Sadahiko Konishi

Single-stage excision of hemivertebrae via the posterior approach alone for congenital spine deformity: follow-up period longer than ten years.

Study Design. Evaluation of the long-term results for single fully segmented hemivertebrae were subjected to single-stage excision via posterior approach alone. Objectives. To describe the long-term results of this procedure. Summary of Background Data. In the case of congenital spinal deformity caused by a single, full hemivertebra, excision of the hemivertebra is ideal for obtaining a good correction percentage even in short segments. Recently, single-stage excision of a hemivertebra using a combined anterior and posterior approach has been reported. Methods. Five patients with a hemivertebra underwent surgery. The hemivertebra involved the thoracolumbar region in three cases and the lumbosacral region in two cases. After removal of a lamina of the hemivertebra, the body of the hemivertebra was visualized easily because the spinal cord had deviated to the concave side of the curve. The vertebral body, along with its cranial and caudal discs, was curetted with this approach. Thereafter, bone chips were grafted into the defect created by vertebrectomy. The results of this surgical procedure, especially those observed during long-term follow-up evaluation, were investigated. Results. For patients with a thoracolumbar hemivertebra, scoliosis improved from 49° ± 6° to 22.3° ± 3.5°, for a 54.3% correction. The correction ratio for kyphosis was 67.4%. Over an average 12.8-year follow up period, loss of scoliotic curvature correction was only 3.7°. In contrast, the hemivertebral correction ratio for patients with a lumbosacral hemivertebra remained 32.5% because of difficulty using internal fixation associated with patient age. At the most recent follow-up assessment, one patient exhibited deterioration of coronal spinal balance. Conclusion. The described procedure was less invasive because it avoided an anterior approach, yet it yielded satisfactory long-term results for thoracolumbar hemivertebrae. Methods. Eight patients with spinal deformity involving a hemivertebra underwent surgery using the aforementioned procedure and were followed up for more than 10 years. One of these patients required an additional operation after loosening of internal fixation. The deformity of another patient involved a wedged vertebra rather than a hemivertebra. Still another patient could not be followed because of her move to a new address. After the exclusion of these three patients, the study included five patients. Of the five patients in the study, four were boys and one was a girl. Their mean age at the time of surgery was 10 years (range, 3.6–13.7 years). The mean follow-up period was 12.8 years (range, 11.5–14.9 years). The hemivertebra involved the thoracolumbar region in three cases and the lumbosacral region in two cases (Table 1). All of the patients with a thoracolumbar hemivertebra exhibited regional kyphosis. To determine operative invasiveness, volume of blood loss was reviewed from the clinical records along with transfusion and operative time. The correction ratios of both the main curve in the standing anteroposterior film and the kyphosis in the lateral standing film were evaluated. The correction ratio of the compensatory curve created above or below the main structural curve also was investigated. Loss of correction for both the main curve and the kyphotic angle in the sagittal plane were reviewed. For cases of lumbosacral hemivertebra, a perpendicular line was drawn from the center of the C7 vertebral body, and the distance from this line to the center of the sacrum was measured to examine pre- and postoperative spinal balance. Table 1. Patient DataF = female; M = male; D&C = distraction and compression; C = compression rod. Operative Procedure. After induction of general anesthesia, the patient was placed in the prone position with the abdomen relieved of all pressure on rolls. The back was prepared and draped in routine fashion. A longitudinal skin incision was made on the back at the center of the hemivertebra. Paravertebral muscle was retracted laterally, and the lamina was explored. The lamina of the hemivertebra was identified and removed with its attached transverse process. Epidural bleeding was controlled with thrombin-soaked Gelfoam (Pharmacia Corp., Peapack, NJ). The dural sac usually had deviated to the concave side of the curve. Generally, the hemivertebrae in the thoracolumbar region also had deviated dorsolaterally because of the kyphotic deformity. The vertebral body of the hemivertebra could therefore be identified posteriorly. Because the pedicle of the hemivertebra was thicker than usual, cancellous bone in the vertebral body was curetted easily via the pedicle. Thereafter, the body of the hemivertebra was resected completely with a high-speed drill. In the pediatric spine, these procedures can be performed easily because the vertebral body is encapsulated by cartilage and periosteum, which is thicker than in the adult spine. After the vertebral disc and endplate in both the cranial and caudal adjacent segments had been curetted, bone chips obtained during curetting of the vertebral body were inserted in the defect. For thoracolumbar hemivertebrae a Harrington compression rod then was applied to the convex side of the curve and a Harrington distraction rod to the concave side (Figure 1). The facet and the lamina to which internal fixation had been applied were decorticated on both the concave and convex sides of the curve. All the bones removed during the laminectomy were used as graft material throughout the area along with the bones grafted from the iliac crest. Figure 1. The operative procedure. A, After the longitudinal skin incision, paravertebral muscle is retracted laterally and the lamina of the hemivertebra identified. B and D, The lamina is removed with its attached transverse process. The spinal cord usually has deviated to the concave side of the curve. Therefore, the body of the hemivertebra is easily recognized. C and E, The vertebral discs above and below the hemivertebra and the vertebral body of the hemivertebra is curetted via a posterior approach. A compression device then is applied to the convex side of the curve and the curetted space closed. Internal fixation was not performed in one 3-year-old patient with a lumbosacral hemivertebra. In this case, after curettage of the vertebral body without removal of disc tissue either above or below the vertebral body, a cast was applied to correct the deformity without any bone grafting. In another patient with a lumbosacral hemivertebra, the discs above and below the vertebral body were curetted, and interbody bone graft was performed with application of a compression device to the convex side of the curve alone. Results. Blood loss in this procedure ranged from 110 to 1360 mL (mean, 660 mL), and the volume of transfusion averaged 200 mL. The operative time ranged from 225 to 425 minutes (mean, 350 minutes). In the patients with a thoracolumbar hemivertebra, the main structural curve was corrected from 49° to 22.3° on the average, and the correction ratio ranged from 46.9% to 60% (mean, 54.3%). For compensatory curves, 31.4% correction was obtained in the upper curve and 61.3% in the lower curve (Table 2). For sagittal curvature, thoracolumbar regional kyphosis was corrected from 48° to 15° on the average, and the correction ratio was 67.4% (range, 58–77.6%). At the most recent follow-up visit, correction loss averaged 3.7° (Table 3). Table 2. Correction Ratio and Loss in Each Patient Table 3. Correction Ratio and Loss of Regional Kyphosis in Each Patient With Thoracolumbar Hemivertebra In the patients with a lumbosacral hemivertebra, scoliosis was corrected from 34.5° to 23.5°, and the correction ratio averaged 32.5%. The upper compensatory curve exhibited 41.4% correction (Table 2). In this type of deformity, decompensation of spinal balance becomes a problem. Table 4 shows the changes in coronal spinal balance from before to after surgery as well as the change observed at the most recent follow-up visit. In one patient decompensation of spinal balance had completely recurred from regrowth of the hemivertebral body. Table 4. Changes in Coronal Spinal Balance* Number indicates distance (cm) between the center of C7 and the perpendicular line drawn to the center of the sacrum.

