Interlaminar Bony Fusion After Cervical Laminoplasty: Its Characteristics and Relationship With Clinical Results

Abstract

A radiographic study in 32 patients with cervical myelopathy.To investigate postoperative interlaminar bony fusion, and its characteristics and relationship to clinical results in patients undergoing laminoplasty.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.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.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).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.