151 - Comparison of Cervical Sagittal Alignment and Kinematics after Posteri...

General Session: MIS-1

Presented by: C.H. Kim - View Audio/Video Presentation (Members Only)


C.H. Kim(1), C.K. Chung(1)

(1) Seoul National University Hospital, Neurosurgery, Seoul, Korea, Republic of


Background: The progression of cervical kyphosis due to injury to the facet joints and musculature is a major concern for posterior foraminotomy especially for patients with cervical lordosis of less than 10°. However, cervical hypo-lordosis (cervical lordosis < 10°) may be improved with the alleviation of pain and muscle spasms, which corresponds with the disappearance of a positive Spurling's test. When surgery is necessary, the spontaneous recovery of cervical curvature may be minimally offset using minimally invasive surgical techniques, such as posterior percutaneous endoscopic cervical foraminotomy (P-PECF).

Objectives: The primary objective was to compare the changes in cervical kinematics between patients with cervical lordosis (≥10°, group I) and hypo-lordosis (< 10°, group II) after P-PECF.

Study Design: This study was a retrospective nested case-control study with the IRB No. H-1210-078-434. Setting: University medical Center, Seoul, Korea.

Methods: P-PECFs were performed for patients with a radiculopathy due to single-level unilateral cervical foraminal soft-disc herniations or foraminal stenosis with minimal degeneration of the disc/facet joints and a positive Spurling's test. A retrospective nested case-control study was performed for 23 patients with cervical lordosis of ≥ 10° (group I; M:F=15:8; age, 52.3±9.8 years) and 23 patients with cervical lordosis of < 10° (group II; M:F=15:8; age, 46.3±12.7 years). P-PECFs were performed using the methods previously reported, and all patients were discharged the next day without limitations of neck motion. The patients were followed at 1, 3, 6 and 12 months postoperatively and yearly thereafter. The follow-up period was 25.8±19.6 months. Clinical outcomes were assessed using the visual analogue pain score of arms. The cervical angles (C2-7, tangential method) were measured on neutral (CA), flexion (CAF) and extension (CAE) lateral radiographs, and range of motion (C-ROM) was calculated by conducting a radiological analysis. A linear mixed model was used to assess the linearity of the changes in cervical curvatures during the postoperative 12 months between the groups.

Results: Significant reductions in arm pain and negative results on Spurling's test were initially achieved in 21/23 patients in group I and in 23/23 patients in group II with means of 1.7 ± 0.31 months and 1.09 ± 0.09 months, respectively. Using the mixed effect models, the interactions between group and time were significant for the CA (p= 0.004), CAE (p< 0.001), and C-ROM (p< 0.001) but not the CAF (p=0.392). The CA (adjusted-p < 0.001), CAE (adjusted-p < 0.001) and C-ROM (adjusted-p = 0.046) exhibited significant between-group differences at the pre-operation. However, during the follow-up, these parameters were significantly changed in group II, especially during the postoperative 3 months. The CA, CAE and C-ROM changed by -11.73°, -19.87° and 20.32°, respectively. Postoperatively, 17/23 patients in group II and 22/23 patients in group I exhibited cervical lordosis of ≥ 10°. Limitations: This study was retrospective in design, and the inherent selection bias and limited statistical power should be considered.

Conclusions: Cervical hypo-lordosis less than 10° may not be a contra-indication for P-PECF when the change of cervical curvature is not a structural change. A larger study is necessary to identify prognostic factors.