Unique biomechanical signatures of Bryan, Prodisc C, and Prestige LP cervical disc replacements: a finite element modelling study

Purpose The purpose of the study is to examine the biomechanical alterations in the index and adjacent levels of the human cervical spine after cervical arthroplasty with Bryan, Prodisc C, or Prestige LP. Methods A previously validated C2-T1 osteoligamentous finite element model was used to perform virtual C5-6 arthroplasty using three different FDA-approved artificial cervical discs. Motion-controlled moment loading protocol was used. Moment was varied until Bryan, Prodisc C, and Prestige LP models displayed the same total range of motion across C3-C7 as the intact spine model at 2 Nm of pure moment loading. Range of motion (ROM) and facet force (FF) were recorded at the index level. ROM, FF, and intradiscal pressure (IDP) were recorded at the adjacent levels. Results Prodisc C and Prestige LP led to supraphysiologic ROM and FF at the index level while decreasing ROM and FF at the adjacent levels. In contrast, Bryan reduced ROM and FF at the index level. Bryan increased ROM and FF at the adjacent levels in flexion, but decreased ROM and FF in the adjacent levels in extension. Prodisc C decreased IDP at the adjacent levels. Bryan reduced IDP in extension only. Prestige LP increased adjacent-level IDP. Conclusions The distinct designs and material compositions of the three artificial discs result in varying biomechanical alterations at the index and adjacent levels in the cervical spine after implantation. The findings confirm the design and material influence on the spine biomechanics, as well as the advantages and contraindications of cervical arthroplasty in general. [GRAPHICS] .