Early post-operative performance of an anatomically designed hybrid thread interference screw for ACL reconstruction:...

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Sports Medicine

Background:

• Anterior cruciate ligament (ACL) reconstruction is common, but graft failure occurs during early rehabilitation.
• Interference screws are standard for graft fixation, yet stability remains a concern.

Purpose of the Study:

• To compare the graft fixation stability of a novel anatomical hybrid thread tapered interference screw (AHTTIS) against a conventional standard interference screw (CSIS).
• To evaluate the biomechanical performance of AHTTIS under simulated worst-case fixation conditions.

Main Methods:

• In vitro mechanical testing of AHTTIS and CSIS using bovine tendon grafts in artificial bone blocks.
• Grafts were subjected to pre-load, cyclic tensile loading, and pullout tests to measure displacement, failure load, and stiffness.
• Tapered and straight bone tunnels were used to match screw geometries.

Main Results:

• No significant differences in most mechanical parameters between AHTTIS and CSIS groups.
• AHTTIS exhibited significantly greater graft displacement at yield and ultimate failure points compared to CSIS (P < 0.05).
• These findings were observed under simulated worst-case (cancellous bone-like) fixation conditions.

Conclusions:

• Graft fixation with AHTTIS is deemed practical for ACL reconstruction, even in challenging bone conditions.
• Further research is needed to mitigate potential graft slippage with AHTTIS under high strain rate loading.
• Optimizing AHTTIS design may enhance stability and reduce graft failure risk in ACL repair.