Study design: Retrospective study.
Objectives: To investigate the efficacy and radiologic changes after anterior transvertebral herniotomy (ATH), in patients followed for at least 10 years after the surgery.
Summary of background data: The theoretical idea of ATH is to remove an extruded herniated mass while preserving disc motion. To our knowledge, no report has been published on the long-term outcome of this procedure.
Methods: Twenty patients underwent single-level ATH at our institution between 1989 and 1995. Clinical outcome was evaluated by visual analog scale for neck and arm pain according to Japanese Orthopaedic Association (JOA) score, and range of motion (ROM) of the cervical spine. Radiologic outcome was evaluated by measuring disc height and range of intervertebral motion of the site on plain radiographs. We also evaluated the operated and the adjacent segments by magnetic resonance imaging (MRI) for degenerative changes.
Results: Fifteen of the 20 patients were evaluated. One patient required additional surgery, 3 patients were lost to follow-up, and 1 patient had died by the time of the evaluation. Therefore, we evaluated the clinical outcome of 15 patients. Both the plain radiographs and MRI were available from 10 patients, and for 3 patients only the plain radiographs were available. Two patients refused x-ray examination at the final follow-up. Regarding clinical outcome, no patient had suffered from neck pain or arm pain. The average visual analog scale was 7.8/100 (%) for neck pain, and 7.0/100 (%) for arm pain. JOA scores improved and remained at a good level. The improvement rate was 88.5%. The average ROM of the cervical spine was 42.7 degrees in flexion, 52.3 degrees in extension, 58.6 degrees in axial rotation, and 25.0 degrees in lateral bending. Although ROM in axial rotation and lateral bending was symmetric, the range was smaller than that in the healthy segments. On plain radiographs, although the disc height in the operated segment was not significantly decreased compared with the other segments, loss of intervertebral motion was noticed on the follow-up roentgenograms in most cases. Only 2 patients had mobility of the operated intervertebral levels (>10 degrees). There was no collapse of the drilled vertebral body in any patient. Four of the 10 patients who underwent MRI showed protrusion of intervertebral discs, including those adjacent to the affected discs. No recurrence of disk herniation at the involved level was seen on the follow-up MRI.
Conclusions: In conclusion, ATH provided a good clinical outcome that was maintained for a long time. Although intervertebral motion at the operated level decreased to some extent, degenerative changes at the adjacent levels were not enhanced.