Surgical outcomes in a tertiary medical center of patients with Ossified Posterior Longitudinal Ligament (OPLL) based on Nurick Grading System and the Modified Japanese Orthopedic Association Scoring System: a follow-up of 1.5 years
Objective: The aim of this study is to evaluate the surgical outcomes of patients with ossification of the posterior longitudinal ligament (OPLL) of the spine using the Nurick grading system and the modified Japanese Orthopedic Association (mJOA) scoring system 1.5 years after surgery.
Methods: A chart review was done from January 2013 to December 2014 from two tertiary medical centers. A total of 26 patients were included in the study. The patients underwent surgical decompression and stabilization via anterior (cervical decompression and fusion), posterior (laminectomy and fusion, or laminoplasty), or both (360-degree fusion) approaches. Patient demographics, co-morbidities, length of hospital stay, and complications were also noted. Outcome scores were taken at a mean of 19 months after surgery based on the mJOA scoring and the Nurick grading system. Patients were interviewed through phone call or social media platform. The answers were then tabulated vis-à-vis surgical intervention and type of OPLL. Severity of functional disability was graded based on the mJOA score. Post-operative recovery rates were then calculated. Outcomes were then classified according to the definition by Hirabayashi.
Results: Twenty six patients were included (17 males, 9 females; mean age: 55 years) in the study. Majority of the patients were Pacific Islanders (n=13). Smokers accounted for 30% of the patient population. Majority of patients had hypertension and diabetes as comorbidities. Twelve patients presented with segmental type of OPLL, 4 were of the continuous type, and 10 were of the mixed type. Average follow-up was at 19 months post-op. Overall average pre-operative Nurick grade was 3 while the post-operative Nurick grade was 0.69. Nurick recovery rate was calculated at 82.63%. On the other hand, the mean pre-operative mJOA was 12. The mean post-op mJOA was 17.19, which was close to the perfect score of 18 (i.e. no motor, sensory, or sphincter dysfunction). The mJOA recovery rate was 88.64%. The average length of hospital admission was 12 days. When grouped according to OPLL type, the segmental variant had the best recovery rate both for Nurick grading and mJOA scoring. The same group also had the lowest mean length of hospital stay. The anterior and posterior surgery (360 degree fusion) had the best mJOA recovery rate at 96%, while Nurick recovery rate was similar (83%) in the anterior approach and 360 degree fusion. The complication rate was computed at 3.84%.
Conclusion: Anterior and/or posterior cervical decompression and fusion is a safe procedure yielding good to excellent outcomes for ossified posterior longitudinal ligament (OPLL) surgery. Overall recovery rates are at 82.63% and 88.64% for Nurick grading and modified Japanese Orthopedic Association scoring system, respectively.