When you finger "snaps" or gets caught in flexion you may have what's known as a trigger finger or stenosing tenosynovitis. Having a trigger finger is a common problem seen by many hand surgeons and hand therapists. It is caused by local inflammation and swelling around the tendon and/or the pulley that hold the tendon down as it passes under the pulley out to the finger. Various treatment options for trigger finger exist including:
Splinting/observation: sometimes the condition resolves spontaneously
Medicinal injection: an anti-inflammatory medication (corticosteroid) in injected around the inflamed tendon and pulley in the palm.
Surgery: a small incision is made in the palm and the pulley is cut so the tendon moves freely