation of phosphorylated-(p)-JNK, p-NFkappaB, p-p38, or at 24 hours for quantitation of gene expression (MMP1 &13, ADAMTS4 &5, TIMP1 &3, CD44, COL1A1 &2A1, ACAN, PTGS2, IL6, TNF) and matrix metalloproteinase (MMP)-13 activity.

Results

The hexadecylamide derivative of HA had significantly better amelioration of IL-1beta-induced gene expression of key matrix degrading enzymes (MMP1, MMP13, ADAMTS5), and inflammatory mediators (IL6, PTGS2) by human OA chondrocytes and synovial fibroblasts. Pre-incubation of cells with the derivatized HA for 1 hour prior to IL-1beta exposure significantly augmented the inhibition of MMP1, MMP13, ADAMTS4 and IL6 expression by chondrocytes. The reduction in MMP13 mRNA by the amide derivative of HA was mirrored in reduced MMP-13 protein and enzyme activity in IL-1beta-stimulated chondrocytes. This was associated in part with a greater inhibition of phosphorylation of the cell signalling molecules JNK, p38 and NF-kappaB.

Conclusions

The present studies have demonstrated several potential key mechanisms whereby the intra-articular injection of a hexadecylamide derivative of HA may be acting in joints with OA.

Characterization of opticin digestion by proteases involved in osteoarthritis development

OBJECTIVE

Opticin is a class III member of the small leucine-rich repeat proteoglycan (SLRP) family, produced in articular joint tissues. In normal and osteoarthritic (OA) cartilage, opticin is degraded. This study aimed to assess whether human cartilage opticin is degraded by the main proteases involved in OA pathophysiology, and to determine the protease cleavage sites of this SLRP.

METHODS

We analyzed the proteolytic activity of matrix metalloproteinases (MMPs)-1, -2, -3, -7, -8 and -9, and ADAMTS-4 and -5 on proteoglycan extracts from normal and moderately fibrillated OA human cartilage, and on recombinant human opticin. Opticin degradation was analyzed by Western blotting and cleavage sites were determined by sequence analysis.

RESULTS

All eight proteases digested opticin from proteoglycan extracts from both normal and OA samples, as well as recombinant human opticin, MMP-2 and MMP-7 are the proteases that degrade recombinant human opticin most efficiently. The opticin cleavage site determined for these MMPs was between the glycosylation and leucine-rich repeat domains. MMP-7 had two additional digestion sites near the N-terminal end of opticin.

CONCLUSION

Opticin is a substrate for several MMPs and aggrecanases involved during OA cartilage degradation, and seems to be a preferential substrate for MMP-7. The role of opticin in cartilage degeneration could be related to decreased levels of intact opticin, followed by its proteolytic degradation, which in turn may stimulate some of the modifications observed in the OA cartilage, such as neovascularisation and changes in the extracellular matrix.

Well-being among older adults with OA: direct and mediated patterns of control beliefs, optimism and pessimism

OBJECTIVES

To assess the contribution of important psychological resources (i.e. optimism, pessimism, control beliefs) to the psychological well-being of older adults with Osteoarthritis (OA); to assess the direct and mediated association of these psychosocial resources to outcomes (depressive symptoms, life satisfaction, and self-esteem). These objectives are important because OA is a significant stressor, treatments are limited, and psychological functioning is at risk for those coping with the condition, even compared to other chronic illnesses.

METHOD

A cross-sectional survey of 160 community-dwelling older adults with OA (81% women). Participants were not randomly selected, but nonetheless reflected the demographic makeup of the selection area.

RESULTS

Ordinary least squares regression analyses using the PROCESS macro revealed that optimism and pessimism were associated with higher depressive symptoms and lower self-esteem indirectly through constraints beliefs. The analysis of life satisfaction showed that optimism and pessimism were each partially mediated through mastery and constraints beliefs.

