Intra-articular botulinum toxin A as an adjunctive therapy for refractory joint pain in patients with rheumatoid arthritis receiving biologics: A report of two cases

The efficacy and safety of intra-articular botulinum toxin type A injection for knee osteoarthritis: A meta-analysis of randomized controlled trials

The purpose of this study was to investigate the efficacy and safety of intra-articular Botulinum Toxin type A (BTA) injection in the management of patients with knee osteoarthritis (KOA). The literature retrieval was conducted based on PRISMA guidelines. Databases including Pubmed, Web of science, EMBASE, and Cochrane Library were searched to identify RCTs that comparing the effects of intra-articular BTA injection with control interventions on patients with KOA. The primary outcomes involved pain and function improvements as well as the occurrence of adverse events. Seven RCTs comprising 548 participants were included in this meta-analysis. Compared with the control group, BTA injection exhibited greater pain reduction at 4 weeks posttreatment (SMD = -0.86, 95% CI [-1.52, -0.19], p = 0.011), but not 8-24 weeks posttreatment (wk 8, SMD = -0.53, 95% CI [-1.21, 0.15], p = 0.127; wk 12, SMD = -0.34, 95% CI [-0.73, 0.04], p = 0.081; wk 24, SMD = -0.65, 95% CI [-1.52, 0.22], p = 0.144). Additionally, no differences were found between BTA injection versus control intervention on functional improvement at all time points assessed (wk 4, WMD = -5.16, 95% CI [-12.31, 2.00], p = 0.158; wk 8, WMD = -0.98, 95% CI [-5.66, 3.71], p = 0.683; wk 12, WMD = -2.52, 95% CI [-7.54, 2.50], p = 0.325); wk 24, WMD = -3.66, 95% CI [-14.09, 6.76], p = 0.491). There was no significant difference in adverse event rate between the BTA and control group (OR = 0.88, 95% CI [0.24, 3.18], p = 0.843). This meta-analysis suggests that intra-articular BTA injection could be an efficious and safe strategy for analgesic treatment of KOA. However, evidence is limited due to the small number and heterogeneity of included studies, this urges further and stronger trials to confirm our findings.

Genicular nerve block in rheumatoid arthritis: a randomized clinical trial

OBJECTIVE

This study highlights the effect of a genicular nerve block (GNB) on pain, function, and inflammation outcome measures in rheumatoid arthritis (RA) knees.

METHODS

A total of sixty-four patients diagnosed with RA using ACR/EULAR 2010 criteria with unilateral persistent knee arthritis were recruited to the study. They were randomly assigned into two groups: group 1 received GNB and group 2 received intra-articular triamcinolone. Both groups were examined by the SOLAR scoring system, visual analog scale (VAS), and Lysholm score at 0, 2, and 12 weeks. A semi-quantitative score was used to assess the tenderness and swelling at the same intervals.

RESULTS

Function and inflammation improved significantly in group 2 at a 2-week interval as compared to group 1, whereas pain improved in both groups with non-significant differences. After 12 weeks, group 1 showed significant improvement as compared with group 2 for the three outcome measures. Neither the disease activity nor the current medication was related to the GNB effect. Disease duration was negatively related to GNB-induced improvement.

CONCLUSION

GNB is a new promising local therapy for RA to control pain, improve function, and alleviate inflammation of the knee joint. Although it has a relatively short-term effect, yet it has outperformed the steroid effect. Key Points • Knee monoarthritis treatment in rheumatoid arthritis is always challenging • GNB has been approved for the treatment of pain in knee osteoarthritis • GNB in this study was able to control active knee arthritis and this effect persisted longer thane intra-articular steroid injection.

Therapeutic Potential of Digital Nerve Block in Rheumatoid Arthritis Patients: A Clinical and Sonographic Prospective Study

BACKGROUND

This study attempted to test the effectiveness of digital nerve block (DNB) in active rheumatoid arthritis (RA) joints with respect to local disease control.

