Treatment of flexor tenosynovitis of the hand ('trigger finger') with corticosteroids. A prospective study of the response to local injection. We developed a protocol to maximize medical therapy for "trigger finger." Fifty-eight patients with 77 episodes of flexor tenosynovitis of the hand that was resistant to rest, therapy with nonsteroidal anti-inflammatory drugs, and/or splinting were treated with single or multiple injections of depo-methylprednisolone acetate or triamcinolone acetonide. Patients were prospectively followed up for an average of 4.6 years. Results showed that symptoms and signs resolved in 61% after a single injection. Recurrent episodes, after prolonged pain-free intervals, occurred in 27% and were effectively re-treated with injection. In 12% of cases, either injection failed or early recurrence required surgical release. Local adverse reactions to injection, including pain at the injection site, stiffness, ecchymosis, or atrophy of subcutaneous fat, were self-limited. No episodes of postinjection infection or tendon rupture occurred. The medical management of flexor tenosynovitis with local corticosteroid injection(s) is effective in nearly 90% of cases and is free from serious adverse reactions. 