Correlation between axial symptoms and cervical sagittal alignment parameters in patients with two-level or three-level cervical spondylotic myelopathy: anterior cervcial discectomy and fusion versus hybird surgery.

OBJECTIVE

To comparatively analyze the correlation between axial symptoms (AS) and cervical sagittal alignment parameters after anterior cervical discectomy and fusion (ACDF) and hybrid surgery (HS).

METHODS

From January 2018 to June 2023, 74 patients who underwent ACDF (n = 36) or HS (n = 38) for two-level or three-level cervical spondylotic myelopathy were retrospectively analyzed. The Visual Analogue Scale (VAS), Japanese Orthopedic Association (JOA), Neck Disability Index (NDI) were recorded to assess clinical outcomes. Cervical sagittal alignment parameters (Cobb's angle C2-7, C7 slope [C7S], and C2-7 sagittal vertical axis [C2-7 SVA]) were measured preoperatively, 3 days postoperatively, and at the last follow-up. The range of motion (ROM) of C2-7 and ROM of surgical segment were measured. The occurrence of AS was observed at the last follow-up. Logistic regression was used to analyze the correlation between postoperative AS and cervical sagittal alignment parameters.

RESULTS

Both in ACDF group and HS group, VAS, JOA and NDI scores showed significant improvements at 3-day postoperation and at the last follow-up (P < 0.05). However, there was no significant difference between the two groups (P > 0.05). The Cobb's angle C2-7 and C7S were significantly increased at 3 days postoperation compared with pre-operatively in both groups (P < 0.05). C2-7SVA was increased in both groups 3 days after surgery compared with pre-operatively, but there was no significant difference (P > 0.05). At the last follow-up, the ROM of C2-7 in ACDF group was significantly smaller than HS group (P < 0.05). The prevalence of postoperative AS in the ACDF group and HS group was 41.7 and 18.4%, respectively, with statistical difference between the two groups (P < 0.05). When simple Logistic regression analysis was used, the last Cobb's angle C2-7 (β = -0.088), the last C2-7SVA (β = 0.099) in ACDF group and the last C2-7SVA (β = 0.222) in HS group were all correlated with the occurrence of postoperative AS. When multiple Logistic regression analysis was used, only the last C2-7SVA (β = 0.181) in the HS group was positively correlated with the occurrence of postoperative AS.

CONCLUSIONS

Both ACDF and HS can achieve satisfied clinical outcomes. ACDF and HS can improve cervical sagittal balance to a certain extent, and HS is superior to ACDF in maintaining ROM. The decrease of the last Cobb's angle C2-7 and the increase of the last C2-7SVA may be related to the occurrence of AS after ACDF. The increase of the last C2-7SVA was an independent risk factor for the occurrence of AS after HS.