@article{MehrenHeiderSaueretal.2019,
  author    = {Mehren, Christoph and Heider, Franziska and Sauer, Daniel and Kothe, Ralph and Korge, Andreas and Hitzl, Wolfgang and W{\"u}rtz-Kozak, Karin},
  title     = {Clinical and radiological outcome of a new total cervical disc replacement design},
  series = {Spine},
  volume    = {44},
  journal   = {Spine},
  number    = {4},
  publisher = {Lippincott Williams \& Wilkins},
  address   = {Philadelphia},
  issn      = {0362-2436},
  doi       = {10.1097/BRS.0000000000002799},
  pages     = {E202 -- E210},
  year      = {2019},
  abstract  = {Study Design. A nonrandomized, prospective, and single- center clinical trial of the ProDisc Vivo prosthesis. Objective. The aim of this study was to investigate the clinical and radiological results of a refined total cervical disc replacement (cTDR), the ProDisc Vivo, with two years of follow-up (FU). The incidence of implant-related complications was recorded as a secondary outcome variable. Summary of Background Data. Previous generations of the ProDisc artificial cervical disc replacement generate high primary stability due to keel-based designs with opening of the anterior cortex during the implantation and subsequent high rates of heterotopic ossifications. Methods. Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), arm and neck pain self-assessment questionnaires. The radiological outcome included the range of motion (ROM) and the occurrence of heterotopic ossifications. The incidence of implant-related complications with new implant design was recorded as a secondary outcome variable. Results. A total of 55 patients received a single-level treatment with the ProDisc Vivo cTDR between C3/4 and C6/7, with a follow-up rate of 78\%. The clinical outcome scores improved in all parameters significantly (P 1/4 0.0001) (NDI: 68.3 -> 17.4; VAS arm: 6.3 -> 1.4; VAS neck: 4.9 -> 1.6). The ROM of the indexsegment did not show a significant change (P 1/4 0.26) (7.9 degrees -> 9.2 degrees). Heterotopic ossifications at the index segment was found as grade 0 in 5\%, grade 1 in 22\%, grade 2 in 10\%, grade 3 (with functional impairment of the prosthesis) in 7\%, and grade 4 in 3\% of the cases. We observed three implant-related complications (5.5\%), with two implant dislocations anteriorly and one low-grade infect. Conclusion. cTDR with ProDisc Vivo demonstrated a significant and sustained improvement of all clinical outcome parameters. A less invasive implantation mechanism with lower primary stability of the cTDR might be a reason for a higher dislocation rate than the keel-based previous generation ProDisc C.},
  language  = {en}
}
@article{MehrenWuertzKozakSaueretal.2019,
  author    = {Mehren, Christoph and Wuertz-Kozak, Karin and Sauer, Daniel and Hitzl, Wolfgang and Pehlivanoglu, Tuna and Heider, Franziska},
  title     = {Implant Design and the Anchoring Mechanism Influence the Incidence of Heterotopic Ossification in Cervical Total Disc Replacement at 2-year Follow-up},
  series = {Spine},
  volume    = {44},
  journal   = {Spine},
  number    = {21},
  publisher = {Lippincott Williams \& Wilkins},
  address   = {Philadelphia},
  issn      = {0362-2436},
  doi       = {10.1097/BRS.0000000000003098},
  pages     = {1471 -- 1480},
  year      = {2019},
  abstract  = {Study Design. A nonrandomized, prospective, and single-center clinical trial. Objective. The aim of this study was to determine whether the prosthesis design, and especially changes in the primary anchoring mechanism between the keel-based ProDisc C and the spike-based ProDisc Vivo, affects the frequency of heterotopic ossification (HO) formation over time. Summary of Background Data. The occurrence of motion-restricting HO as well as underlying risk factors has so far been a widely discussed, but not well understand phenomenon. The anchoring mechanism and the opening of the anterior cortex may be possible causes of this unwanted complication. Methods. Forty consecutive patients treated with the ProDisc C and 42 consecutive patients treated with the ProDisc Vivo were compared with respect to radiological and clinical outcome, with 2 years of follow-up. Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), and arm and neck pain self-assessment questionnaires. Radiological outcomes included the segmental lordosis and range of motion (ROM) of the index-segment as well as the occurrence of HO. Results. The clinical outcome parameters improved in both groups significantly. [ProDisc C: VAS arm and neck pain from 6.3 and 6.2 preoperatively to 0.7 and 1.3; NDI from 23.0 to 3.7; ProDisc Vivo: VAS arm and neck pain from 6.3 and 4.9 to 1.4 and 1.6, NDI from 34.1 to 8.7; 2-year follow-up (FU)]. The ProDisc Vivo cohort demonstrated a significantly lower incidence of HO than the ProDisc C group at 1-year FU (P = 0.0005) and 2-year FU (P = 0.005). Specifically, high-grade HO occurred in 9\% versus 31\%. Conclusion. These findings demonstrate that prosthesis designs that allow primary anchoring without violation of the cortical surface help to reduce the incidence of severe ossification, possibly affecting the functionality and mobility of the artificial disc device over of time.},
  language  = {en}
}