🦵 Section 718.1 · Discoid Lateral Meniscus

Nelson Textbook of Pediatrics 22nd Edition | Discoid lateral meniscus: congenital anatomic variant where the lateral meniscus is thickened and covers a larger portion of the tibial plateau. Classic presentation: snapping knee syndrome. Watanabe classification (Type I complete, Type II incomplete, Type III Wrisberg variant). MRI diagnosis: meniscal width >20% of tibial plateau on coronal view. Treatment: asymptomatic → observation; symptomatic (snapping, pain, locking) → arthroscopic saucerization (partial meniscectomy) with possible peripheral repair. Bilateral in ~20%.

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📋 30 Clinical Scenarios — Discoid Lateral Meniscus

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🩺 Clinical Recognition: Discoid Lateral Meniscus

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📋 Stepwise Management of Discoid Lateral Meniscus

🔑 Key Principles — Nelson Section 718.1
• Definition: Congenital anatomic variant of lateral meniscus that is discoid (thickened, covers >20% of tibial plateau).
• Watanabe Classification: Type I (complete) — full tibial coverage; Type II (incomplete) — partial coverage; Type III (Wrisberg variant) — normal shape but no posterior peripheral attachment (hypermobile).
• Presentation: Snapping knee (90-120° flexion → pop with extension), lateral joint line pain, swelling. May be asymptomatic.
• Imaging: MRI: continuity between anterior and posterior horns on ≥3 sagittal slices; coronal meniscal width >20% of tibial plateau.
• Treatment: Asymptomatic → observation. Symptomatic (snapping, pain, locking, effusion) → arthroscopic saucerization (partial meniscectomy to reshape to normal). Peripheral tears repaired. Wrisberg variant may require peripheral stabilization.

    ⚡ Reflex Prompts — Clinical Decisions

    📖 Summary: Discoid Lateral Meniscus (Nelson 718.1)