Plica syndrome

Overview

Plica syndrome, also known as medial plica syndrome, is a condition that arises when a synovial fold within the knee joint, known as the plica, becomes inflamed or irritated. The plica is a normal anatomical structure—one of several folds in the synovial membrane that lines the knee joint. While most people have plicae that are asymptomatic, in some individuals, particularly those who are physically active or have experienced trauma to the knee, the plica can thicken and cause pain due to friction against other structures within the joint. This syndrome is most commonly seen in adolescents and young adults who engage in repetitive knee-bending activities.

Causes

Plica syndrome typically develops due to irritation, overuse, or trauma to the knee. The primary causes include:

• Repetitive knee movements: Activities such as running, biking, squatting, or stair climbing can stress the plica and cause inflammation.

• Knee trauma: A direct blow or twisting injury to the knee may lead to plica irritation.

• Congenital prominence: In some individuals, the plica is naturally more prominent or thickened, making it more prone to irritation.

• Synovial inflammation: Underlying joint inflammation, such as from arthritis or previous surgery, can cause the plica to swell and become symptomatic.

The most frequently involved structure in plica syndrome is the medial plica, which runs along the inside of the kneecap.

Symptoms

The symptoms of plica syndrome can mimic other knee disorders, making diagnosis challenging. Common signs and symptoms include:

• Knee pain: Usually localized around the inner aspect of the knee, near the patella (kneecap).

• A snapping or clicking sensation: Especially during activities that involve bending and straightening the knee.

• Knee stiffness: A feeling of tightness or fullness, particularly after prolonged sitting or exercise.

• Swelling or puffiness: Around the front of the knee joint.

• Locking or catching: Occasionally, the plica may become caught between the femur and patella, causing mechanical symptoms.

Symptoms are often aggravated by activity and relieved with rest. Patients may report difficulty with sports or activities that require repetitive knee motion.

Diagnosis

Diagnosing plica syndrome is primarily clinical but may be supported by imaging. The diagnostic process includes:

• Physical examination: A physician may detect tenderness along the medial side of the knee and reproduce pain by compressing the plica during knee flexion.

• Medical history: Evaluation of symptoms, duration, and activity-related patterns.

• Magnetic Resonance Imaging (MRI): Useful in ruling out other knee pathologies such as meniscal tears or ligament injuries, and can sometimes visualize an inflamed plica.

• Diagnostic arthroscopy: In cases where the diagnosis is uncertain, minimally invasive arthroscopy allows direct visualization of the plica inside the joint.

Plica syndrome is a diagnosis of exclusion, often made after ruling out other intra-articular pathologies.

Treatment

Initial management of plica syndrome is usually conservative. Treatment options include:

• Rest and activity modification: Reducing or avoiding activities that aggravate the condition.

• Ice therapy: Applying cold packs to the knee to reduce inflammation and pain.

• Nonsteroidal anti-inflammatory drugs (NSAIDs): Such as ibuprofen to relieve pain and swelling.

• Physical therapy: Focused on stretching, strengthening surrounding muscles (especially quadriceps), and correcting biomechanics.

• Corticosteroid injections: In some cases, a steroid injection into the knee joint may help reduce inflammation.

If symptoms persist despite conservative measures, surgical intervention may be necessary:

• Arthroscopic plica excision: Minimally invasive surgery to remove the thickened or fibrotic plica. Recovery is typically quick, with patients resuming normal activity within a few weeks.

Prognosis

The prognosis for plica syndrome is generally favorable. Most individuals respond well to non-surgical treatment within a few weeks to months. For those requiring surgery, outcomes are typically excellent, with a high rate of symptom resolution and return to normal activity. Recurrence is rare, especially when contributing factors such as poor biomechanics or overuse are addressed. Early diagnosis and appropriate management are key to preventing chronic irritation and long-term joint damage.