Knee Plica

Aetiology

 

Knee forms from 3 separate compartments

 

Plica represents normal embryonic synovial septum that persists into adult life

 

Epidemiology

 

20% of knees have medial patellar plica at arthroscopy

 

Symptomatic plicae much less common 1-2%

 

Mean age 14

 

Types

 

1.  Infrapatellar (ligamentum mucosum) 

 

Most common / always asymptomatic

 

Role

- likely stabilises the fat pad to the knee

- may prevent fat pad impingement

 

2.  Suprapatellar 

 

Variable

- often incomplete

- may separate suprapatellar bursa from knee

- may hide loose body

 

2.  Medial patellar 

 

Least common / rarely symptomatic

 

Anatomy

- originate from medial wall of knee joint

- run obliquely to insert in medial infrapatellar fat pad

 

Occasionally symptomatic

- gets caught between patella & femur

 

Patient symptoms

- snapping / clicking

- medial pain

- may be able to palpate / reproduce symptoms

 

MRI

 

Medial Parapatella Plica MRI

 

Arthroscopy

 

Normal

- thin

- no evidence inflammation

- no evidence chondral damage

 

Medial Plica Asymptomatic ThinMedial Parapatella Plica Non Pathological

 

Abnormal

- thickened and inflammed

- obvious signs of chondral damage on MFC

 

Medial Plica Arthrscopy Non PathologicalPathological Plica

 

Arthroscopic resection

 

Divide plica to synovial membrane rather than completely excise