A plica is a ribbon-like fold of joint lining (synovium) which may be present in any knee as an embryological remnant.

Page updated June 2024 by Dr Sheila Strover (Clinical Editor)

ligamentum mucosus
In this illustration, the capsule of the knee has been opened up to show the inner surface (synovium) and several folds which are frequently present - the various plicae (plural) of the knee.

 

 

A plica is a normal structure

A plica is something one is born with, and it may never give cause for concern. Sometimes, however, it may start to cause symptoms, perhaps after being traumatised and becoming a bit inflamed and thickened.

Then it may become nipped between the moving structures of the knee, commonly the femur and patella, and cause intermittent pain.

plica being nipped

Arthroscopic photograph showing a thickened plica being nipped.

 

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How does one diagnose a symptomatic plica?

The patient's story is often suggestive - periodic sudden painful catching in the knee, usually on the medial side of the patella.

Examination may show a positive stutter test, where the examining fingers placed over the affected area may feel a musclular 'stutter' as the knee, hanging over the edge of the examination coach, is bent and straightened. A problematic plica may be seen on arthroscopy, and there may be a split or other damage on the joint cartilage on either side. Finally, the problem may be evident on MRI scan.

 

  • Quote from peer-reviewed paper:

    "....The most frequent complaint was supra-patellar pain and cracking noises following the performance of physical activity of a type or intensity of which the patient was unaccustomed."

    Citation: Camanho GL. Treatment of pathological synovial plicae of the knee. Clinics (Sao Paulo). 2010 Mar;65(3):247-50. doi: 10.1590/S1807-59322010000300002. PMID: 20360913; PMCID: PMC2845763.

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Symptomatic plicae often mimic other conditions

Plicae are normal anatomical structures, so they are often ignored when the surgeon is investigating the problematic knee.

They may cause clicking and catching and be mistaken for a meniscus problem, for example. But usually a careful arthroscopic examination will reveal thickening at areas that are being impinged or a bit of redness and some damage to underlying joint cartilage.

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Synonyms: 
synovial plica
plical fold
plical remnant
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Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

See biography...


Also relevant -


Mr Angus Strover2017 - Plicae - by Mr (Dr) Angus Strover (Retired Knee Surgeon)



More material -


 

eBook about plica problems in the knee

eBook - An overview of plica problems in the knee

An expert look at the various plical folds of the knee and the problems that can be caused by a troublesome plica.

by Dr Lars Blønd (Knee surgeon)