Evaluation of the Association between Neck Pain and the Trapezius Muscles in Patients with Cervical Myelopathy Using Motor Evoked Potential: A Retrospective Study

Risk Factors for Postoperative Loss of Lordosis, Cervical Kyphosis, and Sagittal Imbalance After Cervical Laminoplasty

OBJECTIVE

A retrospective cohort study was undertaken to elucidate the risk factors of loss of cervical lordosis (LCL), kyphotic deformity, and sagittal imbalance after cervical laminoplasty.

METHODS

A total of 108 patients who underwent laminoplasty to treat cervical myelopathy and were followed for ≥2 years were included. Logistic regression analysis and multiple regression analysis were performed to identify preoperative risk factors of LCL, kyphotic deformity (cervical lordosis <0°), and sagittal imbalance (sagittal vertical axis >40 mm) at postoperative 2 years.

RESULTS

Within multivariate multiple regression analysis, C2-C7 lordosis (P = 0.002), and C2-C7 extension capacity (P<0.001) showed significant association with LCL. Furthermore, age (P = 0.043) and C2-C7 lordosis (P = 0.038) were significantly associated with postoperative kyphosis. Receiver operating characteristic curve analysis for postoperative kyphosis showed that preoperative C2-C7 lordosis of 10.5° had a sensitivity and specificity of 81.3% and 82.4%, respectively. Preoperative K-line tilt (P = 0.034) showed a significant association with postoperative cervical sagittal imbalance at postoperative 2 years. Receiver operating characteristic curve analysis showed that a K-line tilt cutoff value of 12.5° had a sensitivity and specificity of 78.6% and 77.7%, respectively, for predicting postoperative sagittal imbalance.

CONCLUSIONS

Higher preoperative C2-C7 lordosis and less preoperative cervical extension capacity were risk factors of LCL. Small preoperative C2-C7 lordosis <10.5° and younger age were risk factors of postoperative kyphosis. Furthermore, a greater K-line tilt would increase the risk of postoperative sagittal imbalance, with a cutoff value of 12.5°.

Axial Neck Pain after Cervical Laminoplasty with Preserving C7 Spinous Process Using C7 Arcocristectomy: A Prospective Study

STUDY DESIGN

Single-blinded, randomized, single-center, prospective study.

PURPOSE

This study aims to compare the radiographical and clinical outcomes between C7 laminoplasty and C7 arcocristectomy, which preserves the C7 spinous process.

OVERVIEW OF LITERATURE

Laminoplasty is a widely used surgical method that decompresses the cervical spinal cord. However, axial neck pain is one of the major factors of dissatisfaction, and still, it is not clearly solved the reduction method of postoperative axial neck pain.

METHODS

Thirty-one patients with multilevel cervical spondylotic myelopathy who required C6-C7 level decompression surgery were operated and followed up for 24 months. One group (15 patients) received C7 arcocristectomy without laminoplasty, and the other group (16 patients) received C7 laminoplasty. Flexion, neutral, and extension angles were measured using the Cobb method at C2-C7 to evaluate preoperative and postoperative radiographic parameters. Range of motion (ROM), ROM preservation rate of the cervical spine, C2-C7 sagittal vertical axis (SVA), and T1 slope were measured using C-spine lateral X-ray. The Visual Analog Scale (VAS) and modified Japanese Orthopedic Association (JOA) score were used to compare preoperative and postoperative clinical symptoms.

RESULTS

Flexion, neutral, extension angles of the cervical spine, C2-C7 SVA, T1 slope, ROM, ROM preservation rate, and modified JOA score were not significantly different between the two groups (p>0.05). In the C7 arcocristectomy group, the average postoperative VAS for axial neck pain was increased in 13.3% (2/15) of the patients, whereas in the C7 laminoplasty group, the average postoperative VAS was increased in 43.8% (7/16) of the patients (p=0.018).

CONCLUSIONS

C7 arcocristectomy, which preserves the C7 spinous process and posterior structures, is a useful technique for relieving axial neck pain.

Anatomical considerations for appropriate mini-plate positioning in open-door laminoplasty to avoid plate impingement and screw facet violation

This study aimed to describe a safe zone for mini-plate positioning that can avoid instrument-related complications in laminoplasty. Fifty-one patients who underwent laminoplasty and were followed up for at least 1 year were retrospectively reviewed. The posterior surface length and inferior pole angle of the lateral mass were measured at each level using computed tomography. The safe zone was defined based on these measurements. Incidences of screw facet violation and plate impingement were recorded. Patient-reported outcome measures were compared between the appropriate position (AP) and inappropriate position (IP) groups. Among 40 patients included, 15 (37.5%) had inappropriate plate positioning, causing screw facet violation or plate impingement, which more commonly occurred at distal (C5, C6) and proximal (C3, C4) levels, respectively. Lateral mass posterior surface length was shorter at the proximal levels, and the inferior pole angle of the lateral mass was smaller at the distal levels, signifying that the lateral mass became thin and long at the distal levels. Patient-reported outcome measures were not significantly different between the two groups. However, cervical range of motion at the final follow-up was significantly less in the IP group (p = 0.01). The suggested safe zone demonstrates that inserting the mini-plate with plate-to-lateral mass inferior pole distances of 4–5 mm and 5–6 mm at the C3–C5 and C6–C7 levels, respectively, would avoid instrument-related complications. The risk of plate impingement was higher at the proximal level, whereas the risk of screw facet violation was higher at the distal level in open-door cervical laminoplasty. These risks coincide with anatomical differences at each level. Despite inappropriate positioning of the mini-plate, clinical outcomes were not adversely affected.