Is cervicothoracic ossification of the posterior longitudinal ligament a distinct clinicoradiological variant? A critical analysis of neurological recovery predictors.

Abstract

Ossification of the posterior longitudinal ligament (OPLL) extending to the cervicothoracic junction presents unique surgical challenges since it represents a transitional zone between the changes in the mobile lordotic cervical spine and a relatively stiff thoracic spine. The literature on cervicothoracic OPLL is limited, and it is unclear whether it differs from subaxial OPLL in terms of radiological characteristics and postoperative outcomes. In this study, the authors aimed to analyze clinicoradiological outcomes and factors predicting neurological recovery in patients who underwent surgery for symptomatic cervicothoracic OPLL. This retrospective study included patients with symptomatic cervicothoracic OPLL who underwent posterior instrumented laminectomy from April 2017 to April 2022 with a minimum follow-up of 2 years. Preoperative imaging included CT-based axial morphology classification (hill, mushroom, plateau), canal occupying ratio (COR), and MRI evaluation of cord signal changes. Clinical parameters, including the modified Japanese Orthopaedic Association score, Nurick grade, hand myelopathy signs, and bladder dysfunction, were recorded. The recovery rate (RR) was calculated using Hirabayashi's formula. Of 53 patients, most were male (81.1%), with a mean age of 55.2 years at presentation. Nurick grade 5 was the most common grade observed, accounting for 34.0% of patients. Hand myelopathy signs were absent in 30.2% of patients. Overall, 28 patients experienced poor recovery (RR < 50%) and 25 had good recovery (RR ≥ 50%). Hill-type morphology was significantly linked to poor outcomes (p = 0.022), and the mean COR was higher in the poor recovery group (67.54 ± 9.74 vs 55.32 ± 11.94, p = 0.001). Univariate analysis identified ossification type, morphology, and COR as significant predictors of RR, while multivariate regression confirmed COR as the only independent predictor (p = 0.006, OR 1.097). Receiver operating characteristic curve analysis indicated that COR had good predictive accuracy (area under the curve 0.777), with a 65% cutoff, providing 68% specificity and 60.71% sensitivity. Cervicothoracic OPLL is a distinct clinicoradiological variant of OPLL, usually associated with severe myelopathy characterized by predominant lower limb symptoms. COR > 65% and axial morphology are key predictors of poor recovery, emphasizing the importance of detailed preoperative imaging and risk assessment.