A new hip epiphyseal prosthesis: design revision driven by a validated numerical procedure

Area of Science:

• Orthopedic biomechanics
• Biomaterials engineering
• Medical device design

Background:

• A novel epiphyseal device was developed for effective bone-prosthesis load transfer.
• Preliminary tests revealed a 23% weakening of the femoral neck post-implantation.
• Existing designs pose risks of fracture, loosening, and bone resorption.

Purpose of the Study:

• To revise the epiphyseal device geometry for enhanced femoral neck strength.
• To maintain the original conceptual design while mitigating failure risks.
• To reduce risks of femoral neck fracture, prosthesis fracture, aseptic loosening, and bone resorption below 100% acceptance threshold.

Main Methods:

• Utilized a validated finite element analysis (FEA) procedure.
• Systematically assessed risks associated with the initial prosthesis geometry.
• Revised the device geometry based on FEA predictions.
• Re-assessed the revised design to confirm effectiveness.

Main Results:

• The initial design predicted high bone strains and cement stresses, exceeding acceptance thresholds (>100% risk).
• The revised geometry demonstrated reduced risks: 45% for bone failure and 60% for cement failure.
• The new design maintained good device stability while enhancing safety.

Conclusions:

• The revised epiphyseal device geometry significantly reduces risks of bone and cement failure.
• FEA predictions suggest the modified device enhances femoral neck strength and patient safety.
• Further clinical validation may expand indications for hip epiphyseal devices.