To evaluate the results of expansive laminoplasty and to investigate the validity of various factors as prognostic indicators.

We studied retrospectively 37 patients between August 1993 and August 1998. The severity of the pre- and postoperative myelopathy was determined with the Japanese Orthopaedic Association (JOA) score. The recovery ratio was calculated. We divided the patients into two groups with good and fair outcomes, and then assessed for prognostic factors such as preop JOA scores, ages, sex, trauma, duration, Pavlov ratios, compression ratios and signal change in cord on T2W MRI.

In 19 patients the percentage recovery of JOA score was higher than 50%, while in 18 patients it was lower than 50%. There were no significant differences in regards to history of trauma, sex, and duration, there was a tendency of good results when there were no changes in the signal in cord on T2W MRI. There were significant differences in the preoperative JOA scores, Pavlov ratios and compression ratios.

The preoperative JOA score, Pavlov ratio, compression ratio and high signal intensity on T2W MRI can be used to predict prognosis.