Establishment of novel artificial intervertebral disc design containing a vertebral body fixation mechanism and its clinical applications

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The objective of this study was to establish a novel artificial intervertebral disc design containing a vertebral body fixation mechanism in both cervical and lumbar spines. The anterior total disc replacement and posterior subtotal disc replacement design were developed. Using an ultrahigh strength bioresorbable material, the porous bioresorbable plate was created in conjunction with the use of bioresorbable pins providing the reliable fixation to the vertebral body. The anterior total disc replacement model in both cervical and lumbar spines as well as the posterior subtotal disc replacement model were fabricated. Using these models, the in vitro biomechanical evaluation was performed in a human cadaveric spine model, as well as the in vivo evaluation until twelve months period in a non-human primate model The in vitro study demonstrated that the replaced spinal segment at C5/6 level revealed biomechanical properties similar to normal spinal segments. The lumbar artificial disc did n … More ot show any device displacement or dislodgement during the testing. The replaced spinal segments demonstrated mechanical properties equivalent to the normal lumbar spinal segments. The in vivo study was conducted using forty-four mature baboons with anterior total and subtotal replacement procedures until twelve months period. The cervical replaced segment demonstrated 108%, 72%, and 65% of ROMs in flexion-extension, axial rotation, and lateral bending loading, respectively at postoperative six months. No neurologic disturbance or device failure was reported in all operated animals. Histologically, the interface between artificial disc and vertebral body demonstrated the direct bony contact and the stable environment. Based on the above experimental results, the clinical trial of human artificial disc replacement was submitted to the ministry of health in Japan, The multicenter study is planned with anterior cervical total disc replacement and posterior lumbar subtotal disc replacement designs. Less