Palsy of the C5 Nerve Root After Midsagittal-Splitting Laminoplasty of the Cervical Spine

Study Design. The imaging characteristics of postoperative C5 nerve root palsy after midsagittal-splitting laminoplasty for cervical myelopathy, including those observed on plain radiography, computed tomography, and magnetic resonance imaging, were analyzed. Objective. To investigate the imaging findings that predict occurrence of C5 nerve root palsy after midsagittal-splitting laminoplasty. Summary of Background Data. There have been several reports on imaging findings for postoperative nerve root palsy after open-door laminoplasty. However, there have been no detailed reports on imaging characteristics that predict the occurrence of nerve root palsy after midsagittal-splitting laminoplasty. Methods. The study included 45 consecutive patients undergoing midsagittal-splitting laminoplasty with sufficient pre- and postoperative imaging examinations: 27 patients with cervical spondylotic myelopathy (CSM), 14 patients with ossification of the posterior longitudinal ligament (OPLL), and 4 patients with cervical disc herniation. Characteristics of pre- and postoperative plain radiographs, computed tomography scans, and magnetic resonance images were compared between the patients with and those without C5 nerve root palsy. Results. Palsy of the C5 nerve root developed in 4 patients, and did not develop in 41 patients. Of the four patients with C5 nerve root palsy, one had CSM and the other three had OPLL. The incidence of C5 nerve root palsy involved 3 of 14 patients with OPLL patients (21.4%) and 1 of 31 patients without OPLL (3.2%) (P = 0.08). For both diseases, the patients with palsy tended to have increased postoperative cervical lordosis (P = 0.21). As for anterior compression on the spinal cord at C3, the P value for the comparison between the group with and the group without palsy was 0.07 for preoperative compression and 0.01 for postoperative compression. Conclusions. The preliminary data suggest that patients who have OPLL with marked anterior compression on spinal cord at C3 can be at risk for postoperative C5 nerve root palsy after midsagittal-splitting laminoplasty. Also, a postoperative increase in cervical lordosis may be the cause of postoperative nerve root palsy.

