Plica syndrome

Last updated
Plica syndrome
Other namesSynovial plica syndrome
Specialty Orthopedics

Plica syndrome is a condition that occurs when a plica (a vestigial extension of the protective synovial capsule of usually the knee) becomes irritated, enlarged, or inflamed. [1]



This inflammation is typically caused by the plica being caught on the femur, or pinched between the femur and the patella. The most common location of plica tissue is along the medial (inside) side of the knee. The plica can tether the patella to the femur, be located between the femur and patella, or be located along the femoral condyle. If the plica tethers the patella to the femoral condyle, the symptoms may cause it to be mistaken for chondromalacia.

The plica themselves are remnants of the fetal stage of development where the knee is divided into three compartments. The plica normally diminish in size during the second trimester of fetal development, as the three compartments develop into the synovial capsule. In adults, they normally exist as sleeves of tissue called synovial folds. The plica are usually harmless and unobtrusive; plica syndrome only occurs when the synovial capsule becomes irritated, which thickens the plica themselves (making them prone to irritation/inflammation, or being caught on the femur).


If the plica tethers the patella to the femoral condyle, the symptoms may cause it to be mistaken for chondromalacia patellae. Diagnosis is often complicated by the thin structures of plicae, fenestrated septum or unfenestrated septum all being too fine to resolve well even in MRI.


Plica syndrome treatment focuses on decreasing inflammation of the synovial capsule. A nonsteroidal anti-inflammatory drug (NSAID) is often used in conjunction with therapeutic exercise and modalities. Iontophoresis and phonophoresis have been utilized successfully against inflammation of the plica and synovial capsule. Failing these, surgical removal of the plica of the affected knee may be necessary.

See also

Related Research Articles

Iliotibial band syndrome

Iliotibial band syndrome (ITBS) is the second most common knee injury caused by inflammation located on the lateral aspect of the knee due to friction between the iliotibial band and the lateral epicondyle of the femur. Pain is felt most commonly on the lateral aspect of the knee and is most intensive at 30 degrees of knee flexion. Risk factors in women include increased hip adduction, knee internal rotation. Risk factors seen in men are increased hip internal rotation and knee adduction. ITB syndrome is most associated with long distance running, cycling, weight-lifting, and with military training.


The femur, or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrate, the largest bone of the human body. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and kneecap, forming the knee joint. By most measures the two femurs are the strongest bones of the body, and in humans, the longest.

Knee Region around the kneecap

In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia, and one between the femur and patella. It is the largest joint in the human body. The knee is a modified hinge joint, which permits flexion and extension as well as slight internal and external rotation. The knee is vulnerable to injury and to the development of osteoarthritis.

Temporomandibular joint Joints connecting the jawbone to the skull

In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that its name is derived. This joint is unique in that it is a bilateral joint that functions as one unit. Since the TMJ is connected to the mandible, the right and left joints must function together and therefore are not independent of each other.

Sartorius muscle Longest muscle in the human body

The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment.

Bakers cyst

A Baker's cyst, also known as a popliteal cyst, is a type of fluid collection behind the knee. Often there are no symptoms. If symptoms do occur these may include swelling and pain behind the knee, or knee stiffness. If the cyst breaks open, pain may significantly increase with swelling of the calf. Rarely complications such as deep vein thrombosis, peripheral neuropathy, ischemia, or compartment syndrome may occur.

Popliteal artery

The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branches into the anterior and posterior tibial arteries.

Chondromalacia patellae

Chondromalacia patellae is an inflammation of the underside of the patella and softening of the cartilage.

Vastus medialis Extensor muscle located medially in the thigh that extends the knee.

The vastus medialis is an extensor muscle located medially in the thigh that extends the knee. The vastus medialis is part of the quadriceps muscle group.

Plantaris muscle One of the superficial muscles of the superficial posterior compartment of the leg,

The plantaris is one of the superficial muscles of the superficial posterior compartment of the leg, one of the fascial compartments of the leg.

Joint capsule

In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint. Each joint capsule has two parts: an outer fibrous layer or membrane, and an inner synovial layer or membrane.

Snapping hip syndrome

Snapping hip syndrome, also referred to as dancer's hip, is a medical condition characterized by a snapping sensation felt when the hip is flexed and extended. This may be accompanied by a snapping or popping noise and pain or discomfort. Pain often decreases with rest and diminished activity. Snapping hip syndrome is commonly classified by the location of the snapping as either extra- articular or intra-articular.

The knee examination, in medicine and physiotherapy, is performed as part of a physical examination, or when a patient presents with knee pain or a history that suggests a pathology of the knee joint.

Articular capsule of the knee joint

The articular capsule of the knee joint is the wide and lax joint capsule of the knee. It is thin in front and at the side, and contains the patella, ligaments, menisci, and bursae of the knee. The capsule consists of an inner synovial membrane, and an outer fibrous membrane separated by fatty deposits anteriorly and posteriorly.

Patellofemoral pain syndrome

Patellofemoral pain syndrome is knee pain as a result of problems between the kneecap and the femur. The pain is generally in the front of the knee and comes on gradually. Pain may worsen with sitting, excessive use, or climbing and descending stairs.

In medicine, joint locking is a symptom of pathology in a joint. It is a complaint by a person when they are unable to fully flex or fully extend a joint. This term is also used to describe the mechanism of lower limb joints held in full extension without much muscular effort when a person is standing.

Knee pain

Knee pain is pain in or around the knee.

Anterior interval release (AIR) is a type of arthroscopic knee surgery performed to alleviate pain and associated symptoms caused by scar tissue accumulation in the anterior region of the knee, behind and under the knee cap, in a condition called arthrofibrosis. In normal, asymptomatic knees, this anterior compartment of the knee comprises mobile, scar-free tissues such as the infrapatellar (Hoffa's) fat pad. With progression, scar tissue leads to closure of the anterior interval, tethering the patella tendon and causing pain, loss of range of motion, damage to knee cartilage, and/or pain, among other symptoms.

Medial knee injuries

Medial knee injuries are the most common type of knee injury. The medial ligament complex of the knee is composed of the superficial medial collateral ligament (sMCL), deep medial collateral ligament (dMCL), and the posterior oblique ligament (POL). These ligaments have also been called the medial collateral ligament (MCL), tibial collateral ligament, mid-third capsular ligament, and oblique fibers of the sMCL, respectively. This complex is the major stabilizer of the medial knee. Injuries to the medial side of the knee are most commonly isolated to these ligaments. A thorough understanding of the anatomy and function of the medial knee structures, along with a detailed history and physical exam, are imperative to diagnosing and treating these injuries.

Clarkes test

In medicine, Clarke's test is a component of knee examination which may be used to test for patellofemoral pain syndrome, Chondromalacia Patellae, Patellofemoral Arthritis, or anterior knee pain. It is not a standard part of the knee examination but is used to diagnose anterior knee pain where the history indicates this as the likely pathology. The patient is asked to actively contract the quadriceps muscle while the examiner's hand exerts pressure on the superior pole of the patella, so trying to prevent the proximal movement of the patella. While it can produce some discomfort even in normal people, the reproduction of the symptoms suggest pain of patello-femoral origin.


  1. Casadei, Kyle; Kiel, John (2020). "Plica Syndrome". StatPearls. StatPearls Publishing. PMID   30570983 . Retrieved 9 January 2021.
External resources