Purpose: The cervical lordosis ratio (CLR), an index of cervical hyperextension and hyperflexion, was used to validate the posterior approach selection strategy in patients with multisegmental cervical spondylotic myelopathy. (MCSM).
Methods:A retrospective review of 141 patients who had undergone posterior cervical surgery for MCSM in our hospital between December 2015 and March 2020 was conducted, with 63 patients receiving laminectomy and fusion (LCF group) and 78 patients receiving laminoplasty (LP group).The demographic characteristics of the two groups (gender, age, BMI, and follow-up time) were compared. C2-7 Cobb angle (CL), C2-7 range of motion (C2-7ROM), flexion Cobb angle (flexCL), extension Cobb angle (extCL), flexion range of motion (flexROM), and extension range of motion (extROM) were compared between the two groups (extROM). The clinical effect indices of the two groups, including the JOA and VAS scores, were compared. The C2-7cobb angle difference before and after operation (ΔCL), namely postoperative C2-7 Cobb angle (postCL) - preoperative C2-7 Cobb angle (preCL), was used to assess cervical lordosis alignment change . Calculate the cervical lordosis ratio (CLR) using 100% flexROM/C2-7ROM.The function of the CLR ratio in predicting postoperative severe cervical lordosis loss (CL -10) was evaluated using ROC curve analysis. All patients were separated into a low ratio group (L-CLR) and a high ratio group(H-CLR) based on the critical value of the CLR ratio (68.5%). The cervical lordosis alignment index and clinical impact index between the two operation groups were once more analyzed in these two ratio groups. The differences of various indicators between the two operating groups and the corresponding indicators between different ratio groups were assessed and compared using an independent sample t-test.
Results: Cervical lordosis alignment index decreased significantly after LCF and LP (p=0.039,p=0.002), and cervical lordosis alignment change(ΔCL) in LP group was greater than that of LCF group (p=0.043), and the difference between the two groups was statistically significant (p=0.043). According to ROC curve analysis, the CLR ratio can predict severe cervical lordosis alignment change (ΔCL≥-10) with great precision (AUC=0.792). There was no significant difference in cervical lordosis alignment change (CL) between the LCF and LP groups in the L-CLR group (p=0.141). The CL of the LP group in the H-CLR group was greater than that of the LCF group (P(ΔCL≥ -10), which had a higher probability of postoperative severe cervical lordosis alignment change (42.6%,28.5%).
Conclusions: The cervical lordosis ratio could be used as a decision-making index for the choice of posterior surgery approach for multisegmental cervical spondylotic myelopathy. Laminoplasty could be considered in the low ratio group, while laminectomy and fusion could be considered in the high ratio group.