Plica: Pathologic or Not? J. Whit Ewing, MD

Abstract

A fold that occurs within a joint is referred to as a plica synovialis. Three such pli- in which the only finding to explain cae are seen with regularity within the human joint. These folds are normal the symptoms is the presence of a structures that represent remnants of mesenchymal tissue and/or septa formed thickened, hypertrophic plica. during embryonic development of the knee joint, and can be seen during arthro- Chronic anteromedial and scopic inspection of the knee joint. Controversy exists within the orthopaedic com- a sense of tightness in the subpatellar munity as to whether a plica can develop pathologic changes sufficient to cause region on squatting are the common disabling knee symptoms. The author defines the clinical syndrome, describes the complaints expressed by patients arthroscopic appearance of pathologic plica, and outlines nonsurgical and surgi- found to have a pathologic plica. The cal methods of management of this uncommon condition. ligamentum mucosum is not a J Am Acad Orthop Surg 1993;1:117-121 source of these types of symptoms. Additional symptoms are snapping sensations, buckling, knee pain on A plica synovialis is a membranous commonly referred to as a medial shelf sitting, and pain with repetitive fold or ridge found in the synovial or medial plica. This shelflike fold of activity.4 Recurrent effusions and lining of a joint. Three such folds are synovial membrane extends from the locking of the knee joint are not typi- found with regularity in the human infrapatellar fat pad to the medial wall cal in patients with this syndrome. knee. In the normal state, these folds of the knee, in the coronal The usual differential diagnosis of are quite filmy, thin, and vascular- plane. The rarely seen plica synovialis patients with anterior knee pain ized, and have no known function. lateropatellaris, or lateral plica, is the includes jumper’s knee, torn menis- The most common plica, the plica same type of structure as the medial cus, patellar malalignment with or synovialis patellaris, usually referred plica. It extends from the fat pad later- without pathologic chondromalacia to as the ligamentum mucosum, is ally to end in the synovium of the lat- of the patella, bipartite patella, and located in the intercondylar notch, eral wall of the knee.2 The medial plica degenerative joint disease. It may be extending from below the level of the may appear to be contiguous with the difficult to distinguish plica syn- articular surface of the femur to the suprapatellar plica. drome from other pathologic condi- tibial plateau. It covers the anterior The suprapatellar plica and the lig- tions that produce similar symptoms. cruciate ligament and frequently amentum mucosum are thought to be However, the cause of the symptoms blocks its visualization during diag- remnants of septa dividing the supra- can often be determined by a careful nostic arthroscopy. patellar bursa and patellofemoral cav- physical examination. The second most frequently found itation and the medial and lateral plica is the plica synovialis supra- femorotibial cavitations, respectively. patellaris, commonly called the The medial and lateral plicae most History and Physical suprapatellar plica. It is located in the likely represent remnants of mes- Examination suprapatellar space, extending from enchymal tissue.3 The significance of the medial wall of the knee toward these folds of synovial tissue resides Approximately 50% of patients the lateral wall, and sometimes cre- in whether they can be the source of with plica syndrome present with a ates a complete septum between the pain and impairment of knee joint suprapatellar bursa and the knee function. Dr. Ewing is Professor of Orthopaedic Surgery, joint proper. It may be fenestrated in Northeastern Ohio Universities College of Medi- its central portion by an oval open- cine, Rootstown. ing, or porta. Wide variations in its Plica Syndrome Reprint requests: Dr. Ewing, Crystal Clinic, 1 shape and width are seen. 3975 Embassy Parkway, No. 102, Akron, OH The third most frequently seen plica Plica syndrome is defined as a 44333. is the plica synovialis mediopatellaris, painful impairment of knee function

