Botulism Toxin Injection as a Treatment for Arthritis of the Basal Thumb Joint

Overview

Basal arthritis of the thumb is a common condition with increased prevalence in post-menopausal women, obese persons, and the elderly. Surgical options are varied and efficacious, but not all patients are candidates for surgery. The successes and pitfalls of previous, similar trials are carefully considered in the creation of our own. Though steroid injection is the standard of care in basal joint arthritis, current data does not support its efficacy beyond placebo effect. No trial has yet examined the efficacy of botulinum toxin type A (BTX-A) injection into the basal thumb joint nor compared it to steroid. Since efficacy of steroid is questionable at best, our hope is that BTX-A injection of the basal joint might be the next great tool in treating this common, debilitating disease.

Purpose: Basal joint arthritis, or carpometacarpal (CMC) osteoarthritis, of the thumb is very common, particularly in the elderly. Morbidities include pain, decreased range of motion, and decreased strength. Nonsurgical treatments for CMC arthritis include oral analgesics, splinting, and steroid injection. In multiple recent trials, botulinum toxin A (BTX-A) injection has been shown to be an efficacious nonsurgical option for osteoarthritis of large joints, including those that have failed steroid injections. To our knowledge, the efficacy of BTX-A injection in thumb CMC arthritis has not been examined. Methods: Patients with a clinical and radiographic diagnosis of basal joint arthritis who are appropriate and willing candidates for injection therapy will be selected. The primary symptom indicating need for injection would be pain not controlled with more conservative measures (e.g. nonsteroidal anti-inflammatory drugs (NSAIDs), splinting, physical therapy, etc.) Weakness and impaired functioning are also considered. Exclusion criteria will include any injection within the last 12 months or surgical treatment. All patients will undergo Eaton staging radiographically prior to treatment. Informed consent will be obtained and patients will be randomly assigned to one of three groups. One group will receive BTX-A injections, the second group will receive triamcinolone plus lidocaine injections, and the third group will receive saline plus lidocaine injections of the thumb CMC joint. Prior to treatment, patients' baseline function will be assessed with pinch, grip, and range of motion measurements, and the affect of their disease will be measured with a visual analog pain scale and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Pain scales and DASH questionnaires will be completed at twenty-four hours, ten days, twelve weeks, six months, and one year after treatment. Pain scales will be recorded for average pain and maximum pain. Clinical evaluations with pinch, grip, and range of motion measurements will occur ten days, twelve weeks, six months, and one year after treatment. All patients will be asked to return when sufficient symptoms recur to warrant further treatment. Expected Results: We hypothesize that BTX-A injection will have equal or better efficacy than steroid injection for the treatment of basal joint arthritis. Expected Conclusion: No study to date has examined BTX-A as a treatment for basal joint arthritis. Some patients are not surgical candidates and are reliant on non-surgical treatments for pain control and maintenance of function. BTX-A has shown to be effective in treating osteoarthritis of larger joints that undergo frequent use, including cases resistant to steroid injections. The basal thumb joint also undergoes frequent use and is often resistant to steroid injection. We believe that BTX-A will provide another efficacious non-surgical option for treatment of the CMC joint of the thumb. We estimate that the study will require approximately three to four years to achieve adequate patient numbers for each group.