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

Abstract

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.

Keywords: Door shaft position; Single-door cervical laminoplasty; Spinal canal area; Spinal cord area.

Fig. 1

Measurement of opening angle (A), and door shaft position (B, C). The door shaft position is in the inner edge of the Lateral Mass, which is further outside than the side opening bone slot, this is defined as the wide opening group (B). The door shaft position is located in the lateral quarter of the lamina, which is defined as the narrow opening group (C)

Fig. 2

The spinal canal area before and after the operation (A, B)

Fig. 3

On the lateral radiograph of cervical spine, we measured the SCD of the C3-C7 segments and used the mean SCD [(a + b + c + d + e)/5] to evaluate the space of spinal canal before and after the operation (A, B), the C2–7Cobb Angle before and after the operation (C, D), the ROM before operation (β1 + β2) and the postoperative (β3 + β4) (E, F, G, H), the CCI before and after the operation, CCI = (a1 + a2 + a3 + a4)/A (I, J)

Fig. 4

Preoperative spinal cord area at C4–5 levels(A), the postoperative spinal cord area at C4–5 levels(B)

Fig. 5

A 65 years old man patient. Preoperative X-ray plain film and middle sagittal film of magnetic resonance showed the cervical spine canal stenosis and the spinal cord compression (A–C). Preoperative X-ray plain film and middle sagittal film of magnetic resonance showed cervical canal expansive, spinal cord decompression and good miniplate fixation (D–F)