How do i treat a dip joint fracture that's not been treated before but has already started to round off? my entire thumb is painful. thanks.

Fracture: This sounds like you have had an x-ray of the affected limb. If this fracture is in the joint then i would recommend surgery. Otherwise there is a high likelihood that you will get degenerative joint disease. If the fracture is not in the joint then immobilization of the finger for up to 8 weeks should help with healing. Icing the area and taking an NSAID will also help. See your hand specialist.

Thumb dip fractures: Can involve the articualr surface, a tendon attachment, or be assocaited with an unappreciated loss of motion, typical treatment may involve splint or thumb spica cast even when it seems late. Of course there are srgical options too but a ot dpends upon specifics inyour cases and one can't adress answer the myriad possibilities.

Joint fracture: "rounding off" suggests that you may very well be beyond the initial healing phase. Having said that, not all non-unions need to be treated surgically i.E depends on the specifics. For example, a small mallet fracture albeit intra-articular can be treated with pain control modalities. Best to see a hand surgeon and discuss all options ps there is no dip joint in the thumb, only and ip. Good luck.