Abstract
Functional restoration of patella kinematics is an essential component of TKA, whether the patella is replaced or not. This goal is accomplished by a multifactorial approach: establish proper component position and alignment, especially rotation; avoid IR of the femoral and ER of the tibial components; maintain correct joint line position; achieve symmetrical soft tissue balance.
Most modern TKA designs have an anatomic trochlear groove shape to enable midline tracking. Patella implants are better designed as well with three equilateral lugs for fixation and either dome or anatomic shape. The apex of the patella component should be aligned with the apex of the patella raphe which is more medial than lateral. This method leaves an island of exposed lateral patella facet which is managed with the “lateral slat technique” to be described. It is essentially an intraosseous lateral release. The early mobilization of modern TKA patients demands watertight closure to prevent soft tissue attenuation and late tracking issues.
When confronted with a patient with a laterally dislocated patella, implementation of the “lateral slat technique” should be done at the approach to obtain midline tracking. Such patients require a median parapatellar (MPP) approach and may need distal-lateral vastus medialis advancement (Insall procedure).
Adherence to the principles iterated herein will produce a happy patient with good patello-femoral kinematics and function.
