A plica is a fold in the lining (the synovium) of the knee joint, and plicae are present in most knees.[1] In most people they cause no symptoms.[2] A plica can become irritated, and an irritated plica can cause plica syndrome.[2]
According to StatPearls, most patients improve with non-operative treatment.[2] One review notes that some studies have not found conservative care particularly successful, although that evidence has generally been low-level.[1]
What is knee plica syndrome?
Plicae are inward folds of the synovial lining and are present in most knees.[1] In most individuals, they remain without symptoms.[2] A plica can become irritated through friction against the kneecap or the inner end of the thigh bone, resulting from overuse or injury, and inflammation or irritation of a plica can cause plica syndrome.[2]
- Plicae are classified by location as suprapatellar (above the kneecap), mediopatellar (on the inner side), infrapatellar (below the kneecap) or lateral (on the outer side).[1]
- The medial plica, on the inner side, is the most commonly symptomatic one.[1]
- The lateral plica is rare.[3]
More on how common it is
Reported prevalence of plica syndrome varies widely, from 3 to 30% in European population studies, and most studies cite a figure of approximately 10%.[1]
What’s covered on this webpage
- What is knee plica syndrome?
- Who gets knee plica syndrome, and what can cause it?
- What are the symptoms of knee plica syndrome?
- How is knee plica syndrome diagnosed?
- How is knee plica syndrome treated?
- When is urgent help needed?
- What should I do next?
Who gets knee plica syndrome, and what can cause it?
Plica syndrome usually affects people of both sexes in their first through third decade of life.[1] Overuse and injury are linked with it.[1][3]
- According to one review, because the problem is mechanical, intensified activity will increase the degree of plica irritation, which may explain why the condition is common in sporting people.[1]
- In adolescence, symptoms can occur during a period of growth spurt.[1]
What are the symptoms of knee plica syndrome?
Plica syndrome can cause pain at the front or inner side of the knee that comes with activity, stiffness, and snapping, catching or pseudolocking (a sensation of the knee locking).[2] People commonly report intermittent, non-specific pain at the front of the knee, snapping, clicking, catching, clunking and grinding.[1] The knee may be tender to the touch, swollen and stiff.[1]
- One review lists pseudolocking of the knee among atypical symptoms.[1]
- Where symptoms are limited to locking and sharp pain, a meniscus problem should be ruled out first, as plica syndrome is then less likely.[1]
More on how it can be confused with a meniscus tear
Plica syndrome can mimic a torn medial meniscus (the cushion of cartilage on the inner side of the knee) or a maltracking kneecap.[3] It can be confused with other conditions, including meniscus pathology.[1] Read about meniscus tears and their treatment.
How is knee plica syndrome diagnosed?
Diagnosis of plica syndrome is mainly clinical, supported by targeted physical examination and selective imaging when necessary.[2]
- Arthrography (a scan taken after dye is injected into the joint), ultrasound (a scan that uses sound waves) and magnetic resonance imaging (MRI, a detailed scan of the knee) can all show the presence of a plica, but they are unreliable in predicting which plicae are pathological.[1]
- The authors suggest that imaging is not required to make an initial clinical diagnosis of plica syndrome or to begin management in primary care.[1]
- Arthroscopy (keyhole surgery with a camera) of the affected joint can confirm the diagnosis, but it is generally not recommended as a diagnostic test.[1]
How is knee plica syndrome treated?
According to StatPearls, most patients improve with non-operative treatment focused on activity modification, anti-inflammatory measures, and strengthening of the quadriceps (the large muscle group at the front of the thigh) and hip.[2] Arthroscopic plica resection (keyhole removal of the plica) is reserved for persistent symptomatic plicae.[2]
- A review of the evidence suggests that plica syndrome responds well to general conservative measures such as activity modification, exercise therapy and symptomatic treatment, although some authors have not found conservative management particularly successful; those contrary findings have generally been low-level and based upon small, retrospective cohorts (studies that looked back at small groups of patients).[1]
- Patients can initially be advised to modify the activities that are known to make plica syndrome worse, such as jumping, squatting or lunging.[1]
- StatPearls states: “At least 3 months of conservative treatment is recommended before advancing to more aggressive therapies.”[2]
- A single retrospective study reported that 86% of patients improved without surgery.[6]
- Topical or oral anti-inflammatory medicines and paracetamol are likely to be sufficient for relieving pain.[1] Check with your doctor or pharmacist before taking any medicine.
