J Korean Orthop Assoc.  2017 Oct;52(5):462-466. 10.4055/jkoa.2017.52.5.462.

Fabella Syndrome: A Rare Cause of Common Peroneal Nerve Palsy

• Shin DS
• Cho CW
• Ryu SM

• KMID: 2393520
• DOI: http://doi.org/10.4055/jkoa.2017.52.5.462

Abstract

The fabella has been considered to have a minor clinical significance. However, there have been a few reports describing the fabella as one of the causes of peroneal nerve palsy (PNP). This report describes a 66-year-old farmer who complained of acute neurologic symptoms involving the fabella. Surgical extirpation was performed and neurologic function was recovered dramatically. Recently, there have been no published reports on fabella syndrome with common PNP. Here, we report an unusual case of common PNP with the fabella as a cause.

Keyword

sesamoid bones; peroneal nerve; paralysis

MeSH Terms

Aged
Farmers
Humans
Neurologic Manifestations
Paralysis*
Peroneal Nerve*
Sesamoid Bones

Figure

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  Figure 1 Preoperative simple anterioposterior (A) and lateral (B) radiograph of the right knee. Fabella is indicated with a black arrows.

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  Figure 2 (A) T2 transverse section magnetic resonance imaging (MRI) of the patient's right knee. Fabella is indicated with a black arrow, and common peroneal nerve (3-mm width) is indicated with a white arrow. (B) T2 transverse section MRI, which is on a lower level than Fig. 2A. Localized edematous common peroneal nerve (8-mm width) is indicated with a white arrow.

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  Figure 3 Sagittal section of ultrasound sonography. “+” showed normal common peroneal nerve, and “×” showed localized edematous change of the common peroneal nerve near the fibular head (FH).

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  Figure 4 (A) The tendon of biceps femoris was retracted, and the common peroneal nerve was seen. (B) The 9×9×6-mm-sized fabella is detached from the lateral head of the gastrocnemius muscle, in which it was imbedded.

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