Surgical Technique for Spine and Spinal Nerves
Vol.4 No.1(2002)

Main theme-1: Advance and limitation posterior approach to the cervical spine
Skip Laminectomy for Cervical Spondylotic Myelopathy with Less Invasion
to the Posterior Extensor Mechanism Including The Deep Extensor Muscles
Tateru SHIRAISHI, et al
Abstract Persistent axial pains, restriction of neck motion and loss of cervical lordosis have been significant postoperative problems often seen after currently used expansive laminoplasties. There is no doubt that intraoperative injuries to the posterior extensor mechanism including the deep extensor musculature cause these problems. To prevent them, the author developed a new procedure for multilevel cervical decompression-SKIP LAMINECTOMY. For consecutive four-level decompression between C3-4 and C6-7 as an example, the C4 and C6 standard laminectomies are performed, combined with removal of the cephalad halves of the C5 and C7 lamina and the ligamenta flava at those four levels. Thus, a four-level decompression is accomplished with the muscular attachments to the C3, C5 and C7 spinous process left untouched. Instead of a standard laminectomy, the cephalad half of the lamina and ligamentum flavum can simply be removed(INTERLAMINAR DECOMPRESSION) at levels where anterior spinal cord compression is insignificant. In cervical spondylotic myelopathy, the posterior anatomical structures which compress the spinal cord are hypertrophic ligamentum flavum and upper margin of the lamina. Limiting surgical invasions to these structures, Skip Laminectomy minimizes intraoperative injuries to the posterior extensor mechanism including the deep extensor musculature. The surgical technique for this new procedure is described in detail.
Clinical Results of Cervical Laminoplasty with Newly Developed Ceramic Spacer
Minoru IKENAGA, et al
Abstract
PURPOSE：
We have performed cervical laminoplasties with a newly developed HA/TCP ceramic spacer since 1993. The aim of this report is to report the clinical results.
MATERIALS AND METHODS：
29 patients who have undergone cervical laminoplasty in our clinic in 1993-1994 were included in this study. 3 patients were lost during follow-up. The age of patients was from 47 to 84(mean 70.9), 15 male and 14 female. They consisted of 14 cases of OPLL and 15 of cervical spondylosis. Operation levels were：C2-7, 14；C1-7, 6；and others, 9 cases.
Operation method：After resection of the spinous process, laminae were thinned to their inner cortex, and cut in the midline with a high-speed burr. With open-door technique, the spinal cord was exposed, were ceramic spacers were sutured to the laminae, and local bone chips with fibrin glue were put in the gutters on both sides. Preoperative, postoperative, and 1y postoperative X-rays were examined and the cervical alignment was recorded.
RESULTS：
Postoperative cervical alignment was well maintained for 1 year. A kyphotic patient preoperatively tends to have a similar kyphosis postoperatively also. Postoperative neck pain did not correlate with cervical alignment. There was no case of spacer breakage or displacement.
DISCUSSION：
Open door laminoplasty by the Kirita-Miyazaki method has an advantage in its eases of operation technique. Ceramic spacers for this type of technique, however, have not been reported before. The newly developed ceramic spacer is easy to fix to the laminae with strings through the yellow ligament. This report shows its usefulness in the opendoor laminoplasty technique for the treatment of patients with cervical myelopathy.
CONCLUSION：
The newly developed ceramic spacer is useful on the Kirita-Miyazaki technique of cervical laminoplasty.
A New Method of Laminoplasty, 'Double Door Laminoplasty'
Futoshi SUETSUNA, et al
Abstract Midline splitting laminoplasty has sometimes caused post-operative bone absorption of the spinous process and interspinous bony fusion because of excision of soft tissue behind the spinous process. We reviewed the radiographic and clinical outcome of our new laminoplasty(double door laminoplasty)using hydroxyapatite ceramics preserving the posterior elements. 27 patients with an average age of 61 years were investigated. The average follow-up time was 21 months. Rates of enlargement of area of spinal canal, changes of cervical lordotic angle and range of motion(C2-7)were examined radiographically. The average enlargement rate of the area of spinal canal was 34.7%. The average preoperative lordotic angle and range of motion were 22.1 degrees and 37.2 degrees respectively, and the average postoperative lordotic angle and range of motion were 19.5 degrees and 21.5 degrees respectively. No case showed bony fusion of the C3-7 interspinous processes or bone atrophy of the spinous process. Recovery rate was 62.5%. Our new laminoplasty prevented bone atrophy of the spinous process and interspinous bony fusion from C3 to 7. In addition, our method caused less deviation of laminae than open door laminoplasty. This method, which is free from the demerits of both open door and midline splitting laminoplasty, will become an accepted foam of laminoplasty for cervical myelopathy.
Parasagittal Approach for Decompression Cervical Laminoplasty
Chiaki HAMANISHI, et al
Abstract We have performed surgery by the left parasagittal approach on 28 patients since 1999. Using this approach, the extensor muscles were stripped from the nuchal ligament and from the spinal processes only on the left side. The spinal processes were then horizontally osteotomized and retracted to the right side with the preserved nuchal ligament and intact right muscles. Both laminae were thinned and ordinary French-window laminoplasty was carried out. In 16 cases, facet fusion was added by grafting chipped bone at levels where radiographic instability was confirmed during surgery. Grafts were covered by the retracted laminae and multifidus muscle was sutured to these laminae. Three layers of the extensor muscles were carefully reattached to the interspinous muscles, the lamellar and the funicular portions of the nuchal ligament respectively. The patients were encouraged to sit up the next day and allowed to stand and walk on the third day. Vigorous isometric extensor muscle exercise was introduced immediately after surgery, and this dynamically maintained or even induced lordotic alignment. Clinical improvement seemed better than in patients managed by the ordinary midline approach, and the intervals before sitting and walking have been reduced markedly. Hospital stay was shortened by more than one month.
