Abstract
This video presentation serves to illustrate the pertinent aspects of bone preparation and implant insertion in cementless total knee arthroplasty (TKA) utilizing porous tantalum as a fixation surface integral to the success of the procedure.
The patient is typical of the surgical candidate frequently encountered for arthroplasty—a 60-year-old female with three compartment osteoarthritis of the knee, and manifesting a 10-degree varus deformity and 5-degree flexion contracture. She is a limited community ambulator without the use of support.
A standard surgical exposure is utilised and the bone preparation is identical to that used in the fixation of cemented implants—no alignment guides, cutting guides, or referencing instrumentation is used that is unique in the femoral or tibial bone preparation. The principal difference is in the patellar preparation. Instrumentation unique to the cementless porous tantalum patella is utilised in order to achieve three goals: a composite implant/residual bone thickness that replicates the thickness of the native patella, the generation of a planar patellar resection that is parallel to the anterior cut of the femur, and secure initial stability of fixation.
Keys to the initial fixation of the porous tantalum tibial and patellar components include the high surface friction of the material against bone, as well as the interference between the hexagonal pegs of each implant within the fixation holes (which are dimensionally smaller in diameter than the major and minor dimensions of the peg geometry). Care must be instituted to ensure that no bone or soft tissue debris is interposed at the mating surfaces of the implants that would compromise interface contact, and to carefully suction the peg holes to ensure that no debris impedes the complete seating of the pegs and the prosthesis. Lastly, all mating surfaces at the implant/bone interface must approach each other in a parallel fashion to optimise contact between the fixation surfaces and the bone resection surfaces.
The procedure is simply, easily performed, and is time saving. Total elapsed time for insertion of all three TKA implants in this video is 90 seconds.
