Impact of subaxial cervical spine surgeries on patients' head-cervical spine mobility: measurement with CROM device

Objective: To assess and compare the impact of two different subaxial cervical spine surgeries (four groups) on patients’ postoperative head-cervical spine mobility (HCSM) function. Method: Using the CROM device, postoperative six-direction active cervical range of motion(ACROM) values(°) were measured for 147 patients who underwent 1-3 segment anterior cervical discectomy and fusion surgery (ACDF1; ACDF2; ACDF3) or laminoplasty (LAMP) surgery. ACROM value data were calculated in the HCSM retention rate(%) by compared with the baseline dataset obtained. Results: Both the ACROM value and HCSM retention rate decreased in six directions, with varying degrees of decrease among the groups: 1) Flexion/Extension (F/E): HSCM decreased in the order of ACDF1 (40.13°/48.37°, 85.37%-82.70%), ACDF2 (34.71°/42.24°, 74.99%/73.34%), LAMP (35.10°/42.19°, 75.00%/71.58%) and ACDF3(30.89°/36.81°,65.69%/62.87%), with no significant difference between the ACDF-2 group and LAMP group; 2) Lateral bending (LB): The HCSM function of ACDF1 was the best (33.33°/30.27°, 85.08%/85.32%), followed by ACDF2 and LAMP (30.33°/28.52°,77.84%/79.17%), with ACDF3 being the worst (30.33°/28.52°,77.84％/79.17％); 3) Axial Rotation (AR): The retention rate in ACDF3 was inferior to those of ACDF1, ACDF2, and LAMP (49°VS 53°-59°,75% VS 82%-91%). Conclusions: Subaxial cervical spine surgeries caused varying degrees of HCSM decline in patients. The postoperative HCSM function of patients with ACDF1 and ACDF3 was the best and worst among the four groups, respectively,with HCSM retention rates of 85% -90% and 60% -72%.The retention rates of ACDF2 and LAMP is similar, approximately 75% -80%. The expected postoperative HCSM differences in different subaxial cervical spine surgeries will aid preoperative decision making in the future.