Stems in TKR

Dr. Ashok Rajgopal
Stem extensions have become an important feature in the TKA armamentarium while dealing with complex primary or revision situations. They distribute the load away from the femoral condyles and the tibial plateau thereby protecting the bone-implant interface. Stem help in optimizing the mechanical alignment and increasing stability of the construct. The important concerns regarding use of stems are those relating to determining the ideal stem length, the problem of juxta-articular stress shielding, and the mode of fixation (cemented, press-fit or hybrid). Stems help in bypassing the bony defects in the proximal tibia and distal femur and provide an expanded interface for implant fixation to the bone, thus are useful in patients with severe osteopenia. Offset stems avoid the potential for axial malalignment owing the femoral and tibial morphology, particularly in the diaphyseal engaging stems. Stems are a valuable tool which greatly increase the mechanical stability and alignment in difficult and revision TKR cases.