Plica Syndrome Flashcards
Definition/Description
The elastic nature of synovial plicae allow normal movement of the bones of the tibiofemoral joint, without restriction. Yet, when repeating the same knee movement too often, such as bending and straightening the knee, or in the case of a trauma to the knee, these plicae can become irritated and inflamed. This can result in a disorder called the plica syndrome. It refers to an internal derangement of the knee which prevents normal functioning of the knee joint.
It is an interesting problem, particularly seen in children and adolescents and occurs when an otherwise normal structure in the knee becomes a source of knee pain due to injury or overuse. The diagnosis might sometimes be difficult because the main symptom of non-specific anterior or antero-medial knee pain can point to various knee disorders. But if a plica has been diagnosed beyond any doubt as being the source of knee pain, it can be treated correctly
Types of Plica - Suprapatellar plica
The suprapatellar plica, also referred to as the plica synovialis suprapatellaris, superior plica, supramedial plica, medial suprapatellar plica or septum is a domed, crescent shaped septum that generally lies between the suprapatellar bursa and the tibiofemoral joint of the knee. It runs downward from the synovium at the anterior side of the femoral metaphysis, to the posterior side of the quadriceps tendon, inserting above the patella.Its free border appears sharp, thin, wavy or crenated in normal conditions.
This type of plica can be present as an arched or peripheral membrane around an opening, called porta. It often blends into the medial plica. As the suprapatellar plica is anteriorly attached to the quadriceps tendon, it changes dimension and orientation when moving the knee
Types of Plica - Medial patella plica
The medial patellar plica is also known as plica synovialis mediopatellaris, medial synovial shelf, plica alaris elongata, medial parapatellar plica, meniscus of the patella or after its first two descriptors as Iion’s band or Aoki’s ledge. It is found along the medial wall of the joint. It attaches to the lower patella and the lower femur and crosses the suprapatellar plica to insert in the synovium surrounding the infrapatellar fat pad. Its free border can have different appearances.
As the medial plica is attached to the synovium covering the fat pad and ligamentum patellae, it also changes dimension and orientation during knee movement. The medial plica is known to be the most commonly injured plica due to its anatomical location and it is usually this plica which is implicated when describing the plica syndrome.
Similar to the suprapatellar plicae, the medial plicae has also can be classified by appearance.
Types of Plica - Infrapatellar plica
The infrapatellar plica is also called as ligamentum mucosum, plica synovialis infrapatellaris, inferior plica or anterior plica. It is a fold of synovium which originates from a narrow base in the intercondylar notch, extends distally in front of the anterior cruciate ligament (ACL) and inserts into the inferior of the infrapatellar fat pad.
It is often difficult to differentiate the infrapatellar plica from the ACL. Mostly it appears as a thin, cord-like, fibrous band. The infrapatellar plica is considered to be the most common plica in the human knee. Discussion is on-going whether this plica is structurally important to regular knee movement or whether it is redundant.
Types of Plica - Lateral plica
The lateral plica is also known as plica synovialis lateralis or lateral para-patellar plica. It is longitudinal, thin and is located 1-2 cm lateral to the patella. It is formed as a synovial fold along the lateral wall above the popliteus hiatus, extending inferiorly and inserting into the synovium of the infrapatellar fat pad.
Some authors doubt whether it is a true septal remnant from the embryological phase of development or whether it is derived from the parapatellar adipose synovial fringe.
This type of plica is only seen on rare occasions; its incidence being well below 1%
Epidemiology /Etiology
Synovial plicae mostly are asymptomatic and of little clinical consequence. However, they can become symptomatic when they are injured or irritated. This can be the result of various conditions, such as direct trauma or blow to the plica, blunt trauma, twisting injuries, repetitive flexion and extension of the knee, increased activity levels, weakness of the vastus medialis muscle, intra-articular bleeding, osteochondritis dissecans, torn meniscus, chronic or transient synovitis,
When the initial injury has healed, patients can be symptom-free for some time, but then suddenly anterior knee pain can develop week or over months later.
The term plica syndrome is used to refer to the internal derangement of the knee caused by an inflammation or injury to the suprapatellar, the medial patellar or the lateral plica, or a combination of the three, and which prevents normal functioning of the knee joint.
The medial plica is known to be the most commonly injured plica due to its anatomical location.The infrapatellar plica is normally not implied in the occurrence of the plica syndrome. The plica syndrome is thus often the result of excessive use of the knee and is therefore often encountered in people engaged in exercises involving repeated flexion-extension movements such as the ones seen in cycling, running, team sports, gymnastics, swimming and rowing sports and is particularly common in adolescent athletes.
The reported incidence for synovial plicae shows a wide variation, as does the incidence for plica syndrome. These differences are mainly the result of interpretations by the individual investigators and differences in nomenclature and assessment procedure.
