New Horizons in Pharmacologic Treatment for Rheumatic Disease Pain

Primary total hip arthroplasty in elderly patients over 85 years old: risks, complications and medium-long term results

INTRODUCTION

The elderly population candidate for total hip arthroplasty (THA) is increasing exponentially in developed countries, due to the high prevalence of osteoarthritis (OA). The objective is to identify the overall survival in patients over 85 years with primary OA who underwent THA.

MATERIAL AND METHODS

Retrospective observational study in patients over 85 years with primary hip OA undergoing THA between 2012 and 2019. Demographic, clinical, comorbidity, complications, functionality and pain variables were collected. A descriptive analysis was performed, survival was estimated with the Kaplan-Meier method and the differences in pain and functionality before and after surgery with the McNemar-Bowker test.

RESULTS

We included 66 patients, 40 women and 26 men with a mean age of 87.22 years, of whom 15 had high comorbidity (Charlson>2). Only 14 patients presented complications in the postoperative period, the most frequent was confusional syndrome (5); and the most serious was a death (1), with a median hospital stay of 8 days. Two cases of dislocation were detected over a mean follow-up of 3.61 years, without requiring revision surgery. Improvement of pain was evident after surgery (p<.0001). The median overall survival is 6.77 years, with no difference in survival adjusted by the Charlson index (p=.75) or by ASA anaesthetic group (p=.23).

CONCLUSIONS

With good patient selection, THA is a good option for patients over 85 years of age with functional limitations or pain due to OA.

A Review on Chronic Pain in Rheumatoid Arthritis: A Focus on Activation of NR2B Subunit of N-Methyl-D-Aspartate Receptors

Chronic pain is a debilitating condition that occurs after tissue damage, which substantially affects the patient's emotional state and physical activity. The chronic pain in rheumatoid arthritis (RA) is the result of various autoimmune-induced inflammatory reactions in the joints. Both types of peripheral and central pain processing can lead to sensitisation. Non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs (DMARDs) can result in potent anti-inflammatory effect. However, these drugs are not able to suppress the pain from RA for a prolonged period. For years, researchers have examined the role of the N-methyl-D-aspartic acid receptor 2B (NR2B) subunit of N-methyl-D-aspartate receptors (NMDAR) in chronic and neuropathic pain models. This NMDAR subtype can be found in at the peripheral and central nervous system and it represents an effective therapy for RA pain management. This review focuses on the NR2B subunit of NMDAR and the different pathways leading to its activation. Furthermore, specific attention is given to the possible involvement of NR2B subunit in the peripheral and central pathogenesis of RA.

Combatting joint pain and inflammation by dual inhibition of monoacylglycerol lipase and cyclooxygenase-2 in a rat model of osteoarthritis

BACKGROUND

Endocannabinoids are showing great promise as effective mediators for controlling joint inflammation and pain. One strategy that could be harnessed to promote endogenous cannabinoid function is to inhibit the enzymatic break down of endocannabinoids locally in the joint. KML29 is an inhibitor of monoacylglycerol lipase (MAGL) activity which has been shown to promote increased 2-arachodonylglycerol (2-AG) levels in the circulation and in peripheral tissues. It is also known that 2-AG can be metabolised via the cyclo-oxygenase-2 (COX-2) pathway leading to the production of pro-inflammatory prostaglandins, which may counteract the effects of 2-AG. Therefore, this study examined the effect of KML29 alone as well as in combination with low-dose celecoxib (CXB) on joint pain and inflammation in the monoiodoacetate (MIA) model of osteoarthritis (OA) pain.

METHODS

Injection of MIA (3 mg) into the knee joints of male Wistar rats was used to model OA pain, inflammation, and nerve damage. Pain behaviour was assessed by von Frey hair algesiometry, and inflammation was evaluated using intravital microscopy to measure leukocyte trafficking in the synovial microvasculature.

RESULTS

Intra-articular injection of MIA produced mechanical hypersensitivity as measured by von Frey hair algesiometry. Local injection of KML29 (700 μg) reduced joint pain at day 14 post-MIA induction, and this analgesic effect was blocked by the cannabinoid receptor antagonists AM281 and AM630 (P < 0.0001; n = 6). During the acute inflammatory phase of the MIA model (day 1), a significant reduction in withdrawal threshold (P < 0.0001; n = 6-8) and leukocyte trafficking was seen after treatment with KML29 + CXB (P < 0.0001; n = 6-8). Early treatment of MIA-injected knees (days 1-3) with KML29 + CXB ameliorated the development of mechanical secondary allodynia (P < 0.0001; n = 8) in the later stages of the MIA model.

CONCLUSIONS

Combination therapy of KML29 plus CXB reduced joint pain and inflammation. Thus, dual inhibition of MAGL and cyclooxygenase-2 pathways could be a useful approach to alleviate joint inflammation and pain in OA joints.

