• Quanjin Zang, Jiaxi Li, Yanming Liu, Haopeng Li, Kai Cao, Shuai Guo, Ke Li, Lei Sun, and Xijing He.
• Department of Orthopaedics, Second Affiliated Hospital of Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi, P.R. China.
• Spine. 2022 Jun 1; 47 (11): 825-832.

Study DesignA biomechanical in vitro investigation.ObjectiveTo evaluate the function and stability of self-designed biomimetic artificial atlanto-odontoid joint (BAAOJ) replacement on the atlantoaxial joint.Summary Of Background DataUpper cervical fusion surgery is a common treatment for various atlantoaxial disorders, and favorable clinical outcome has been achieved. However, the fusion surgery results in loss of atlantoaxial motion as well as adjacent segments degeneration, reducing the quality of life of patients and might produce severe neurological symptoms. Non-fusion technology is expected to solve the above problems, but various designed devices have certain defects and are still in the exploratory phase.Materials And MethodsBiomechanical tests were conducted on 10 fresh human cadaveric craniocervical specimens in the following sequence: 1) intact condition, 2) after the BAAOJ arthroplasty, 3) after BAAOJ fatigue test, 4) after odontoidect-omy, and 5) after anterior rigid plate fixation. Three-dimensional movements of the C1-C2 segment were evaluated to investigate the function and stability of BAAOJ arthroplasty compared with the intact condition after the BAAOJ fatigue test, odontoidect-omy, and rigid plate fixation.ResultsComparing the BAAOJ implantation to the intact state, the range of motion and neutral zone were slightly reduced in all directions (P > 0.05). Compared with the rigid plate fixation, the BAAOJ implantation significantly increased the range of motion and neutral zone in all directions, especially in the axial rotation (P < 0.05).ConclusionWe designed a BAAOJ for correcting atlantoaxial disorders arising from atlantoaxial instability. As a non-fusion device, the most critical feature of BAAOJ replacement is the retention of flexion-extension, lateral bending, and axial rotation range of motion similar to the normal state. It can also stabilize the atlantoaxial complex, and the BAAOJ itself has a good initial stability.Level of Evidence: 4.Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.

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