Findings: Plain film - ossific density within the medial compartment of the knee joint. MRI - rounded area of signal abnormality within the posterior horn of the medial meniscus following marrow signal characteristics.

Diagnosis: Meniscal ossicle.

Discussion: Meniscal ossicles

• Meniscal ossicles are rare
• Etiology unknown: vestigial, trauma
• Patients can be asymptomatic or have local pain and swelling
• Location - most commonly found within the posterior horn of the medial meniscus
• Radiographically, these ossicles often are mistaken for intra-articular loose bodies
• MR demonstrates a corticated structure following marrow signal characteristics of all sequences
• Arthroscopy can also diagnose the meniscal ossicle, which can appear as a swelling in the meniscus
• If the patient is asymptomatic before the time of diagnosis, removal of the ossicle may not be indicated and normal function is possible with the ossicle retained

Schnarkowski. Meniscal Ossicle: Radiographic and MR Imaging
Findings. Radiology 1995 July;196(1):47-50.

Tuite. MR Imaging of a Meniscal Ossicle. Skeletal Radiology
1995 Oct; 24(7):543-545.

Yu. Meniscal Ossicle: MR Imaging Appearance in Three Patients.
Skeletal Radiology 1994 Nov; 23(8):637-639.

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