Wear assessments of a new cervical spinal disk prosthesis: Influence of loading and kinematic patterns during in vitro wear simulation

Abstract

Surgical treatment is one of the effective methods of treatment in cervical spondylosis. The traditional method of operation is decompression fusion; however, this surgery results in restricted movement of cervical vertebra and adjacent segment degeneration. Due to the deficiency of traditional surgery, scholars have widely carried out artificial cervical disk replacement surgery and have achieved good clinical effects. Comparing to the characteristics of the common artificial cervical disk which is used frequently, we developed a new artificial cervical intervertebral disk prosthesis. The purpose of this study was to determine the wear behavior in a cervical total disk replacement system. The total disk replacement system tested consists of a ultra-high-molecular-weight polyethylene inlay articulating between a Ti6Al4V alloy superior plate and an inferior plate, using a spine wear simulator, per the ISO 18192-1:2011 standard test methods. Three rotations and axial force were applied on each station. The specimens were removed at 5 × 105 and 106 cycles and at intervals of 106 cycles thereafter to determine the actual mass loss. The serum was replaced every 5 × 105 cycles. The specimens were changed periodically among the different stations. A mean ultrahigh molecular weight polyethylene inlay wear rate of 0.53 mg per million cycles (standard = 0.13 mg per 106 cycles) was found after 107 cycles. All inferior plates showed slight scratching after 107 cycles. The impingement wear simulation introduced here proved to be suitable to predict in vivo impingement behavior in regard to the contact pattern seen on retrieved devices of the Pretic-I disk arthroplasty design in a preclinical test.