METHODS

The study included 83 RA patients aged 18 years or above and diagnosed, after American College of Rheumatology/European League Against Rheumatism criteria 2010, with bilateral proximal interphalangeal (PIP) arthritis. PIPs were examined by European League Against Rheumatism-outcome measures in rheumatoid arthritis clinical trials scoring system at 0, 2, and 8 weeks. Visual analog scales for each hand were also done at the same intervals. DNBs of the second and third PIPs were performed to the dominant hand in 50% of participants. The other hand was used as a control, and saline was injected in the same level at the control side.

RESULTS

At 2 weeks and 8 weeks intervals, the active side showed significantly less clinical and ultrasound scores when compared to the control side and the baseline values. The mean OMERACT score for the active hand dropped from 3.37±1.43 at 0 time to 2.31±1.66 after 2 weeks and 2.55±1.43 at 8 weeks (P<0.001). Also, visual analog scale decreased from 59 at 0 time to 41 at 2 weeks and 43 at 8 weeks (P<0.001). The amelioration was greater when the active side was the dominant one. The injected PIPs showed maximum improvement at 2 weeks. Improvement was more significant in the second PIP. Early patients achieved better outcomes.

CONCLUSION

DNB is a new promising therapy for RA. It can control pain and inflammation of the PIPs. It has relatively short-term effect, yet it could limit escalation of systemic treatment plans.

Impact of an Upper Respiratory Tract Infection on Botulinum Toxin Efficacy in Spasmodic Dysphonia Patients

OBJECTIVE

To determine whether the presence of a concomitant upper respiratory tract infection (URI) impacts upon Botulinum toxin (BoNT) efficacy in spasmodic dysphonia (SD) patients.

STUDY DESIGN

Case series and literature review.

METHODS

All SD patients with a concurrent URI, presenting for BoNT therapy at a clinical research center from November 2016 to December 2017 were included. A total of 12 patients were identified. Patients were followed for at least two BoNT treatment cycles (approximately 6 months). The primary outcome measure was efficacy of the initial BoNT injection and the secondary outcome measure was the efficacy of the subsequent BoNT injection.

RESULTS

All subjects had adductor type SD (ADSD). There were 10 females and two males with a median age of 55 years (±19.5). All patients were well established on a consistent BoNT treatment regime, with an average administered dose of 1.0 unit (range 0.2-1.80 units). Bilateral injections were administered to 10 patients. Regarding the primary outcome measure, five failed to have any response to BoNT (41.7%), four had a partial response (33.3%), and three had a positive response to treatment (25.0%). When patients had their follow-up injection in the absence of URI symptoms, 11 patients had a positive response to treatment (91.7%).

CONCLUSION

While the interplay between illness and BoNT efficacy is yet to be elucidated, we report that some patients are affected. We recommend that SD patients presenting for BoNT administration with a concomitant URI, should be counseled that their treatment might have decreased effect.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1746-1749, 2020.

Ultrasound-guided intra-articular triamcinolone acetonide injection for treating refractory small joints arthritis of rheumatoid arthritis patients

To investigate the efficiency and clinical safety of intra-articular triamcinolone acetonide (TA) injection under the guide of ultrasonography combined with standard treatment for treating refractory small joints arthritis in rheumatoid arthritis (RA) patients.TA was injected upon confirmation of the needle inserting into the articular cavity. The dose was 40 mg for the wrist, 20 mg for the metacarpophalangeal (MCP) joint and 20 mg for the proximal interphalangeal (PIP) joint, respectively. Visual analogue scale (VAS) for joint pain, swelling, tenderness, synovial hyperplasia and power Doppler signal scores were evaluated at pretreatment, and post-treatment 24 hours, 1 week, 4 weeks as well as 12 weeks.The VAS for pain and tenderness scores showed gradual improvement at 24 hours, 1 week, 4 weeks and 12 weeks after treatment compared with the baseline levels (P' < .005). The swelling showed no changes at 24 hours after treatment compared with the baseline, and showed gradual improvement at 1 week, 4 weeks and 12 weeks after treatment (P' < .005). Significant decrease was noticed in the synovial hyperplasia score at 4 weeks and 12 weeks compared with the baseline level. Power Doppler signal score showed significant decrease at post-treatment 24 hours, which showed further decrease at 1 week and 4 weeks.Ultrasound-guided intra-articular TA injection is effective for treating RA patients with refractory small joints arthritis without changing the original treatment plan.

