J Korean Orthop Assoc.  2018 Oct;53(5):429-434. 10.4055/jkoa.2018.53.5.429.

Meniscal Extrusions on a Non-Traumatic and Young Knee: Magnetic Resonance Imaging Study

• Sim JC
• Jeon JH
• Seo YR
• Park DW
• Nam TS

• KMID: 2424102
• DOI: http://doi.org/10.4055/jkoa.2018.53.5.429

Abstract

PURPOSE
The aim of this study was to assess the size and extrusion of the meniscus in young and non-traumatic knees, especially in Korean males.
MATERIALS AND METHODS
The participants (n=91 knees, 77 patients) were consecutive patients observed at an orthopedic outpatient clinic who had another problem unrelated to the knee joint. The patients were excluded from the study if they had a history of trauma and pain on the knee joint. The patients received a magnetic resonance imaging (MRI) scan on the knee joint. The size, extrusion, and extrusion ratio of the meniscus on an MRI scan were evaluated.
RESULTS
The mean age of the participants was 21.6±1.1 years (range, 19-24 years). The mean size of the medial meniscus on the coronal plane was 9.0±1.1 mm (range, 7.1-11.9 mm). The extent of extrusion on the coronal plane was 2.0±1.0 mm (range, 0-4.4 mm). The extrusion ratio (extruded size/total size×100) of the medial meniscus on the coronal plane was 22.7%±11.5% (range, 0%-53.7%). The extent of extrusion on the sagittal plane was 1.6±1.1 mm (range, 0-4.0 mm). The extrusion ratio (extruded size/total×100) of the medial meniscus on the sagittal plane was 18.0%±11.9% (range, 0%-40.7%). The incidence of medial meniscal extrusion on the coronal and sagittal plane are 92.3% and 80.2%, respectively. The mean size of lateral meniscus on the coronal plane was 11.1±3.4 mm (range, 7.3-22.9 mm). The extent of extrusion on the sagittal plane was 0.5±0.7 mm (range, 0-2.5 mm). The extrusion ratio of the lateral meniscus on the sagittal plane was 4.0%±6.7% (range, 0%-26.3%). The incidence of lateral meniscal extrusion on the coronal plane was 34.1%. No extrusion of the lateral meniscus was observed on the sagittal plane.
CONCLUSION
In young and non-traumatic knees, the extrusion of meniscus was common, especially medial meniscus than lateral meniscus.

Keyword

meniscus; position; magnetic resonance imaging

MeSH Terms

Ambulatory Care Facilities
Humans
Incidence
Knee Joint
Knee*
Magnetic Resonance Imaging*
Male
Menisci, Tibial
Orthopedics

Figure

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  Figure 1 Extrusion was defined as the distance from the tibial plateau to the outer edge of the meniscus. Relative percentage of extrusion (RPE) was defined as (a) the absolute value of extruded meniscus divided by (b) the width of the whole meniscus (%).

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