The trial is a multicentre, randomized, superiority, controlled, participant and outcome assessor (debridement versus placebo surgery randomization cohort) and trialist blinded (both arms) superiority, umbrella trial with two randomized cohorts (1. debridement or placebo surgery, 2. repair or physiotherapy) which both include two 1:1 parallel arms. The primary objective is to investigate the superiority of 1) debridement over placebo surgery and 2) repair over physiotherapy in two randomized cohorts using Patient-Rated Wrist Evaluation (PRWE) at one year post randomisation as the primary outcome.

Triangular fibrocartilage complex (TFCC) injuries are often considered the cause of ulnar wrist pain. TFCC lesions can be traumatic or degenerative according to classification suggested by Palmer and Atzei. Primary treatment is conservative, but if symptoms persist, operative treatment is an option. Depending on the morphology of the tear, the treatment can be either debridement or repair. Trialists have observed improvement of symptoms after TFCC repair but all these trials are observational cohorts without proper controls. Efficacy of surgery has not been studied in randomized controlled trial (RCT) setting.

The investigators planned a multicentre, randomized, superiority, controlled, participant and outcome assessor (debridement versus placebo surgery randomisation cohort) and trialist blinded (both arms) superiority, umbrella trial with two randomized cohorts which both include two 1:1 parallel arms. Participants in the first cohort (central or radial TFCC tear) will undergo randomization to either arthroscopic debridement or placebo surgery. In the second cohort (peripheral TFCC tear), participants will be randomized to arthroscopic/open TFCC repair or physiotherapy. Our primary objective is to investigate the superiority of 1) debridement over placebo surgery for central (Palmer 1A) and radial (Palmer 1D) TFCC tears, and 2) repair over non-operative treatment (physiotherapy) for ulnar (Palmer 1B) TFCC tears in two randomized cohorts using Patient-Rated Wrist Evaluation (PRWE) at one year post randomisation as the primary outcome.

Institutional Review Board (IRB) of Tampere university hospital has approved the study protocol. All participants will give written informed consent. The results of the trial will be disseminated as published articles in peer-reviewed journals.

Outcome measures for different studies are often derived from what clinicians, rather than patients, thinks to be important. The investigators chose to base the efficacy assessment on the measure of patient's subjective disability and pain.

There is no clear evidence of the efficacy of the treatments (debridement and repair). It is justified and ethically correct to compare these treatments to placebo surgery and physiotherapy. Placebo surgery and physiotherapy are less invasive than debridement and repair and because of this are even safer to patients than comparable treatments.

Inclusion Criteria:

• Ulnar sided wrist pain
• Age more than 18 years
• Suspicion of TFCC tear in clinical examination
• Ability to fill the Danish, Finnish or Swedish versions of questionnaires
• Symptom duration more than 3 months, and unsuccessful non-operative treatment
• Central (Palmer 1A), ulnar (Palmer 1B) or radial (Palmer 1D) TFCC tear explaining the pain in arthroscopy

Exclusion Criteria:

• Gross instability of DRUJ which will be defined as "obvious instability in clinical examination in each forearm and wrist position"
• Distal (Palmer 1C) TFCC tear in arthroscopy
• Ulnocarpal or DRUJ arthrosis (Atzei class 5)
• Ulnar variance ≥ +2 mm in x-ray
• Age above 65 years
• Rheumatoid arthritis or other inflammatory disease effecting radio- or ulnocarpal or DRUJ
• Lunotriquetral instability diagnosed in arthroscopy
• ECU instability
• Massive tear and degenerated edges or frayed tear which fails suture (Atzei class 4A-4B)

All the IPD will be shared with other researchers by request.

Data will be available after the publication and it will be available for 15 years.

By request.

Operating surgeon, operating theatre staff, coordinating research assistant (CRA), and research assistants (RA) cannot be blinded to the allocation. In central or radial tear randomization cohort, outcome assessors will be blinded and they will not participate in the care at any other point in the trial, except during follow-up visits. The participants are also blinded, resulting in a triple-blinded randomization cohort since also trialist are blinded in data analysis phase as in foveal tear randomization cohort. In the ulnar tear cohort, randomization cannot be blinded due to differing postoperative treatment.