Injection of Botulinum Toxin for Thumb Carpometacarpal Arthritis

Inclusion Criteria: * Adult patients (\> 18 years old) with a diagnosis of thumb CMC OA * Diagnosis of thumb CMC OA * History, clinical exam, and radiographic findings, as done in prior studies on this topic. * Subjective: thumb or wrist pain at rest or with activity, joint stiffness * Exam: basal joint tenderness, decreased mobility, deformity, instability * Radiograph: joint space narrowing, subchondral sclerosis, osteophytes, subchondral cysts, Eaton-Littler stage. * Failed conservative management with oral pain medication and splinting for at least 3 months. Exclusion Criteria: * Severe osteoarthritis (Eaton-Littler stage 4) or too large osteophytes to allow for injection into the joint space Inflammatory arthritis * Any concomitant hand conditions (i.e. carpal tunnel, trigger finger, etc) * Prior significant hand trauma related to the thumb or first CMC joint * Prior intervention or hand surgery * Patients with fibromyalgia or complex regional pain syndrome (CRPS) * Pregnant and breastfeeding patients will also be excluded. We also will exclude individuals attempting to conceive or who could become pregnant within 6-months of treatment.