54 Fig. 1 Intraoperative visualization of medial synovial plica 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 com- plain 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 [11]. 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 Curr Rev Musculoskelet Med (2008) 1:53–60 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 [8]. 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 usu- ally obtained by physical exam. A normal examination of the patellofemoral joint should always include an exami- nation of the patient’s medial synovial plica fold to determine if they have any irritation of this structure. In examining the medial synovial plica, it is important to make sure that the patient is relaxed, which is usually accomplished by having the patient lie supine on the examining table with both legs relaxed. The examiner then palpates for the medial synovial plica by rolling ones ﬁn- gers over the plica fold which is located between the medial border of the patella and the adductor tubercle region of the medial femoral condyle (Fig. 2). The medial synovial plica will present as a ribbon-like fold of tissue under ones ﬁnger which can be rolled directly against the underlying medial femoral condyle [12]. While some patients may have a sensation of mild pain when palpating the medial synovial plica, it is important to ascertain while performing this test if this reproduces their symptoms. It is also very important to compare the sensation to the con- tralateral normal knee to see if there is a difference in the amount of pain produced. It has been well demonstrated that this portion of the medial joint line and synovium is well innervated and irritation of the medial plica can be quite painful in some patients [4]. As with any other physical diagnosis, it is important to concurrently ascertain if there are other areas of pathology for structures that are located close to the medial synovial plica to conﬁrm one’s diagnosis. In acute injuries, one should make sure that there is no injury to the meniscofe- moral portion of the superﬁcial medial collateral ligament. In this instance, one would apply a valgus stress to the knee and palpate at the joint line for both any potential joint line opening to application of the valgus stress and also to see if there is any well localized pain or edema in the region of the meniscofemoral portion of the superﬁcial medial collateral ligament (Fig. 3). In addition, in acute injuries, one should make sure that there has not been a lateral patellar