Reconstruction According to Zonal Fixation and Adequate Imaging Techniques in Revision Total Knee Arthroplasty: A Narrative Review.

Aseptic loosening is one of the main causes of failure for both primary and revision total knee arthroplasty (rTKA). Bone loss and bone quality can vary significantly across anatomical regions, potentially challenging long-term fixation. In recent years, zonal fixation in rTKA has become increasingly popular; this approach divides areas of fixation based on anatomy into 3 zones: epiphysis, metaphysis, and diaphysis. This system emphasizes the importance of preoperative planning and encourages surgeons to carefully select the fixation method for each respective zone. To plan proper fixation, adequate imaging is required to document bone defects and areas of sclerosis. While anteroposterior and lateral radiographs remain the gold standard for defect classification, computed tomography imaging has facilitated 3-D defect evaluation and bone density assessment. For many years cemented and hybrid fixation have been the main modes of fixation in rTKA, but recently these modes of fixation have been augmented by the use of uncemented cones and sleeves. Through bone ingrowth this type of fixation provides lasting fixation in the metaphysis and seems to reduce the need for longer stem fixation in the diaphysis. This narrative review provides an overview of advanced imaging techniques, defect grading, and principles of implant fixation using the concept of zonal fixation.