A cast, splinting, ace 1 arthrogram hasn't helped my metacarpal out for 3 months. i've seen an ortho 3x. what could this be? a torn tendon/something

Try this: Trigger point injection containing 80mg Depo-Provera medrol, 1cc 2% lidocain with epinephrine, 1cc 0.5% Marcaine in 3cc syring inject at most painful point. Take naprosyn (naproxen) 500 mg twice daily., and ultram 50mg twice daily both for 2 weeks. Give rest to ypur hand. It will help.

Ligament injury: Hard to say what is going on from your complaint. Overuse tendinitis is a possibility. If your ortho doc is not sure what is causing your pain ask about seeing a hand surgeon.