The aims of this Discoid Meniscus (DiMe) project are to analyze DM tears characteristics in the pediatric European population to describe current treatment options in symptomatic DM, and to evaluate clinical outcomes. To reach these objectives, a prospective database including symptomatic DM and variables associated with DM characteristics, type of tears, treatment, imaging, and clinical follow-up will be implemented. Data collection platform will provide future studies to understand the best treatment option for skeletally immature patient with symptomatic DM according to their history and lesion characteristics.

This is a multicentric international prospective cohort study. All eligible consecutive patients will be identified prospectively by the local participating clinical teams according to Inclusion/Exclusion Criteria. Prospective data entry is mandatory.

Data collection will be conducted in three phases:

• Phase 1 will register patients to the study, document symptomatic DM, collect the details of patient demographics, sport characteristics, PROMS, imaging classification and consent of the patient's legal representatives. Once the patient has reached the age of majority, the date of his/her own consent will be recorded.
• Phase 2 will register surgical treatment and arthroscopic video and photographs collected during surgery, collect intraoperative DM instability, arthroscopic classification, and surgical details. Post-operative complication will also be collected.
• Phase 3 will collect short-, medium- and long-term outcome data. Short follow-up data collection will plan at 1 month follow-up then 3 and 6-months follow-up. Then annual data collection will be performed.

The foreseen timeframe of follow-up will be 15 years for each patient. At the end of the 15-year follow-up, the data will be stored for an additional 10 years before being deleted. Data will be recorded if the patients are willing to comply with the annual data collection. Should the DiMe Project be terminated at one stage, the data will be stored for 10 years after termination of the project before being deleted.

Inclusion Criteria:

• symptomatic DM confirmed by a senior orthopedic surgeon based on physical examination and MRI
• age less than eighteen years
• informed consent freely granted and acquired before the start of the study from legal representative

Exclusion Criteria:

• concomitant or previous knee surgeries
• concomitant ligament knee injury that requires a surgical treatment
• concomitant fractures
• inflammatory or arthritic diseases.

Children diagnosed with symptomatic DM confirmed on the basis of physical examination and MRI