Tibial component fixation in deficient tibial bone stock

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Materials Science

Background:

• Total knee arthroplasty (TKA) requires stable tibial component fixation.
• Bone stock defects in the tibial plateau present significant fixation challenges.
• Evaluating fixation methods for compromised tibial bone is crucial for TKA success.

Purpose of the Study:

• To assess the mechanical stability of different fixation methods for simulated tibial bone defects in TKA.
• To compare the effectiveness of cement, screws, spacers, and custom components in supporting tibial trays under load.
• To determine optimal strategies for reconstructing deficient tibial bone stock during TKA.

Main Methods:

• A wedge-shaped defect was created in the medial tibial plateau of autopsy specimens.
• Five distinct methods of tibial component fixation were evaluated.
• Axial (1780 N) and varus (1340 N at 28 Nm) loads were applied.
• Vertical deflections and stem bending were measured using strain gauges.

Main Results:

• Cement alone resulted in the greatest vertical deflections.
• Adding cancellous screws offered minimal improvement over cement.
• Solid spacers (Plexiglas or metal) provided further enhancement in stability.
• An integral custom-made tibial component demonstrated the most secure support.
• A metal wedge was identified as a practical alternative for defect reconstruction.

Conclusions:

• Custom-made tibial components provide the most robust fixation for tibial bone defects in TKA.
• Metal wedges represent a clinically relevant and effective alternative for reconstructing tibial bone stock defects.
• Fixation strategies significantly impact mechanical stability, with custom solutions and metal wedges outperforming simpler methods.