DISCUSSION

These results suggest that prior research, which has assessed these psychological resources as having singular relationships to outcomes, may have underestimated the importance of the relationship between these variables. We discuss possible points of intervention for older adults with OA who may experience increasing constraints beliefs over time.

A biological therapy to osteoarthritis treatment using platelet-rich plasma

INTRODUCTION

Osteoarthritis (OA) is a degenerative disease affecting the synovial joint. It is caused by cells exposure to non-physiological stimuli, either mechanical or biochemical, and the loss of bone-cartilage homeostasis. Some of these changes, however, may be reversed by the use of single or combined growth factors, suggesting that the treatment of OA could be addressed using a pool of growth factors.

AREAS COVERED

This review addresses current molecular and biological knowledge and implicates the recapitulation of some developmental processes during endochondral ossification in OA aetiology and pathogenesis. Platelets act as carriers of endogenous morphogens that may modulate cell fate and therefore affect joint tissues structure and function. We shed light on the platelet-rich plasma effects on biological level that might drive the osteoarthritic joint's improvement both in structure and function.

EXPERT OPINION

We present the therapeutic potential of plasma rich in growth factors (PRGF-Endoret), an endogenous biological therapy that might modulate the gene expression of cells such as chondrocytes, synoviocytes, macrophages, and mesenchymal stem cells, and thereby influence an anabolic microenvironment of synovial joint which is conducive to maintaining the homeostatic state of the joint's tissues, and hence reduce pain and improve the joint motion.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanisms of chronic pain in osteoarthritis

Pain is a major clinical problem of osteoarthritis (OA). Recently, OA has been thought to be a disease of the whole joint with both destruction of cartilage and inflammatory components such as synovitis and bone marrow lesions. Clinical studies have documented a significant inflammatory soft tissue contribution to the severity and frequency of OA pain. Both clinical and experimental studies have provided evidence for the sensitization of pain pathways during OA, involving pronounced changes in joint nociceptors and changes of the nociceptive processing in the spinal cord, brainstem, and thalamocortical system. Additionally, evidence has been provided for neuropathic pain components in OA models. Concerning molecular mechanisms of OA pain and potential options for pain therapy, studies on nerve growth factor, cytokines, sodium channel blockers, hyaluronic acid preparations, and others are addressed in this review.

Differential diagnosis and early management of rapidly progressing hip pain in a 59-year-old male

OBJECTIVE AND IMPORTANCE

Rapidly progressing degeneration of the hip joint is an uncommon condition presenting to physical therapy. Differential diagnosis can often be difficult, as clinical and radiographic findings do not always coincide leaving clinicians with difficult decision making regarding course of treatment. The purpose of this case report was to describe the differential diagnosis and early management of a patient with rapidly progressing hip pain.

CLINICAL PRESENTATION

A 59-year-old male with a complicated medical history was referred with a diagnosis of severe bilateral hip osteoarthritis. Clinical presentation of insidious onset, severe bilateral groin and anterior thigh pain with rapid progression of functional decline lead to the differential diagnosis of bilateral avascular necrosis.

INTERVENTION

The patient received seven manual physical therapy sessions over the course of one month.

CONCLUSION

During this time, the patient's Lower Extremity Functional Scale score worsened from 33 to 21. The persistence of the patient's painful symptoms and continued functional decline helped determine cessation of manual therapy and referral back to his GP for further diagnostic testing and eventual correct diagnosis. This case highlights the importance of monitoring patient prognosis using outcome measures leading to a change in patient management strategies.

Sclerostin: A Novel Player Regulating Bone Mass in Inflammation?

Inflammation is a common albeit overlooked cause of local and systemic bone loss which results from an imbalance between bone formation and bone resorption. The Wnt pathway, which plays an essential role in the regulation of bone turnover, has been proposed as a potential molecular link between inflammation and inflammatory bone loss. We here recapitulate present knowledge about sclerostin, a Wnt pathway inhibitor, and bone damage in inflammation. A better understanding of sclerostin action and regulation might help in designing an effective treatment strategy in inflammatory bone loss.