Three Centimeter Skin Incisional Minimally Invasive Cervical Expansive
Open-door Laminoplasty Using Spinoplastic Hydroxyapatite Spacer
Shun-ichi KIHARA, et al
Abstract Seventy-one patients with cervical spondylotic myelopathy and OPLL underwent a cervical open-door laminoplasty using a hydroxyapatite spinoplastic spacer in combination with spinoplasty, during the period from October 2000 to May 2001, as described below. Briefly, the left sides of the laminas were exposed from the upper part of C3 to the upper part of C7, and the spinous processes were then cut and detached from the laminas together with the nuchal ligament. We generally opened the door on the left side and made the curved hinge on the right side. Using two-angled curettes, the laminas were slowly lifted on the open side and fixed with a hydroxyapatite spinoplastic spacer. After that, the tips of the spinous processes, which had been detached from the laminas, were tied up with the laminas and the spacer. All patients showed remarkable neurological improvement after surgery with JOA scores from 6.13 to 14.11 on the average. We consider that preservation of the posterior cervical supporting component is useful for the preservation of lordosis.
The Clinical Study of Modified Atlanto-axial Fusion Using Tekmiron Thread for Atlanto-axial Subluxation
Hitoshi HASE, et al

Abstract
［Purpose］The clinical results of a modified a Brooks operation using ultra-high molecular weight polyethylene(Tekmiron)instead of metal wire are reported.
［Patients and Methods］47 patients with atlanto-axial subluxation were treated since 1991 with a modified Brooks operation using Tekmiron, and followed up from one year to eight years and nine months(average period, 4.2 years). There were 16 men and 31 women(3-71 years).43 had RA, three had os odontoideum and one was a case of trauma. We report the radiographic assessment, clinical results and complications.
［Results］ADI and A-A angle were 10.5+/-2.7 mm and 14.2+/-13.4°(pre-op.), reduced to2.6+/-1.7 mm and 25.8+/-10.1°(postop.). 39 of 47cases(83%)had bony fusion, five(11%)fibrous union, and three(6%)non-union. In 9 recent cases, there was only one fibrous union and no non-union. Neurological complications or laminar fractures were not seen.
Discussion］Tekmiron thread has strength equal to metal wire as well as flexibility, which makes it safe to pass under the lamina. It does not cause artifacts on MRI. With the use of a developed tightening device, rigid fixation of grafted bone and solid fusion can be obtained without hard orthosis or halo-vest. We are now developing a new procedure using a HA spacer.
［Conclusion］This procedure is considered safe and useful for posterior fixation of the atlas and axis.

Occipito-Cervical Fusion Using Tekmilon Tape
Yurito UEDA, et al
Abstract We performed occipito-cervical fusion for rheumatoid patients who suffered from myelopathy with atlantoaxial and subaxial subluxation.
We formerly used metal wires and rods for occipito-cervical segmental spinal instrumentation, but recently we used tekmilon tape instead of metal wires. The purpose of the present study was to compare the clinical outcome of occiputo-cervical fusion with metal wires and tekmilon tape. Materials and methods Five patients with a diagnosis of rheumatoid arthritis who underwent occipito-cervical fusion using metal wires and rods, and six patients who underwent the same operation using tekmilon tapes and rods, were compared.
Result There were no statistically significant difference between the metal wire group and the tekmilon group in operation time, blood loss at operation, Ranawat's neurological score or pain score.
Summary In pursuit of the safer segmental spinal instrumentation, we established that tekmilon tape could be a substitute for metal wire.
Posterior Atlantoaxial Arthrodesis Using a Titanium Mesh Cage
-A Preliminary Report-
Takashi TSUJI, et al
Abstract We have used an interlaminar titanium mesh cage(TMC)in conjunction with transarticular screw fixation to enhance the biomechanical stability of posterior atlantoaxial arthrodesis. The preliminary results of this new surgical method were reviewed. Interlaminar TMC was used in five patients with atlantoaxial subluxation. Four patients had rheumatoid arthritis and one had Os odontoideum. After exposure of the C1 and C2 laminae and facet joints, a guide wire was inserted into the atlantoaxial joints according to Magerl's technique. TMC filled with autologous cancellous bone was placed between the C1 and C2 laminae and tightened with titanium cables that had been passed under those laminae. Cannulated screws were inserted into the atlantoaxial joint and finally the titanium cables were tightened. Solid bony fusion was obtained in all cases. An average atlantoaxial angle of 24 degrees(range；13-37)was obtained, which was close to the optimal angle of 20 degrees, so that development of severe postoperative kyphosis due to hyperextended fixation of the atlantoaxial joint could be prevented. TMC functions as a spacer enhancing the biomechanical stability of the construct and protecting interlaminar grafts from collapse and absorption. The preliminary results of this procedure have been satisfactory.
Posterior Cervical Rigid Fixation with Summit PCR
Naoki ASAMI
Abstract The Summit PCR system permits rigid fixation allowing alignment correction by bicortical lateral mass screwing in combination with pedicle screwing at the caudal end of the construction.17 patients suffering from trauma, spondylosis and RA(mean age 56 y. o.)were treated with the Summit PCR system from January to December 2001. There were no major complications such as vertebral artery damage, but there were two cases of screw loosening and one case of infection. This system frees the patients from postoperative cervical casting. The author prefers open door laminoplasty with this system for bone fusion.
