The Surgical Learning Curve for Cervical Disk Replacement

Study Design: Retrospective study. Objective: To characterize an experienced single surgeon learning curve for cervical disk replacement (CDR). Summary of Background Data: A single surgeon learning curve has not been established for CDR. Methods: Patients undergoing CDR were included. The cumulative sum of operative time was utilized to separate cases into 3 phases: learning, practicing, and mastery. Demographics, perioperative characteristics, complications, patient-reported outcomes (PROs), and radiographic outcomes were collected preoperatively and up to 1 year postoperatively. PROs included Patient-reported Outcomes Measurement Information System Physical Function, 12-item Short Form-12 Physical Component Score, 12-item Short Form-12 Mental Component Score, visual analog scale (VAS) arm, VAS neck, Neck Disability Index. Radiographic outcomes included segmental angle/segmental range of motion/C2-C7 range of motion. Minimum clinically important difference achievement was determined through a comparison of previously established values. Results: A total of 173 patients were identified, with 14 patients in the learning phase, 42 patients in the practicing phase, and 117 patients in the mastery phase. Mean operative time and mean postoperative day 0 narcotic consumption were significantly higher in the learning phase. The preoperative segmental angle was significantly lower for the learning phase, though these differences were eliminated at the final postoperative time point. Patients in the learning phase reported worse improvement to 6-week postoperative, final postoperative, and worse overall final postoperative VAS Arm scores compared with practicing and mastery phases. Conclusions: For an experienced spine surgeon, the learning phase for CDR was estimated to span 14 patients. During this phase, patients demonstrated longer operative times, higher postoperative narcotic consumption, and worse postoperative VAS Arm scores. Radiographically, no postoperative differences were noted between different phases of mastery. This single surgeon learning curve demonstrates that CDR may be performed safely and with comparable outcomes by experienced spine surgeons despite decreased operative efficiency in the learning phase.