Knee osteoarthritis related pain: a narrative review of diagnosis and treatment

BACKGROUND

Osteoarthritis is a common progressive joint disease, involving not only the joint lining but also cartilage, ligaments, and bone. For the last ten years, majority of published review articles were not specific to osteoarthritis of the knee, and strength of evidence and clinical guidelines were not appropriately summarized.

OBJECTIVES

To appraise the literature by summarizing the findings of current evidence and clinical guidelines on the diagnosis and treatment of knee osteoarthritis pain.

METHODOLOGY

English journal articles that focused on knee osteoarthritis related pain were searched via PubMed (1 January 2002 - 26 August 2012) and Physiotherapy Evidence Database (PEDro) databases, using the terms 'knee', 'osteoarthritis' and 'pain'. In addition, reference lists from identified articles and related book chapters were included as comprehensive overviews.

RESULTS

For knee osteoarthritis, the highest diagnostic accuracy can be achieved by presence of pain and five or more clinical or laboratory criteria plus osteophytes. Some inconsistencies in the recommendations and findings were found between the clinical guidelines and systematic reviews. Generally, paracetamol, oral and topical non-steroidal anti-inflammatory drugs, opioids, corticosteroid injections and physical therapy techniques, such as therapeutic exercises, joint manual therapy and transcutaneous electrical nerve stimulation, can help reduce pain and improve function. Patient education programs and weight reduction for overweight patients are important to be considered.

CONCLUSIONS

Some inconsistencies in the recommendations and findings were found between the clinical guidelines and systematic reviews. However, it is likely that a combination of pharmacological and non-pharmacological treatments is most effective in treating patients with knee osteoarthritis.

[Pharmacological therapy of arthrosis]

The pharmacological management of osteoarthritis includes pure analgesia, anti-inflammatory drugs and substances supporting tissue maintenance in osteoarthritic joints. The decision for the treatment modality is made depending on the affected joint, the stage of the disease, the extent and frequency of inflammatory flares and the patient risk profile. This article gives an overview of the current treatment modalities including the advantages and disadvantages.

Diagnosis and treatment of osteoarthritis

Osteoarthritis presents in primary and secondary forms. The primary, or idiopathic, form occurs in previously intact joints without any inciting agent, whereas the secondary form is caused by underlying predisposing factors (eg, trauma). The diagnosis of osteoarthritis is primarily based on thorough history and physical examination findings, with or without radiographic evidence. Although some patients may be asymptomatic initially, the most common symptom is pain. Treatment options are generally classified as pharmacologic, nonpharmacologic, surgical, and complementary and/or alternative, typically used in combination to achieve optimal results. The goals of treatment are alleviation of symptoms and improvement in functional status.

Diclofenac epolamine medicated plaster in the treatment of minor soft tissue injuries: a multicenter randomized controlled trial

OBJECTIVE

To investigate the efficacy and safety of a topical plaster containing diclofenac epolamine (DHEP) 1.3% in the treatment of patients with acute minor soft tissue injuries in China.

RESEARCH DESIGN AND METHODS

This prospective, randomized, double blind, placebo-controlled study had balanced random assignment to DHEP medicated plaster and placebo plaster. A total of 384 patients, aged 18-74 years, with minor soft tissue injury occurring within 72 hours of study entry were enrolled and randomized. Plasters were applied twice daily for seven consecutive days. Outcomes were assessed in three visits over 7 days, in addition to patients' daily self-assessment and an adverse events follow-up visit on day 21.

MAIN OUTCOME MEASURES

The primary efficacy endpoint was the mean change from baseline in pain on movement on a 100 mm Visual Analogue Scale (VAS) after 7 days of treatment. Secondary efficacy endpoints included pain on movement day-by-day evaluation, summed pain intensity difference, overall treatment efficacy, rescue medication consumption, and treatment tolerability.

