Factors predicting loss of cervical lordosis following cervical laminoplasty: A critical review

Abstract

Background: Laminoplasty is a method of posterior cervical decompression which indirectly decompresses the spinal column. Unfortunately, many patients undergoing laminoplasty develops postoperative loss of cervical lordosis (LCL) or kyphotic alignment of cervical spine even though they have sufficient preoperative lordosis which results in poor surgical outcome. Objective: We would like to highlight the relationship between various radiological parameters of cervical alignment and postoperative LCL in patients undergoing laminoplasty. Methods: We performed extensive literature search using PubMed, Google Scholar, and Web of Science for relevant articles that report factors affecting cervical alignment following laminoplasty. Results: On reviewing the literature, patients with high T1 slope have more lordotic alignment of cervical spine preoperatively. They also have more chances of LCL following laminoplasty. C2–C7 sagittal vertical axis (SVA) has no role in predicting LCL following laminoplasty though patients with low T1 slope (≤20°) and high C2–C7 SVA (>22 mm) had correction of kyphotic deformity following laminoplasty. C2–C7 lordosis, Neck Tilt, cervical range of motion, and thoracic kyphosis has no predictive value for LCL. Lower value of T1 slope (T1S-CL) and CL/T1S has more incidence of developing LCL following laminoplasty. The role of C2–C3 disc angle has not yet been evaluated in patients undergoing laminoplasty. Dynamic extension reserve determines the contraction reserve of SPMLC and lower dynamic extension reserve is associated with higher chances of LCL following laminoplasty. Conclusions: Cervical lordotic alignment is important in maintaining cervical sagittal balance which ultimately is responsible for global spinal sagittal balance and horizontal gaze. Among various radiological parameters, T1 Slope has been reported to be the most important factor affecting cervical alignment following laminoplasty.

True Continuous Segment of Ossification of Posterior Longitudinal Ligament is Protective Against Postoperative Early Kyphosis Progression After Laminoplasty

“…12,33 Our analysis indicates a positive correlation between preoperative cervical lordosis and LoL, a result that invites further debate as it contrasts with previous studies suggesting a significant correlation between small preoperative cervical lordosis and postoperative kyphosis progression. 18,[34][35][36] Furthermore, our logistic regression analysis revealed a negative correlation between preoperative extension C2-7 Cobb angle and kyphosis progression, reinforcing the widely accepted concept that extension capacity correlates negatively with LoL or kyphosis progression. 16,34,37 Despite many advantages on LP, a balanced perspective is vital.…”

“…18,[34][35][36] Furthermore, our logistic regression analysis revealed a negative correlation between preoperative extension C2-7 Cobb angle and kyphosis progression, reinforcing the widely accepted concept that extension capacity correlates negatively with LoL or kyphosis progression. 16,34,37 Despite many advantages on LP, a balanced perspective is vital. Some report that mixed or continuous OPLL types are more prone to progression.…”

“…Second, certain parameters were excluded from our study due to specific constraints. We could not include the T1 slope, frequently associated with LoL in cervical alignment studies involving LP, 16,34 due to challenges visualizing the T1 upper endplate in many cases. Given that C2 slope cannot be a direct substitute for T1 slope, this omission represents a study limitation.…”

Preoperative Range of Motion in Extension May Influence Postoperative Cervical Kyphosis After Laminoplasty

“…Preoperative T1S and C2-C7 SVA are considered predictors of cervical kyphosis after cervical surgery. [16][17][18][19] High T1S values are associated with a poorer ability to compensate for and adjust cervical sagittal malalignment, and vice versa. 20 The reported incidence of postoperative kyphosis in patients with a high preoperative T1S undergoing laminoplasty is as much as 15.4%, whereas only 8% of such patients with a low preoperative T1S have postoperative kyphosis.…”

“…Preoperative T1S and C2–C7 SVA are considered predictors of cervical kyphosis after cervical surgery 16–19 . High T1S values are associated with a poorer ability to compensate for and adjust cervical sagittal malalignment, and vice versa 20 .…”