Application of customized augments fabricated by rapid prototyping for severe bone defects of the knee

With the population aging and an increasing desire for a high quality of life,millions of patients who suffered knee arthropathy have undergone total knee arthroplasty （TKA）.Although the success rate for primary TKA has been quite high,the number of revision surgeries can not be ignored.Bone loss is one of the challenges confronting surgeons who perform revision TKAs as it can impair alignment accuracy and the long-term stability of the implant.Although several options are available for bone loss after TKA--cement,bone grafting,standard augments,and hinged implants--there is no single ideal option available for all patients with a severe bone defect because of the variety and severity of the defects.1 The burgeoning rapid prototyping （RP） technique,which has been used to fabricate components with complex and unique structures,may offer a novel option in these cases.Keywords：rapid prototyping; severe bone defects; knee