Cervical Lordosis Ratio as a Novel Predictor for the Loss of Cervical Lordosis After Laminoplasty

Abstract

Objective: Maintaining cervical lordosis (CL) after laminoplasty is important for indirect decompression of the spinal cord. This study aimed to identify preoperative dynamic radiographic predictors for the loss of CL after laminoplasty. Methods:We retrospectively analyzed 141 consecutive patients who underwent cervical laminoplasty for cervical myelopathy. The following radiographic parameters were measured before surgery and at 1-year of follow-up: CL, C7 slope, C2-7 sagittal vertical axis (SVA), C2-7 range of motion (ROM), CL in flexion, CL in extension, ROM of flexion (Flex ROM), and ROM of extension. The CL ratio (CLR) was defined as 100 × Flex ROM/C2-7 ROM. ΔCL was defined as postoperative CL -preoperative CL.Patients were classified into two groups: group K (kyphotic change group, ΔCL ≤-10) and group C (control group, ΔCL >-10). Results:The patient population comprised 94 men and 47 women (mean age, 70.9 ± 9.4 years), with 24 patients (17.0%) classified into group K. CL, C7 slope, and CLR were significantly higher in group K than in group C. The groups did not significantly differ in age, sex, C2-7 SVA, and C2-7 ROM. On multivariable analysis, the CLR was significantly associated with postoperative kyphotic changes. On receiver-operating characteristic curve analysis (area under the curve = 0.717, P <0.001), the cut-off value for CLR was 68.9%, with sensitivity and specificity of 87.5% and 57.3%, respectively. Conclusion:The CLR, reflecting the balance between flexion and extension mobility, was identified as a novel predictor for CL loss after laminoplasty, with a cut-off value of 68.9%.

Effect of preoperative dynamic cervical sagittal alignment on the loss of cervical lordosis after laminoplasty

“…Our study reported a high negative correlation between Ext ROM and LCL, which implies that enough Ext ROM is a highly reliable factor in preventing LCL after CLP. Similar to the results of previous studies [10,17,[28][29][30], our study shows the positive correlation between Flex ROM and LCL. Cervical exion mobility is blocked by degenerative structures, such as bone, ligaments, or muscles.…”

“…LCL was de ned as preoperative CL -postoperative CL. Patients were classi ed into the following three groups according to the LCL [10,20]: stability group: (LCL ≤ 5°); mild loss group (5° < LCL ≤ 10°); and severe loss group (LCL > 10°). The owchart of study is displayed in Fig.…”

“…Therefore, prevention of LCL and investigation of its risk factors after CLP are necessary. Several studies have reported many preoperative predictors of LCL after laminoplasty [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. and the relationship between static cervical sagittal alignment and kyphotic changes has been well described [5-8, 12, 14, 16, 17, 19-21].…”

“…and the relationship between static cervical sagittal alignment and kyphotic changes has been well described [5-8, 12, 14, 16, 17, 19-21]. However, only a few of those studies focus on preoperative dynamic cervical sagittal alignment [10,13,15] and the study of different degrees of LCL is lacking.…”

Commentary on “Surgical and Functional Outcomes of Expansive Open-Door Laminoplasty for Patients With Mild Kyphotic Cervical Alignment”

“…Recently, many dynamic concepts, not static concepts, have been presented in laminoplasty studies. 10,11 Now, we need to develop an extended indication that can be safely applied laminoplasty to more patients, rather than simply limiting mild kyphotic alignment as a contraindication. Dr Nagoshi and colleagues 1 well explained the tendency of mild kyphosis patients to change to a lordotic curve after laminoplasty and relatively good clinical results.…”