- Rest, ice and elevation may provide additional relief during acute episodes.[1]
- For sprains and strains, the NHS advises applying an ice pack (or a bag of frozen vegetables wrapped in a tea towel) for up to 20 minutes every 2 to 3 hours during the first 2 to 3 days.[7]
- An exercise programme can aim to strengthen the vastus medialis oblique muscle (a muscle on the inner side of the thigh, often weak in patients with front-of-knee pain) and the quadriceps in general.[1]
- A systematic review cited in one review article did not support the use of taping, either as a long-term treatment or as part of a short-term intervention.[1]
More on when surgery is considered
The review by Lee and colleagues (2017) suggests that patients who do not improve significantly despite following conservative measures over a reasonable period of time (3 to 6 months) should be offered further investigation and management.[1] The plica should only be removed if the diagnosis is clearly supported by examination and history, and conservative measures have been unsuccessful.[1]
A meta-analysis (a study that pools the results of several studies) of six studies and 527 patients found that both surgical and conservative treatments improved knee function.[4] At 12 to 24 months there was no statistically significant difference favouring either approach, although the studies varied substantially from one another.[4] The evidence was level IV.[4] The authors found no evidence supporting the superiority of surgical procedures for medial plica syndrome.[4]
A review that pooled 23 studies of surgical removal of the plica reported: “At a mean follow-up of 27.5 months, 64 % of patients were symptom free, 26 % improved and 10 % considered failures.”[5]
On the rare occasions that surgical treatment is warranted, the review reports that studies it cites suggest approximately 10% of patients continue to have disabling problems and 26% have occasional problems but can return to activity.[1]
Reasons to be referred for further assessment include diagnostic uncertainty, failed conservative treatment, severe symptoms or noticeable functional limitation, relapse after successful physiotherapy, and recurrence after plica surgery.[1]
When is urgent help needed?
The list below covers the signs that should not wait for a routine appointment, including a knee that is stuck and will not straighten.
What should I do next?
For anyone with persistent pain, snapping or catching at the front or inner side of the knee, an assessment is a sensible next step. It brings together the patient’s story, an examination and any tests that help, so that the patient and clinician can decide what to do next. An appointment supports an informed decision. It is not a commitment to surgery.
- Read about meniscus tears and their treatment and about knee fat pad syndrome.
- Arrange a knee assessment when you are ready.
- Browse the Knee Hub for other knee problems, or more articles.
- Read more about Dr Sean Leo, who is named as the author of this page.
This page provides general information and cannot diagnose an individual condition. OrthoKinetics does not provide emergency or urgent care through this webpage or its WhatsApp contact.
References
- Lee PYF, Nixion A, Chandratreya A, Murray JM, et al. Synovial Plica Syndrome of the Knee: A Commonly Overlooked Cause of Anterior Knee Pain. Surg J (N Y). 2017;3(1):e9-e16. doi:10.1055/s-0037-1598047. PMID:28825013.
- StatPearls. Plica Syndrome. Bookshelf ID NBK535362. PMID:30570983. https://www.ncbi.nlm.nih.gov/books/NBK535362/
- Dupont JY. Synovial plicae of the knee. Controversies and review. Clin Sports Med. 1997;16(1):87-122. doi:10.1016/s0278-5919(05)70009-0. PMID:9012563.
- Franco P, Baumert P, Di Maria F, Jolly A, et al. Surgical and conservative management of medial plica syndrome: A systematic review and meta-analysis. J Exp Orthop. 2025;12(4):e70473. doi:10.1002/jeo2.70473. PMID:41189766.
- Schindler OS. ‘The Sneaky Plica’ revisited: morphology, pathophysiology and treatment of synovial plicae of the knee. Knee Surg Sports Traumatol Arthrosc. 2014;22(2):247-262. PMID:23381917.
- Results of treatment of plica syndrome of the knee. Acta Ortop Bras. 2021. doi:10.1590/1413-785220212902241609. PMID:34248404. PMCID:PMC8244843.
- NHS. Sprains and strains. https://www.nhs.uk/conditions/sprains-and-strains/
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