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Discoid medial meniscus
Yomei Tachibana1, Yuji Yamazaki, Setsuo Ninomiya
1Division of Sports Medicine, Saitama Medical School, Iruma-gun, Saitama, Japan. yomei@saitama-med.ac.jp
Summary
Discoid medial meniscus is a rare anomaly. This study highlights 4 cases and suggests bilateral cases may be more common than previously thought, especially with advanced MRI diagnostics.
Area of Science:
- Orthopedics
- Radiology
- Medical Imaging
Background:
- A discoid meniscus is a rare congenital anomaly where the meniscus has a disc-like shape instead of the usual crescent shape.
- Symptomatic discoid medial menisci are exceptionally rare, presenting diagnostic challenges.
Observation:
- This study presents four cases of symptomatic discoid medial meniscus.
- Magnetic resonance imaging (MRI) revealed bilateral discoid medial menisci in two patients and unilateral discoid lateral meniscus in one.
- In two cases, both medial and lateral menisci were discoid in the affected knees.
Findings:
- The actual incidence of bilateral discoid medial menisci remains unknown.
- Previous diagnostic methods like arthrograms or arthrotomy may have underestimated the prevalence of bilateral cases.
- Modern MRI techniques, particularly axial multiplanar gradient-recalled-echo imaging, simplify the recognition of discoid menisci.
Implications:
- The prevalence of bilateral discoid medial menisci is likely underestimated and may increase with routine contralateral knee MRI screening.
- Improved MRI visualization can aid in accurate diagnosis and understanding of meniscal anomalies.
- This finding has implications for surgical planning and understanding knee biomechanics in patients with meniscal variations.