Multivariate analysis of factors associated with spinal cord area in single-door cervical laminoplasty with miniplate fixation

Objectives

To explore the factors associated with the increased spinal cord area in single-door cervical laminoplasty (SDCL) with miniplate fixation.

Methods

A retrospective study enrolled 83 patients underwent SDCL with miniplate fixation and the patient characteristics such as age, gender, tobacco use, alcohol use, diabetes mellitus, hypertension, diagnosis, operative level, etc., were obtained. The opening angle, door shaft position and spinal canal area of the patients were measured after surgery. The sagittal canal diameter (SCD), the C2–7 Cobb angle, the cervical curvature index (CCI), the range of motion (ROM) and the spinal canal area were measured before and after operation. The increased cervical spinal cord area was also measured before and after surgery, and the correlation between the above indicators and the increased cervical spinal cord area was studied through Pearson’s correlation analysis and multivariate logistic regression analysis.

Results

There were 34 patients in small spinal cord area increment group (SAI group), 29 patients in middle spinal cord area increment group (MAI group) and 20 patients in large spinal cord area increment group (LAI group). The preoperative diagnosis(P = 0.001), door shaft position (P = 0.008), preoperative spinal canal area (P = 0.004) and postoperative spinal canal area (P = 0.015) were significant different among the 3 groups. The multivariate analysis showed that the preoperative diagnosis (OR = 2.076, P = 0.035), door shaft position (OR = 3.425, P = 0.020) and preoperative spinal canal area (OR = 10.217, P = 0.009) were related to increased spinal cord area.

Conclusions

The preoperative diagnosis, door shaft position and preoperative spinal canal area might be associated with increased spinal cord area after cervical laminoplasty with miniplate fixation. Preoperative symptoms are mostly caused by compression of the spinal cord, so spinal cord area enlargement can bring a better recovery in patients alongside long-term. Spine surgeons should pay more attention to the accuracy of the preoperative diagnosis, the preoperative measurement of spinal canal area and the door shaft position during the operation.

A modified cutting line in the single-door cervical laminoplasty via a computed tomography-based morphological study of the subaxial cervical spine

OBJECTIVE

To modify the conventional methods of grooving and direction during the single-door cervical laminoplasty (SDCL) in the subaxial cervical spine.

METHODS

The distance between the left and the right lamina-lateral mass junction at the upper, middle, and lower levels of each segment (DLL-U, DLL-M, DLL-L), angle between the posterior edge of the vertebral body and the lamina (AVL) and thickness of lamina (TL) were measured in the transverse plane. The parameters of preoperative computed tomography scans of 200 patients who had undergone SDCL were measured. The patients were divided into male and female groups and developmental canal stenosis (DCS) and non-DCS (NDCS) groups.

RESULTS

DLL-M gradually increased from the cranial to the caudal except for C7, and DLL-L > DLL-M > DLL-U in each vertebra. AVL increased from C3 to C7, TL decreased from C3 to C5 and increased from C5 to C7, with both parameters showing no significant differences between the left and right sides. AVL of the DCS group was less than that of the NDCS group (P < 0.01).

CONCLUSIONS

In the SDCL, the ideal surgical trough should be several discontinuous lines sloping from top to bottom, rather than a straight line. The abduction angle during drilling should gradually increase from C3 to C7 in the SDCL averaging 40 degrees. This method mentioned above improves the efficiency of the operation with less blood loss as an extended cut into the lateral mass is avoided.

Nomogram for predicting kyphotic deformity after laminoplasty in cervical spondylotic myelopathy patients without preoperative kyphotic alignment

BACKGROUND

Kyphotic deformity occurrence after cervical laminoplasty is not rare. Several studies have emphasized the development of postoperative kyphotic deformity (PKD) will impair the functional outcome of cervical laminoplasty. We established and validated a nomogram prediction model for kyphotic deformity after laminoplasty in cervical spondylotic myelopathy patients (CSM) without preoperative kyphotic alignment.

METHODS

Preoperative and 1-year postoperative data of 369 patients who underwent single-door cervical laminoplasty (SDCL) at the author's hospital between July 2010 and February 2018 were collected. Using the least absolute shrinkage and selection operator (LASSO) method, significant parameters were selected to develop a nomogram prediction model. The prognostic performance of the model was evaluated using concordance index (C-index) and calibration curve. The discriminatory ability of the prediction model was evaluated by the area under (receiver operating characteristic) curve (AUC).

RESULTS

Of the 369 patients, 31 developed PKD in 1 year after the surgery. Using the LASSO regression, six significant variables composed the final model: age, C2-7 sagittal vertical axis, C7 slope, C2-7 angle, flexion range of motion and operation level were selected. The AUC of the nomogram was 0.771. The C-index for the prediction nomogram was 0.771 (95 % CI: 0.672-0.870). The calibration curve also indicated good consistency.

CONCLUSION

A nomogram for predicting PKD after SDCL was established and validated. For patients evaluated by this model with predictive high risk of developing postoperative kyphosis, an alternative approach to the subaxial cervical spine such as anterior surgery should be considered.