Sclerostin is expressed in articular cartilage but loss or inhibition does not affect cartilage remodeling during aging or following mechanical injury

OBJECTIVE

Sclerostin plays a major role in regulating skeletal bone mass, but its effects in articular cartilage are not known. The purpose of this study was to determine whether genetic loss or pharmacologic inhibition of sclerostin has an impact on knee joint articular cartilage.

METHODS

Expression of sclerostin was determined in articular cartilage and bone tissue obtained from mice, rats, and human subjects, including patients with knee osteoarthritis (OA). Mice with genetic knockout (KO) of sclerostin and pharmacologic inhibition of sclerostin with a sclerostin-neutralizing monoclonal antibody (Scl-Ab) in aged male rats and ovariectomized (OVX) female rats were used to study the effects of sclerostin on pathologic processes in the knee joint. The rat medial meniscus tear (MMT) model of OA was used to investigate the pharmacologic efficacy of systemic Scl-Ab or intraarticular (IA) delivery of a sclerostin antibody-Fab (Scl-Fab) fragment.

RESULTS

Sclerostin expression was detected in rodent and human articular chondrocytes. No difference was observed in the magnitude or distribution of sclerostin expression between normal and OA cartilage or bone. Sclerostin-KO mice showed no difference in histopathologic features of the knee joint compared to age-matched wild-type mice. Pharmacologic treatment of intact aged male rats or OVX female rats with Scl-Ab had no effect on morphologic characteristics of the articular cartilage. In the rat MMT model, pharmacologic treatment of animals with either systemic Scl-Ab or IA injection of Scl-Fab had no effect on lesion development or severity.

CONCLUSION

Genetic absence of sclerostin does not alter the normal development of age-dependent OA in mice, and pharmacologic inhibition of sclerostin with Scl-Ab has no impact on articular cartilage remodeling in rats with posttraumatic OA.

Osteoarthritis guidelines: a progressive role for topical nonsteroidal anti-inflammatory drugs

Current treatment guidelines for the treatment of chronic pain associated with osteoarthritis reflect the collective clinical knowledge of international experts in weighing the benefits of pharmacologic therapy options while striving to minimize the negative effects associated with them. Consideration of disease progression, pattern of flares, level of functional impairment or disability, response to treatment, coexisting conditions such as cardiovascular disease or gastrointestinal disorders, and concomitant prescription medication use should be considered when creating a therapeutic plan for a patient with osteoarthritis. Although topical nonsteroidal anti-inflammatory drugs historically have not been prevalent in many of the guidelines for osteoarthritis treatment, recent evidence-based medicine and new guidelines now support their use as a viable option for the clinician seeking alternatives to typical oral formulations. This article provides a qualitative review of these treatment guidelines and the emerging role of topical nonsteroidal anti-inflammatory drugs as a therapy option for patients with localized symptoms of osteoarthritis who may be at risk for oral nonsteroidal anti-inflammatory drug-related serious adverse events.

Is neuromuscular electrical stimulation effective for improving pain, function and activities of daily living of knee osteoarthritis patients? A randomized clinical trial

CONTEXT AND OBJECTIVE

Neuromuscular electrical stimulation (NMES) has been used in rehabilitation protocols for patients suffering from muscle weakness resulting from knee osteoarthritis. The purpose of the present study was to assess the effectiveness of an eight-week treatment program of NMES combined with exercises, for improving pain and function among patients with knee osteoarthritis.

DESIGN AND SETTING

Randomized clinical trial at Interlagos Specialty Ambulatory Clinic, Sao Paulo, Brazil.

METHODS

One hundred were randomized into two groups: NMES group and control group. The following evaluation measurements were used: numerical pain scale from 0 to 10, timed up and go (TUG) test, Lequesne index and activities of daily living (ADL) scale.

