Study design: A radiographic study in 32 patients with cervical myelopathy.
Objective: To investigate postoperative interlaminar bony fusion, and its characteristics and relationship to clinical results in patients undergoing laminoplasty.
Summary of background data: Laminoplasty is being increasingly performed for multi-segmental cervical myelopathy, and its superior long-term results have been reported in some articles. We often see cases that develop postoperative interlaminar bony fusion after laminoplasty.
Methods: In 32 patients, lateral cervical radiographs were obtained every year after surgery, and postoperative interlaminar bony fusion was evaluated. Range of motion (ROM) of the cervical spine at last follow-up was compared with the respective preoperative values. Furthermore, the neurologic recovery rates at last follow-up were compared to preoperative values.
Results: Postoperative interlaminar bony fusion was shown in 17 patients (53%, group 1), and in most, fusion appeared within 3 years after surgery. Average age at surgery in group 1 and the remaining 15 patients (group 2) was 64.6 years and 57.0 years, respectively (P < 0.04). Preoperative and postoperative ranges of motion in group 1 were 45.6 degrees and 28.1 degrees on average, respectively. However, those of group 2 were 50.3 degrees and 39.8 degrees on average, respectively. Postoperative ROM in group 2 was significantly better maintained than that in group 1(P < 0.04). In group 1, the average preoperative Japanese Orthopedic Association score was 9.56 points, which improved to 13.6 points at the final follow-up, providing a 55.6% average recovery. In group 2, it was 10.9 points, which improved to 14.1 points at the final follow-up, providing a 56.5% average recovery. There was no significant difference in the average percentage of recovery between the 2 groups (P > 0.93).
Conclusions: Postoperative interlaminar bony fusion occurred in 53% of patients, with marked frequency at C2/3 after laminoplasty. It did not influence neurologic recovery, but it did reduce the postoperative sagittal ROM of the cervical spine.