This is a very complex case and it is difficult to give you accurate advice without reviewing all of your medical history and X-rays and of course without examining you. Your knee joint could be stiff because of degenerative arthritis
in the knee joint as a result of your injury
and your prolonged complicated treatment. Your knee could be stiff because of soft tissue
scarring and contracture. There are treatments for both of these issues. You could have an examination and stretching of your knee under anaesthesia and then undergo physiotherapy
and treatment with continuous passive motion - a machine that bends your knee. We also sometimes use JAS splints which have a ratchet mechanism to force your knee into more movement. Surgical soft tissue releases may be necessary. If your knee is arthritis then some type of knee replacement
may be your only option but this would be risky based on your previous injury and infections.