RESULTS

Eighty-two patients completed the study. From intention-to-treat (ITT) analysis comparing the groups, the NMES group showed a statistically significant improvement in relation to the control group, regarding pain intensity (difference between means: 1.67 [0.31 to 3.02]; P = 0.01), Lequesne index (difference between means: 1.98 [0.15 to 3.79]; P = 0.03) and ADL scale (difference between means: -11.23 [-19.88 to -2.57]; P = 0.01).

CONCLUSION

NMES, within a rehabilitation protocol for patients with knee osteoarthritis, is effective for improving pain, function and activities of daily living, in comparison with a group that received an orientation program. CLINICAL TRIAL REGISTRATION ACTRN012607000357459.

Migfilin's elimination from osteoarthritic chondrocytes further promotes the osteoarthritic phenotype via β-catenin upregulation

Osteoarthritis (OA) is a debilitating disease of the joints characterized by cartilage degradation but to date there is no available pharmacological treatment to inhibit disease progression neither is there any available biomarker to predict its development. In the present study, we examined the expression level and possible involvement of novel cell-ECM adhesion-related molecules such as Iintegrin Linked Kinase (ILK), PINCH, parvin, Mig-2 and Migfilin in OA pathogenesis using primary human articular chondrocytes from healthy individuals and OA patients. Our findings show that only ILK and Migfilin were upregulated in OA compared to the normal chondrocytes. Interestingly, Migfilin silencing in OA chondrocytes rather exacerbated than ameliorated the osteoarthritic phenotype, as it resulted in even higher levels of catabolic and hypertrophic markers while at the same time induced reduction in ECM molecules such as aggrecan. Furthermore, we also provide a link between Migfilin and β-catenin activation in OA chondrocytes, showing Migfilin to be inversely correlated with β-catenin. Thus, the present study emphasizes for the first time to our knowledge the role of Migfilin in OA and highlights the importance of cell-ECM adhesion proteins in OA pathogenesis.

The relationship of tibial bone perfusion to pain in knee osteoarthritis

OBJECTIVE

To confirm altered perfusion within tibial bone marrow lesions (BMLs) and improve our understanding on the relationship between BMLs and pain in knee osteoarthritis (OA).

METHODS

Participants with moderate to severe knee OA were recruited and pain was assessed using the pain subscale of the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Subchondral tibial BMLs were identified and graded on magnetic resonance imaging (MRI) proton density-weighted (PDW) fat suppressed images. A pharmacokinetic model was used to analyze perfusion parameters on dynamic contrast enhanced (DCE) MRI which represent transfer rates in and out of the BMLs. The relation between perfusion and pain was evaluated using multivariable linear regression after adjustment for BML grade, age, gender and body mass index (BMI).

RESULTS

There were 37 participants (mean age 64.9 years, range 46-86) with radiographic Kellgren and Lawrence grades of 3 and 4 in the study knee; 75.6% had BMLs that were classified grades 1 and 2. The mean WOMAC pain score was 10.3 (0-20 scale). There was a significant correlation between BML K(el) (rate of contrast elimination) and BML grade (P = 0.001 univariate, P = 0.002 multivariate analyses), although we did not demonstrate any significant multivariate association between BML perfusion and pain. We also found an inverse relationship between pain at sleep and BML grade (P < 0.05).

CONCLUSIONS

The absence of any significant association between bone perfusion and pain implies that the relationship of tibial BMLs to pain in OA is still incompletely understood. BMLs are just one component of the whole knee joint and are formed from various causes, all of which interact and collectively contribute to the genesis of pain in OA.

