Biomechanical Evaluation of a Novel Bionic Hip Prosthesis Designed for Optimized Load Transfer and Initial Stability

In total hip arthroplasty, the femoral component design requires a trade-off between initial stability and stress shielding. We designed the new bionic hip arthroplasty (BHA) prosthesis with compression and tension screws to mimic compression and tension trabeculae for bionic reconstruction. This prosthesis is designed to reduce stress shielding by mimicking physiological load transfer while ensuring sufficient initial stability for successful bone integration. This study aimed to biomechanically evaluate the initial stability and migration pattern of the BHA prosthesis under dynamic and static loading conditions.

The BHA prostheses were implanted into ten Sawbones fourth-generation composite non-osteoporotic femurs. In dynamic fatigue testing, the irreversible displacements and migration patterns in vertical and rotational directions were analyzed after 1,000,000 loading cycles. In static failure testing, the failure load of the BHA implanted model was analyzed.

In dynamic fatigue testing, the irreversible subsidence displacement of the BHA prosthesis was (0.3683 ± 0.1046) mm and the irreversible retroversion displacement was (0.0328 ± 0.0157)°. The irreversible displacements in both vertical and rotational directions stabilized at 100,000 loading cycles. In static failure testing, the failure load of the BHA implanted model was (4485 ± 702) N.

The irreversible subsidence displacement of the BHA prosthesis was below the interface failure threshold of 1.5 mm, and secondary fixation was accomplished at 100,000 loading cycles. The average failure load was approximately 6.4 times body weight, much higher than the daily load range of hip joints. The BHA prosthesis suggests potential for adequate axial initial stability to facilitate bone ingrowth, which is expected to reduce revision rates in patients.