Hydroxyapatite granule graft combined with recombinant human bone morphogenic protein-2 for solid lumbar fusion.

The purpose of this study was to evaluate the availability of recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with hydroxyapatite (HA) and autogenous bone. Posterolateral intertransverse fusion between the fifth and sixth lumbar vertebrae was performed in 27 adult Japanese white rabbits. These 27 rabbits were classified into three groups: the autogenous bone group, the HA group, and the bone morphogenic protein (BMP) group. In the HA group, HA (0.5 g) mixed with iliac bone was grafted. In the BMP group, HA (0.5 g) soaked with rhBMP-2 (100 mg) and iliac bone was grafted. At 6 weeks after the procedure, bone union was evaluated. In the BMP group, all cases showed solid bone union, and fusion masses were stiffer than the masses obtained in the other group. Biomechanically and histologically, grafts of HA soaked with rhBMP-2 and iliac bone was clearly effective in obtaining a solid intertransverse arthrodesis.

Effect of preserving paraspinal muscles on postoperative axial pain in the selective cervical laminoplasty.

Study Design. A retrospective clinical study. Objective. To evaluate the effect of preservation of paraspinal muscles attached at the spinous process of C2 or C7 in selective laminoplasty on postoperative axial pain. Summary of Background Data. Several methods of modified laminoplasty such as selective decompression and/or reconstruction of detached paraspinal muscles have been reported. It is still unclear, however, which posterior muscles need to be preserved to reduce postoperative problems. Methods. The study group consisted of 145 patients who underwent cervical laminoplasty. The level of decompression was decided based on preoperative cervical magnetic resonance imaging. The level of detachment of muscle from the spinous process was from 1 cranial to the decompression level and to the same level caudal to the level of decompression. Clinical outcome was evaluated based on improvement ratio of Japanese Orthopedic Association (JOA) score. In addition, the risk factors for postoperative axial pain were examined by multivariate logistic regression analysis. Results. In 113 patients, C2 paraspinal muscles were detached, with elevation of the C3 lamina, and the improvement ratio of JOA score was 56.0%. In 32 patients, the muscles were preserved, without elevation of the C3 lamina, with corresponding ratio of 54.8%. In 112 patients, C7 paraspinal muscles were detached, with elevation of the C7 lamina, and in 33 patients the muscles were preserved; the improvement ratios of JOA score for these groups were 56.7% and 52.4%, respectively. There were no significant differences in clinical outcome among the groups. Older age (odds ratios: 0.17, 95% confidence intervals: 0.04–0.72) and preservation of muscles attached at the C2 spinous process (OR: 0.13, 95% CI: 0.02–0.98) decreased the risk of postoperative axial pain. Conclusion. Muscle-preserving selective laminoplasty yielded clinical outcomes equivalent to those of conventional C3–C7 laminoplasty in cervical compression my elopathy. Preservation of the muscles attached at C2 resulted in reduction of postoperative axial pain.

Clinical outcome of microsurgical bilateral decompression via unilateral approach for lumbar canal stenosis: minimum five-year follow-up.

