Background: OPLL extending to the cervicothoracic junction (CT-OPLL) presents unique surgical challenges since it represents a transitional zone between the mobile lordotic cervical spine changes and a relatively stiff thoracic spine. The literature on CT-OPLL is limited, and it is unclear whether it differs from sub-axial OPLL in terms of radiological characteristics and postoperative outcomes. The objective of the study is to analyse the clinicoradiological outcomes and factors predicting postoperative outcomes in patients operated on for symptomatic CT-OPLL.

Materials and Methods: This retrospective study included patients with symptomatic CT OPLL who underwent posterior instrumented laminectomy from April 2017 to 2022, with a minimum follow-up of 2 years. Demographic data, including age, sex, mean symptom duration, and comorbidities, were collected. Clinical data like preoperative Nurick’s grade, mJOA score, presence of hand myelopathy signs and presence of bowel/bladder symptoms were noted. In addition, radiological data, including morphology, pattern, OP-Index, K-line positivity, dural ossification, level of maximum stenosis, and OPLL occupancy ratio (OR), were analysed.

Results: Fifty-three patients were included in the study. The majority of patients were male (81.1%), and the mean age of presentation was 55.2 years. The mean duration of symptoms was 12.2 months. Nurick grade 5 was the most common grade observed in nearly 33.9% of patients. The mean preoperative mJOA score was 9.9. We observed that hand myelopathy signs were absent in 30.2 % of patients. CT scans revealed that the most common OPLL pattern was continuous (47.2%) and mixed (37.7%). We observed that 47.2% of the cases had hill-type morphology, while 37.7% had mushroom-type morphology. The mean OP-index was 8, and it had a positive correlation with ossification disorders at caudal levels. The mean postoperative mJOA score was 13.14. The average neurologic recovery rate was 44.1%.  Among the various predictors of neurological recovery, we observed that the occupancy ratio was the most important, with an OR > 55% associated with poor neurological recovery.

Conclusion: Cervico-thoracic OPLL represents a unique clinicoradiological variant of OPLL and is usually associated with severe myelopathy with predominant lower limb symptoms and absent hand myelopathy signs. They usually have poor neurologic recovery compared to sub-axial OPLL, especially in patients with OR> 55%.