K-line guided approach selection and outcomes assessment for Cervical Ossification of Posterior Longitudinal Ligament (OPLL): A case series with literature review from Pakistan

Objectives: To analyze the efficacy of K-line in surgical planning of approach selection for ossification of posterior longitudinal ligament (OPLL) and outcomes assessment by Nurick grading and Modified Japanese Orthopaedic Association (mJOA) scores. Methods: This is a retrospective case series study conducted at the Departments of Neurosurgery, Punjab Institute of Neurosciences, Lahore in the months of January and February 2024. Patients with complete records were considered. Google Form was used for data. Nurick grading and Modified Japanese Orthopaedic Association (mJOA) scores were calculated for each patient pre- and post-operatively. K-line assessment was done on computerized tomography (CT). Data analysis was performed using Microsoft excel in terms of frequency and percentages. Results: This study included ten patients with the mean age at presentation was 48.20 +/- 9.37 years. Preoperative Nurick grading in our patients was Grade-V (five patients), Grade-IV (two patients) and Grade-III (three patients) with mean of 4.2 +/- 0.91 SD whereas six months follow-up Nurick grading was Grade-V (three patients), Grade-IV (three patients) and Grade-III (four patients) with the mean of 3.90 +/- 0.87 SD, which indicates neurological improvement. Types of OPLL present in our patients were segmental (4, 40%), continuous (3, 30%), mixed (2, 20%) and localized/ others (1, 10%). There were 2 (20%) K-line (+) and 8 (80%) K-line (-) cases. Anterior approach was used in 2 (20%) cases whereas posterior approach was used for the rest of 8 (80%) cases. Mean preoperative mJOA was 10.30 +/- 2.45 and mean postoperative mJOA was12.40 +/- 2.01 at 6-month follow up, which indicates improvement in our cases. Conclusion: K-line is a useful radiological indicator in selecting anterior versus posterior approach for patients with cervical OPLL in terms of Nurick grading and mJOA scores.