Comparison between intra-articular Botulinum toxin type A, corticosteroid, and saline in knee osteoarthritis: a randomized controlled trial

OBJECTIVE

To compare the effectiveness of intra-articular injection (IAI) with Botulinum toxin type A (BTA), triamcinolone hexacetonide (TH), and saline in primary knee osteoarthritis.

DESIGN

A randomized controlled trial, with blinded patients and assessor.

SETTING

Outpatient rheumatology service.

SUBJECTS

Patients with knee osteoarthritis grades II and III.

INTERVENTIONS

Patients received IAI with 100 IU BTA, 40 mg TH, or isotonic saline solution (SS) 0.9%.

MAIN MEASURES

Patients were assessed at baseline and at 4, 8, and 12 weeks with the following instruments: visual analog scale for pain during movement (VASm; primary outcome) and visual analog scale for pain at rest (VASr), Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) questionnaire, 6-minute walk test, Timed Up and Go test, Short Form (SF)-36 questionnaire, range of motion of knee, and ultrasound (US) measurement of synovial hypertrophy.

RESULTS

In total, 105 patients were randomized, with 35 in each group; 96 were female (91.4%) and 9 were male (8.6%), with a mean age of 64.2 years (±6.9). At 12 weeks, the TH group showed better results only for VASm. At four weeks, the TH group showed better results than the BTA and SS groups for VASm (-68.9% (37.8) vs. -35.3% (40.3) vs. -35.9% (51.4)), WOMAC pain (-56.0% (30.7) vs. -30.8% (34.3) vs. -30.0% (39.9)), WOMAC stiffness (-53.4% (38.4) vs. -17.2% (59.3) vs. -17.3% (78.1)), WOMAC function (-48.2% (34.6) vs. 30.8% (33.6) vs. -13.6% (64.9)), WOMAC total score (-51.2% (31.0) vs. -30.9% (30.0) vs. -18.8% (54.8)), and US measurement of synovial hypertrophy (-11.6% (44.9) vs. -1.5% (47.9) vs. +28.6% (81.3)).

CONCLUSION

IAI with TH had a higher effectiveness than that with TBA or SS in the short-term assessment (four weeks) for pain in movement, WOMAC, and US measurement of synovial hypertrophy.

Assessing adverse effects of intra-articular botulinum toxin A in healthy Beagle dogs: A placebo-controlled, blinded, randomized trial

OBJECTIVE

To investigate the clinical, cytological, and histopathological adverse effects of intra-articularly injected botulinum toxin A in dogs and to study whether the toxin spreads from the joint after the injection.

METHODS

A longitudinal, placebo-controlled, randomized clinical trial was conducted with six healthy laboratory Beagle dogs. Stifle joints were randomized to receive either 30 IU of onabotulinum toxin A or placebo in a 1:1 ratio. Adverse effects and spread of the toxin were examined by evaluating dynamic and static weight-bearing of the injected limbs, by assessing painless range of motion and pain on palpation of joints, and by performing synovial fluid analysis, neurological examination, and electrophysiological recordings at different examination time-points in a 12-week period after the injections. The dogs were then euthanized and autopsy and histopathological examination of joint structures and adjacent muscles and nerves were performed.

RESULTS

Intra-articular botulinum toxin A did not cause local weakness or injection site pain. Instead, static weight-bearing and painless range of motion of stifle joints decreased in the placebo limbs. No clinically significant abnormalities associated with intra-articular botulinum toxin A were detected in the neurological examinations. Electrophysiological recordings showed low compound muscle action potentials in two dogs in the botulinum toxin A-injected limb. No significant changes were detected in the synovial fluid. Autopsy and histopathological examination of the joint and adjacent muscles and nerves did not reveal histopathological adverse effects of the toxin.

CONCLUSION

Intra-articular botulinum toxin A does not produce significant clinical, cytological, or histopathological adverse effects in healthy dogs. Based on the electrophysiological recordings, the toxin may spread from the joint, but its clinical impact seems to be low.