Main theme-2：Operative strategy for aged spinal disorders
Modified Fenestration Technique with Partial Removal
of Spinous Process for Lumbar Canal Stenosis
Keiichi AKATSUKA, et al
Abstract We introduce a modified technique of fenestration for lumbar canal stenosis. Fenestration was shown to be a good decompression technique for preserving the posterior elements. An extended laminotomy was required for lateral decompression when hypertrophy of the facet joint was revealed or the lesion was at a high level in the lumbar spine. After bilateral exposure of the lamina at the level of the lesion, preserving the supraspinous and interspinous ligaments, a minimal laminotomy was done, namely half of the caudal side at the base of the spinous process, was drilled out. Efficient wide decompression could be performed from the contralateral side and through the fenestration under the spinous rocess, using a microscopic technique. We applied this technique to 6 cases, and all of them showed good results without any complications. Our procedure was a minimal laminar fenestration, preserving the bony structure and posterior elements, and it enabled satisfactory decompression of the lateral part of the spinal canal including the nerve roots.
A Minimally Invasive Muscle Splitting Lumbar Microdiscectomy
Kiyoshi HIDAKA, et al.
Abstract The microscopic tubular retractor system(METRx system)is a minimally invasive technique for lumbar discectomy. Sequential soft tissue dilatation using dilators is less traumatizing for the paraspinal muscles. However, microdiscectomy through the tubular retractor may occasionally encounter difficulties in establishing microscopic visualization because of soft tissue interruption at the distal tip of the tubular retractor, and some surgeons do not feel comfortable with the limited working space within the tunnel shaped tubular retractor. We introduced sequential dilators for conventional microdiscectomy and developed specially designed specula fits for the An approximately 2.5 cm paramedian skin incision was made at the level of the appropriate disc space, followed by fascial incision. The muscle was sequentially dilated. After dilatation of the paraspinal muscles, a specially designed specula was placed over the largest dilator, extending down to the lamina. Microdiscectomy was then performed. This minimally invasive muscle splitting microdiscectomy was a less invasive but effective procedure for lumbar microdiscectomy.
Surgical Technique of X Laminotomy for Lumbar Spinal Canal Stenosis
HIRABAYASHI, et al
Abstract The objects of X laminotomy for patients with lumbar spinal canal stenosis are as follows：1)to resect the spinous processes of the odd-numbered vertebrae at the base while preserving those of the even-numbered vertebrae in order to obtain a good operative field and easily perform decompression, 2)to completely perform decompression of the neural tissues at any zone from the central to the extraforaminal, especially both the dorsal root ganglion and the nerve roots in the lateral recess underneath the lamina, through a medial and lateral approach without performing total facetectomy, 3)to graft the resected spinous processes at the lateral decompression site in order to avoid fracture at the isthmus. The most favorable candidate for X laminotomy is a relatively young patient without instability or spondylolisthesis of the lumbar spine. In conclusion, complete decompression from the central to the extraforaminal zone, preserving the lamina and the facet joint, is possible in X laminotomy.
Posterior Instrumentation and Thoracoscopic Anterior Decompression
for Delayed Paralysis Due to Osteoporotic Compression Fracture
Yutaka HIRAIZUMI, et al
Abstract Osteoporotic spinal compression fractures often induce persistent back pain or delayed paralysis due to vertebral pseudoarthrosis. In our institution, thoracoscopic anterior spinal cord decompression and fusion have been performed for such technically demanding pathology. Thirteen patients underwent this endoscopic procedure. Ages ranged from 49 to 78, average 61.4 years. Operative time ranged from 150 to 580, averaging 300 min. Patients stayed at postop-ICU for an average of 1.6 days. No case showed grafted bone or titanium cage migration into the adjacent vertebrae during follow-up period. By avoiding conventional open thoracotomy, this endoscopic surgical technique caused less postoperative wound pain as well as improved respiratory function for such high-risk patients.
Posterior Instrumentation for Osteoporotic Compression Fracture
Toru OSAWA, et al
Abstract The treatment of osteoporotic compression fracture with the late neurological complications and persistent back pain is controversial. The purpose of this study is to investigate the necessity of the reconstruction of the anterior support with the posterior instrumentation. Posterior fixation was performed in total 22 cases. Posterior bone grafting was performed in 9 cases, and reconstruction of the anterior support was performed in 13 cases. All cases were clinically and radiologically assessed. In all cases, the mean kyphosis Cobb angle was 29.7 degrees preoperatively, and changed to 13.3 degrees postoperatively, then became 27.4 degrees finally. In the anterior support group, the mean kyphosis Cobb angle was 26.8 degrees preoperatively, and changed to 8 degrees postoperatively, then became 18.8 degrees finally. The corrective positions had been kept relatively good in this group. When Luque instrument was used, the final corrective position after operation was not satisfactory. In this study, the good corrective position could be kept in the anterior support cases, though some complications and limitations were existed. It was indicated that the anterior support reconstruction may be necessary to keep good corrective sagittal alignment with the posterior instrumentation.
