Hi There I Recently Tore My ACL Completly And Partly

hi there i recently tore my ACL completly and partly tore my MCL and MEDICAL MINISCUS which also tore away some cartlige with it too. i did it in aug and still cannot straighten or fully bend my leg 'properly' the doctor said he cannot operate at the moment cause of my 'lack of range' else he said it will go like 'concrete' he thinks that if i get my range of motion back i will not need an operation, but after all my research your ACL will not repair itself... is this correct ?