During embryologic development mesenchymal tissue form a shelf-like membrane called synovial plica and these folds resorb over time. However, remnants of the plica may remain as incomplete folds within the knee joint

There are discernible synovial folds:

• Suprapatellar
• Medial
• Lateral
• Inferior (ligamentum mucosum)

Plica may be asymptomatic in 50 % of cases

Direct trauma to the knee may cause the plica to become inflamed and symptomatic. The resolving trauma and/or inflammation to the plica may cause a residual hard bowstring plica. It is usually the medial plica that becomes symptomatic. The medial plica runs from the medial aspect of the knee joint to the infrapatellar fat pad.

Presentation of medial plica syndrome:

• Anteromedial knee pain
• Pseudolocking/clicking
• Crepitations under the patellar
• Palpable plica fold between the patellar and medial femoral condyle

Non surgical

• Analgesia
• Local anaesthetic and corticosteroid injection
• Physiotherapy
• Rehabilitation: strengthening and stretching of the muscles around the knee joint (quadriceps, hamstring, adductors, abductors, M gastrognemius and soleus muscles)

Principles of stretching and strengthening:

• Stretching knee with foam roller under ankle
• Prone passive knee extension lying with leg off side of bench
• Straight leg raises
• Mini squats
• Leg press (short arc range of motion)

Arthroscopic plica debridement considered for failed conservative treatment.

1. Medial plica syndrome. Tal Sznajderman, Yossi Smorgick, Dror Linder, Yiftah Beer, Gabriel Agar. Isr Med Assoc J.2009 Jan;11(1):54-7.
2. Plica Syndrome. Kyle Casadei, John Kiel. StatPearls Publishing; 2020 Jan. 2020 Apr 29.