Studies of at least 10 patients which focused on the assessment of predictors for surgical outcome of cervical OPLL cases and reported statistical analysis were eligible for inclusion in the review.
The mean age of patients in included studies ranged from 51.3 to 62.6 years. Most patients in all studies were male. Both anterior and posterior approaches were used in surgeries. Factors assessed in included studies were age, sex, ossification type (based on the Investigative Committee on OPLL of the Japanese Ministry of Public Health), duration of preoperative symptoms, surgical level, spinal cord evoked potentials, diabetes, preoperative neurological score, radiographic assessments and history of trauma.
One reviewer selected the papers for the review.