Radiographic Evaluation of Cervical Disk Replacement

Study design This was a retrospective review. Objective Provide a validated method of radiographic evaluation of cervical disk replacement (CDR) patients linked to outcomes. Summary of background data Preoperative radiographic criteria for CDRs and the impact of intraoperative positioning remain without formalized guidelines. The association between preexisting degenerative changes, optimal implant positioning, and patient-reported outcome measures (PROMs) are not well understood. Our study establishes a systematic radiographic evaluation of preoperative spondylosis, implant placement, and associated clinical outcomes. Methods Preoperative radiographs for CDR patients were evaluated for disk height, facet arthrosis, and uncovertebral joint degeneration. Postoperative radiographs were scored based on the position of the CDR implant on anterior-posterior (AP) and lateral radiographs. PROMs including Visual Analogue Scale (VAS) arm pain, VAS neck pain, Neck Disability Index (NDI), Short Form 12 physical health (SF12-PCS) and mental health (SF12-M) were collected preoperatively, at early follow, and at late follow-up. Results A total of 115 patients were included. Preoperative disk height had the highest reliability, intraclass correlation coefficient of 0.798). Facet arthrosis had the lowest intraclass correlation coefficient at 0.563. Preoperative disk height scores showed a significant correlation with AP radiographs and implant positioning score. Patients with more advanced uncovertebral degenerative changes showed less improvement 6 months postoperatively, based on SF-12 PCS scores (R=0.446, P=0.025). Postoperative implant position on lateral radiograph showed a significant correlation with SF-12 MCS scores at follow-up beyond 6 months (R=0.385, P=0.011). Overall postoperative implant position scores demonstrated significant correlation with SF-12 PCS (R=0.350, P=0.046) scores. Conclusion This study provides a systematic method of evaluation of preoperative and intraoperative radiographs that can optimize outcomes. On the basis of our study, spine surgeons performing cervical disk replacement surgery should consider: (a) the presence of preexisting uncovertebral joint degeneration can negatively impact outcomes, (b) achieving optimal implant positioning can be increasingly difficult with more severe loss of disk height, and (c) overall implant position as judged on AP and lateral fluoroscopy can impact outcomes.