Long-term Follow-up Results and Radiographic Findings of Anterior Surgery With Cloward Trephination for Cervical Spondylotic Myelopathy

Abstract

Serial retrospective long-term follow-up study. To assess the long-term results of anterior surgery with Cloward trephination and iliac strut grafting for cervical spondylotic myelopathy. Anterior surgery remains the most common surgical option and generally gives good results, although early and late deterioration after initial postoperative improvement has been noted. Although anterior decompression with trephination is a variant of the Cloward technique, little information is available concerning the long-term results after this procedure. One hundred sixty-eight consecutive patients treated with this technique by the same author from the years 1978 to 1992 were followed serially. One hundred and seven patients were followed for over 10 years (mean: 14.1 y) (follow-up rate: 71.8%). Clinical results were evaluated according to the Japanese Orthopedic Association system and the results at different postoperative intervals were analyzed. Thirty-six patients returned for the final follow-up. Plain radiographs were taken in neutral and flexion-extension positions and computed tomography scans were taken at fused segments and unfused levels. The mean recovery rate was 56.8% at final follow-up. Deterioration of 2 Japanese Orthopedic Association points or more was experienced in 44 patients at various postoperative periods and was more frequent at over 10 years follow-up. Kyphosis of fused segments was noted frequently on the radiographies of the 36 patients with a mean of 7.8 degrees. A straight or misaligned cervical spine was found in 28 (77.8%) patients and these deformities were more serious in multilevel fusions. Stenosis of the canal at fused segments was found in 15 (41.7%) patients owing to osteogenesis resulting from inadequate decompression or pseudoarthrosis. At unfused levels, the incidence of spondylolisthesis, bony bridge, disc hernia, and thickening or bulging of the ligament flavum was 19.4%, 27.8%, 33.3%, 19.4%, respectively, and these abnormalities almost always occurred at levels adjacent to the fusion. Radiographic abnormalities were pejorative for long-term clinical results. Anterior surgery with Cloward trephination provides generally acceptable long-term results with considerable incidences of deterioration and radiographic abnormalities. This underlines the need for thorough decompression and preservation of the subchondral endplate bone for solid fusion and maintenance of the cervical lordotic curvature.