Meniscal Ossicle

Meniscal ossicles are small osseous bodies located within the meniscus, typically located in the medial meniscus posterior horn. The definitive cause is unknown; the ossicle may have congenital, degenerative or traumatic origins.¹

 

 

 

Meniscal Ossicle: Clinical Presentation

Meniscal ossicles are typically incidental findings on MR, although they may be symptomatic causing intermittent pain. In contrast with loose osseous bodies, meniscal ossicles will rarely cause locking or mechanical symptoms. If symptomatic, initial management is conservative / non-interventional, with consideration of arthroscopic resection of the ossicle only if resistant to conservative therapy.¹

 

 

Meniscal Ossicle: Pathology

Causes of meniscal ossicles are not well established. Potential origins may be:

• Congenital
• Traumatic
• Degenerative

Although, the traumatic origin is favored given the association with the posterior horn of the medial meniscus.² Meniscal ossicles are made up of cancellous bone with a cartilage interface. Neither fibroblast proliferation nor neovascularization exist.⁴

 

 

Meniscal Ossicle: Differential Diagnosis

• Intra-articular loose body
• Fracture fragment
• Fabella
• (On MRI): Intrameniscal cyst ³

 

 

Meniscal Ossicle: MRI Findings

Meniscal ossicles are typically the same as bone marrow signals in sequences:

• T1 results in hyperintense signals (resembles bone marrow)
• T2FS / STIR results in hypointense signals ³
  
  

 

 

Meniscal Ossicle: Treatment

• Conservative treatments are initially undertaken if the ossicle is symptomatic.
• Minimally invasive methods such as arthroscopic resection would take place if conservative treatments were ineffective.³

 

 

 

Meniscal Ossicle: Example

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In image 1, (53-year-old female) the ossicle is located within the medial meniscus at the posterior root-horn junction (green arrow). Note the smooth edges, which will differentiate from an avulsed fragment. Signal consistent with adjacent bony structures on this T1 image will differentiate from intrameniscal cyst.

  

 Image 1 - Sagittal T1 FSE                                       Image 2 - PD T2 Sagittal

 

In image 2, (46-year-old female) the ossicle is again present in the medial meniscus posterior horn. This ossicle is visualized on T2 / PD sequence (green arrow), with adjacent capsulosynovial cysts (pink arrow). Here, the signal difference between ossicle and cyst is clearer, leading to the determination of meniscal ossicle over intrameniscal cyst.

Related Cases

 

 

 

Meniscal Ossicle: Appendix

Epidemiology

Data indicates 0.15% of the general population develop meniscal ossicles.⁵

 

 

 

Meniscal Ossicle: References

1. Ersoy H., personal communication on meniscal ossicle, December 2017.
2. Mohankumar R, Palisch A, Khan W et-al. Meniscal ossicle: posttraumatic origin and association with posterior meniscal root tears. AJR Am J Roentgenol. 2014;203 (5): 1040-6.
3. Muzio BD, Morgan MA et-al. Meniscal ossicle: Radiopaedia (sourced 10Jan2018): https://radiopaedia.org/articles/meniscal-ossicle
4. Ohishi T, Suzuki D, Yamamoto K et-al. Meniscal pullout repair following meniscal ossicle resection: a case report. Knee. 2013;20 (1): 52-7.
5. Schnarkowski P, Tirman PF, Fuchigami KD et-al. Meniscal ossicle: radiographic and MR imaging findings. Radiology. 1995;196 (1): 47-50.

 

   

 

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