Indications and Selection of Operative Methods for Spinal Instrumentation
in the Very Elderly(over 80 years)Using the Sliding Scale
Keisuke ISHI, et al
Abstract Tolerance of the elderly to surgery is poor and there is a limit to its invasiveness. We previously devised a sliding scale to assess the limits of operating time and blood loss based on age, and we have since selected our operative methods to lie within that range. This study reviewed the validity of such selection of operative methods for spinal instrumentation in persons aged 80 years or older. We performed thoracicor lumbar instrumentation on 18 very elderly persons. The average age of the patients at the time of surgery was 82 years. There were 11 patients who deviated from the sliding scale only in operating time and 2 who deviated in two categories. As regards postoperative general complications, transient heart failure, pleural effusion, and hypotension were each seen in one patient, while delirium was seen in 7 patients, but there were no serious complications. There were no such complications in patients who fitted in the sliding scale. There was a complication in one of the two patients who deviated in 2 categories and 7 of the 11 patients who deviated in 1 category from the sliding scale. Better results were obtained in very elderly persons by performing spinal instrumentation with consideration of certain limitations. Our sliding scale was useful for the selection of operative methods.
Main theme-3：New approaches and techniques for spinal surgery
Dorsal Root Entry Zone Lesion(DREZ-lesion)as a Treatment for Patients
with Intractable Pain Caused by Cord, Root, or Nerve Lesions
Hiroshi TAKAHASHI
Abstract DREZ-otomy(Sindou)is one of the few effective methods to treat patients with intractable pain caused by cord injury, root avulsion, postherpetic neuralgia or RSD. We have operated on 18 cases so far. Of these, 11 had traumatic cord or root lesions, 4 intramedullary cord tumors, 2 syringomyelia and 1 postherpetic neuralgia. In cases with root avulsion, we simply opened the posterior horn and coagulated there to a depth of 2-3 mm. In the other cases, we opened and coagulated the posterior horn from the lateral side of the posterior rootlets. Recently, instead of the usual method of DREZ-otomy, we performed posterior rhizotomy and aspiration of the posterior horn in a case with traumatic conus and cauda lesions causing paraplegia and intractable pain, with successful results. Directly after the operations, 94% of the cases had good pain control, and the follow-up study showed that pain control was obtained in 81%. Complications occurred in 5 cases. However, 80% were temporary and improved within a month after the operation.
Liquorrhoea of Thoracotomy for Removal of Spinal Tumor
Hiroshi DOI, et al
Abstract Surgical treatment of CSF leakage in the thoracic space is difficult for two reasons：1．The space between the ribs is narrow 2．Strong liquorrhoea and postoperative thoracic drainage may cause brain herniation. Case：64-year-old female who was admitted for paraparesis. MRI showed massive thoracic neurinoma in the mediastinum and spinal canal. The approach, material, operative techniques and results are described. The dural incision was closed successfully by dural suture with fibrin glue and pleural sutures manufactured by Gore-tex. Our two revisions to check for defects have also been sealed effectively. The thoracic approach using a microscope is the technique of choice for dural repair after the removal a the thoracic spinal tumor.
Endoscopic Anterior Correction and Instrumentation for Idiopathic Scoliosis by Eclipse
Motonobu NATSUYAMA, et al
Abstract We started endoscopic anterior correction and instrumentation for idiopathic scoliosis. The purpose of this article is to describe this promising operative procedure, and discuss problems.
Materials and Methods：Case 1；The patient was a 23-year-old female. The preoperative Cobb angle was 50 degrees. Case 2；The patient was a 12-year-old female. The preoperative Cobb angle was 82 degrees. Case 3：The patient was a 17-year-old female. The preoperative Cobb angle was 83 degrees. By preoperative CT Scan,
we measured the transverse length of the vertebral bodies, and identified the relations between the vertebral bodies and the great vessels. Eclipse was used for these cases. The procedure was performed with the patient in the left lateral position with six portals being used. Single lung anaesthesia was used. Following discectomy and elevation of rib heads, 6.5 mm screws were inserted under image intensifier and endoscopic control. Bone graft taken from ribs was inserted. A 4.5 mm rod was secured and compressed.
Results：Case 1；The levels instrumented were from T5 to T11. The operative time was 8 hours and 55 minutes. The blood loss was 470 ml. The postoperative Cobb angle was 10 degrees, so that 80% of correction was achieved. A chest drain was reinserted due to a hydrothorax. Case 2；The levels instrumented were from T6 to T12. The operative time was 10 hours and 20 minutes. The blood loss was 330 ml. The postoperative Cobb angle was 10 degrees, so that 88% of correction was achieved. Case 3；The levels instrumented were from T5 to T11. The operative time was 8 hours and 35 minutes. The blood loss was 450 ml. The postoperative Cobb angle was 40 degrees.
Discussion：Initial results of this technique gave satisfactory correction rates and especially good cosmetic results. No serious complications have occurred.
Although this procedure is promising, we need long-term follow up data.
Anterior Cannulated Screw Fixation for the Upper Cervical Spine
Toshinori TAMADA, et al
Abstract Anterior screw fixation of odontoid fracture has become popular as a way to treat it directly with minimal invasion. This technique requires cannulated screw systems with biplanar fluoroscopy. The major limitation of anterior fixation technique is inability to reduce the fracture and restore atlantoaxial(C1-C2)alignment.
We developed a new surgical instrument to treat this upper cervical spine pathology. Our drill guide has an angled tongue that sits on the C1 anterior arch. The other drill guides with spikes must be held steady；otherwise the reduction will be unstable or malaligned. Our drill guide with tongue permitted pre- and intraoperative C1-C2 alignment to be restored.
Anterior cannulated screw fixation was suited for 3 cases of odontoid fracture and one of C1-C2 instability due to RA. Odontoid screw fixation was performed using our surgical instrument for precise screw insertion, while atlantoaxial transarticular screw fixation could be performed with a similar anterior technique.
In conclusion, minimally invasive spinal surgery using our new drill guide was useful for the anterior approach to the upper cervical spine.
