Medial plica irritation: diagnosis and treatment
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Medial plica irritation of the knee is a very common source of anterior knee pain. Patients can complain of pain over the anteromedial aspect of their knees and describe episodes of crepitation, catching, and pseudo-locking events with activities. Patients commonly have pain on physical examination upon rolling the plica fold of tissue over the anteromedial aspect of their knees and often have tight hamstrings. The majority of the patients will respond well to a non-operative treatment program consisting of quadriceps strengthening along with concurrent hamstring stretching. In cases which do not respond initially to an exercise program, an intraarticular steroid injection may be indicated. In those few patients who do not respond to a non-operative treatment program, an arthroscopic resection of their medial plica may be indicated, especially in those cases where a shelf-like plica has been found to be causing damage to the articular cartilage of the medial femoral condyle.
In all patients, the medial synovial plica will glide over the anteromedial aspect of the medial femoral condyle with flexion and extension of the knee. In most patients, this gliding motion of the plica will occur without any symptoms, because of the high viscosity of the native synovial fluid of the knee. However, in patients with effusions, which decreases the viscosity of their synovial fluid, patients may either have crepitation or a catching of their medial synovial plica with flexion and extension of the knee. This crepitation or catching can occur with patients while going up or down stairs, squatting and bending, and other types of activities.
Since the medial synovial plica does have an attachment to the genu articularis muscle, and also an indirect attachment to the quadriceps musculature due to its attachment to the joint lining, it is dynamically controlled by the quadriceps muscles . Thus, medial plica irritation is more common in patients who have poor quadriceps tone or other problems with joint muscle balance around the knee.
Diagnosis of medial plica pathology
One of the most important points in diagnosing medial synovial plica pathology is obtaining an appropriate history from the patient. Patients usually describe pain which is dull, achy, and increases with activity. When asked to point to the area of their pain, they will commonly point to the proximomedial aspect of the knee, proximal to the medial joint line. While some patients may note a history of trauma to this area of the knee, most patients do not have any specific history of trauma to their medial plica. Over half of patients have a history of participating in some type of strenuous activity which requires repetitive flexion and extension motion of the knee, which then irritates their patellofemoral joint.
Most patients will complain of an achy type pain over the medial aspect of their knee, which is aggravated by activity and can be particularly bothersome at night. Their complaints of night pain over this area of the knee are due to the effects of inflammation, which can be particularly bothersome with activities. Patients most commonly complain of pain with activities which stress their patellofemoral joints, such as ascending and descending stairs, squatting and bending, and arising from a chair after sitting for an extended period of time . In addition, they may note difficulty with sitting still for long periods of time without having to move and stretch their knees. They also may complain of a catch over the anteromedial aspect of their knee upon arising from a chair following prolonged periods of sitting. In some patients, plica catching may present as a pseudo-locking event to their knee when they have been sitting down for an extended period of time and they first arise. Some patients may describe these pseudo-locking events as instability or catching of their patella. Clicking, giving way, and pseudo-locking have been reported in approximately 50% of all patients who present with medial plica irritation . Patients who might have problems with activity-related effusions may also complain of pain over the anterior aspect of their knee. While these activity-related effusions may not be directly caused by medial plica pathology, and are more commonly due to underlying quadriceps mechanism weakness, meniscal tears, and/or osteoarthritis, but they can cause secondary medial plica irritation. In addition, patients who have had postoperative or post-injury weakness of their affected extremity may develop pain over the anteromedial aspect of their knee in the region of the medial synovial plica.
A definitive diagnosis of medial plica irritation is usually obtained by physical exam. A normal examination of the patellofemoral joint should always include an examination of the patient’s medial synovial plica fold to determine if they have any irritation of this structure.
It is recommended to obtain a standing AP, lateral, and 45° patellar sunrise (axial) radiographs of the knee to rule out other sources of pathology. While many patients who have an irritated medial synovial plica have normal radiographs, it is important to rule out that the patients do not have any underlying arthritis, areas of osteochondritis desiccans, osteophyte formation, fractures, or other bony pathology which could be contributing to the irritation of the medial synovial plica.
In addition, diagnosis of medial plica irritation on MRI scans is non-specific . The physical exam should be able to demonstrate any significant thickening and fibrosis of a medial synovial plica. MRI’s are more useful in determining if there are other pathologies contributing to medial synovial plica irritation rather than in directly diagnosing pathology in this portion of the knee.
Treatment of medial plica irritation
In cases where patients are not getting better with a physical therapy program, or in those patients who have such an irritated plica that a therapy program may not be beneficial directly, consideration for an intraarticular corticosteroid injection is necessary. In candidates for an intraarticular steroid injection, we perform the injection to attempt to quiet down their knee symptoms such that they can participate in an exercise program to address their medial plica irritation. It is not sufficient solely to rely on the injection to quiet down ones knee because the underlying problem of a weak quadriceps mechanism and tight hamstring muscles may persist after the injection and result in a recurrence of the medial plica irritation after the beneficial effects of the injection wear off. Thus, it is very important to make sure that the patients do participate in an exercise program, even if they have complete relief of their symptoms, after an intraarticular steroid injection to treat medial plica irritation. It is usually necessary to have the patients refrain from exercising or placing any significant stress to their knee for the first 24–48 h after their steroid injection because the knee may have more post-injection soreness. In addition, it is important to document with the patients whether or not they had good pain relief while the local anesthetic portion of the injection was working to verify that they do have an intraarticular knee cause of their knee pain.
It is rare that patients need arthroscopic surgery to treat isolated medial plica pathology, because the medial plica is a part of the joint lining and resection of it will result in the joint lining growing back. Since the body heals back this type of resection with scar, the tissue may heal back with painful scar and the patient may have more symptoms. Since the treatment of a painful plica after an arthroscopic resection can often cause patients to have more pain than they did prior to the arthroscopic resection, it is important to make sure that a patient has pathology of this area which is not responsive to an exercise program, and possibly injections, prior to consideration of resection of this tissue . It is important to recognize that surgery for an irritated plica is uncommon, and historically it comprised only 2–5% of all arthroscopic surgery at a time when magnetic resonance imaging scans were not commonly used and more surgeries were performed for diagnostic reasons . We have found that arthroscopic resections of irritated plicas are rarely performed today. The usual instances where one may have some benefit from resection of a medial synovial plica may be where the plica is acting as a shelf which is catching over the medial femoral condyle and causing some erosion of the articular cartilage in this area [3, 13, 14]. In these circumstances, patients may have good pain relief and decreased catching sensations in their knee after an arthroscopic resection of their medial plica. In this instance, it is usually not recommended to divide the pathologic plica and resect it totally because the pathologic plica may grow back and the patient may have recurrence of their symptoms . It has also been noted that the results of arthroscopic plica excision are more successful in adolescents than in older patients .
Indirect treatment of the medial plica irritation may also be very beneficial to patients. In these instances, the pathology is deep within the knee. Treatment of localized areas of arthritis, meniscal tears, or other knee pathologies, may decrease the pain and swelling of the knee which resulted in secondary irritation of the medial plica. In these instances, it may be beneficial for the patient to undergo surgery to treat the secondary cause of plica irritation. In these circumstances, it is not recommended to resect the medial synovial plica, because there is a very good chance that it will get better with an exercise program after surgery and patients may not have pain relief of their plica irritation if it is resected arthroscopically.
- 11.LaPrade, RF. “Medial Synovial Plica Irritation”, e-Medicine, http://www.emedicine.com/SPORTS/topic75.htm 2001.