Efficacy and safety of cannabidiol followed by an open label add-on of tetrahydrocannabinol for the treatment of chronic pain in patients with rheumatoid arthritis or ankylosing spondylitis: protocol for a multicentre, randomised, placebo-controlled study

INTRODUCTION

Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) are chronic, systemic, inflammatory diseases, primarily in the musculoskeletal system. Pain and fatigue are key symptoms of RA and AS. Treatment presents a clinical challenge for several reasons, including the progressive nature of the diseases and the involvement of multiple pain mechanisms. Moreover, side effects of pain treatment pose an implicit risk. Currently, no well-controlled studies have investigated how medical cannabis affects pain and cognitive functions in RA and AS. The present study aims to evaluate the efficacy and safety of medical cannabis in the treatment of persistent pain in patients with RA and AS with low disease activity.

METHODS AND ANALYSIS

A double-blinded, randomised, placebo-controlled study of cannabidiol (CBD), followed by an open label add-on of tetrahydrocannabinol (THC) with collection of clinical data and biological materials in RA and AS patients treated in routine care. The oral treatment with CBD in the experimental group is compared with placebo in a control group for 12 weeks, followed by an observational 12-week period with an open label add-on of THC in the primary CBD non-responders. Disease characteristics, psychological parameters, demographics, comorbidities, lifestyle factors, blood samples and serious adverse events are collected at baseline, after 12 and 24 weeks of treatment, and at a follow-up visit at 36 weeks. Data will be analysed in accordance with a predefined statistical analysis plan.

ETHICS AND DISSEMINATION

The Danish Ethics Committee (S-20170217), the Danish Medicines Agency (S-2018010018) and the Danish Data Protection Agency approved the protocol. The project is registered in the European Clinical Trials Database (EudraCT 2017-004226-15). All participants will give written informed consent to participate prior to any study-related procedures. The results will be presented at international conferences and published in peer-reviewed journals.

Clinical outcome following primary total hip or knee replacement in nonagenarians

Introduction The Elective Orthopaedic Centre in Epsom has an established patient reported outcome measures programme, into which all patients are enrolled. Postoperative complications, Oxford hip/knee scores (OHS/OKS) and EQ-5D™ (EuroQol, Rotterdam, Netherlands) scores are collected up to the second postoperative year. Our population is ageing and the number of joint replacements being performed on the very elderly is rising. The aim of this study was to investigate the outcome of joint replacements in a nonagenarian population. Methods Our dataset was reviewed retrospectively for a cohort of nonagenarians undergoing either a primary total hip replacement (THR) or total knee replacement (TKR) between April 2008 and October 2011. Postoperative complications, mortality rates and functional outcomes were compared with those of a time matched 70-79-year-old cohort. Results Nonagenarians requiring a THR presented with a lower preoperative OHS (p=0.020) but made a greater improvement in the first postoperative year than the younger cohort (p=0.040). The preoperative OKS was lower for nonagenarians than for the control group (p=0.022). At one and two years after TKR, however, there was no significant difference between the age groups. The nonagenarians had a greater risk of requiring a blood transfusion following both THR (p=0.027; 95% confidence interval [CI]: 1.11-5.75) and TKR (p=0.037; 95% CI: 1.08-16.65) while the latter cohort also required a longer stay than their younger counterparts (p=0.001). Mortality rates were higher in the nonagenarian group but these were in keeping with the life expectancy projections identified by the Office for National Statistics. Conclusions Over a two-year period, the functional outcome and satisfaction rates achieved by nonagenarians following a THR or TKR are comparable with 70-79-year-olds.

The role of glia in the spinal cord in neuropathic and inflammatory pain

Chronic pain, both inflammatory and neuropathic, is a debilitating condition in which the pain experience persists after the painful stimulus has resolved. The efficacy of current treatment strategies using opioids, NSAIDS and anticonvulsants is limited by the extensive side effects observed in patients, underlining the necessity for novel therapeutic targets. Preclinical models of chronic pain have recently provided evidence for a critical role played by glial cells in the mechanisms underlying the chronicity of pain, both at the site of damage in the periphery and in the dorsal horn of the spinal cord. Here microglia and astrocytes respond to the increased input from the periphery and change morphology, increase in number and release pro-nociceptive mediators such as ATP, cytokines and chemokines. These gliotransmitters can sensitise neurons by activation of their cognate receptors thereby contributing to central sensitization which is fundamental for the generation of allodynia, hyperalgesia and spontaneous pain.

Pain treatment in arthritis-related pain: beyond NSAIDs

Managing pain from chronic conditions, such as, but not limited to, osteoarthritis and rheumatoid arthritis, requires the clinician to balance the need for effective analgesia against safety risks associated with analgesic agents. Osteoarthritis and rheumatoid arthritis pain is incompletely understood but involves both nociceptive and non-nociceptive mechanisms, including neuropathic mechanisms. Prevailing guidelines for arthritis-related pain do not differentiate between nociceptive and non-nociceptive pain, sometimes leading to recommendations that do not fully address the nature of pain. NSAIDs are effective in treating the nociceptive arthritis-related pain. However, safety concerns of NSAIDs may cause clinicians to undertreat arthritis-related pain. In this context, combination therapy may be more appropriate to manage the different pain mechanisms involved. A panel convened in November 2010 found that among the currently recommended analgesic products for arthritis-related pain, fixed-low-dose combination products hold promise for pain control because such products allow lower doses of individual agents resulting in decreased toxicity and acceptable efficacy due to synergy between the individual drugs. Better evidence and recommendations are required to improve treatment of chronic arthritis-related pain.

