Impact of T1 Slope as a Predictor of Loss of Cervical Lordosis and Health-Related Quality of Life After Laminoplasty in Patients with Ossification of the Posterior Longitudinal Ligament : A Retrospective Cohort Study.

Objective: This study aimed to identify risk factors predicting the loss of cervical lordosis (LCL) in patients with multilevel ossification of the posterior longitudinal ligament (OPLL) after laminoplasty. Additionally, we evaluated the impact of these factors on health-related quality of life (HRQOL).

Methods: We retrospectively analyzed data from patients who underwent laminoplasty at XX University Hospital between January 2013 and December 2022. A range of radiological parameters and clinical outcome measures were collected perioperatively. Patients were divided into 2 groups based on the severity of LCL. We then evaluated preoperative radiological parameters associated with LCL and clinical outcomes, including HRQOL.

Results: A total of 110 patients (93 men and 17 women; mean age, 61.31 ± 10.80 years) were included in the analysis. A higher T1 slope (T1S) (β = -0.412, p=0.004) and a lower extension ratio (β = 0.107, p=0.006) were associated with an increased risk of LCL. T1S proved to be an excellent predictor of LCL, with a cutoff value of 28° (p < 0.001, area under the curve = 0.918). Furthermore, T1S was the only factor significantly correlated with HRQOL after laminoplasty (r = -0.330, p<0.001).

Conclusion: T1S was significantly associated not only with LCL but also with HRQOL among patients with multilevel OPLL after laminoplasty. With a T1S cutoff of 28°, a T1S exceeding this threshold can be considered an important prognostic factor when planning laminoplasty in these patients.