Xuan Cai1, Xijing He, Haopeng Li, Dong Wang. 1. Department of Orthopaedic Surgery, Second Affiliated Hospital of Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.
Abstract
BACKGROUND: Atlanto-odontoid joint arthroplasty is a motion restoring procedure suggested as an alternative to rigid fixation after surgical decompression. The purpose of this study was to evaluate the kinematics and pullout strength of a novel Total Atlanto-odontoid Joint Arthroplasty System using human cadaveric specimens. METHODS: Nondestructive biomechanical tests were performed on 24 fresh craniocervical specimens separated into two groups: 1) the prosthesis implantation group and 2) Harms transoral atlantoaxial plate fixation group. The following configurations were investigated: intact, after decompression, and instrumented. Range of motion and neutral zone were calculated for the C1-C2 segment. In a second experimental series, 8 sets of fresh atlantoaxial specimens were used to test the pullout strength of the atlas-axis components. FINDINGS: Compared with Harms rigid fixation, the Total Atlanto-odontoid Joint Arthroplasty System significantly increased the range of motion and neutral zone in all directions (P<.001). In addition, compared with the intact state, the only significant change in the range of motion and neutral zone with the Total Atlanto-odontoid Joint Arthroplasty System implantation was an increase in lateral bending (P<.001). The pullout strength created by the anterior C2 transpedicular screw was greater than that of the C2 vertebral screw and C1 lateral mass screw (P<.001), and the C1 lateral mass screw was stiffer than the C2 vertebral screw (P=.02). INTERPRETATION: Biomechanical analyses suggest that the Total Atlanto-odontoid Joint Arthroplasty System was able to provide reliable fixation strength and preserve the normal kinematics of the C1-C2 segment after decompressive procedures.
BACKGROUND:Atlanto-odontoid joint arthroplasty is a motion restoring procedure suggested as an alternative to rigid fixation after surgical decompression. The purpose of this study was to evaluate the kinematics and pullout strength of a novel Total Atlanto-odontoid Joint Arthroplasty System using human cadaveric specimens. METHODS: Nondestructive biomechanical tests were performed on 24 fresh craniocervical specimens separated into two groups: 1) the prosthesis implantation group and 2) Harms transoral atlantoaxial plate fixation group. The following configurations were investigated: intact, after decompression, and instrumented. Range of motion and neutral zone were calculated for the C1-C2 segment. In a second experimental series, 8 sets of fresh atlantoaxial specimens were used to test the pullout strength of the atlas-axis components. FINDINGS: Compared with Harms rigid fixation, the Total Atlanto-odontoid Joint Arthroplasty System significantly increased the range of motion and neutral zone in all directions (P<.001). In addition, compared with the intact state, the only significant change in the range of motion and neutral zone with the Total Atlanto-odontoid Joint Arthroplasty System implantation was an increase in lateral bending (P<.001). The pullout strength created by the anterior C2 transpedicular screw was greater than that of the C2 vertebral screw and C1 lateral mass screw (P<.001), and the C1 lateral mass screw was stiffer than the C2 vertebral screw (P=.02). INTERPRETATION: Biomechanical analyses suggest that the Total Atlanto-odontoid Joint Arthroplasty System was able to provide reliable fixation strength and preserve the normal kinematics of the C1-C2 segment after decompressive procedures.