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Meniscal tears of the knee
The menisci spread load across the knee; an acute tear in a young patient from a twisting injury is usually repaired when possible, whereas a degenerative tear in an older patient with wear is treated with physiotherapy rather than arthroscopy — except for a locked knee.
Why it matters in the exam
Questions separate two very different situations. The first: a young patient who twisted a flexed knee, with joint-line pain, swelling that develops slowly (usually the next day) and catching or locking; the medial meniscus is injured more often because it is more firmly attached to the capsule. The second: a middle-aged patient with gradual knee pain and an MRI showing a degenerative tear, often together with osteoarthritis. Controlled trials showed that in the second situation arthroscopic partial meniscectomy is no better than physiotherapy, so first-line treatment is conservative. A special situation that needs early surgery is the locked knee, which cannot be fully straightened because a bucket-handle tear is caught in the joint. The choice between repair and resection depends on the tear zone: the outer third of the meniscus has a good blood supply (the red-red zone) and suits repair, especially for an acute longitudinal tear in a young patient and together with ACL reconstruction; a tear in the avascular inner part is treated with minimal partial resection. Extensive resection greatly increases load on the cartilage and the risk of early wear, so the aim today is to preserve as much meniscus as possible. On examination, joint-line tenderness, the McMurray test and the Thessaly test support the diagnosis, and MRI confirms it. In children, think of a discoid lateral meniscus, which causes a snapping knee. When choosing treatment, ask whether symptoms are truly mechanical — real locking — or pain alone, because the decision depends on it.
Key points
- Acute tear in a young patient: twisting on a flexed knee, delayed swelling and locking.
- The medial meniscus is injured most often.
- Vascular zone (outer third) — repair.
- Degenerative tear in an older patient — physiotherapy, not arthroscopy.
- Locked knee — early surgery.
Summary table
| Feature | Acute tear in a young patient | Degenerative tear in an older patient |
|---|---|---|
| Mechanism | Twisting on a flexed knee in sport | Gradual, without significant trauma |
| Symptoms | Joint-line pain, delayed swelling, locking or catching | Gradual pain, often with cartilage wear |
| Imaging | MRI: longitudinal or bucket-handle tear | MRI: horizontal or complex tear, often osteoarthritis |
| Treatment | Repair in the vascular zone; early surgery for a locked knee | Physiotherapy and analgesia; arthroscopy is not first-line |
| Prognosis | Good after repair; extensive resection increases wear | Depends mainly on cartilage wear |
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Sources
- Campbell's Operative Orthopaedics, 14th ed. (2021) — Knee Injuries
- BMJ Rapid Recommendation, 2017 — Arthroscopic surgery for degenerative knee arthritis and meniscal tears
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.