AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Background

The medial suprapatellar plica of the knee is an intra-articular synovial fold on the medial aspect of the knee. This plica is one of the most common sources of knee pain in patients; however, a proper rehabilitation program allows most patients to recover from the symptoms associated with irritation of this structure.

Frequency

United States

No exact numbers on the incidence of patients with an irritated synovial plica are available; however, it is estimated that approximately 50% of patients who present with knee pain to a physician's office have some irritation of their patellofemoral joint. In this group of patients, most of them have some amount of suprapatellar plical irritation.

Functional Anatomy

The suprapatellar plica is an intra-articular synovial fold, which has its main component on the medial aspect of the knee. When the knee is in full extension, the suprapatellar plica commonly forms a shelf, which can be palpated by an examiner. Proximally, the plica is attached to the articularis genu muscle. Distally, it is attached to the anterior horn of the medial meniscus and the medial edge of the retropatellar fat pad. In some patients, this plical shelf can become fibrotic and may impinge on the medial edge of the medial femoral condyle.

Sport-Specific Biomechanics

The quadriceps muscles and the articularis genu muscle dynamically control the medial suprapatellar plica. Good quadriceps tone seems to result in normal motion of this plica, whereas patients with poor quadriceps tone or tight hamstring muscles (antagonists of the quadriceps) commonly have irritation of their synovial plica.

CLINICAL

Section 3 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

History

• Medial suprapatellar plical irritation is a common finding in patients who present with complaints of anterior knee pain.
• • Symptoms include complaints of pain and stiffness over the anteromedial aspect of the knee upon arising from a prolonged sitting position, pain going up and/or down stairs, and pain with prolonged walking.
  • The symptoms often wax and wane over periods of time until the patient presents to a physician's office because of persistent irritation.
  • Some patients may have had a previous arthroscopy for complaints of medial-sided knee pain without alleviation of their symptoms after the arthroscopy, regardless of whether they had some medial meniscus or medial compartment articular cartilage pathology addressed at the time of their arthroscopy. Such patients usually did not have physical therapy or participate in an exercise program either before or after this surgery.

Physical

• The examiner can palpate the plica by rolling one's fingers along the tissue between the medial epicondyle and the medial border of the patella. The plica is most commonly palpated about 1-2 fingerbreadths medial to the medial edge of the patella.
• Patient pain and irritation upon the examiner rolling the medial suprapatellar plica under his or her fingers is a classic finding on physical examination. The examiner should ascertain whether the elicited pain is due to palpation of this well-innervated area of the synovium or whether the examiner is producing the type of pain that the patient experiences with activities.

Causes

• Any type of dysfunction of the patellofemoral joint may cause irritation of the medial synovial plica. This dysfunction can be due to overuse, injury, or abnormal mechanics.
• Patients often have concurrent patellar subluxation or apprehension, and this should be assessed as part of the physical examination. In addition, these patients often have a component of tight hamstrings or concurrent irritation of the pes anserine bursa. Measuring the hamstring-popliteal angle allows the examiner to assess the patient's hamstring tightness, whereas direct palpation helps to assess irritation of the pes anserine bursa. 

  (See also the eMedicine article Pes Anserine Bursitis [in the Sports Medicine section] and Pes Anserinus Bursitis [in the Physical Medicine and Rehabilitation section].)

• Direct blows to the knee can also result in irritation of the medial plica (eg, dashboard injuries, fall onto a flexed knee).
• Other pathology in the knee joint, such as a meniscal tear or arthritis, may cause knee effusions or quadriceps atrophy, which could result in plical irritation. (See also the eMedicine article Knee, Meniscal Tears (MRI).)

DIFFERENTIALS

Section 4 of 10  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Other Problems to Be Considered

Knee Osteochondritis Dissecans
Medial meniscus tear

WORKUP

Section 5 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Imaging Studies

• Plain radiographs should be ordered in most patients to rule out the differential diagnosis or concurrent possible pathology of a medial synovial plica. Routine radiographs should include a standing anteroposterior (AP), lateral view, and a 45° patellofemoral view. These radiographs help to demonstrate any evidence of medial compartment arthritis, osteochondritis dissecans, or patellofemoral joint pathology.