Microcervical Foraminotomy with En-bloc Laminoplasty for Radiculopathy
Kunihiko SASAI, et al
Abstract To investigate the surgical outcome and radiographic changes after microcervical foraminotomy with en-bloc laminoplasty, thirty-four consecutive patients with radiculopathy were followed more than one year(average 2.1 years). In twenty-two patients, pre-operative radicular pain completely disappeared after surgery. On the other hand, the remaining 12 patients were diagnosed as cervical spondylotic amyotrophy. The pre-operative manual muscle test of the deltoid muscle gave a score of 0 in 6 patients, 1 in 5, and 2 in one. In 11 patients, excluding one postoperatively diagnosed as a neurological disorder, the score was significantly increased at the last follow-up：2 in one patient, 4 in 6, and 5 in 4(p=0.0025, Wilcoxon signed rank test). Cervical lordosis, flexion angle, extension angle, and range of motion did not significantly change after surgery. Microcervical foraminotomy was performed at 49 sites and less than half of the facet joint was removed at all sites. The angulation and slip at the 49 sites did not significantly change between preoperation and the last follow-up. The surgical outcome of this method for radiculopathy, including cervical spondylotic amyotrophy, was satisfactory in every case. This evidence suggests that by using microcervical foraminotomy, not only the posterior root but also the anterior root could be decompressed. By adding this technique to laminoplasty, whole neural structures(spinal cord, rootlets, and nerve roots)could be decompressed. If foraminotomy is performed on less than half of the facet joint, instability at the affected level is unlikely to occur.
Microscopic Decompression Through Unilateral Approach in Elderly Patients
with Lumbar Spinal Canal Stenosis
Yuichiro NISHIJIMA, et al
Abstract The purpose of this report is to present a method of microscopic decompression of the dural sac through a unilateral approach in patients with lumbar spinal canal stenosis.
[Indications] Patients who had the following conditions were selected.
1 ．The main clinical symptom was cauda equina intermittent claudication.
2 ．The main pathology was dural compression by hypertrophied yellow ligaments.
3 ．Symptoms related to an unstable spine were moderate.
4 ．Over 3 months of conservative therapy had failed to improve the claudication.
[Methods] A 2-3 cm posterior midline incision was enough. A deformed and hypertrophied inferior facet was resected with a surgical airtome. Hypertrophied yellow ligaments were excised with a Kerrison punch until pulsation of CSF was seen in the decompressed dural sac. To observe the contralateral spinal canal, the light axis of the microscope was changed. It was possible to remove contralateral yellow ligaments by using the microscope.
[Patients] We performed this unilateral approach microscopic decompression in 20 patients over than 65 years old.
[Results] There was no intraoperative nerve injuries. Postoperative results were evaluated by the JOA score. sixteen preoperative points of JOA score were improved to 24 points postoperatively(recovery rate；62%).
[Conclusion] We should perform spinal surgery on elderly patients as minimally as possible. When we use a microscope we can perform total decompression of the dural sac with a unilateral approach.
Lumbar Spinal Canal Stenosis Treated by MED System
Shoji YAGI, et al
Abstract Sixteen patients with lumbar spinal canal stenosis underwent microendoscopic laminectomy using the MED system(METRx). There were 8 men and 8 women, with a mean age of 60.7 years(49-80).
The tubular retractor was inserted under lateral fluoroscopic control. The endoscope was inserted into the tubular retractor. An ipsilateral partial laminectomy was performed using a Kerrison rongeur and a high speed drill. The laminectomy was extended cephalad beyond the disc level. After complete ipsilateral decompression, the tubular retractor was angulated medially to afford visualization across the midline beneath the interspinous ligament. The unilateral approach allowed access for contralateral partial laminectomy, and all soft tissue and pathological material causing bone stenosis was resected.
The average operating time was 102 minutes(70-130). The recovery rate on the JOA score averaged 68.6%(21-90). The described approach using the MED system has the following advantages；1)less invasion of the paraspinal muscle；2) unilateral approach；3)preservation of the inter-supraspinous ligament；4)little dead space.
The Experience of Mini-ALIF with Translaminar Screw Fixation for Chronic Low Back Pain
Takeshi UCHIDA, et al
Abstract I report the early clinical results of treatment by mini-ALIF with translaminar screw fixation in eight cases of degenerative disc disease with chronic low back pain. The mean age at time of operation was 33 years(range, 21-50). The average operative time was 398 minutes and the average blood loss 408 ml. Fusion was achieved at the L4/L5 level in five patients, L5/S1 in one and L4-S1 in two. Our early clinical results were that five patients had no low back pain and three were found to be clinically improved.
There were no major complications. The immediate stabilization provided by anterior interbody fusion cage fixation alone was not achieved in all cases, because micro-motion of facet joints after ALIF was observed, in addition to the stress force on both spinous processes of the fused segments. Therefore, to achieve solid fusion, supplemental posterior fixation such as translaminar screw fixation should be considered.
Free papers
Idiopathic Spinal Cord Herniation
-A Case Report-
Motoo KUBOTA, et al
Abstract We report a case of spontaneous thoracic spinal cord herniation presenting as a gradually progressive Brown-Sequard syndrome for two years in a 68-year-old woman. Magnetic resonance imaging(MRI)of the thoracic spinal canal demonstrated a 'c' -shaped anterior kinking of the spinal cord with widening of the dorsal subarachnoid space at the T4-5 level. A CT myelogram revealed a boomerang-shaped deformity and transdural herniation of the spinal cord. The patient underwent a T4-5 laminectomy. The herniated part of the spinal cord was microsurgically reduced, and the dural defect was repaired with a Gore-Tex sheet. The neurological symptoms improved after surgery, and the herniation was seen to be successfully reduced on a postoperative MRI.