TNFα induces co-trafficking of TRPV1/TRPA1 in VAMP1-containing vesicles to the plasmalemma via Munc18-1/syntaxin1/SNAP-25 mediated fusion

Transient receptor potential (TRP) A1 and V1 channels relay sensory signals, yet little is known about their transport to the plasmalemma during inflammation. Herein, TRPA1 and TRPV1 were found on vesicles containing calcitonin gene-related peptide (CGRP), accumulated at sites of exo- and endo-cytosis, and co-localised on fibres and cell bodies of cultured sensory neurons expressing both. A proinflammatory cytokine, TNFα, elevated their surface content, and both resided in close proximity, indicating co-trafficking. Syntaxin 1-interacting protein, Munc18-1, proved necessary for the response to TNFα, and for TRPV1-triggered CGRP release. TNFα-induced surface trafficking of TRPV1 and TRPA1 required a synaptic vesicle membrane protein VAMP1 (but not 2/3), which is essential for CGRP exocytosis from large dense-core vesicles. Inactivation of two proteins on the presynaptic plasma membrane, syntaxin-1 or SNAP-25, by botulinum neurotoxin (BoNT)/C1 or /A inhibited the TNFα-elevated delivery. Accordingly, enhancement by TNFα of Ca(2+) influx through the upregulated surface-expressed TRPV1 and TRPA1 channels was abolished by BoNT/A. Thus, in addition, the neurotoxins' known inhibition of the release of pain transmitters, their therapeutic potential is augmented by lowering the exocytotic delivery of transducing channels and the resultant hyper-sensitisation in inflammation.

Usefulness of intra-articular botulinum toxin injections. A systematic review

Botulinum toxin is a proven and widely used treatment for numerous conditions characterized by excessive muscular contractions. Recent studies have assessed the analgesic effect of botulinum toxin in joint pain and started to unravel its mechanisms.

LITERATURE-SEARCH-METHODOLOGY

We searched the international literature via the Medline database using the term "intraarticular botulinum toxin injection" combined with any of the following terms: "knee", "ankle", "shoulder", "osteoarthritis", "adhesive capsulitis of the shoulder".

RESULTS

Of 16 selected articles about intraarticular botulinum toxin injections, 7 were randomized controlled trials done in patients with osteoarthritis, adhesive capsulitis of the shoulder, or chronic pain after joint replacement surgery. Proof of anti-nociceptive effects was obtained in some of these indications and the safety and tolerance profile was satisfactory. The studies are heterogeneous. The comparator was usually a glucocorticoid or a placebo; a single study used hyaluronic acid. Pain intensity was the primary outcome measure.

DISCUSSION-CONCLUSION

The number of randomized trials and sample sizes are too small to provide a satisfactory level of scientific evidence or statistical power. Unanswered issues include the effective dosage and the optimal dilution and injection modalities of botulinum toxin.

Intra-articular botulinum toxin A for the treatment of osteoarthritic joint pain in dogs: a randomized, double-blinded, placebo-controlled clinical trial

The aim of this study was to investigate the efficacy of intra-articular (IA) botulinum toxin A (IA BoNT A) for the treatment of osteoarthritic joint pain in dogs. The study was a placebo-controlled, randomized, double-blinded clinical trial with parallel group design and 12-week follow-up. Thirty-six dogs with chronic lameness due to stifle, hip or elbow osteoarthritis were randomized to receive an IA injection of 30IU of BoNT A or placebo. The main outcome variables were vertical impulse (VI) and peak vertical force (PVF) measured with a force platform, and Helsinki chronic pain index (HCPI). Subjective pain score and the need for rescue analgesics were secondary variables. The response to treatment was assessed as the change from baseline to each examination week. The variables were analyzed by ANOVA with repeated measurements and results were considered statistically significant if P ⩽ 0.05. The improvement from baseline to 12 weeks after baseline was statistically significant in VI, PVF and HCPI in the treatment group (P=0.001, P=0.054 and P=0.053, respectively). Additionally, there were statistically significant improvements in VI in the treatment group at 2, 4 and 8 weeks after baseline (P=0.037, P=0.016 and P=0.016, respectively). The difference between groups in improvement in VI was statistically significant at 12weeks after baseline (P=0.005). There was no significant change in the subjective pain score or in the requirement for rescue analgesics in either group. No major adverse events thought to be related to trial protocol were detected. These results suggest that IA BoNT A has some efficacy in reducing osteoarthritic pain in dogs.