Vol 1, No 2, Nov/Dec 1993 117 Plica history of blunt trauma to the ante- A common source of anterior knee ate to institute a course of nonsurgical rior aspect of the knee. They will on pain, particularly in the active treatment.6 This treatment includes many occasions have a latent period younger age group, is infrapatellar rest from all strenuous physical activ- free of symptoms after the healing tendinitis, or jumper’s knee. Jumper’s ities, a course of nonsteroidal anti- of the initial injury, only to have the knee can be ruled out by careful inflammatory medication, moist heat delayed onset of anterior knee pain examination of the infrapatellar ten- applications, and hamstring stretch- some weeks or months later. Most don prior to an arthroscopic exami- ing. Resistive strengthening exercises of the remaining patients with this nation. This is done by depressing the should be avoided because they will syndrome have a history of the superior pole of the patella in the aggravate the symptoms, particu- development of pain following a relaxed fully extended knee, to ele- larly in the early phases of treatment. prolonged period of a strenuous vate the inferior pole of the patella. If there is relief of symptoms, the repetitive physical activity, such as The examiner then palpates the inser- patient can gradually be brought running, weight lifting, or step aer- tion of the infrapatellar tendon with back to his or her former activity level obics. Only a few patients will pre- the index finger by directing pressure with the usual counsel regarding sent without a history of trauma or superiorly, along the long axis of the alteration of level of participation in repetitive physical activity. leg. Extreme tenderness can be order to prevent a recurrence. Patients with plica syndrome elicited in the patient suffering from Intraplical injection of local cortico- usually present with tenderness in tendinitis. By establishing the diag- steroids has been advocated by some the medial parapatellar region. nosis of jumper’s knee in this fashion, as a treatment alternative,7 but I have Provocative tests to elicit this ten- many arthroscopic plica excisions no experience with this method of derness have been described by can be avoided. management. Failure to respond to Koshino and Okamoto5 and are Continued postoperative com- nonsurgical management leaves helpful in assessing patients with plaints of knee pain, aggravated by arthroscopic excision of the patho- anterior knee pain. The first test is attempts to strengthen the quadri- logic plica as the treatment of choice. done by palpating the medial bor- ceps mechanisms by resistive exer- der of the patella while producing cises, suggest infrapatellar tendinitis medial patellar displacement with either as a primary or an associated Arthroscopic Findings one hand and simultaneously pro- cause of anterior knee pain. A proper ducing knee valgus and internal or preoperative diagnosis can prevent Arthroscopically, the pathologic external rotation of the lower leg significant postoperative anxieties. medial plica appears as a thickened, with the other hand. The second avascular, wide (greater than 12 provocative test is referred to as the Diagnostic Tests mm), membranous band of tissue holding test. The patient is asked to (Fig. 1). It is best seen with the hold the knee in full extension while Routine radiographs of the affected arthroscope placed in the supra- the examiner attempts to flex it knee with plica syndrome are normal. patellar lateral portal.5,8 When pal- against the patient’s resistance. The Double-contrast arthrograms may pated with a blunt probe, the examiner again pushes the patella show the presence of a suprapatellar pathologic medial plica has the feel medially while palpating its medial plica, but cannot aid in determining of a taut bowstring. The medial plica border. Pain produced with or with- whether the plica is producing symp- may be seen to impinge between the out a click is considered a positive toms. Magnetic resonance imaging medial facet of the patella and the test in either case. has not been helpful to date in estab- medial surface of the trochlea when Additional findings include a lishing the diagnosis of plica syn- the knee is slowly flexed. The plica painful, palpable medial parapatellar drome. Routine laboratory tests, does not have to impinge between cord that can be rolled and popped including the standard chemistry the patella and the trochlea to be beneath the examining finger. Ten- panels ordered for establishing a considered pathologic. The charac- derness immediately over the joint diagnosis of inflammatory joint dis- teristic thickened, bowstring appear- line is the exception rather than the ease, are normal. ance of the plica is indicative of its rule. The knee should not exhibit any pathologic nature. signs of ligamentous instability or The pathologic suprapatellar patellar malalignment. The finding of Nonsurgical Treatment plica is usually somewhat thickened, a knee effusion is unusual; when pre- but never quite assumes the menis- sent, causes other than the plica syn- If a tentative diagnosis of plica syn- coid appearance of the abnormal drome should be considered. drome has been made, it is appropri- medial plica, which acts like a bow-

