Anatomy data driven mechanical adaptation of bone tunnel-screw interface in ACL reconstruction

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Medical Imaging

Background:

• Anterior cruciate ligament (ACL) reconstruction outcomes can be improved by understanding bone microstructure at attachment sites.
• Conventional imaging techniques have limitations in characterizing complex trabecular bone architecture.

Purpose of the Study:

• To quantitatively characterize trabecular bone structure at ACL femoral and tibial attachment sites using P45 plastination.
• To establish a biomimetic strategy for guiding bony tunnel orientation and depth in ACL reconstruction.
• To design and evaluate functionally graded interference screws for enhanced mechanical compatibility.

Main Methods:

• Sixty human knee specimens underwent P45 plastination.
• U-Net convolutional neural networks and MATLAB were used for image segmentation and quantitative analysis of trabecular bone morphometrics (porosity, number, anisotropy, orientation).
• Finite element simulations evaluated mechanical performance of uniform and functionally graded screw models (Double Gyroid, Diamond, Fischer-Koch S, Octet).

Main Results:

• Distinct, site-specific trabecular patterns were identified at ACL attachment sites.
• Femoral site: rectangular area, perpendicular trabeculae; Tibial site: larger rectangular area, parallel trabeculae.
• Gradient Double Gyroid screws showed superior mechanical compatibility at the femoral site (8.86 MPa), and gradient Octet screws at the tibial site (12.26 MPa).

Conclusions:

• An integrated approach for analyzing ACL attachment site bone structure was developed.
• Biomimetic screw designs and bone tunnel positioning strategies were informed by quantitative bone parameters.
• Findings offer a framework to enhance anatomic and biomechanical compatibility in ACL reconstruction, potentially improving surgical success.