Anti-inflammatory effects of botulinum toxin type a in a complete Freund's adjuvant-induced arthritic knee joint of hind leg on rat model

The objective of the study is to verify histopathologically the anti-inflammatory effect of botulinum toxin type A (BoNT-A) in a Complete Freund's Adjuvant (CFA)-induced arthritic knee joint of hind leg on rat model using immunofluorescent staining of anti-ionized calcium-binding adaptor molecule 1 (Iba-1) and interleukin-1β (IL-1β) antibody. Twenty-eight experimental rats were injected with 0.1 ml of CFA solution in the knee joint of the hind leg bilaterally. Three weeks after CFA injection, the BoNT-A group (N = 14) was injected with 20 IU (0.1 ml) of BoNT-A bilaterally while the saline group (N = 14) was injected with 0.1 ml of saline in the knee joint of the hind leg bilaterally. One and two weeks after BoNT-A or saline injection, joint inflammation was investigated in seven rats from each group using histopathological and immune-fluorescent staining of Iba-1 and IL-1β antibody. The number of Iba-1 and IL-1β immune-reactive (IR) cells was counted in the BoNT-A and saline groups for comparison. There was a significant reduction in joint inflammation and destruction in the BoNT-A group at 1 and 2 weeks after BoNT-A injection compared with the saline group. The binding of Iba-1 and IL-1β antibody was significantly lower in the BoNT-A group than the saline group at 1 and 2 weeks after BoNT-A injection. The number of Iba-1 and IL-1β-IR cells at 1 and 2 weeks after the injection of BoNT-A were significantly different from the corresponding number of Iba-1 and IL-1β-IR cells in the saline group. To conclude, BoNT-A had an anti-inflammatory effect in a CFA-induced arthritic rat model, indicating that BoNT-A could potentially be used to treat inflammatory joint pain.

A closer look to botulinum neurotoxin type A-induced analgesia

Chronic pain indicates a type of pain that lasts over time and is accompanied by diagnostic and therapeutic difficulties. It follows that treatment failures are common and patients roam from doctor to doctor in search of an effective care program. So there is an urgent need for long-acting and effective therapeutics to alleviate symptoms of the varied forms of chronic pain. During the past few years, a good success has been achieved with a derivative of a neurotoxin. It has been shown that administration of this toxin can block the release of neurotransmitters and pain mediators. Botulinum neurotoxin type A (BoNT/A) is well known as a treatment for neuromuscular conditions such as dystonia and spasticity. However, the clinical application for BoNT/A has continued to expand. Its analgesic effect has been used in clinical practice with satisfactory results. This review provides an introduction of a hypothesis for the mechanism by which BoNT/A eases chronic pain. It also summarizes the clinical therapeutic effects of BoNT/A in different types of chronic pain and its potential prospects.

A comparison of the short-term effects of a botulinum toxin type a and triamcinolone acetate injection on adhesive capsulitis of the shoulder

OBJECTIVE

To evaluate the short-term clinical effects of the intra-articular injection of botulinum toxin type A (BoNT-A) for the treatment of adhesive capsulitis.

METHODS

A prospective, controlled trial compared the effects of intra-articular BoNT-A (Dysport; 200 IU, n=15) with the steroid triamcinolone acetate (TA; 20 mg, n=13) in patients suffering from adhesive capsulitis of the shoulder. All patients were evaluated using a Numeric Rating Scale (NRS) of the pain intensity and a measurement of the range of motion (ROM) at baseline (before treatment) and at 2, 4, and 8 weeks post-treatment.

RESULTS

The NRS at 2 weeks (BoNT-A vs. TA; 5.0 vs. 5.2), 4 weeks (4.1 vs. 4.9) and 8 weeks (3.8 vs. 4.6) of both treatment groups were significantly lower than that measured at baseline (7.4 vs. 7.6). The ROM of patients' shoulders increased significantly from baseline in both treatment groups. There was no significant difference in the NRS of pain intensity or the ROM between the two groups. Reduction in the pain intensity score was maintained for 8 weeks post-injection in both groups. There were no significant adverse events in either treatment group.

