It is often suggested that patella tracking after total knee arthroplasty (TKA) with an asymmetrical patella groove is more
physiological than with a symmetrical patella groove. Therefore, this study tried to address two questions: what is the effect
of TKA on patella tracking, and is patella tracking after asymmetrical TKA more physiological than patella tracking after
symmetrical TKA? The patellar and tibial kinematics of five cadaveric knee specimens were measured in the intact situation,
after the incision and suturing of a zipper, and after placement of a symmetrical TKA and an asymmetrical TKA, respectively.
The patellae were not resurfaced. The flexion-extension kinematics were measured with an internal and external tibial moment
to determine the envelope of motion (laxity bandwidth) of the tibio-femoral and patello-femoral articulation. The kinematics
after TKA showed statistically significant changes in comparison to the intact situation: patellar medio-lateral translation,
patellar tilt and tibial rotation were significantly affected. No statistically significant differences in knee kinematics
were found between the symmetrical and the asymmetrical TKAs. We conclude that conventional TKA significantly changes physiological
patello-femoral kinematics, and TKA with an asymmetrical patella groove does not improve the non-physiological tracking of
the patella.
Keywords Knee - Patella - Prostheses and implants - Biomechanics - Prosthesis design