Suboptimal knee prosthesis design for Vietnamese women: a computed tomography-based arthrometric study

Mismatches between knee dimensions and implant sizes can result in poor outcomes and dissatisfaction following total knee replacement. We aimed to evaluate knee morphology in Vietnamese women and assess the compatibility of available prostheses.

Using full-leg CT scan datasets, we reconstructed 3D models of knee joints with software. After simulating femoral and tibial bone cuts with mechanical alignment, the anteroposterior (AP) and mediolateral (ML) widths of the resection surfaces were measured. Six available prostheses were analysed for their compatibility and coverage percentage of the resected bone.

The study included 40 female patients with osteoarthritis (aged 51-79). AP and ML dimensions of distal femur were 63.07 ± 3.05 mm and 57.46 ± 3.06 mm; those of proximal tibia were 48.95 ± 3.01 mm and 67.14 ± 3.49 mm. Smaller knees exhibited a higher femoral aspect ratio (ML/AP) than larger knees. Increasing the tibial AP resulted in a smaller ML length of the proximal tibia relative to the tibial component. With the AP and ML mismatch set at ± 1.5 and ± 3 mm, the prosthesis system provided the best femoral component fit at only 67.5%. Tibial component coverage rates varied among implant systems, with the best fit prosthesis system covering 92.5% at a tolerance of ± 3 mm for both AP and ML dimensions.

The current prosthetic options show significant mismatches with the knee morphology of Vietnamese women, highlighting the need for better suited implant designs. Further research is necessary to develop suitable prosthetic solutions.