After an injury or knee surgery, it is helpful to know a little bit about assessing blood circulation in the lower limb. These features suggest poor blood flow to the limb:
If a bandage is too tight the circulation away from the limb can be obstructed and the toes might become swollen and darker in colour. Loosening the dressing should improve blood flow.
A serious problem of circulation after knee injury, and sometimes after surgery, is 'compartment syndrome'. The calf muscles and vessels are contained within fibrous compartments, and any bleeding within a compartment may cause an increase in pressure there, causing pressure damage to the blood supply and the nerves. Compartment syndrome is rare but is a clinical emergency - the calf will be tense, pain will be severe and constant, the limb pale and the patient will experience pins and needles.