The goal of this clinical trial is to compare the intervention arthroscopic lysis and lavage to the intervention operative arthroscopy in treating disabling and painful temporomandibular joint disc displacement with reduction. The main questions it aims to answer are: * Which surgical method that best improves mouth opening capacity, TMJ pain, and TMJ disability? * If any pre- or peri-operative variable/-s could be identified as a predictor for surgical outcome? Researchers will compare arthroscopic lysis and lavage to operative arthroscopy to see if operative arthroscopy works better to treat temporomandibular joint disc displacement. Participants will: * Have one of the two interventions under general anesthesia, not knowing which intervention. * Visit an external clinic for regular checkups at 1, 3, 6, 12, and 24 months after surgery. * Answer three different quality of life surveys at the checkups.