Plica Syndrome

Introduction and prevalence

Plica is a fibrous fold of synovial membrane in the knee that can become inflamed and thickened causing pain. Interestingly, plica is only present in 50% of individuals. Most reports indicate a 10% prevalence of Plica Syndrome in the general population, however this can be under-reported as many cases of knee pain are unclassified.

Etiology and Pathophysiology

Plica typically involute when the fetus is around 12 weeks old, but studies show that plica is present in 50% of adults. The location of the plica can be suprapatellar, infrapatellar, medial, or lateral. Medial plica is usually the most common plica to become symptomatic. Plica can become inflamed and thickened as a result of overuse injury, giving rise to Plica Syndrome.

Clinical presentation

The presenting complaints are not specific and usually include anterior knee pain, snapping sensation along the medial patella with flexion, clicking, tenderness along the peripatellar region, swelling, mechanical symptoms, and decreased range of motion.

Physical examination

With the patient supine, tenderness over a bandlike tissue fold in the inferomedial patella can be suggestive of Plica Syndrome. In Plica Syndrome, this pain usually improves when the knee is flexed to 90 degrees. In addition, two physical exam techniques, the Stutter test and the Hughston test, can be suggestive of Plica Syndrome.

  • In the Stutter test, the symptomatic knee is flexed to 90 degrees while the patient is sitting on the exam table, then the examiner puts their fingers on the patella and ask the patient to extent their knee while feeling for patellar stutter, which feels like the jumping motion of the kneecap.

  • In the Hughston test, the patient is supine while the examiner pushes the patella medially and internally rotates the tibia while taking the patient's knee through flexion and extension.

Investigations

Plica syndrome is often a diagnosis of exclusion. A 3-4 view plain radiography of the knee can rule out bony pathology, while MRI can be used to assess intraarticular pathology. US has been shown to have a sensitivity of 90% and a specificity of 83% for Plica syndrome.

Management

Conservative therapy is the mainstay and includes stretching and strengthening exercises with the goal of strengthening the joint capsule musculature, hamstrings, and quadriceps. Reducing the amount of activity, along with NSAIDs and icing have also shown to be helpful. After three months of conservative therapy, Plica injection with corticosteroid can be considered. In one study more than 70% of patients that received steroid plica injections recovered completely from Plica Syndrome 15 symptoms. After thorough investigation and trial of above therapeutics, resection of the plica membrane via arthroscopy is another good option for Plica Syndrome.