Abstract
Cementless fixation in TKA has been inconsistently adopted since its early use but is increasing due to a number of factors, predominantly related to a demand for improved survivorship in younger patients. Modern biomaterials have demonstrated optimal bone ingrowth and have also contributed to a renewed confidence by surgeons to utilise cementless fixation in TKA. With a modern design and appropriate surgical technique, optimal mechanical stability of new designs have been demonstrated and can build upon the excellent long-term outcomes that have rivaled traditional cemented TKA. Paramount to obtaining successful long-term osseointegration and clinical survivorship with cementless fixation is an awareness of the past failure mechanisms to improve implant modern implant design, and should also guide meticulous surgical technique.
A robust implant design with optimal surgical technique is critical to success when employing cementless fixation in TKA. The tried and true principles of sufficient mechanical stability to minimise micromotion of an osteoconductive implant surface with intimate contact against viable bone are essential to allow osseointegration and long-term survivorship. The surgical techniques and tips for “getting it right” include: 1.) Meticulous planar cuts - Prevention of saw blade deviation (particularly anterior femoral cortex and sclerotic medial tibial plateau), Appropriate tolerances in cutting guides (particularly 4-in-1 femoral cutting guide), Appropriate interference fit for tibial keel/stem, patella planar cut, Perfect planar cut on tibial surface confirmed with “4-corner test”. 2.) Implantation of components to maximise mechanical stability - Intimate implant contact with bone (minimizing gaps), Consider bone slurry to minimise gaps, Prevention of femoral component flexion with impaction, Ensure parallel position of tibial baseplate with tibial cut surface during impaction, Peripheral fixation on tibial baseplate, either screws or pegs, to provide supplemental fixation and stability in titanium tray designs.
