Adults with degenerative meniscal tear receiving arthroscopic surgical management or knee drainage (arthrocentesis) +/- intra-articular steroid injection will be recruited to this non-interventional cohort study. The aim is to investigate whether measurement of an individual's synovial fluid biomarker response to a degenerative meniscal tear with symptoms predicts symptomatic and functional outcome suggestive of osteoarthritis (OA) of the knee.

Inclusion Criteria:

1. Male or female aged 30-60 years.
2. Participant able and willing to give informed consent.
3. Clinical assessment demonstrates mechanical symptoms suggestive of meniscal pathology (focal knee pain +/- 1 or more of: catching/locking, giving way, focal joint-line tenderness, effusion, McMurray's positive) within last 12 months.
4. Evidence on clinical MRI knee of meniscal tear.
5. Participant is either in secondary care or has the potential to be referred to secondary care due to severity of symptoms.
6. Patient has failed conservative therapy and elected for surgical arthroscopic treatment, or is due knee drainage/injection for clinical reasons.
7. Competency of the English language to complete questionnaires independently.

Exclusion Criteria:

1. Pre-existing advanced radiographic OA (KL grade 3-4) of index knee at baseline.
2. Evidence of anterior cruciate ligament rupture, or more extensive soft tissue injury.
3. History of an acute knee injury (within 12 weeks), or acutely locked knee
4. Known history of inflammatory/septic arthritis of index knee.
5. Knee replacement or other non-arthroscopic knee surgery (e.g. high tibial osteotomy) - previous or planned within 1 year of study start.
6. Index knee surgery within last 3 months, including meniscectomy.
7. Steroid injection to index knee in last 3 months.
8. Active other (treated) inflammatory disease or infection.
9. Positive pregnancy test.
10. Unable to provide blood samples.
11. Unable to give informed written consent.

Patients with a confirmed meniscal tear, likely degenerative in nature, will be invited to participate in the MenTOR study. Male and female adults with a MRI-evident meniscal tear and evidence of no/minor osteoarthritic change (KL grade 2 or less) who are undergoing arthroscopic treatment, or planned arthrocentesis/injection will be identified in clinics all located at the Nuffield Orthopaedic Centre (NOC). The primary source of recruitment is anticipated to be the secondary care orthopaedic knee service. The patient's symptoms will be such that they warrant further management.