LAUSR

Cervical disc arthroplasty (CDA) is a surgical option for patients with cervical radiculopathy symptoms that have failed conservative management. CDA has a lower incidence of adjacent segment disease as well as reoperation rates. Proper surgical technique is critical for success of CDA surgery. The aim of this study was to investigate whether implant positioning has an impact on the outcomes of CDA surgery. Following local Institutional Review Board (IRB) approval, a retrospective study was conducted on consecutive patients undergoing CDA with the Mobi-C implant (Zimmer Biomet, IN) between January 2016 and December 2018. Immediately postoperative lateral and AP radiographs were assessed by 3 spine surgeons for implant positioning. Our scoring criteria included rotational, sagittal, and coronal placement as well as size matching. AP and lateral radiographs were scored independently and the overall postoperative score was calculated as the sum of the 2 scores. The overall postoperative score was correlated with 5 patient reported outcomes measures (PROMS); Visual Analogue Scale (VAS) arm, VAS neck, Neck Disability Index (NDI), and Short Form 12 Physical health (SF12-P) and mental health (SF12-M). Radiographs of 85 patients, and 110 levels, that underwent CDA were assessed. Of those, 41 patients were excluded from the PROMS analysis due to inadequate follow-up. Inter-rater reliability for radiographic assessment was good to excellent. Mean follow-up was 8 mo and ranged from 6 to 24 mo. The overall implant positioning scores showed strong correlation with NDI and SF12-P outcomes measures at latest follow up (P = .007, P = .028, respectively). Proper implant sizing and implant rotational and translational positioning have a significant impact on functional and disability outcomes of patients undergoing CDA surgery. Further research is warranted to investigate other parameters that affect the outcomes of CDA surgery.