ABSTRACT
The mechanism of the loosening after arthroplasty is considered that micromotion makes a gap between implant and bone, the subsidence of implant and osteolysis around the implant. The loosening of femoral component after total knee arthroplasty(TKA) might be related to the improper support of posterior condylar area, the causes of which may be inaccurate osteotomy, improper cementing technique and poor bone quality, etc. The authors found four cases of flexed displacement and osteolysis around the femoral component after TKA. The types of implant were one case of PS type and three cases of High Flex PS type. Revision arthroplasty was done in three patients who had severe clinical symptoms with diffuse bone loss around the distal femur. We evaluated the mechanism of the early loosening by clinical and radiologic assessment of four patients.