Plica is a term used to describe a fold in the lining of the knee joint. Imagine the inner lining of the knee joint as nothing more than a sleeve of tissue. This sleeve of tissue is made up of synovial tissue, a thin, slippery material that lines all joints. The synovial sleeve of tissue has folds of material that allow movement of the bones of the joint without restriction.
Four plica synovial folds are found in the knee, but only one seems to cause trouble. This structure is called the medial plica. The medial plica attaches to the lower end of the knee cap and runs sideways to attach to the lower end of the thighbone at the side of the knee joint closest to the other knee.
The plica only becomes a problem when the knee is irritated, causing an inflammation in the synovial sac. This is called plica syndrome. When the synovium is inflamed, the area of the medial plica becomes thicker. This thickened area then begins to catch on the femur as the knee moves. This in turn keeps the medial plica inflamed resulting in continued injury.
Over time the medial plica can be irritated by certain exercises, repetitive motions, or kneeling. Activities that repeatedly bend and straighten the knee, such as running, biking, or use of a stair-climbing machine, can irritate the medial plica and cause plica syndrome.
The primary symptom of plica syndrome is pain. There may also be a snapping sensation along the inside of the knee, as the knee is bent, due to the rubbing of the thickened medial plica over the edge of the thighbone. If the plica has become severely irritated, the knee may become swollen. Pain from plica syndrome usually occurs when the knee is straightened from a flexed or bent position to a straight position.
Remember that most plica syndrome problems happen at the contact phase of gait (when the foot hits the ground) due to increased biomechanical stress at this point.
Golden rule- Don’t ignore the problem, it won’t go away!
The way we function biomechanically is predominantly controlled by genetics, its hereditary (runs in the family). The way you function is set and cannot be cured. What you can do however is control lower limb biomechanics by altering foot position during the contact phase of gait. This can be achieved by wearing a good shoe (see our shoe guide) with orthotics (foot beds), knee strengthening and knee support.
1. Check your footwear
Are your running shoes worn and in need of replacing? If so change them. The chances of medial plica injury is greatly increased with higher impact forces so a good shock absorbing shoe is a must. For more advice on running trainers our running shoe advice page is worth reading. Read more->
Below are a selection of trainers that are ideal for athletes.
Trainers for a neutral or under pronating foot type
Trainers for over pronators
rectify Poor biomechanics with orthotics
The way your foot strikes the ground and the forces that are placed on it can have a direct effect on causing plica syndrome and can also delaying healing times. Check our biomechanics page for detailed information. Read more->
The single best exercise to improve the strength of the muscles around the knee is eccentric loading. This is usually done none weight bearing, however the use of a wobbleboard is an excellent way to strengthen muscles around the knee, foot and ankle in a controlled gentle manner. Whilst our clinicians have found it a brilliant way to strengthen muscles around the knee, traditionally a wobbleboard was used to help balance (proprioception). Proprioception is the nerve connection from the brain to the foot. This is often damaged/ disrupted after injury and can increase the chances of injury from recurring. It can also significantly delay recovery.
Use of a wobbleboard therefore has a dual benefit in the treatment of plica syndrome.
Consider purchasing a knee brace . This device provides extra stability to the knee when playing sports. The material also causes localised vasodilation (opening of the blood vessels) increasing circulation to the area. This is vital as all ligaments have a notoriously poor blood supply. Increasing circulation to the ligaments can reduce the chance of injury. Stabilising the knee also reduces the mechanical stresses that can irritate the medial plica.
Plica syndrome prevention checklist summary
- Rectify Biomechanics if necessary
- Check Running shoes
- Knee strengthening
- Knee support
Returning to Activity
The goal of rehabilitation is to return you to your sport or activity as soon as is safely possible. If you return too soon you may worsen your plica syndrome injury, which could lead to permanent damage. Everyone recovers from plica syndrome at a different rate. Return to your activity is determined by how soon your medial plica recovers, not by how many days or weeks it has been since your injury occurred.
You may safely return to your sport or activity when, starting from the top of the list and progressing to the end, each of the following is true:
You have full range of motion in the injured leg compared to the uninjured leg.
You have full strength of the injured leg compared to the uninjured leg.
You can jog straight ahead without medial plica pain.
You can sprint straight ahead without plica syndrome symptoms.
You can do 45-degree cuts, first at half-speed, then at full-speed.
You can do 20-yard figures-of-eight, first at half-speed, then at full-speed.
You can do 90-degree cuts, first at half-speed, then at full-speed.
You can do 10-yard figures-of-eight, first at half-speed, then at full-speed.
You can jump on both legs without medial plica pain and you can jump on the injured leg without pain.