  (See also the eMedicine articles Knee Osteochondritis Dissecans, as well as Medial Compartment Arthritis and Osteochondritis Dissecans [in the Orthopedic Surgery section].)

• Magnetic resonance imaging (MRI) may also be useful to confirm the presence of a thickened plica (axial view) and to rule out other causes of medial-sided knee pain (eg, medial meniscus tear, bone bruise, osteochondritis dissecans).

Procedures

• Diagnostic intra-articular lidocaine injections can be useful in some patients in whom it is difficult to determine if the pathology is intra-articular or extra-articular. Continued pain after an intra-articular lidocaine injection would point to an extra-articular cause of a patient's pain.

TREATMENT

Section 6 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Acute Phase

Rehabilitation Program

Physical Therapy

The first mode of treatment for suprapatellar plical irritation of the knee is nonoperative.¹ All patients should have a program of physical therapy established for them, which includes closed-chain quadriceps kinetic exercises and a hamstring-stretching program. A closed-chain quadriceps exercise program should include the use of an exercise bike, leg presses, straight-leg raises (with and without leg weights), and the performance of mini-squats or use of a squat rack machine.

An important consideration to recognize is that patients who participate in open-chain quadriceps exercises, especially those who work on knee-extension exercises on a weight machine, often have an increase in their suprapatellar plical irritation.

In addition, patients should recognize that a hamstring-stretching program must be performed several times daily to maximize improvement. Approximately 50% of patients notice a significant improvement with an exercise program in the initial 6 weeks, with a larger percentage of the remaining patients improving with an additional 6 weeks of rehabilitation.

Recreational Therapy

Patients who have medial synovial plical irritation should avoid those activities that cause irritation of their knees until they note improvement with a physical therapy or home exercise program. Such precluding activities may include avoidance of stairs, squatting activities, or long-distance jogging or running.

Medical Issues/Complications

The most common complication associated with medial synovial plical irritation is continued pain or increased pain after surgery.^{1, 2} For this reason, it is important to have exhausted all nonoperative forms of treatment for patients before any attempts at surgery.

Surgical Intervention

In patients who have exhausted all other means of therapy, an arthroscopic evaluation of the knee may be indicated. Because a debrided synovial plica results in alleviation of symptoms in only about 60-70% of cases, with some of the remaining patients actually having more pain after surgery, it is recommended that the synovial plica be debrided only if significant scar tissue is present in the plica or if shelf erosion is noted on the medial femoral condyle from a fibrotic plica.

Consultations

Any patient in whom conservative and/or surgical treatment protocol fails should have consultation with a subspecialist fellowship-trained orthopedic surgeon who deals with knee pathology.

Other Treatment

In patients who have persistent pain after a rehabilitation or home therapy program for synovial plical irritation, consideration should be given for a possible combined local anesthetic and corticosteroid injection to try and decrease some of the inflammation.³

Patients who undergo this injection need to recognize that their underlying quadriceps dysfunction and hamstring tightness still need to be addressed. After the injection, these individuals should either be enrolled in a physical therapy program or have a well-instituted home therapy program to maximize their chances for a good outcome.

Maintenance Phase

Rehabilitation Program

Physical Therapy

Once a patient has recovered from medial synovial plical irritation, the individual needs to recognize that there is very likely a risk for the recurrence of symptoms if he or she does not participate in a maintenance rehabilitation program. Always recommend to these patients that they try to work on a routine exercise program indefinitely to minimize their chances of recurrence of their knee pain.

MEDICATION

Section 7 of 10  

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• Clinical
• Differentials
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• Follow-up
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• References

Any of the nonsteroidal anti-inflammatory drugs (NSAIDs) may be used to try to supplement the physical therapy program. Generally, it is recommended to start with over-the-counter (OTC) NSAIDs first. If these agents do not work, or if they work only in the maximum doses, prescription drugs may be utilized based upon the patient's previous success with these medications, drug allergies, or other medications.

Drug Category: Nonsteroidal anti-inflammatory agents

NSAIDs have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but these agents may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

FOLLOW-UP

Section 8 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Return to Play

Patients/athletes may return to participation in sports based upon their symptoms. Athletes are recommended to start out slowly and observe how their knee reacts overnight, before advancing their workout/exercise regimen. This gradual progression is important to follow because plical irritation appears to involve some tissue inflammation, which may take hours to develop after activities. Usually, it is safe to say that if a patient does not have pain or swelling with an activity, that it is safe to continue or attempt to advance in that activity.