Management of chronic pain in the rheumatic diseases with insights for the clinician

Pain that accompanies musculoskeletal conditions should be regarded as an illness entity in its own right and deserves treatment in parallel with the management of the underlying condition. Recent understanding of the pathophysiology of rheumatic pain invokes interplay of the nociceptive mechanisms driven by local tissue factors and the neurogenic responses that sustain chronic pain. In line with other pain conditions, ideal treatment of rheumatic pain should be through a multimodal approach, integrating nonpharmacologic as well as pharmacologic treatments. In the light of this new concept of pain mechanisms, future pharmacologic treatment options may encompass a wider scope than the use of traditional analgesics and nonsteroidal anti-inflammatory drugs. There is currently limited experience for use of pharmacologic treatments that act primarily on neurogenic mechanisms in rheumatic conditions. Drug combination studies are lacking, but this strategy seems clinically reasonable to allow for an approach to treating pain from different mechanistic perspectives. An added advantage would be the opportunity to use lower doses of individual drugs and thereby reduce the side effect profile. Ideal pain management must also include attention to the important co-associates of pain such as effects on sleep, mood and energy, which all have an impact on the global burden of suffering. Although complete relief of pain is still an unrealistic objective, reasonable outcome goals for symptom relief should be accompanied with an improvement in function.

Spinal cathepsin S and fractalkine contribute to chronic pain in the collagen-induced arthritis model

OBJECTIVE

The induction of rheumatoid arthritis (RA) by active and passive immunization of mice results in the development of pain at the same time as the swelling and inflammation, with both peripheral and central sensitization contributing to joint pain. The purpose of this study was to examine the development of pain in the rat model of collagen-induced arthritis (CIA) and to evaluate the contribution of neuroimmune interactions to established arthritis pain.

METHODS

Mechanical hypersensitivity was assessed in female Lewis rats before and up to 18 days after induction of CIA by immunization with type II collagen. The effect of selective inhibitors of microglia were then evaluated by prolonged intrathecal delivery of a cathepsin S (CatS) inhibitor and a fractalkine (FKN) neutralizing antibody, from day 11 to day 18 following immunization.

RESULTS

Rats with CIA developed significant mechanical hypersensitivity, which started on day 9, before the onset of clinical signs of arthritis. Mechanical hypersensitivity peaked with the severity of the disease, when significant microglial and astrocytic responses, alongside T cell infiltration, were observed in the spinal cord. Intrathecal delivery of microglial inhibitors, a CatS inhibitor, or an FKN neutralizing antibody attenuated mechanical hypersensitivity and spinal microglial response in rats with CIA.

CONCLUSION

The inhibition of microglial targets by centrally penetrant CatS inhibitors and CX(3) CR1 receptor antagonists represents a potential therapeutic avenue for the treatment of pain in RA.

Microglial signalling mechanisms: Cathepsin S and Fractalkine

A recent major conceptual advance has been the recognition of the importance of immune system-neuron interactions in the modulation of spinal pain processing. In particular, pro-inflammatory mediators secreted by immune competent cells such as microglia modulate nociceptive function in the injured CNS and following peripheral nerve damage. Chemokines play a pivotal role in mediating neuronal-microglial communication which leads to increased nociception. Here we examine the evidence that one such microglial mediator, the lysosomal cysteine protease Cathepsin S (CatS), is critical for the maintenance of neuropathic pain via cleavage of the transmembrane chemokine Fractalkine (FKN). Both CatS and FKN mediate critical physiological functions necessary for immune regulation. As key mediators of homeostatic functions it is not surprising that imbalance in these immune processes has been implicated in autoimmune disorders including Multiple Sclerosis and Rheumatoid Arthritis, both of which are associated with chronic pain. Thus, impairment of the CatS/FKN signalling pair constitutes a novel therapeutic approach for the treatment of chronic pain.

The role of the rheumatologist in managing pain therapy

Despite the clinical importance of pain in patients with rheumatic diseases, rheumatologists have not delegated a proportionate amount of effort to its investigation and treatment. Some of the assumptions that have hindered progress in pain management for rheumatologists include a preference for immunologic research over pain research, a reluctance to provide opioid therapy, and inadequate compensation. Contrary to these assumptions, pain management is becoming an area of increasing research and clinical effort in the field of rheumatology. This article discusses how the barriers to effective pain management can be overcome, although the relative differential compensation for psychosocial versus interventional therapy remains a concern. In the future, rheumatologists will need to expend greater time and effort in the study of pain management to remain pertinent to the needs of their rheumatic disease patients.