Botulinum Toxin Injection for Painful Adductor Pollicis Contracture after Thumb Carpometacarpal Resection Arthroplasty.

Pollux adductus deformity is an accompanying symptom of thumb carpometacarpal osteoarthritis. We describe a case of a patient who presented with increased muscle tone of the adductor pollicis muscle and chronic pain in the thenar musculature, i.e., recurrence of an adduction deformity. The patient reported a symptom-free period of 5.5 years after having received resection-suspension-arthroplasty for stage IV thumb carpometacarpal osteoarthritis until spasmodic pain appeared. Due to the functional impairment of this condition, we administered therapy including 100 units of Botox (onabotulinumtoxinA, Allergan, Dublin, Ireland) injected with a fanning technique into the adductor pollicis muscle. Thus, we observed a substantial improvement in the patient-reported outcome measures as well as pain levels compared with initial values. The current case shows the pivotal role of the adductor pollicis muscle when patients report pain at the base of the thumb, which can cause considerable impairments despite the complication-free surgical treatment of thumb CMC OA.