Deformable titanium for acetabular revision surgery: a proof of concept

Area of Science:

• Biomaterials Engineering
• Orthopedic Surgery
• Medical Device Design

Background:

• Custom-made triflange acetabular implants are crucial for complex revision surgeries with compromised bone stock.
• Existing triflange cups often lead to stress-shielding, hindering long-term implant success.
• A new approach is needed to mitigate stress-shielding and improve implant integration.

Purpose of the Study:

• To introduce and evaluate a novel triflange acetabular implant concept using deformable porous titanium.
• To assess the deformability and primary stability of implants designed with this new concept.
• To reduce stress-shielding by redirecting forces to the underlying bone stock.

Main Methods:

• Three highly porous titanium cylinder designs were mechanically tested under compression.
• The optimal design was incorporated into acetabular implants with either an integrated deformable layer or a separate mesh.
• Implants were tested in sawbones with acetabular defects, subjected to cyclic compression (1800N for 1000 cycles).

Main Results:

• A porous titanium design with 4mm cell size and 0.2mm strut thickness demonstrated superior mechanical properties.
• Implants with an incorporated deformable layer achieved immediate primary fixation.
• Cyclic testing showed an average subsidence of 0.25mm in the initial 1000 cycles, with minimal subsequent subsidence.

Conclusions:

• A deformable titanium layer integrated behind acetabular cups can achieve primary fixation and stability in simulated complex acetabular revision surgery.
• This innovative design shows promise for reducing stress-shielding in challenging orthopedic cases.
• Further clinical research is necessary for the widespread adoption of these advanced implants.