Article ID: JNMS.2020_87-202
Background: Unicompartmental knee arthroplasty (UKA) has been becoming popular over the last decades for its good outcome. On the other hand, several accompanying complications have been reported. Tibial implant alignment is considered to be one of the important causes of these complications. There have been some reports about it, but an optimal alignment of the tibial implant is still controversial. The purpose of this study was to observe the changes in stress distribution in the proximal tibia after UKA at various tibial implant alignments by using 3-dimensional finite element analysis.
Methods:A 3-dimensional finite element model was created with CT-DICOM data of a medial osteoarthritic knee. The change in stress distribution of tibial implant alignment in the coronal plane (middle position, varus 5°, valgus 5°) and in the sagittal plane (0°, 5°, 10°) under the conditions of loose boundary between implant and bone and no loosening condition was observed using 3dimensional finite analysis.
Results: With no loosening, high stress distribution was observed at the lateral rim of the subchondral bone in the varus alignment model, and the high stress distribution was moving from anterior to posterior with the posterior tilting from 0° to 10°. With loosening, high stress distribution was observed at the proximal tibial medial cortex in the valgus alignment model.
Conclusions: In UKA, optimal alignment of the tibial implant might be at the middle position in the coronal plane and at the posterior inclination similar to each patient's original inclination in the sagittal plane to reduce complications.
