Plica Syndrome: Snapping and Pain at the Inner Front of the Knee

What is a plica?

The inside of the knee is lined by a thin membrane called the synovium. Before birth, this lining divides the knee into compartments. As the knee develops, the divisions usually shrink away, but in many people a fold remains. These leftover folds are called plicae, and most people who have one never know it.

The one that most often causes problems is the medial plica, which runs along the inner side of the kneecap. If it is irritated by overuse or a knock, it can swell, thicken and lose its elasticity. Instead of gliding smoothly, it then rubs or flicks over the end of the thigh bone each time you bend the knee. That is plica syndrome.

Symptoms in patients' own words

• "My knee snaps or clicks on the inside when I bend it"
• "It aches at the inner front of the knee, next to the kneecap"
• "It hurts after I've been sitting for a long time, like on a flight or in the car"
• "Stairs, squats and cycling make it worse"
• "Sometimes it catches, but it doesn't really lock"

There is usually little or no swelling, and the knee does not truly give way. Plica pain is often confused with front-of-knee pain from the kneecap or with a meniscus tear.

Causes and who gets it

Plica syndrome is most common in teenagers and young adults, especially those who repeatedly bend and straighten the knee: runners, cyclists, footballers, rowers, dancers and gym-goers doing lots of squats or lunges. A sudden increase in training, for example ramping up indoor cycling or treadmill running during the Qatar summer, is a common trigger. A direct blow to the inner side of the knee can also start it.

Weak quadriceps and tight hamstrings increase the load on the front of the knee and make irritation more likely.

Diagnosis

Plica syndrome is a diagnosis made carefully, because other conditions can feel similar. Dr. Gelber examines the knee for a tender, cord-like band at the inner edge of the kneecap that may snap under the finger as the knee bends. He also checks the meniscus, the kneecap and its tracking, and the tendons.

An MRI can sometimes show a thickened plica, but it is mainly used to exclude other causes such as a meniscus tear or cartilage damage. Many plicae seen on MRI cause no symptoms at all, so the scan must be interpreted alongside the examination.

Non-surgical treatment

• Reduce or pause the activity that provokes it, such as cycling, deep squats and stairs training, then reintroduce it gradually
• Ice after activity and a short course of anti-inflammatory medicine if suitable for you
• Physiotherapy focusing on quadriceps and hip strengthening and hamstring and quadriceps stretching, which is the core of treatment
• In selected patients, a steroid injection near the plica to calm the inflammation

Many patients improve within six to eight weeks of a consistent programme, though some take a few months.

Surgical treatment

If symptoms continue despite several months of good rehabilitation, and other causes have been excluded, knee arthroscopy can be considered. Through small keyhole incisions, the thickened plica is trimmed or removed (plica resection). At the same time, the rest of the knee is inspected, which can identify other problems.

The plica is a leftover fold with no essential function, so removing it does not weaken the knee.

Recovery and when to see a specialist in Doha

After arthroscopic plica resection, most patients walk the same day, return to desk work within about a week and return to sport over roughly four to eight weeks, depending on the knee and the sport. Physiotherapy afterwards remains important to prevent the front of the knee becoming irritated again.

See a knee specialist if snapping or aching at the inner front of the knee has lasted more than a few weeks, keeps coming back, or stops you training. Seek prompt care if the knee truly locks, swells significantly or gives way, because these point to a different problem. Dr. Gelber sees patients at Aman Hospital in Doha.