Abstract
Total knee arthroplasty (TKA) is a successful operation associated with a high rate of clinical success and long-term durability. Cementless technology for TKA was first explored 30 years ago with the hope of simplifying the performance of the procedure and reducing an interface for potential failure by eliminating the use of cement. Poor implant design and the use of first generation biomaterials have been implicated in many early failures of these prostheses due to aseptic loosening and reflected the failure of either the tibial or patellar component. Despite this, many excellent intermediate and long-term series have clearly demonstrated the ability of cementless TKA to perform well with good to excellent survival, comparable to that of cemented designs.
Lessons learned from the initial experiences with cementless technology in TKA have led to improvements in prosthetic design and materials development. One of the most innovative biomaterials introduced into orthopaedics for cementless fixation is porous tantalum. Compared to other commonly used materials for cementless fixation, porous tantalum has the highest surface friction against bone, optimizing initial stability at the implant-bone interface as a prerequisite for long-term stability of the reconstruction.
At the 2013 AAOS Annual Meeting, Abdel presented the 5-year Mayo Clinic experience with cementless TKA utilizing a highly porous monoblock tibial component in 117 knees and found NO difference in survivorship compared to cemented fixation with a re-operation rate of 3.5% in both groups. They had no revisions for aseptic loosening. These early to intermediate results reflect our own experience with all cementless TKA utilizing a cobalt-chromium fibermesh femoral component, as well as monoblock porous tantalum tibial and patellar components with up to 11-year follow up. In that series of 115 patients, there was a 95.7% survival of implants, with no revisions of any components for aseptic loosening.
Further advantages to using cementless fixation include the elimination of concerns with regard to monomer-induced hypotension, thermal necrosis from PMMA polymerization, and third body wear secondary to retained or fragmented cement. Savings are also realised from elimination of the costs of cement, a PMMA mixing system, cement gun, pulse lavage system, and irrigation solution. Perhaps the greatest cost savings is derived from the reduction in operating room time. At our institution–a Level 1 county trauma center with an orthopaedic residency training program–we typically spend an average of 19 minutes of operating room time for the cementing of a total knee arthroplasty. Our average time expended for insertion of all three cementless implants is 47 seconds–representing a significant savings in the hospital operating room time charge. From the standpoint of the patient, the shorter operating time reduces the time under anesthesia, the blood loss, the risk of venous thromboembolism, as well as the infection risk–optimizing the conditions for a reduction in post-operative complications, directly impacting a potential reduction in morbidity and mortality.
Overall, the performance of all cementless TKA at our facility is cost-saving, is easily performed and reproduced by orthopaedic residents, and brings potential advantages to the patient in the form of a reduction in complications and an improvement in outcomes. Cementless fixation is the wave of the future, and the future is now.
