Final answer:
The most appropriate treatment for the volleyball player's jammed finger is immobilization, using a splint or buddy taping, along with the RICE method to reduce pain and swelling. A specialist referral may be required if symptoms persist.
Step-by-step explanation:
The most appropriate treatment for a volleyball player who jammed his left 5th finger with full passive range of motion (ROM) but not active extension of the distal phalanx, with a normal hand x-ray, is to immobilize the finger. Immobilization can be achieved with a splint or buddy taping, which stabilizes the finger and allows for proper healing of the affected tendons or ligaments. Furthermore, recommending rest, ice, compression, and elevation (RICE) can help to reduce swelling and pain.
In cases where active extension is not possible, there may be an issue with the extensor mechanism, such as a mallet finger, and if symptoms persist, referral to a specialist may be necessary.