The effect of posterior unilateral exposure and selective channel-assisted laminoplasty in the treatment of multilevel degenerative cervical spondylosis

English Keywords:Laminoplasty  Selective channel-assisted  Unilateral exposure  Effect

English Abstract:

  【Abstract】 Objectives: To evaluate the clinical safety and effectiveness of posterior unilateral exposure and selective channel-assisted laminoplasty(SCA-LP) in the treatment of multi-level degenerative cervical spondylosis and to compare the clinical outcomes of three types of posterior open-door laminoplasty. Methods: A total of 114 patients underwent posterior laminoplasty(LP) from March 2020 to July 2021 were analyzed retrospectively, including 62 males and 52 females, with an average age of 58.27±7.36 years. Among them, there were 52 cases of multilevel cervical spondylotic myelopathy(MCSM), 25 cases of cervical canal stenosis(CCS), and 37 cases of ossification of posterior longitudinal ligament(OPLL). 39 patients received unilateral exposure and SCA-LP (SCA-LP group), 33 patients received unilateral exposure and contralateral paravertebral musle-preserved(MP) LP(MP-LP group) and 42 patients were treated with traditional open-door LP(LP group). The patients were followed up for 12-28 months(18.46±5.75 months). Patient characteristics such as age, gender and body mass index(BMI) were compared between groups. Surgical parameters such as the operative time, blood loss, amount of post-operative drainage, and average length of hospital stay were collected and compared. At before operation, immediately after operation, 2 and 12 months postoperatively, and final follow-up, clnical parameters such as visual analog scale(VAS) assessing neck and arm pains, neck disability index(NDI) assessing cervical function and Japanese Orthopedic Association(JOA) scores assessing neurological status were recorded and compared between groups respectively; and C2-C7 Cobb angle and the cross-sectional area of spinal canal were measured on lateral X-ray films of cervical spine to compare the effects of the three surgical methods on C2-C7 Cobb angle and the increase of spinal canal area(the increase of each segment and the average increase of each patient). Results: There were no significant differences in age, gender and BMI between the three groups(P>0.05). All patients underwent the operation uneventfully, and no serious complications such as nerve injury or infection occurred. MP-LP group was the shortest and LP group was the longest in operative time and average length of hospital stay, and MP-LP group was the smallest and LP group was the biggest in the volume of blood loss and postoperative drainage, with signicant differences(P<0.05). The postoperative NDI and JOA scores of the three groups of patients were significantly improved compared with those before operation(P<0.05), and no significant differences were found in NDI and JOA scores between the three groups before operation, immediately after operation, 2 and 12 months after operation and at the last follow-up(P>0.05). In the LP group, the VAS score of neck pain immediately after operation was higher than that before operation, and at 12 months after operation and final follow-up it was lower than that before operation, and the differences were statistically significant(P<0.05); and no difference was found between 2 months after operation and before operation(P>0.05). In the SCA-LP group and MP-LP group, the VAS score of neck pain immediately after operation was not statistically different from that before operation(P>0.05) and it was significantly lower at 2 months, 12 months after operation and the last follow-up than that before operation(P<0.05). The VAS score of neck pain in the SCA-LP group and MP-LP group was lower than that in LP group immediately after operation and at 2-month follow-up(P<0.05), and there was no significant difference between the three groups at 12 months after operation and the last follow-up(P>0.05). The C2-C7 Cobb angle immediately after operation in the three groups had no significant differences than before operation(P>0.05); In LP group, it was smaller at 2 and 12 months after operation and the last follow-up than before operation(P<0.05). In the SCA-LP group and MP-LP group, at 2 months after operation it was not significantly different from that before operation(P>0.05), and it was significantlly lower at 12 months after operation and the last follow-up than that before operation(P<0.05). There was no significant difference between the three groups in the differences of C2-C7 Cobb angle between before operation and immediately after operation(P>0.05). The C2-C7 Cobb angle in the SCA-LP group and MP-LP group was significantly bigger than that in LP group at 2 and 12 months after operation and the last follow-up(P<0.05). There was no significant difference in the increased percentage of average area of spinal canal between the three groups immediately after operation, 2 and 12 months after operation and at the last follow-up(P>0.05). In the SCA-LP group, C7(100%) of all the patients, C6(30.77%) of 12 patients, and C3(15.38%) of 6 patients needed to make hinge under the channel. The increase of C7 spinal canal area in the SCA-LP group and LP group was larger than that in MP-LP group immediately after operation, 2 and 12 months after operation and the last follow-up(P<0.05); There was no significant difference in the increase of C3-C6 spinal canal area between the three groups(P>0.05). Conclusions: Comparing with LP, the two improved surgical methods can effectively reduce the injury of muscles and ligaments on the hinge side, enhance recovery after surgery, lower the incidence of early postoperative axial neck pain. SCA-LP can increase the area of the spinal canal of operative segment more effectively than MP-LP.