Synovial plicae of the knee joint: the role of advanced MRI

Infrapatellar plica injury: Magnetic resonance imaging review of a neglected cause of anterior knee pain

Synovial plicae are normal remnants of synovial membranes within the knee joint cavity and are usually asymptomatic. Pathological infrapatellar plica, which is mostly due to plica injury, may be a potential cause of anterior knee pain, but is often overlooked and under-reported on magnetic resonance imaging (MRI). This pictorial review illustrates the MRI findings of infrapatellar plica injury and associated knee injuries, with emphasis on its differentiation from the mimics of plica injury.

Clinical Management of Medial Patellar Plica Syndrome: Mini Review from Diagnosis to Treatment

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Synovial plicae are thickenings of the synovial knee membrane; they are very frequent and often asymptomatic. However, they can become symptomatic due to idiopathic or secondary causes, like trauma and inflammation of the synovial tissue. Currently, synovial plicae are classified as infrapatellar, mediopatellar and suprapatellar. The prevalence of the mediopatellar plica over the other forms of plicae varies between 18% and 60%. The most reported symptom of the mediopatellar plica is pain located medial to the patella above the joint line. Magnetic Resonance Imaging (MRI) is the most useful examination to highlight the presence of the plica, its measurement and exact location. The treatment is initially conservative, i.e. medical treatment and physiotherapy, however when these fail, the plica should be removed surgically via arthroscopy.

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In the current paper, we aim to report our clinical experience in the management of medial patellar plica syndrome by describing the clinical presentation and diagnosis of this condition as well as its treatment.

Magnetic resonance assessment of medial plica syndrome of knee from child to adult with arthroscopic correlation: A single center experience and literature review

Objective:

Synovial plicae are mesenchymal tissue remnants invaginating into the knee joint. Their classification is based on the location as lateral, mediopatellar, suprapatellar, and infrapatellar. Mediopatellar plica is commonly symptomatic. The purpose of this study was to identify magnetic resonance (MR) characteristics of the medial plica and to correlate with arthroscopy for cause confirmation in patients with painful knee.

Materials and Methods:

The current study was undertaken over a 2-year period between July 2017 and June 2019 in the department of radiology at a tertiary care hospital in India. MR examinations of the knee joint were performed using QUADKNEE coil on a 1.5-T scanner (Signa, General Electric Medical Systems, Milwaukee, WI, USA). The criteria studied were: presence of the plica, interposition into the femoropatellar joint, intraarticular effusion, and fenestrated aspect. Twenty-two knees (20 patients) diagnosed with mediopatellar plica syndrome on MR imaging (MRI), and with no other knee pathology, were treated with arthroscopic division of plicae.

Results:

Only two (20.0%) of the ten knees in which the plicae had not been divided have shown improvement and six (85.7%) of the seven knees in which plica had been divided (P < 0.05) have shown improvement. Subsequent division of the plicae resulted in improvement in seven of the eight knees (87.5%) (P < 0.01). Patients presented with crepitus in 9% of cases (2 of 22), instability in 13.6% (3 of 22), pseudo-locking in 45.4% (10 of 22), and quadriceps atrophy in 54.5% (12 of 22). Fourteen knees (63.6%) had Grade 2 plica based on thickness. Twelve knees demonstrated (54.5%) Grade 2 intermediary effusion. Plica was fenestrated in three patients (13.6%). All patients regained full range of motion. Lysholm knee scale scores were compared prior to and postsurgery (preoperative status, 65.22 ± 7.41 vs. postoperative status, 89.43 ± 8.72) which revealed a significant clinical improvement (P < 0.001). Average visual analog scale (VAS) scores (0 – no pain, 10 – excruciating pain) when compared demonstrated a mean improvement was 4 points; from 6 points before surgery and 2 points' postsurgery after a mean follow-up of 3 months. About 68% of patients after arthroscopic resection had an average VAS score of 0 point and were totally pain free.

Conclusion:

Noninvasive capability of MRI can be used as a screening method in the diagnosis of mediopatellar plica syndrome and should be included in the differential diagnosis of internal derangement of the knee.

Management of suprapatellar synovial plica, a common cause of anterior knee pain: a clinical review

BACKGROUND AND AIM OF THE WORK

Suprapatellar synovial plica is caused by a congenital thickening of the synovial membrane and is generally asymptomatic. In the literature, suprapatellar plicae are described as one of the causes of anterior knee pain however, their real role in determining symptoms is controversial. The aim of the current paper is to describe the anatomy, classifications, pathophysiology, symptoms and management of suprapatellar plica syndrome, as well as the differential diagnosis from other causes of anterior knee pain.

METHOD

Via a search within the MEDLINE/PubMed database, a current review was conducted, and the results summarized.

RESULTS

Due to idiopathic, traumatic or inflammatory conditions, plicae can become pathological, causing anterior knee pain with possible knee clicking, swelling, giving way and locking after prolonged flexion of the knee. The diagnosis should be formulated based on an accurate medical history and clinical examination, followed by an appropriate imaging study. However, arthroscopy remains the "golden standard" for detecting all synovial plica.