CONCLUSION

The results suggest that there are no significant short-term differences between the intra-articular injections of BoNT-A and TA. Although BoNT-A has a high cost, it may be used as a safe alternative of TA to avoid the steroid-induced side effects or as a second-line agent, for patients who have failed to respond to the current treatments.

Use of botulinum toxin in musculoskeletal pain

Chronic musculoskeletal pain is a common cause of chronic pain, which is associated with a total cost of $635 billion per year in the U.S. Emerging evidence suggests an anti-nociceptive action of botulinum toxin, independent of its muscle paralyzing action. This review provides a summary of data from both non-randomized and randomized clinical studies of botulinum toxin in back pain and various osteoarticular conditions, including osteoarthritis, tennis elbow, low back pain and hand pain. Three randomized controlled trials (RCTs) of small sizes provide evidence of short-term efficacy of a single intra-articular injection of 100 units of botulinum toxin A (BoNT/A) for the relief of pain and the improvement of both function and quality of life in patients with chronic joint pain due to arthritis. Three RCTs studied intramuscular BoNT/A for tennis elbow with one showing a significant improvement in pain relief compared with placebo, another one showing no difference from placebo, and the third finding that pain and function improvement with BoNT/A injection were similar to those obtained with surgical release. One RCT of intramuscular BoNT/A for low back pain found improvement in pain and function compared to placebo. Single RCTs using local injections of BoNT in patients with either temporomandibular joint (TMJ) pain or plantar fasciitis found superior efficacy compared to placebo. One RCT of intramuscular BoNT/B in patients with hand pain and carpal tunnel syndrome found improvement in pain in both BoNT/B and placebo groups, but no significant difference between groups. Most evidence is based on small studies, but the use of BoNT is supported by a single, and sometimes up to three, RCTs for several chronic musculoskeletal pain conditions. This indicates that botulinum toxin may be a promising potential new treatment for chronic refractory musculoskeletal pain. Well-designed large clinical trials are needed.

Neuromodulators for pain management in rheumatoid arthritis

BACKGROUND

Pain management is a high priority for patients with rheumatoid arthritis (RA). Despite deficiencies in research data, neuromodulators have gained widespread clinical acceptance as adjuvants in the management of patients with chronic musculoskeletal pain.

OBJECTIVES

The aim of this review was to determine the efficacy and safety of neuromodulators in pain management in patients with RA. Neuromodulators included in this review were anticonvulsants (gabapentin, pregabalin, phenytoin, sodium valproate, lamotrigine, carbamazepine, levetiracetam, oxcarbazepine, tiagabine and topiramate), ketamine, bupropion, methylphenidate, nefopam, capsaicin and the cannabinoids.

SEARCH METHODS

We performed a computer-assisted search of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, 4th quarter), MEDLINE (1950 to week 1 November 2010), EMBASE (Week 44, 2010) and PsycINFO (1806 to week 2 November 2010). We also searched the 2008 and 2009 American College of Rheumatology (ACR) and European League against Rheumatism (EULAR) conference abstracts and performed a handsearch of reference lists of articles.

SELECTION CRITERIA

We included randomised controlled trials which compared any neuromodulator to another therapy (active or placebo, including non-pharmacological therapies) in adult patients with RA that had at least one clinically relevant outcome measure.

DATA COLLECTION AND ANALYSIS

Two blinded review authors independently extracted data and assessed the risk of bias in the trials. Meta-analyses were used to examine the efficacy of a neuromodulator on pain, depression and function as well as their safety.

