Abstract
In properly chosen patients, cementless total knee arthroplasty has achieved success rates equal to cemented designs. The initial variable results of early cementless total knee replacements were a function of design, surgical technique and patient selection. Important design considerations that have enhanced biologic ingrowth include the use of commercially pure titanium with optimal pore size and porosity, and avoidance of porous-coated stems and plugs that cause stress shielding of the bone-implant interface. Factors in surgical technique that enhance bone ingrowth include precise bone cuts that maximize bone-implant contact, and the application of autogenous bone slurry to cut surfaces. Additional factors are restoration of normal alignment, appropriate ligament balance, and the reproduction of the patient's native tibial slope in order to prevent tibial component subsidence. Young and active patients are ideal biological hosts for the use of cementless knee fixation. Their relatively dense cancellous bone and rich blood supply provides for robust purchase for initial fixation and the appropriate milieu for long-term biologic fixation. With increasing life expectancy, this more durable interface is desirable. With avoidance of porous-coated stems and pegs and prevention of fibrous tissue attachment, potential future revisions are more bone-sparing relative to methylmethacrylate fixation. Numerous reports, as well as the authors' published 10- to 14-year results, demonstrate that cementless fixation in appropriately selected patients provides results comparable to cemented TKA, with the advantage of conserving bone stock and eliminating the potential problems of cement fixation.