RESULTS

Reduction in pain on movement after 7 days of treatment, the primary efficacy endpoint, was statistically significantly greater in the DHEP plaster group than with placebo (reduction in VAS pain scores -53.78 ± 16.96 vs -37.02 ± 18.30 for DHEP vs placebo, p < 0.0001). The greater analgesic effect of DHEP plaster was evident by day 1 and increased progressively throughout the treatment period. Global pain relief and overall treatment efficacy were significantly better with DHEP. Both DHEP and placebo plaster were well tolerated with few adverse events, mostly application site reactions.

CONCLUSIONS

A medicated plaster containing DHEP applied to the affected site in Chinese patients with minor soft tissue injury, such as sprains, strains and contusions, was significantly more effective than placebo at reducing pain scores. Onset of action was rapid and the DHEP plaster was safe and well tolerated. The main limitation was the use of a subjective, though validated, self-reported VAS to assess the primary endpoint.

A closer look at osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis affecting 26.9 million Americans. OA is a degenerative disorder of the synovial joint that leads to pain, stiffness, and decreased function of the affected joint. An understanding of both the nonpharmacologic and pharmacologic management of OA is essential for nurse practitioners.

Pharmacologic treatment of hand-, knee- and hip-osteoarthritis

Osteoarthritis (OA) is a joint disease of high prevalence and affects > 90 % of the population, depending on several risk factors. Symptomatic OA is less frequent, but requires an individually tailored therapeutic regimen consisting of non-pharmacological and pharmacological treatment modalities. Pharmacologic therapy, however, is mainly limited to analgetic and anti-inflammatory agents; structure modifying remedies do not exist. The therapeutic approach to hand-, knee- and hip-OA is basically similar and differs only at some minor points. Generally, topical agents or paracetamol are recommended as first-line agents. If unsuccessful oral non-steroidal anti-inflammatory drugs (NSAIDs) or COX-2-selctive inhibitors should be introduced. Tramadol is an option in the case patients will not respond satisfactorily to NSAIDs. Glucosamine and chondroitine sulphate are no longer recommended in knee and hip OA, but chondroitine might be efficient in treating hand OA. Oral NSAIDs should be prescribed with caution due to potential side effects. Opioids are not recommended as their benefits are outweighed by an increased risk for serious adverse events.

Tolerability of diclofenac sodium 1% gel with concomitant medications known to interact with diclofenac

Background

Topical diclofenac sodium 1% gel (DSG) has demonstrated efficacy and tolerability in patients with osteoarthritis (OA) of the knees or hands, including elderly patients and those with an increased risk of gastrointestinal, cardiovascular, and renal adverse events (AEs). Medications known to interact with diclofenac were disallowed in a clinical trial of DSG for knee OA; however, patients were not to be discontinued for intake of disallowed treatment, unless there was a safety issue. This post hoc analysis examined the frequency and type of AEs in patients who received DSG concomitantly with drugs known to have potential interactions with diclofenac.

Materials and methods

This was a post hoc analysis of a randomized controlled trial of DSG for knee OA pain. Patients (n = 254) aged ≥ 35 years with OA in one or both knees, but with clinical OA symptoms in only one knee, administered DSG topically to the target knee four times daily (total dose, 16 g/d) for 12 weeks. Drugs with the potential for major or moderate drug–drug interactions (DDIs) were identified via Drugs.com. AE rates were compared in patients with versus those without ≥1 potential DDI.

Results

At least one AE was experienced by 62.6% (107/171) of patients with ≥1 DDI and by 55.4% (46/83) of patients with no DDIs. Gastrointestinal AEs (upper and lower) were reported in 5.3% (9/171) and 7.2% (6/83), cardiovascular AEs in 4.7% (8/171) and 1.2% (1/83), renal AEs in 1.2% (2/171) and 0%, and hepatic AEs in 0% and 1.2% (1/83) of patients with ≥1 DDI compared with patients with no DDIs, respectively.

Conclusion

Concurrent use of DSG with medications that had potential for major to moderate DDIs had little impact on the frequency of AEs in this population. Further research is needed to consider how factors such as dose, duration, and timing of concomitant drug administration may affect the likelihood of clinically evident AEs resulting from a potential DDI.