MAIN RESULTS

Four trials with high risk of bias were included in this review. Two trials evaluated oral nefopam (52 participants) and one trial each evaluated topical capsaicin (31 participants) and oromucosal cannabis (58 participants).The pooled analyses identified a significant reduction in pain levels favouring nefopam over placebo (weighted mean difference (WMD) -21.16, 95% CI -35.61 to -6.71; number needed to treat (NNT) 2, 95% CI 1.4 to 9.5) after two weeks. There were insufficient data to assess withdrawals due to adverse events. Nefopam was associated with significantly more adverse events (RR 4.11, 95% CI 1.58 to 10.69; NNTH 9, 95% CI 2 to 367), which were predominantly nausea and sweating.In a mixed population trial, qualitative analysis of patients with RA showed a significantly greater reduction in pain favouring topical capsaicin over placebo at one and two weeks (MD -23.80, 95% CI -44.81 to -2.79; NNT 3, 95% CI 2 to 47; MD -34.40, 95% CI -54.66 to -14.14; NNT 2, 95% CI 1.4 to 6 respectively). No separate safety data were available for patients with RA, however 44% of patients developed burning at the site of application and 2% withdrew because of this.One small, low quality trial assessed oromucosal cannabis against placebo and found a small, significant difference favouring cannabis in the verbal rating score 'pain at present' (MD -0.72, 95% CI -1.31 to -0.13) after five weeks. Patients receiving cannabis were significantly more likely to suffer an adverse event (risk ratio (RR) 1.82, 95% CI 1.10 to 3.00; NNTH 3, 95% CI 3 to 13). These were most commonly dizziness (26%), dry mouth (13%) and light headedness (10%).

AUTHORS' CONCLUSIONS

There is currently weak evidence that oral nefopam, topical capsaicin and oromucosal cannabis are all superior to placebo in reducing pain in patients with RA. However, each agent is associated with a significant side effect profile. The confidence in our estimates is not strong given the difficulties with blinding, the small numbers of participants evaluated and the lack of adverse event data. In some patients, however, even a small degree of pain relief may be considered worthwhile. Until further research is available, given the relatively mild nature of the adverse events, capsaicin could be considered as an add-on therapy for patients with persistent local pain and inadequate response or intolerance to other treatments. Oral nefopam and oromucosal cannabis have more significant side effect profiles however and the potential harms seem to outweigh any modest benefit achieved.

Intraarticular botulinum toxin A for refractory painful total knee arthroplasty: a randomized controlled trial

OBJECTIVE

To assess short-term efficacy of single intraarticular botulinum toxin (IA-BoNT/A) injection in patients with chronically painful total knee arthroplasty (TKA) in a randomized, placebo-controlled, triple-blind study.

METHODS

Patients with chronic TKA pain (pain > 6 on 0-10 scale and > 6 months post-TKA) evaluated in and referred from orthopedic surgery clinics were recruited. The primary outcome, proportion of patients with clinically meaningful decrease of at least 2 points on 0-10 visual analog scale (VAS) for pain, was compared between treatment groups at 2 months using comparison of proportions test and for all efficacy timepoints (2, 3, and 4 months) using generalized estimating equations (GEE). Secondary outcomes of global assessment, function, and quality of life were compared using GEE, duration of pain relief by t-test, and adverse events by chi-square test.

RESULTS

In total, 54 patients with 60 painful TKA were randomized, with main analyses restricted to one TKA per patient (49 TKA in 49 patients). Mean age was 67 years, 84% were men, and mean duration of TKA pain was 4.5 years. A significantly greater proportion of patients (71%) in the IA-BoNT/A group compared to IA-placebo (35%) achieved clinically meaningful reduction in VAS pain at 2 months (p = 0.028) and at all efficacy timepoints (p = 0.019). Duration of meaningful pain relief was significantly greater after IA-BoNT/A, 39.6 days (SD 50.4) compared to IA-placebo, 15.7 days (SD 22.6; p = 0.045). Statistically significantly better scores were seen in IA-BoNT/A vs IA-placebo for all efficacy timepoints for the following outcomes: "very much improved" on physician global assessment of change (p = 0.003); Western Ontario McMaster Osteoarthritis Index physical function (p = 0.026), stiffness (p = 0.004), and total scores (p = 0.024); and Short-Form 36 pain subscale score (p = 0.049). Number of total and serious adverse events was similar between groups, with no patients in either group with new objective motor or sensory deficits during followup.

CONCLUSION

In this single-center randomized trial, single IA-BoNT/A injection provided clinically meaningful short-term improvements in pain, global assessment, and function in patients with chronic painful TKA. A multicenter trial is needed to confirm these findings.