CONCLUSIONS

In patients with anterior knee pain, where doubt is present in the imaging investigation for intraarticular or periarticular lesions, pathological suprapatellar synovial plica must be suspected. The treatment should initially be conservative, but in cases where symptoms persist, patients should undergo arthroscopy to confirm diagnosis and to determine a suitable treatment. In the presence of pathological plica associated with cartilage damage of the femoral condyle or patella at the time of diagnostic arthroscopy, plicae excision leads to favourable results in a high number of cases.

Suprapatellar plica classification and suprapatellar plica syndrome

Background

Plicae around the knee are anatomically normal structures that are remnants of embryonic membranes and are generally asymptomatic. Synovial plica syndrome is known to cause knee symptoms; however, its pathological contribution has been rarely reported. This study aimed to investigate the clinical significance of suprapatellar plicae as well as the morphological characteristics of suprapatellar plicae in patients with knee symptoms who required arthroscopic treatment.

Methods

Of 223 arthroscopic knee surgeries, 125 patients undergoing primary arthroscopy for various diseases were eligible for inclusion in this study. All affected knees were preoperatively examined by two skilled physicians in a routine manner. Each patient was diagnosed with one primary disease entity based on clinical examinations and arthroscopic findings. At least two skilled orthopedic physicians watched the surgical videos together and defined the type of plicae based on the Dandy classification (Dandy DJ. 1990) as follows: (A) absent, (B) the plica was up to one-quarter of the width of the suprapatellar pouch, (C) the plica was between one-quarter and one-third of the width of the suprapatellar pouch, (D) the plica was between one-third and two-thirds of the width of the suprapatellar pouch, (E) the plica was more than two-thirds of the width of the suprapatellar pouch, (F) the plica had a complete membrane, (G) the plica was perforated, (H) arch, (I) pillar, or (J) lateral. Suprapatellar plica syndrome was considered when (1) the patient complained of anterior knee pain and had localized tenderness above the suprapatellar pouch, (2) magnetic resonance imaging revealed suprapatellar plica structures, and (3) other suspicious pathologies accounting for knee symptoms were excluded. We investigated primary disease type, type of plica, and the relationships between them.

Results

The results revealed that meniscus injuries and anterior cruciate ligament injuries caused the majority of primary diseases (approximately 80%). Regarding plica forms, 23 knees were classified as having absent (type A) plicae, 14 knees as having a complete septum (type F), and 88 knees were classified as “other.” There were no significant relationships between disease type and the morphological characteristics of the plicae (chi-squared test, p = 0.35). Suprapatellar pain was observed in five cases, of which two patients were diagnosed with intra-articular free body, one patient with synovitis combined osteoarthritis, and two patients with suprapatellar plica syndrome with a complete septum. The latter two cases experienced knee symptom resolution soon after arthroscopic resection of the plica.

Conclusions

Although the results did not show any relationship between forms of plica remnants and primary disease type, all patients diagnosed with suprapatellar plica syndrome showed complete septum type suprapatellar plicae. A large population study is required in the future.

Synovial Plica Syndrome of the Knee: A Commonly Overlooked Cause of Anterior Knee Pain

Synovial plica syndrome (SPS) occurs in the knee, when an otherwise normal structure becomes a source of pain due to injury or overuse. Patients may present to general practitioners, physiotherapists, or surgeons with anterior knee pain with or without mechanical symptoms, and the diagnosis can sometimes be difficult. Several studies have examined the epidemiology, diagnosis, and treatment of SPS. We review these resources to provide an evidence-based guide to the diagnosis and treatment of SPS of the knee.

Hoffa's fat pad abnormalities, knee pain and magnetic resonance imaging in daily practice

Hoffa's (infrapatellar) fat pad (HFP) is one of the knee fat pads interposed between the joint capsule and the synovium. Located posterior to patellar tendon and anterior to the capsule, the HFP is richly innervated and, therefore, one of the sources of anterior knee pain. Repetitive local microtraumas, impingement, and surgery causing local bleeding and inflammation are the most frequent causes of HFP pain and can lead to a variety of arthrofibrotic lesions. In addition, the HFP may be secondarily involved to menisci and ligaments disorders, injuries of the patellar tendon and synovial disorders. Patients with oedema or abnormalities of the HFP on magnetic resonance imaging (MRI) are often symptomatic; however, these changes can also be seen in asymptomatic patients. Radiologists should be cautious in emphasising abnormalities of HFP since they do not always cause pain and/or difficulty in walking and, therefore, do not require therapy. Teaching Points • Hoffa's fat pad (HFP) is richly innervated and, therefore, a source of anterior knee pain. • HFP disorders are related to traumas, involvement from adjacent disorders and masses. • Patients with abnormalities of the HFP on MRI are often but not always symptomatic. • Radiologists should be cautious in emphasising abnormalities of HFP.