Study Design. A retrospective study. Objective. To evaluate minimum 5-year clinical outcome and radiologic changes in patients who underwent microsurgical bilateral decompression via a unilateral approach. Summary of Background Data. Some authors have reported satisfactory short-term results of minimally invasive decompressive procedures such as microscopic or microendoscopic decompressive laminotomy for lumbar spinal stenosis (LSS). However, there have been a few reports on the long-term clinical outcome of these procedures. Methods. The study consisted of 57 patients who underwent this surgery and had been followed for at least 5 years. The preoperative diagnoses were LSS without instability in 27 patients, degenerative lumbar spondylolisthesis (DS) in 20 patients, and degenerative lumbar scoliosis (DLS) in 10 patients. The mean duration of follow-up was 6 years. Clinical outcome was evaluated by Japanese Orthopedic Association (JOA) score. Complications, rate of reoperation, and radiographic changes after surgery on plain radiograph were evaluated. Results. The mean JOA score was 13.8 ± 3.6 points before surgery, and improved to 24.9 ± 3.1 points at 3 months and 22.6 ± 4.7 points at the latest follow-up. There were no significant differences in JOA score at the latest follow-up among patients with LSS, DS, and degenerative scoliosis (22.3 ± 5.3, 23.3 ± 4.4, and 21.6 ± 2.6, respectively). Four patients (7%) underwent reoperation; 2 had DS and 2 had DLS. The preoperative percentages of slippage in patients with LSS, DS, and DLS were 0.4% ± 2.2%, 13.2% ± 5.9%, and 0.0% ± 1.3%, respectively, whereas degrees of progression of slippage at latest follow-up were 1.2% ± 3.1 %, 2.4% ± 4.7%, and 0.0% ± 0.0%, respectively. There were no significant differences in progression of slippage among these 3 disease groups. Conclusion. Microsurgical bilateral decompression via a unilateral approach is a minimally invasive technique that yielded satisfactory surgical outcomes even on minimum 5-year follow-up.

An experimental study of the effects of nerve root retraction on the posterior ramus.

STUDY DESIGN The histologic and ultrastructural changes in the posterior ramus after posterior lumbar surgery were studied in rabbits. OBJECTIVE To investigate the structural changes in the posterior ramus after posterior lumbar surgery that may cause injury to the posterior ramus after the procedure. SUMMARY OF BACKGROUND DATA Investigators in previous studies have pointed out that low back discomfort after lumbar discectomy relates to neurogenic changes and/or myogenic changes of paravertebral muscle. However, no previous study has demonstrated the effects of excessive nerve root retraction on spinal posterior rami. METHODS Eighteen male Japanese White rabbits were used. The posterior ramus arising from the S1 nerve root was examined after exposure of the lamina only, fenestration, or retraction of the S1 nerve root, with light microscopy and transmission electron microscopy at 2, 4, and 6 weeks after the procedure. Results were compared with a those in control specimens that did not undergo the procedure. RESULTS In the exposed group, no distinct difference was found compared with the control specimen. In the fenestration group, especially at 6 weeks, some attenuation and splitting of myelin sheaths was observed. In the retraction group, the structural alteration was most severe. Even at 2 weeks, fragmentation of many myelin sheaths was detected. Examination of specimens by electron microscopy indicated phagocytosis of myelinated fibers at 4 and 6 weeks. CONCLUSIONS Findings showed that posterior lumbar procedures, including retraction of paravertebral muscle, fenestration of the lamina, and retraction of the nerve root affect the posterior ramus. Excessive retraction of the nerve root has an especially disastrous effect on the posterior ramus. Such a violent maneuver within the spinal canal must be avoided.

Risk factor analysis for motor deficit and delayed recovery associated with L4/5 lumbar disc herniation.

Study Design Retrospective study of multivariable analysis for the risk factors of motor deficit associated with lumbar disc herniation (LDH). Objectives To identify the risk factors for motor deficit and delayed recovery after surgery in patients with LDH. Summary of Background Data LDH can cause motor deficit as well as pain and sensory disturbance. Even though motor deficit can lead to disabilities and affect treatment plans, few studies have described motor deficit and its risk factors in LDH patients. Methods Seventy-six consecutive patients who underwent microsurgical or microendoscopic discectomy for LDH at the L4/5 level were retrospectively reviewed. Motor deficit was defined as tibialis anterior muscle strength of lower than grade 4 by the manual muscle test, and delayed recovery was defined as cases requiring longer than 3 months to achieve complete recovery. The possible risk factors including sex, age, symptom duration, preoperative radiographic parameters, and type of herniation were evaluated by multivariate logistic regression analysis. Results Forty-three patients (56.6%) suffered from motor deficit before surgery. Forty cases (93%) completely recovered within a mean duration of 4 months. Multivariate logistic regression analysis revealed that noncontained-type (P=0.012, odds ratio=13.7) and migrated herniated nucleus pulposus (P=0.033, odds ratio=9.8) were important risk factors for motor deficit. Furthermore, severe motor deficit (preoperative manual muscle test⩽3; P=0.019, odds ratio=19.6) and noncontained type (P=0.049, odds ratio=5.17) were identified as important risk factors for delayed recovery. Conclusions Noncontained-type or migrated herniated nucleus pulposus seem to be the most important risk factors for motor deficit in LDH, whereas severe motor deficit and noncontained type seem to be associated with delayed recovery. The treatment options for patients with these factors at first visit should be carefully chosen during the follow-up period.

