Spinal canal enlargement procedure by restorative laminoplasty for the treatment of lumbar canal stenosis

Abstract

Background context Multilevel fenestration or laminectomy is generally performed to treat the patient with lumbar canal stenosis (LCS). However, in patients requiring laminectomy, little attention has been paid to the later development of lumbar pain possibly caused by a removal of the posterior elements of the spine. In general, spinal instrumentation and fusion has been generally performed when laminectomy might cause severe postoperative spinal instability. Surgical methods where osteotomized vertebral arches are repositioned rather than removed have long been performed. However, they have never become widespread, possibly because of the complicated surgical procedures and poor postoperative arch stability, which leads to a long period of postoperative immobilization. Purpose The purpose of the present report was to introduce our surgical procedures of spinal canal enlargement using restorative laminoplasty and to report the results. Study design/setting This retrospective study was conducted to analyze the clinical results in 33 patients with lumbar canal stenosis who had been treated by our surgical procedures of spinal canal enlargement using restorative laminoplasty. Patient sample Subjects were 33 patients followed for at least 2 years after surgery. Meyerding Grade I degenerative spondylolisthesis was found in 10 patients, and degenerative scoliosis of more than 5 degrees was seen in 20 patients. Nine patients demonstrated both degenerative spondylolisthesis and degenerative scoliosis. Outcome measures Using the Japanese Orthopedic Association (JOA) scoring system, lumbago, sciatica, leg numbness, muscle strength and gait were quantified before surgery, 1 year after surgery and at final examination (at least 2 years after surgery) to calculate improvement rates. Furthermore, correlations to age, gender, disease duration, degenerative spondylolisthesis and degenerative scoliosis were statistically analyzed. Methods Our surgical procedures of spinal canal enlargement using restorative laminoplasty were performed for all patients. In our procedures, posterior elements were reapplied with an absorbable fixation (poli-L-lactic acid pins). No other fusion procedure was performed jointly. Results The mean number of restored vertebral arches was 2.2, and mean surgery time was 131 minutes. Mean volume bleeding during surgery was 328.0 ml. In all patients, successful bone healing was obtained at a mean of 5 months after surgery. Mean improvement rate for the total JOA score was 80.6%. Mean improvement rates for lumbago and sciatica were 70.0% and 87.7%, respectively. Mean improvement rate for leg numbness was 50.8%. Mean improvement rates for leg muscle strength and intermittent claudication were 70.0% and 98.9%, respectively. No significant correlation was found between gender and overall improvement rate, between age and overall improvement rate, between age and leg numbness or between number of restored vertebral arches and overall improvement rate. The tendency was that the longer the disease duration, the lower the overall improvement rate, and the more severe the residual numbness. No significant correlation was found between disease duration and muscle strength or lumbago. A significant correlation was not found between the presence of preoperative Grade I degenerative spondylolisthesis and overall improvement rate or lumbago. However, a significant difference in severity of lumbago existed between patients with degenerative scoliosis of 9 degrees and below and those with degenerative scoliosis of 10 degrees and above. Conclusion Our surgical procedures of spinal canal enlargement using restorative laminoplasty produce complete decompression and anatomical reconstruction of the posterior elements, ligaments and muscles. Improvement in complaints of lumbago may be a consequence of the anatomical reconstruction of the posterior spinal elements. Overall, favorable results were obtained. The best results were obtained if surgery is performed within 2 years of the onset of LCS.