Cementless fixation in total knee replacement has seen limited use since reports of early failure surfaced in the late 1980s and early 1990s. However, the emergence of improved biomaterials, particularly porous titanium and tantalum, has led to a renewed interest in developing a cementless tibial component to enhance long-term survivorship of the implants. Cement is commonly used to mechanically fix orthopaedic implants, but represents a weak interface between the implant and the bone. The elimination of cement and application of these new biomaterials, which theoretically provide improved stability and ultimate osseointegration, would likely result in greater knee replacement success. Additionally, the removal of the cement from this procedure would eliminate the time needed for curing, thereby minimizing surgical durations and decreasing the risk of infection. The purpose of this biomechanical study was twofold. The first goal was to assess whether vibration analysis techniques can be used to evaluate and characterize initial mechanical stability of cementless implants more accurately than the traditional method of micromotion determination, which employs linear variable differential transducers (LVDTs). The second goal was to perform an evaluative study to determine the comparative mechanical stability of five designs of cementless tibial components under mechanical loading designed to simulate in vivo forces. The test groups included a cemented Triathlon Keeled baseplate control group, three different 2-peg cementless baseplates with smooth-, mid-, and high- roughness, and a 4-peg cementless baseplate with mid-roughness.