Characteristics/Clinical Presentation
When a plica becomes pathologic, the usual characteristics of the tissue will change due to the inflammatory process. They may become hypertrophic, show increased vascularity, hyalyinisation and lose their typical characteristics as loose and elastic connective tissue. As a result they may also become edematous, thickened and fibrotic, and they will most certainly intervene in normal patello-femoral movement.
Chronic cases will show fibrocartilaginous metaplasia, increasing collagenisation and calcification. Particularly the medial patellar plica may bowstring across the trochlea and the medial femoral condyles or impinge between the medial patella facet and the medial condyle when flexing the knee. Over time this might lead to softening, degeneration (chondromalacia) or even erosion of the cartilage of the medial patellar facet and the trochlea. The plica will intrude in the patello-femoral joint (usually between 30° and 50° of flexion), further subluxing over the medial femoral condyle. The same mechanism can be seen with a pathological lateral plica, but in that case the lateral femoral condyle will be affected. A pathological suprapatellar plica will impinge between the quadriceps tendon and the femoral trochlea.
Plica syndrome can cause a series of symptoms, such as pain, clicking, popping, effusion, localised swelling, reduced range of motion, intermittent medial joint pain, instability and locking of the patello-femoral joint. It is more commonly seen in teenagers and young adults, even more so in women than in men.
Patients often report that symptoms are absent in the early phases of sporting activities, but can come up suddenly and worsen progressively. They are often accompanied by a pain which can be described as intermittent, dull and aching and which will aggravate when performing patello-femoral loading activities such as walking up or down stairs, squatting, kneeling or after holding the knee in flexed position for some time.
When the symptoms occur they are not easily distinguishable from other intra-articular conditions and knee derangements of the knee joint.The pain can be located at different places like the supra- patellar and the mid-patellar region when extending the knee. You can also hear cracking noises when flexing of extending the knee.The combination of contracting the quadriceps and the compression of the supra-patellar pouch can also be the cause of pain.What occurs frequently in patients with plica syndrome is that they often have a sense of instability when walking upstairs, downstairs or slopes.
It should only be considered as the primary cause of the patient’s symptoms when the patient fails to respond to appropriate management of patellofemoral pain.
Examination
One of the most important points in diagnosing medial synovial plica pathology is obtaining an appropriate history from the patient.
The pain is often described as a dull pain in the proximo-medial aspect of the knee and along the border of the patella. Frequently there’s is an internal hydrops and a string palpable.The pain increases with activity, overuse and is practically bothersome at night. Most patients have complaints when doing stairs, squats and standing up from a chair because these movements create a stress on the patello-femoral joint. The patient may also complain of pain following prolonged periods of sitting. About 50% of the patients let us know that they have been doing exercises with repetitive flexion and extension. Injury or overuse of the other plica can cause the same complaints but these are seen less frequently.
Specific physical tests for the diagnosis of a medial plica include the plica and the mediopatellar plica stutter tests. Yet, the plica stutter test will not work when the joint is swollen. Other methods of examination that may indicate the presence of a medial plica include the medial subluxation test, McMurray’s, Appley’s test for instability and Cabot’s test.
The MPP test is
The MPP test is conducted with the patient in supine position and the knee extended. Manual force is then applied to the inferomedial part of the patellofemoral joint with the thumb, checking the presence of tenderness. If this tenderness clearly diminishes at 90° of flexion while applying the same manual force, the test is considered positive. When compared to arthroscopy, the sensitivity and specificity of this test were 89.5% and 88.7%, respectively, with a diagnostic accuracy of 89.0%.
Other tests?
Other provocation tests for the diagnoses of medial plica syndrome can be the knee extension test or flexion test. For the active extension test, a quick extension of the tibia is performed as if making a kicking movement. The test is considered positive when painful, because of the abrupt tension on the plica from the quadriceps femoris muscle. The flexion test is performed by quickly swinging the tibia from a position of full extension into flexion and interrupting the swing between 30 and 60° of flexion. The test is again positive when painful, as the plica is then stretched with eccentric contraction of the quadriceps muscle.
Plica snap test?
The plica snap test can be used to verify if there is irritation of the medial plica. For the palpation of the medial synovial plica the patient lies supine on the examining table with both legs relaxed. For the medial synovial plica the examiner palpates the ligament by rolling the fingers over the plica fold, which is located between the medial border of the patella and the adductor tubercle region of the medial femoral condyle. Under the finger, which rolls directly against the underlying medial femoral condyle, the ligament will present itself as a ribbon-like fold of tissue. The test is positive when it reproduces the symptoms such as a sensation of mild pain. But also compare it with the normal knee to see if there is a difference in the amount of pain. It is demonstrated that it can be quite painful in some patients because the medial joint and synovium is well innervated.