Review of the world literature revealed 43 reported cases including the present case, with 41 of these cases published since 1990. The clinical features and radiological diagnosis are summarized briefly from the literature. To ensure a better outcome, biopsy of the herniated part of the spinal cord, direct retraction of the spinal cord, and careless separation of the herniated cord and the edge of the dural defect should be avoided.
Surgical Anatomy of the Lower Cervical Vertebral Artery and Surrounding Structures
Motoo KUBOTA, et al
Abstract Foramen magnum decompression(FMD)for Chiari type 1 malformation associated with syringomyelia is introduced in this paper. FMD aims to improve the CSF flow though the foramen magnum. We remove the far lateral bony edge of the foramen magnum using a high-speed drill. For sufficient decompression, we usually add laminectomy of the atlas. The dura mater of the posterior fossa and upper cervix is incised in a'Y'shape, and is patched with a large Gore-Tex sheet. Because we make every effort not to tear the arachnoid membrane during this procedure, we have not experienced any surgical complications.
We assessed 46 patients who underwent FMD and were followed-up for at least one year. In most cases, the postoperative courses were quite satisfactory. Tonsils have begun to rise during surgery and syringes have decreased in size on MRI, taken three months after surgery. In eight of 46 patients(17.4%), however, syringes have been slow to shrink. These patients had a wider basal angle, narrower clivoaxial angle(CAA)and a severely lordotic cervical spine adiographically. Those with CAA narrower than 130 degrees showed significant delay in shrinking of the syringes. However, none of these patients showed any deterioration in clinical symptoms. FMD seemed to be safe and effective for patients with Chiari malformation even with mild basilar impression. The CAA could accurately predict the time course of syrinx shrinkage after FMD.
Total Sacrectomy and Reconstruction of the Sacrum for Sacral Chordoma
-A Report of Two Cases
Morio MATSUMOTO, et al
Abstract We report two cases(74-year-old-male and 58-year-old female)of sacral chordoma treated by two-staged total sacrectomy and reconstruction of the sacrum. For the reconstruction, we made a construct which provides 4-point anchoring to the ilium by connecting bilateral longitudinal rods secured by iliac screws and a sacral bar, using the ISOLA system. This construct has a strong resistance to rotational stress between the lumbar spine and the pelvis, thereby enhancing the stability of the spine-pelvis complex. Both patients obtained successful surgical results by means of this construct.
Mobile Schwannoma Arising from Cauda Equina Close to Epiconus Medullaris Complicated with Syrinx of Spinal Cord
Eiichiro HONDA
Abstract A patient with a mobile schwannoma arising from the epiconus medullaris was encountered. The clinical episode revealed an interesting change in which radiating pain to the right thigh and leg moved to the left side within 7 months. The tumor was located on the left T12/L1 on MRI, but it moved down about one half vertebral body to L1 on myelography. Left hemilaminectomy between T11 and L1 was performed. Postoperative symptoms comprised painful sensation over the right L4 and L5 dermatomes. The left leg was pain free. Furthermore, postoperative MRI demonstrated the syrinx of the upper epiconus of the spinal cord. The likely explanation is that the spinal cord in the region of the epiconus medullaris was twisted by the mobile schwannoma so that alternative symptoms were caused and syrinx resulted due to ischemia of the spinal gray matter distorted by stress. However, this event could not be confirmed, as hemilaminectomy unfortunately failed to expose the whole appearance of the lesion.
"Meshplating”, a New Method of Spondylolysis Repair
Shigeo SANO, et al
Abstract A new technique("Meshplating”)was performed on 7 patients with spondylolytic spondylolisthesis and on 1 patient with spondylolysis alone. The"Meshplate”was made of Titanium mesh and composed of a cylinder part and a plate part. The"Meshplating”was the method of lysis repair, filling the cylinder part with cancellous bone and attaching it to the lamina with screws in the plate part. In the case with spondylolysis alone, AO cancellous screws were inserted bilaterally to pedicles for modified Scott's wire fixation of the Meshplated lamina. In the 7 patients with spondylolisthesis, the slip was first reduced by intradiscal mobilization and opening of the disc space by Colis'interspace shaper(PLIG)(First reduction)and then by drawing back with the temporary instrument(Second reduction)followed by PLIF with cage, fixation of the lamina by the modified Scott method, PLF, and final instrumentation. The Meshplating was technically easier and provided much better stability than previous grafting methods. Though the follow-up was short(3-19 months；avg 10 months), the results seemed to be excellent with JOA score improvement of 81% in the first 5 patients, and slip reduction of 80% in 7 patients, without any complications or signs of pseudoarthrosis.
Special session-I
Operative Method Under Spinal Cord Monitoring for Tight Filum Terminale
Kenji ENDO, et al
Abstract This paper introduces a spinal cord monitoring for avoiding misidentification of the filum terminale and cauda equina in tight filum terminale(TFT). The operation was carried out in 52 cases(33 male, 19 female, average 27.7 years old). The recording electrode was placed in the dorsal extradural space at the level of Th12. At the S1 to S2 level where the terminal sac may be located, laminectomy was performed and a bipolar stimulating electrode was placed on the filum terminale after the opening of the dura and arachnoid mater. If evoked potentials were not recorded, it was identified as the filum terminale and transected. As a result, there was no complication after these operations, and the recovery score of the Japanese Orthopaedic Association(JOA)was 74±26%(mean±SD). In particular, there was recovery from pain in 98%, from bladder and bowel disturbance in 79% and from spinal stiffness in 82%.
