We studied the surgical results of 35 patients with cervical compression myelopathy using sagittal T1-weighted magnetic resonance imaging (MRI). There were 15 cases of cervical spondylotic myelopathy (CSM) and 20 cases of ossification of the posterior longitudinal ligament (OPLL). The preoperative compression rate and restoration rate at the maximum involved level, and the spinal cord curvature were measured on MRI. Clinical results were assessed using the Japanese Orthopaedic Association (JOA)

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... scare. The mean preoperative JOA score of 11.5±2.3 points was significantly different compared to the postoperative score of 14.2±1.9 (p<0.0001, paired t-test). The mean recovery rate of the JOA score was 45.2±31.3%. The mean preoperative compression rate was 54.3±12.1% and the mean restoration rate was 44.5±30.6%. The compression rate and restoration rate significantly contributed to the outcome (p<0.0001 and p<0.003 respectively), as shown by multiple regression anaiysis which assessed the influence on the recovery rate of age, duration of symptoms, preoperative JOA score, original disease, compression rate, multiplicity of involve-