118 Journal of the American Academy of Orthopaedic Surgeons J. Whit Ewing, MD

A B C

Fig. 1 Pathologic medial plica. A, The arthroscope was placed in the superolateral portal, and a 70-degree fore-oblique lens was used for this image obtained with the knee in full extension. The patella is seen above the plica, which exhibits a dense, meniscoid appearance. B, The knee is flexed to 40 degrees. Note the impingement of the plica between the medial facet of the patella and the medial portion of the trochlea. C, After partial resection of the plica, the taut bowstring effect can be appreciated. string in flexion and impinges on the and inflammation is capable of pro- degree fore-oblique lens placed into femur rather dramatically. In con- ducing changes of a pathologic the posterior compartments through trast, the normal plica easily yields nature within a plica.6 the intercondylar notch. and folds away from structures with Inspection of the patellofemoral which it comes into contact. joint is carried out by bringing the leg Plicae that have a silky, areolar Surgical Technique into full extension, and maintaining feel when probed are not likely to this position by resting the patient’s produce symptoms. On those rare The patient is placed supine on the foot on a padded sterile-draped occasions when a lateral band is operating table, with a tourniquet instrument stand. A superolateral encountered, the same identifying and leg-holding device in place. Gen- portal is then used for placement of criteria for pathologic characteriza- eral or regional anesthesia is pre- the arthroscopic cannula. This portal tion should be used. It is important ferred. The lower end of the table is is created at a point three finger that the entire knee be carefully visu- flexed. A superomedial portal is cre- breadths above the superior pole of alized in an organized fashion. ated along the medial patellofemoral the patella of the extended knee, The diagnosis of plica syndrome joint line approximately two finger along the lateral patellofemoral joint is often one of exclusion. When the breadths above the superior pole of line. Placement of the arthroscope in diagnosis of a ruptured meniscus is the patella of the fully extended leg, this portal provides an excellent not confirmed by arthroscopy and and an automated inflow system is view of the entire patellofemoral the characteristic signs of a patho- utilized to distend the knee with ster- joint (Fig. 2). (If the inflow cannula logic plica are seen, the correct diag- ile saline solution. A distention pres- creates an obstruction to visualiza- nosis of plica syndrome can be sure of approximately 50 mm Hg is tion, it can be transferred to the assumed. Conversely, if a plica is used. already created anterolateral portal.) seen to be pathologically thickened A complete arthroscopic inspec- The medial plica is clearly seen from in the presence of a torn meniscus, it tion of the femorotibial joint is carried this position. The suprapatellar plica should not be classified as evidence out through standard anteromedial can be seen by rotating the fore- of plica syndrome, but rather as a and anterolateral portals. This obliquity of the lens or by using an secondary finding. A simple exci- includes probing of both menisci, accessory portal placed laterally near sion of the plica, as a part of the visualization of the intercondylar the superior pole of the patella. meniscectomy or meniscus repair, is notch, inspection of both sulci, and If the medial plica is determined to appropriate. The plica in this posteromedial and posterolateral be pathologic, it is removed by utiliz- instance is an incidental finding. compartment visualization. The pos- ing a lateral portal, best located with Any primary disorder of the knee terior compartment inspections are the use of a probing 18-gauge spinal that can produce chronic swelling carried out with the use of a 70- needle used for portal-site selection.

Vol 1, No 2, Nov/Dec 1993 119 Plica

A B C

Fig. 2 Wide, dense pathologic medial plica. A, Patella is seen above the plica in this superolateral view. B, There is only the suggestion of impingement in this instance. A basket forceps is inserted through an accessory lateral portal to begin the removal of the pathologic plica. C, Completed resection of the medial plica.