Under spinal cord monitoring, the transection of TFT could be performed safely and with good clinical results.
Experience of Intraoperative Ultrasonography in Spinal Surgery
Hiroshi TAKESHITA, et al
Abstract Intraoperative ultrasonography of spinal cord motion during spinal surgery, using a 6.5 MHz ultrasound probe with a saline-filled operative field as described in other reports, was done in 7 cases of posterior shortening spinal osteotomy and 22 cases of thoracic-lumbar unstable injuries. Dura and spinal cord could be observed in the case of posterior shortening spinal osteotomy over the dural field after laminectomy by means of sagittal and axial sections. Moreover, neuroparalysis could be avoided, because whatever was pressing the dura or the neural tissue was removed in real time. There were many cases in which it clearly could be seen that bone fragments of the posterior wall were compressing the spinal canal and the dural pulsation returned after they were removed. This is a very effective way to perform decompression of the spinal cord by posterior spinal osteotomy with chisel and interspinal disc forceps without causing neuroparalysis. Intraoperative ultrasonic diagnosis with saline-filled operative fields is a simple, easy and effective examination by which we can observe the intradural and extradural conditions and the dural pulsation without invasion.
Posterolateral Fusion for Lumbar Spine with "Lumbar Magerl's Method"
Masao DEGUCHI, et al
Abstract Purpose：Translaminar facet joint screw fixation(Magerl；1984)is a logical method to stabilize the lumbar spine. The purpose of this study was to determine the fusion rate, the complication rate, and the clinical outcome of posterolateral fusion with translaminar facet joint screw fixation for lumbar canal stenosis and lumbar disc herniation. Materials & Methods：A total of 27 patients(11 male, 26 female, 26 to 74 y/o)underwent decompression of neural elements and posterolateral fusion with translaminar facet joint screw fixation between 1998 and 1999, and all were followed up for an average period of 2.4 years. All patients were clinically and radiologically assessed. Results：Twenty-three patients showed solid union functionally and radiologically, but 4 developed pseudoarthrosis. DXA showed a tendency of more osteoporotic spines in these 4 patients(0.812±0.120 g/cm2)than in the others, who showed solid fusion(0.901±0.160 g/cm2), though it was not statistically significant. The average JOA score was 13.8 points preoperatively and 25.6 postoperatively. Discussion and Conclusion： Although past biomechanical studies have shown that translaminar facet joint screw fixation, provided as much stability as pedicle screw fixation, especially under flexion loading, this method should not be recommended for osteoporotic or widely laminectomized spines. However, in selected patients this method is still a good alternative for spinal fusion.
Fenestration with Spinous Process Flap for Lumbar Degenerative Spondylolisthesis Using Posterolateral Fusion with H. H. R.
Yoshihito SAKAI, et al
Abstract We have been using H. H. R. as a substitute for pedicle screws during posterolateral fusion for lumbar degenerative spondylolisthesis since April, 2000. We report the usefulness of fenestration with a spinous process flap in combination with this technique.
A total of 10 patients who underwent the following operation for spondylolisthesis was reviewed. The mean age at the time of surgery was 60.1 years. Average time after surgery was 9.5 months.
The average operation time was 167.5 minutes and estimated blood loss was 329.8 ml. Bony fusion was achieved in all patients within 3.9 months. The Mean JOA score was improved from 7.3 points preoperatively to 12.9 points postoperatively； the improvement ratio was 70.5%. The percent slip measured before, and immediately after operation and at the time of bony fusion was 18.0%，9.5% and 16.0% respectively. The slip angle was 6.3°, -0.4°and 0.4°.
Fenestration with a spinous process flap which can preserve the facet joint and the integrity of the posterior elements is an effective method for lumbar degenerative disorders with instability. The use of H. H. R., which enables fluoroscopy during operation to be avoided, can prepare a sufficient graft bed and optimizes the chances of fusion.
NNC Rod for Spinal Fusion and Flexible Stabilization
―A Preliminary Report―
Yuji MATSUBARA, et al
Abstract Spinal fusion with a pedicle screw system may cause degeneration and instability at the segment adjacent to lumbar fusion. We designed a new implant NNC rod to which we could attach a Graf band to prevent such problems. In this study we report a series in which we used the NNC rod for lumbar spinal fusion and stabilization of the adjacent segment.
Fifteen consecutive cases who had undergone PLIF and stabilization of the adjacent segment with the NNC rod were reviewed. There were eight men and seven women, with an average age of 63 years at surgery. The mean follow-up period was eight months. All patients underwent one level fusion(PLIF)and stabilization with a Graf band of the upper adjacent segment and NNC rod. The operation time averaged 250 minutes and the estimated blood loss averaged 568 ml. The preoperative JOA score was 12.3 and the postoperative was 24.5. The mean recovery rate was 73.7%. Lumbar lordosis was not significantly changed by operation. The range of motion at the adjacent segment definitely decreased after stabilization. No complications associated with instrumentation were seen in this series.
Because of the short follow-up time it is impossible to be certain that this system is effective. However, stabilization using the NNC rod and Graf band at the segment adjacent to fusion can be expected to prevent adjacent segment problems.