CCR2 chemokine receptor signaling mediates pain in experimental osteoarthritis

Osteoarthritis is one of the leading causes of chronic pain, but almost nothing is known about the mechanisms and molecules that mediate osteoarthritis-associated joint pain. Consequently, treatment options remain inadequate and joint replacement is often inevitable. Here, we use a surgical mouse model that captures the long-term progression of knee osteoarthritis to longitudinally assess pain-related behaviors and concomitant changes in the innervating dorsal root ganglia (DRG). We demonstrate that monocyte chemoattractant protein (MCP)-1 (CCL2) and its high-affinity receptor, chemokine (C-C motif) receptor 2 (CCR2), are central to the development of pain associated with knee osteoarthritis. After destabilization of the medial meniscus, mice developed early-onset secondary mechanical allodynia that was maintained for 16 wk. MCP-1 and CCR2 mRNA, protein, and signaling activity were temporarily up-regulated in the innervating DRG at 8 wk after surgery. This result correlated with the presentation of movement-provoked pain behaviors, which were maintained up to 16 wk. Mice that lack Ccr2 also developed mechanical allodynia, but this started to resolve from 8 wk onwards. Despite severe allodynia and structural knee joint damage equal to wild-type mice, Ccr2-null mice did not develop movement-provoked pain behaviors at 8 wk. In wild-type mice, macrophages infiltrated the DRG by 8 wk and this was maintained through 16 wk after surgery. In contrast, macrophage infiltration was not observed in Ccr2-null mice. These observations suggest a key role for the MCP-1/CCR2 pathway in establishing osteoarthritis pain.

Expression of the histamine H4 receptor in dermal and articular tissues

Histamine H(4) receptor was identified in 2000 and is the most recently identified of the four histamine receptors. It is expressed primarily in immune cells and is involved in physiologic functions related to inflammation and allergy. Recently, the H(4) receptor was highlighted as a promising therapeutic target in atopic dermatitis, asthma, and chronic arthritis. In fact, some H(4) receptor antagonists have reached clinical trials for the treatment of asthma, atopic dermatitis, and allergic rhinitis. Based on an initial assessment of distribution, the H(4) receptor has been referred to as the histamine receptor of the hematopoietic system. However, the H(4) receptor has also been implicated in the regulation of other non-hematopoietic systems. Here, we review the expression and function of the H(4) receptor with a focus on dermal and articular tissues. In skin, the H(4) receptor is expressed in both the epidermis and dermis, with stronger receptor expression in the epidermis. In articular tissue, H(4) receptor expression has been detected in synovial cells. Chondrocytes, a major cell sources for cartilage tissue engineering, also express the H(4) receptor. Further understanding of the functions of H(4) receptors in non-hematopoietic cells might lead to novel treatments for diseases with unmet needs.

Limb Idleness Index (LII): a novel measurement of pain in a rat model of osteoarthritis

OBJECTIVES

Mechanical allodynia during ambulation in osteoarthritis (OA) animal models can be assessed as decreased extent of loading or decreased duration of loading. We propose to measure gait adaptation to pain by both mechanisms with the development of Limb Idleness Index (LII) in a rat model of knee OA.

METHODS

Rats were assigned to anterior cruciate ligament transection (ACLT), Sham, or Normal group (n = 6). Gait data were collected at pre-injury, 1, 2, 3 and 6 months post-injury. Ratios of target print intensity, anchor print intensity, and swing duration were combined to obtain LII. The association of gait changes with pain was assessed by buprenorphine treatment at 3 and 6 months post-injury. At 6 months, OA-related structural changes in knee joints were examined by μCT and results from histological scoring were correlated with LII.

RESULTS

As compared to pre-injury level (range 0.75-1.20), LII in ACLT group was increased at 6 months post-injury, which was significantly higher than that in Sham and Normal groups (P = 0.024). The increase in LII in ACLT group was effectively reversed by buprenorphine treatment (P = 0.004). ACLT group exhibited a significantly higher maximum Osteoarthritis Research Society International (OARSI) score as compared to Sham (P = 0.005) and Normal (P = 0.006) groups. Significant correlation was found between LII and side-to-side difference in OARSI score (r = 0.893, P < 0.001).

CONCLUSIONS

LII presents a good measurement for OA-related knee pain in rat model.

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

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