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.

Long-Term Oral Administration of Capsicum baccatum Extracts Does Not Alter Behavioral, Hematological, and Metabolic Parameters in CF1 Mice

Our group showed that crude ethanol (CE) and butanol (BUT) extracts of Capsicum baccatum presented anti-inflammatory and antioxidant properties. Furthermore, the flavonoid and total phenolic contents were positively correlated with both of these properties observed for C. baccatum extracts. The present study demonstrated that 60 days of oral administration of CE and BUT (200 mg/kg) in mice did not cause significant differences in the following parameters evaluated: hematological profile, body weight and relative weight of visceral organs, systemic lipid profile, glucose homeostasis (GTT), kidney and hepatic biochemical markers, and spontaneous locomotion and anxiety-like behavior. Altogether, these results indicate for the first time that the long-term oral administration of C. baccatum extracts does not affect specific aspects of CF1 mice physiology, suggesting their safety, building up the venue to test their efficacy in animal models underlying persistent activation of oxidative and inflammatory pathways.

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.

Topical NSAIDs for chronic musculoskeletal pain in adults

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly taken orally, but they are also available in topical preparations to be applied to or rubbed onto the skin of a painful joint, typically one affected by arthritis, with the aim of relieving pain locally. Topical NSAIDs are widely used in some parts of the world for acute and chronic painful conditions, but have not been universally accepted until recently. One of the problems has been that older clinical studies were generally short, lasting four weeks or less, and short duration studies are not regarded as adequate in ongoing painful conditions.

OBJECTIVES

To examine the use of topical NSAIDs in chronic musculoskeletal pain, focusing on studies of high methodological quality, and examining the measured effect of the preparations according to study duration. The principal aim was to estimate treatment efficacy in longer duration studies of at least 8 weeks.

SEARCH METHODS

A series of electronic searches, together with bibliographic searches, and searches of in-house databases were combined with electronic searches of clinical trial registers and manufacturers of topical NSAIDs, or companies known to be actively researching topical NSAIDs. There had to be at least 10 participants in each treatment arm, with application of treatment at least once daily.

SELECTION CRITERIA

Randomised, double blind studies with placebo or active comparators, where at least one treatment was a topical NSAID product, in any topical formulation (cream, gel, patch, solution), in studies lasting at least two weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study quality and validity, and extracted data. Numbers of participants achieving each outcome were used to calculate relative risk (RR) and numbers needed to treat (NNT) or harm (NNH) compared to placebo or other active treatment.

MAIN RESULTS

Information was available from 7688 participants in 34 studies from 32 publications; 23 studies compared a topical NSAID with placebo. Topical NSAIDs were significantly more effective than placebo for reducing pain due to chronic musculoskeletal conditions. The best data were for topical diclofenac in osteoarthritis, where the NNT for at least 50% pain relief over 8 to 12 weeks compared with placebo was 6.4 for the solution, and 11 for the gel formulation. There were too few data of good quality to calculate NNTs for other individual topical NSAIDs compared with placebo. Direct comparison of topical NSAID with an oral NSAID did not show any difference in efficacy. There was an increase in local adverse events (mostly mild skin reactions) with topical NSAIDs compared with placebo or oral NSAIDs, but no increase in serious adverse events. Gastrointestinal adverse events with topical NSAID did not differ from placebo, but were less frequent than with oral NSAIDs.A substantial amount of data from unpublished studies was unavailable. Much of this probably relates to formulations that have never been marketed.

AUTHORS' CONCLUSIONS

Topical NSAIDs can provide good levels of pain relief; topical diclofenac solution is equivalent to that of oral NSAIDs in knee and hand osteoarthritis, but there is no evidence for other chronic painful conditions. Formulation can influence efficacy. The incidence of local adverse events is increased with topical NSAIDs, but gastrointestinal adverse events are reduced compared with oral NSAIDs.