Efficacy of intra-articular botulinum toxin type A in painful knee osteoarthritis: a pilot study

OBJECTIVE

To evaluate the efficacy and safety of botulinum toxin type A (BoNT-A) injected intra-articularly in 60 subjects with moderate pain and functional impairment secondary to knee osteoarthritis. The study investigators hypothesized that intra-articular BoNT-A would result in statistically significant improvements in pain and function at 8 weeks.

DESIGN

Double-blind, randomized, single tertiary care academic medical center trial with 6-month follow-up.

PATIENTS

Sixty patients aged 40 years or older with painful osteoarthritis of the knee who had failed physical therapy, medications, and/or injection therapy presenting to the musculoskeletal or orthopedic outpatient clinics at a large tertiary care medical institution. All 60 patients completed 8-week follow-up, but only 32 patients completed the 26-week follow-up.

METHODS

Subjects were randomized to receive a single injection of corticosteroid, low-dose BoNT-A (100 units), or high-dose BoNT-A (200 units). Outcome measures were compared at baseline, 4, 8, 12, and 26 weeks after injection.

MAIN OUTCOME MEASUREMENTS

The primary outcome measure was pain visual analog scale (VAS) at 8 weeks. Secondary outcome measures included Western Ontario McMaster Arthritis Index, Short Form-36 scores, patient global assessment, 40-meter timed walk, and adverse effects.

RESULTS

The primary end point was pain VAS score at 8 weeks, which decreased within each group but only reached statistical significance in the low-dose BoNT-A group. In the intra-articular corticosteroid group, VAS decreased from 6.4 +/- 1.8 to 5.4 +/- 2.3 (P = .15); for low-dose BoNT-A, from 6.6. +/- 1.9 to 4.5 +/- 2.2 (P = .01); and for high-dose BoNT-A, from 6.6 +/- 1.4 to 5.9 +/- 2.4 (P = .15). All groups showed statistically significant improvements in Western Ontario McMaster Arthritis Index scores (pain, stiffness, function) at 8 weeks. No serious adverse events were noted in any group.

CONCLUSIONS

This pilot study supports a possible role for BoNT-A as a treatment option for symptomatic knee osteoarthritis; however, larger double-blind randomized studies are needed to determine whether BoNT-A is more effective than placebo in this patient population.

Intra-articular Botulinum Toxin Type A: a new approach to treat arthritis joint pain

There is a growing need for novel treatments of refractory arthritis joint pain as the aging population is expanding with many patients who are unable to undergo joint replacement surgery. We are studying the efficacy and safety of intra-articular injection of Botulinum Toxin Type A (IA-BoNT/A) into joints with arthritis pain. In several small open label studies, initial effects for IA-BoNT/A were encouraging because two thirds of the patients had more than 50% reduction in joint pain severity that was associated with a significant improvement in function. Importantly no serious adverse effects of IA-BoN/A were noted. Based on these initial results, we have completed two pilot randomized controlled trials in painful shoulder joints and painful knee joints. In the shoulder study, IA-BoNT/A produced a significant decrease in shoulder pain severity at one month (6.8-4.4 on VAS, p=.002) that was also significantly better than the non-significant change after IA-Saline placebo (1.6 unit difference favoring IA-BoNT/A, p=.014). In the knee study IA-BoNT/A produced a significant 48% decrease in McGill Total Pain Score at one month (p=.01 1) that was still significant at 3 mo after injection (p=.002). There was a strong placebo response in one third of those but the decrease in pain severity was not significant. We are currently conducting a RCT of IA-BoNT/A for painful prosthetic knee joints. Based on these initial studies of IA-BoNT/A we have gone 'back to the bench' to standardize a menu of pain behaviors for mice with acute inflammatory arthritis pain and chronic inflammatory arthritis pain. IA-BoNT/A significantly reduced arthritis joint tenderness (evoked pain score) in acute and chronic inflammatory arthritis and normalized impaired spontaneous wheel running in mice with chronic inflammatory arthritis but not in those with acute inflammatory arthritis. With these models of arthritis and pain behavior methods we will be able to screen potential intra-articular analgesics, define dose response curves and injection schedule, and study the relationships of articular pain and loss of function.