Knee pain can have causes that aren't due to underlying disease. Examples include heavy physical activity, lack of use, injuries such as sprains or strains, sitting in a constrained area or sitting on knees for a prolonged period.
Signs and symptoms that sometimes accompany knee pain include:
Swelling and stiffness.
Redness and warmth to the touch.
Weakness or instability.
Popping or crunching noises.
Inability to fully straighten the knee.
During the physical exam, your doctor is likely to:
Inspect your knee for swelling, pain, tenderness, warmth and visible bruising
Check to see how far you can move your lower leg in different directions
Push on or pull the joint to evaluate the integrity of the structures in your knee