Complications

Nonoperative complications include continued medial synovial plical irritation, which over time could potentially lead to a fibrotic plica. The most common complication, which is a poorer result than a complication, is increased pain after surgical debridement due to increased scar-tissue formation after surgery. The best way to avoid these complications is to make sure that the patient is enrolled in an appropriate physical therapy or home exercise program.

Prevention

The best way to prevent continued medial synovial plical irritation is to avoid those activities that cause irritation and to address the problem that caused the plical irritation in the first place. Such prevention strategies would include surgery to address meniscal tears or cartilage flaps or enrollment in a proper physical therapy program for those with patellofemoral dysfunction.

Prognosis

The overall prognosis for most patients with medial synovial plical irritation is good. Most patients will respond to a physical therapy program within the first 6-8 weeks, with most of the other patients responding over the next few months. Surgical intervention for a medial synovial plica should be reserved for those patients in whom all other modalities previously described in this article have failed (see Treatment, Acute Phase, Rehabilitation Program and Other Treatment).

Education

Most patients need to be instructed in a home exercise program to address their underlying quadriceps weakness and hamstring tightness. In addition, many of these patients may have a recurrence of some symptoms over time. Patients need to be informed of this possibility and be instructed to work on a home exercise program first, before consulting their physician's office, because they can frequently have an alleviation of symptoms with their home exercise program.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Multimedia
• References

Media file 1:  Medial plica of left knee.
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Media type:  Photo

Media file 2:  Patella in a male patient, medial aspect.
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Media type:  Photo

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
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• Follow-up
• Multimedia
• References

1. Amatuzzi MM, Fazzi A, Varella MH. Pathologic synovial plica of the knee. Results of conservative treatment. Am J Sports Med. Sep-Oct 1990;18(5):466-9. [Medline].
2. Broom MJ, Fulkerson JP. The plica syndrome: a new perspective. Orthop Clin North Am. Apr 1986;17(2):279-81. [Medline].
3. Rovere GD, Adair DM. Medial synovial shelf plica syndrome. Treatment by intraplical steroid injection. Am J Sports Med. Nov-Dec 1985;13(6):382-6. [Medline].
4. Brushøj C, Albrecht-Beste E, Bachmann M, Hölmich P. Acute patellofemoral pain: aggravating activities, clinical examination, MRI and US findings. Br J Sports Med. Jun 11 2007;epub ahead of print. [Medline].
5. Dorchak JD, Barrack RL, Kneisl JS, Alexander AH. Arthroscopic treatment of symptomatic synovial plica of the knee. Long-term followup. Am J Sports Med. Sep-Oct 1991;19(5):503-7. [Medline].
6. Gurbuz H, Calpur OU, Ozcan M, Kutoglu T, Mesut R. The synovial plicae in the knee joint. Saudi Med J. Dec 2006;27(12):1839-42. [Medline].
7. Hardaker WT, Whipple TL, Bassett FH 3rd. Diagnosis and treatment of the plica syndrome of the knee. J Bone Joint Surg Am. Mar 1980;62(2):221-5. [Medline]. [Full Text].
8. Kim SJ, Choe WS. Arthroscopic findings of the synovial plicae of the knee. Arthroscopy. Feb 1997;13(1):33-41. [Medline].
9. Kim SJ, Shin SJ, Koo TY. Arch type pathologic suprapatellar plica. Arthroscopy. May 2001;17(5):536-8. [Medline].
10. Lyu SR. Relationship of medial plica and medial femoral condyle during flexion. Clin Biomech (Bristol, Avon). Nov 2007;22(9):1013-6. [Medline].
11. Patel D. Plica as a cause of anterior knee pain. Orthop Clin North Am. Apr 1986;17(2):273-7. [Medline].
12. Uysal M, Asik M, Akpinar S, et al. Arthroscopic treatment of symptomatic type D medial plica. Int Orthop. Aug 28 2007;epub ahead of print. [Medline].

Article Last Updated: Oct 15, 2007