I'm 4 and a half weeks into wearing my splint for boxers fracture on 5th metacarp. still a lot of stiffness and don't see a knuckle really. normal?

Normal: Your fracture has shortened and has shifted. I would start immediate motion and stretching. If you don't see good improvement in the next 3-4 weeks with your motion, i would see a hand therapist. Unfortunately, your loss of the prominence of the 5th metacarpal head will be permanent.

Boxers fracture: It's not unusual to lose prominence of your knuckle with these fractures, which often angle. Functionally this should not typically be an issue with proper exercise and therapy. Stiffness after immobilization is expected and if you were properly immobilized should work itself out. If there are any other issues, you should discuss with your physician.