The Knee Society index of severity for failed total knee arthroplasty - Practical application

Previous classifications of severity for total knee arthroplasty revisions have been based largely on bone loss of the femur and tibia. These approach es failed to address the more technically difficult issues in revision surg ery such as surgical exposure, contractures, extremity alignment, implant r emoval, soft tissue stability (in the anteroposterior and in the sagittal p lanes), extensor mechanism integrity, and patellar revisability. Through th e Knee Society, the authors developed a severity index that incorporated th ese latter factors into one measure. The current authors describe the appli cation of the Knee Society Index of Severity for failed total knee arthropl asty and its method of scoring.