Analysis of the spastic gait caused by cervical compression myelopathy

We evaluated the spastic gait of patients with cervical myelopathy with a three-dimensional gait analysis system. Fifteen patients with cervical myelopathy (S group) were investigated. The results obtained were compared with those of normal volunteers (N group). The S group exhibited significant reduction of gait velocity and step length (p < 0.01). In the knee flexion–extension curve, two peaks were observed in the N group. In the S1 group (symptomatic period <1 year), the anterior peak was not smooth, whereas in the S2 group (symptomatic period >1 year), no peak was observed. The pelvis tilted to the side of the standing leg in the N group. However, in the S1 group, this tilting was much less pronounced, and in some patients tilting toward the nonsupporting leg was observed. In the S2 group, the pelvis again tilting toward the supporting side was observed.

Psoas Strapping Technique: A New Technique for Laparoscopic Anterior Lumbar Interbody Fusion

Recently endoscopy has started to be used for spinal surgery. The benefit of using endoscopy is that it is less invasive, and the small incision results in a shorter hospital stay. In a standard technique for laparoscopic anterior lumbar fusion, the conventional approach for L1/2-L4/5 is retroperitoneal. This approach has a critical point in retracting the iliopsoas muscle because this muscle is bulky at the level of L4/5 and contains a lot of peripheral nerves. We report on a new technique called the “psoas strapping technique,” in which the psoas muscle was retracted by being circled with a nonelastic tape passed through posterior skin. Disc tissue was resected under retraction of the muscle with this technique and a titanium fusion cage was inserted under laparoscopic observation. TECHNIQUE Under general anesthesia, a patient was placed in the right lateral decubitus position. After retroperitoneal insufflation with carbon dioxide to a pressure of 8 mmHg, three trocars were placed in the abdomen. A nonelastic tape was inserted into retroperitoneal space through the portal. An end of the tape was passed below the psoas muscle as close as possible to the lateral side of the vertebral disc, and then passed through the posterior skin. The other end of the tape was inserted into the retroperitoneal space, passed in front of the muscle, and pulled out through the same hole in the posterior skin. Pulling both ends of the tape made it possible to retract the

High serum levels of menatetrenone in male patients with ossification of the posterior longitudinal ligament.

Study Design. This work was performed to investigate the role of vitamin K (VK) in the pathogenesis of ossification of posterior longitudinal ligament (OPLL), by analyzing the biochemical markers of the blood samples of OPLL patients and responses of ligament cells derived from OPLL lesion to VK2. Objectives. The pathogenesis of OPLL, classified as a form of diffuse idiopathic skeletal hyperostosis, is still unclear. In this study, we investigated the role of menaquinone (VK2) in patients with OPLL (OPLL patients) and the effects of VK2 on ligament cells isolated from OPLL lesion. Methods. Serum levels of intact osteocalcin, glu-osteocalcin, MK-4, -7 (VK2 variants) and other minerals in spot blood samples were measured in 24 OPLL patients and in 24 age-matched control patients (non-OPLL patients). The cultured cells isolated from an OPLL patient were treated with MK-4. Alkaline phosphatase (Al-p) activity and osteocalcin release were measured after 2 weeks of culture. Results. In the clinical study, the serum MK-4 in male OPLL patients was significantly higher than that in male non-OPLL patients. However, among female patients, the difference was not significant. Although the serum osteocalcin in females was significantly higher than that in males, there was no significant difference between the OPLL and non-OPLL groups. In in vitro study, MK-4 did not increase Al-p activity in the ligament cells isolated from nonossified region of OPLL patient. Osteoblastic activity of the cultured cells was not stimulated by MK-4. Conclusion. From these results and previous reports, we propose the possibility of the impediment in VK2 metabolism in OPLL patients. The results also implicate the gender tendency in OPLL, because the difference of serum level of MK-4 in OPLL patients was significant only in male.