An Analysis of the Interference Between the Tibial Component with Stem and the Tibial Cortex

Abstract

Objective: A tibial component with stem is frequently used in revision total knee arthroplasty (TKA) because it improves the mechanical stability of the tibial components. However, it is possible that the tibial component stem interferes with the cortex of the proximal tibial metaphysis. In this study, we investigated the percentage of interference between the tibia component stem and tibial cortex in patients with primary TKA by computed tomography-based 3-dimensional (3D) preoperative planning software.

Methods: This was a retrospective simulation study. We analyzed 102 knees that underwent TKA in our hospital by using 3D template software. There were 13 men and 48 women with a mean age of 76.2 years (SD, 8.0 years; range, 54-91 years). The tibial implants, namely Vanguard^TM PS system I-beam and Vanguard^TM SSK system supplied by Zimmer-Biomet Holding Inc., were used for the simulation in this study. We identified the following types of simulation: type A- no contact between the tibial component stem and the tibial cortex; type B- some contact between the stem and the tibial cortex; and type C- the stem undoubtedly invaginated, or perforated the tibia cortex.

Results: The Vanguard^TM PS system I-beam simulation results showed that 91 knees (89.2%) corresponded to type A, nine knees (8.8%) to type B, and two knees (2.0%) to type C, respectively. The Vanguard^TM SSK system simulation showed that 61 knees (60.0%) corresponded to type A, 36 knees (35.2%) to type B, and five knees (4.9%) to type C, respectively. Female patients has especially small sized tibial components and tended to fall within the B or C type simulations by the Vanguard^TM SSK system.

Conclusion: A tibial component with stem is useful for mechanical stability in revision TKA, but it should be borne in mind that some cases have a possibility of an interference between the stem of tibia component and the tibial cortex.