Full knee extension is essential for normal knee function. While a certain loss of flexion is well tolerated, losing just a few degrees of extension creates an imbalance in gait with a limp when walking and can even rebound, generating pain at the hip and lumbar level. The knee is more able to tolerate inflammation at about 20 degrees of flexion. So the usual tendency is that people after an operation tend to put the knee slightly bent. That is why after surgery, you must work intensively to recover full extension. This work should be done with high intensity in the first 8 weeks. After the first 2 or 3 months, the ability to restore more extension deficit decreases considerably. While after this time a flexion deficit can be recovered relatively easily with a simple operation releasing knee scars, the surgical treatment of extension loss is much more complex to be corrected.