In this case, loads are concentrated in the so called primary
contact area. In most cases, the offset misalignment between pieces is the consequence of an improper surgical technique,
compromising the performance of the prosthetic joint [32]. As a consequence, it is not unusual to report adverse events such
as the premature wear of the primary contact areas, fracture of the components and aseptic loosening, since the pieces are
not designed to withstand the peak loads that result from the deviation of the mechanical axis [3,33].
After the fracture of the baseplate, the gaps and relative displacements between the pieces increased significantly. Fig. 7a
shows the top side of the tibial joint with linear displacements in the lateral-medial direction of approximately 8.0 mm, and
5.5 mm in the front-rear direction. Fig. 7b shows the inferior side of the assembly with the position of the fracture in the
medial region of the baseplate and rotation of the insert.
The relative displacements between the pieces allowed an increase of the bending moment in the medial direction, the
fracture location in the tibial base.