In November I had trigger thumb and carpal tunnel surgery. At the 2 week follow up I was on target with improved motion. Two weeks after that while putting on my shoe I experienced a loud pop and horrific pain. Dr stated tendon was enact and emobilized it for approximately one month with no improvement. He then started me on physical therapy (still no MRI ) also with no improvement for 2 months. Finally got a MRI and it shows that I have a longitudinal split tear flexor pollicus longus tendon at the base of the proximal phalanx. What could cause this and what should I expect. The dr says he has never seen this and wants to discuss options with colleagues.