Post-traumatic osteoarthritis could emerge immediately after an injury or one year after a bone fracture, ligament injury, and meniscal tears. In this case report, we present a 30 years old male who previously suffered from joint injury and thus lost the ability to flexion. This patient has already under went internal bone implantation surgery involving the implantation but was removed due to pain, and there was protruding implant on the left knee. On physical examination, there was varus deformity with flexion ranged between 0-5°. On radiological examination, malunion and narrowing of the joint surface were, as shown, clinically inhibit the flexion of the knee. We diagnose the patient with malunion supracondylar femur sinistra and post traumatic osteoarthritis genu sinistra. Liberation procedure (soft tissues release) and osteotomy of the distal femur were performed on this patient. On post-op radiological examination, the implant successfully widens the joint surface and holds the fracture fragment after it was reduced. The joint was immediately mobilize using the machine. It was shown that in a relatively short period, the range of motion could reach 90°. Three months post-op, evaluation was done, and it was clearly shown that the range of motion had not decreased.