Contact stress-based optimization design of customed unicompartmental knee prosthesis for Chinese population

The clinical outcomes of customized unicompartmental knee arthroplasty (UKA) prosthesis design remain controversial and purely anatomy-based design method still need optimization. This study established initial medial UKA prosthesis designs based on the measured anatomical parameters of 58 Chinese knees. The individual and interactive effects of the prosthesis design parameters on the maximum contact stress were quantified via finite element analyses (FEA). The UKA prosthesis design parameters were optimized based on an automatic FEA optimization scheme, and a contact stress–based customized design scheme was proposed. Tibial insert contact stress and prosthesis coverage improvements were evaluated through three randomized cases. The results indicated that the femoral coronal anterior radius (FCR1), distal radius (FCR2) and sagittal distal radius (FSR2), and the tibial sagittal length (L), coronal width (D) and coronal radius (TCR), significantly contributed to the articular contact stress. The optimized FSR2, FCR1 and FCR2 values for femoral prosthesis type 1∼4 and L, D and TCR values for tibial prosthesis type 1∼5 were determined respectively. Three randomized cases demonstrated that the maximum contact stress in the optimized design was reduced by 9%, 17%, and 7%, respectively. The prosthesis coverage exceeded 98%. These findings suggest that a direct anatomy-based customized UKA prosthesis design may not always yield optimal biomechanical performance, whereas a contact stress–optimized design scheme shows the potential to improve biomechanical outcomes. The proof-of-concept contact stress–optimized design scheme proposed in this study may offer a novel pathway for the rapid design and selection of customized UKA prostheses for the future.