This maybe caused by:

• Inflamed (enlarged) lymph nodes which signify infection or malignancy in the area of drainage of the nodes.
• Aneurysms of popliteal artery or vein.
• Lymphomas
• Abscess
• Neuromas
• Popliteus muscle tumor
• Baker's cyst – protrusion of synovium through the knee joint capsule.
• Septic arthritis of the knee joint

For surgical management of these conditions, the topographic anatomy of the contents must be minded.

Popliteal artery entrapment syndrome

• Caused by compression of popliteal artery between gastrocnemi
• Presents with features of leg and foot ischaemia usually intermittent.

Popliteal artery aneurysms

• Can rupture or thromboembolise and cause limb loss

Popliteal vein fat embolism

• May follow supracondylar fracture femur

• Nerve can be inadvertenty sectioned during biceps femoris tenotomy as in when easing contractures
  
  
• Nerve may be compressed against lateral femoral condyle