The plica should be removed entirely the overlying , in order to with return to full activities in 4 to 6 by resecting it to its base throughout avoid excessive bleeding. If bleeding weeks. its length. If the diseased plica is sim- is noticed, arthroscopic electrosurgi- ply divided to remove its bowstring cal instrumentation may be used to Prevalence effect, it may heal itself, with recur- coagulate the bleeding points, thus rence of the patient’s symptoms.6,9 avoiding postoperative hemarthrosis, Published papers in the refereed lit- The same approach is used to which is one of the complications of erature report a prevalence of plica resect a pathologic suprapatellar plica plica surgery. When the surgical pro- syndrome of 3.8% to 5.5%, as (Fig. 3). In this instance, it is occasion- cedure has been completed, a soft-tis- assessed by arthroscopic examina- ally prudent to use the anterior infer- sue bandage is used. Weight-bearing tion of the knee.4,10-12 In my personal olateral portal for placement of the as tolerated with crutches is allowed experience, a retrospective review of operating instruments. Care should on the day of surgery. Routine post- 564 consecutive cases of knee be taken not to carry the resection into operative management is carried out, arthroscopy disclosed 13 patients

A B C

Fig. 3 Pathologic suprapatellar plica. A, A fringe of is present on the edge of the plica, which has a fibrous texture. B, Partial resec- tion of the suprapatellar plica renders the patella easier to identify. A proximal lateral portal was used for surgical instrument placement. C, View of the patellofemoral joint illustrates complete resection of the pathologic plica.

120 Journal of the American Academy of Orthopaedic Surgeons J. Whit Ewing, MD with plica syndrome, a prevalence of Summary repetitive strenuous knee exercise is 2.3%. The average patient age in this present. In patients with persistent series was 23.8 years. A pathologic plica synovialis can be symptoms following nonsurgical the sole cause of disabling painful care, arthroscopic resection of the Surgical Results symptoms in the knee. This syn- pathologic plica is curative in 75% to drome accounts for 5% or fewer of 91% of cases. Understanding that The results of surgical treatment of pathologic conditions that serve as plica syndrome is uncommon and plica syndrome in carefully selected indications for arthroscopic surgery. exercising closer attention to detail in patients have been reported to be The syndrome usually presents with the evaluation of the patient should good, excellent, or satisfactory in a history of blunt trauma that pre- lead to a reduction in the number of 75% to 91% of cases.4,9-12 Ten (77%) of cedes the onset of chronic anterome- arthroscopic procedures being per- 13 patients had satisfactory results in dial knee pain. In the absence of a formed for the removal of normal pli- my personal series. history of blunt trauma, a history of cal tissue.

References 1. Dandy D: Anatomy of the medial supra- painful shelf (plica synovialis mediopa- 9. Jackson RW, Marshall DJ, Fujisawa Y: patellar plica and medial synovial shelf. tellaris) under arthroscopy. Arthroscopy The pathologic medial shelf. Orthop Clin Arthroscopy 1990;6:79-85. 1985;1:136-141. North Am 1982;13:307-312. 2. Kurosaka M, Yoshiya S, Yamada M, et 6. Hardaker WT, Whipple TL, Bassett FH 10. Dorchak JD, Barrack RL, Kneisl JS, et al: al: Lateral synovial plica syndrome: A III: Diagnosis and treatment of the plica Arthroscopic treatment of symptomatic case report. Am J Sports Med 1992;20: syndrome of the knee. J Bone Joint Surg synovial plica of the knee: Long-term 92-94. Am 1980;62:221-225. follow-up. Am J Sports Med 1991;19: 3. Ogata S, Uhthoff HK: The development 7. Rovere GD, Adair DM: Medial synovial 503-507. of synovial plicae in human knee joints: shelf plica syndrome: Treatment by 11. Richmond JC, McGinty JB: Segmental An embryologic study. Arthroscopy intraplical steroid injection. Am J Sports arthroscopic resection of the hyper- 1990;6:315-321. Med 1985;13:382-385. trophic mediopatellar plica. Clin Orthop 4. Nottage W, Sprague NF III, Auerbach 8. Brief LP, Laico JP: The superolateral 1983;178:185-189. BJ, et al: The medial patellar plica syn- approach: A better view of the medial 12. Broom MJ, Fulkerson JP: The plica syn- drome. Am J Sports Med 1983;11:211-214. patellar plica. Arthroscopy 1987;3: drome: A new perspective. Orthop Clin 5. Koshino T, Okamoto R: Resection of 170-172. North Am 1986;17:279-281.

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