You may consider knee replacement surgery if you have a stiff, painful knee that makes it difficult to perform even the simplest of activities. - Medial Uni - Lateral Uni - PFJ Replacement You should consider knee surgery when its painful to walk or if your knee bends outswards. Damaged cartilage and bone is taken out and replaced with a man made joint. Visit - http://simoncoffey.com.au/knee-surgery/