Intrasacral Fixation for L5 Spondylolysis and Spondylolisthes
Tokumi KANEMURA, et al
Abstract The aim of this study was to evaluate the surgical results of spinal fusion for L5 spondylolysis and spondylolisthesis using the intrasacral fixation technique. We evaluated 25 consecutive patients with L5 spondylolysis and spondylolisthesis who had been treated by intrasacral fixation. They were followed up for a minimum of 1 year. We analyzed the surgical results, fusion rates, JOA scores and any complications. The patients consisted of 10 men and 15 women with a mean age of 48 years(11-71). All patients but one were operated on by PLIF with intrasacral fixation and the remaining patient by PLF with intrasacral fixation followed by anterior interbody fusion. The fusion rate was 96% and the recovery rates by JOA score were 70%. Complications occurred in 4 patients. In one case, the nerve root was injured by the intrasacral rod and the patient had post-operative neurological symptoms, but they resolved. It has been reported that the intrasacral technique provides the greatest stability for lumbosacral fixation. We obtained successful surgical results and the technique was effective for L5 spondylolysis.
Special session-II
Fatal Bone Marrow Embolism During Correction Osteotomy
of Ankylosing Spondylitis with Spinal Instrumentation
-A Case Report-
Kenichi WATANABE, et al
Abstract A thirty-two year old man with ankylosing spondylitis was admitted with chief complaints of difficulty in walking and inability to see straight ahead due to marked fixed round back deformity. The first operation was posterior lumbar osteotomy with posterior spinal instrumentation on 15 Nov 1999, and was completed without significant complications.
Postoperatively, however, the kyphosis progressed. The second operation was undertaken under endotracheal general anesthesia on 19 Dec 2000. At first a posterior V shaped osteotomy was carried out from T5 to T12, followed by spinal instrumentation, but satisfactory correction was not obtained. Vertebral osteotomy through the posterior approach was then attempted at T12. Suddenly the heart rate and blood pressure fell and cardiac arrest occurred. He was resuscitated during surgery but postoperatively
he developed pulmonary edema and died the next day. Autopsy examination revealed marked bone marrow embolism with fragments of cancellous bone and cartilage in more than fifty percent of the peripheral pulmonary arterioles of both lungs.
Discussion：Bone marrow embolism is well known to occur in association with intramedullary nailing of femoral fractures and with total hip replacement. But reports of bone marrow embolism are rare in correction with spinal surgical procedures. Since it has been reported that esophageal monitoring by echogram can demonstrate this phenomenon during spinal surgery, we should keep in mind that this complication, pulmonary embolism with fat, or bone marrow, can occur intraoperatively in spinal surgery. And that not only TEE(transesophageal echocardiography)but also intraoperative monitoring of ETCO2(end-tidal CO2)and, ETCO2/PCO2 are useful for detecting pulmonary embolism.
Anterior Decompression Using a Modified Costotransversectomy for Thoracic Myelopathy Due to Severe Thoracic Kyphosis Developing after Spinal Tuberculosis
Masafumi SAITO, et al
Abstract Although the association of kypthotic deformity with paraplegia has been frequently recognized in cases of spinal tuberculosis, delayed myelopathy as a sequela of late-developing severe kyphosis has rarely been observed after initial healing of tuberculous thoracic spondylitis.
We have had the opportunity to treat nine patients surgically for myelopathy due to severe angular thoracic kyphosis by the costotransversectomy approach.
The costotransversectomy approach was initially described for treatment of Pott's disease of the spine and it has been applied to the treatment of compressing pathology of the spinal cord. We modified costotransversectomy for this lesion. The modified costotranversectomy we performed consisted of two surgical procedures. The first procedure was laminectomy and pediclectomy on one side with posterior approach, and the second was anterior decompression of the apical vertebra with lateral approach.
Between 1989 and 2001, nine patients underwent anterior decompression using a modified costotransversectomy. The ages of the patients ranged from 40 to 65 years, with a mean of 51 years. There were five women and four men. All patients had severe angular kyphosis of the thoracic spine. The average angle of thoracic kyphosis was 113 degrees(range, 70 to 140 degrees). In all nine patients, a progressive paraparesis occurred spontaneously due to anterior compression of the spinal cord at the apex of the thoracic kyphosis.
Blood loss during the surgery ranged from 320 to 815 ml, with an average of 557 ml. Operating time averaged 159 minutes(range, 115 to 225 minutes).
After anterior decompression using the modified costotoransversectomy approach, neurologic functions improved well in all patients. There was no neurological deterioration.
In conclusion, severe thoracic kyphosis after spinal tuberculosis should be recognized as a cause of progressive myelopathy that can be managed successfully with anterior decompression using modified costotransversectomy, though this is technically demanding.
A Case of Super Spondylectomy for Giant Cell Tumor of the Thoracic Spine
Junji NAGANO, et al
Abstract Postoperative local recurrence is one of the most troublesome complication of spinal giant cell tumor.
We treated a case of thoracic GCT by super spondylectomy using anterior bone graft and posterior instrumentation. The patient was a 39-year-old male. His chief complaints were gait disturbance and dysuria. Images of MRI and CT scan demonstrated 7th thoracic spine tumor which severely compressed the spinal cord and also infiltrated into the surrounding soft tissue. Histological diagnosis was performed by CT guided needle biopsy before complete resection. We planned anterior and posterior approaches for the safe management of the patient. After thoracotomy, spinal segmental arteries were ligated. Thoracic discs and proximal parts of ribs were resected for second operation. Five days after the 1st operation, we performed super spondylectomy through a posterior approach. The defect of the spinal column was replaced by autogenous iliac bone and rib grafts. The pleural defect was patched with silicon sheet. Posterior instrumentation was used to stabilize the thoracic spine. Two years after these operations, stabilization of the spine has been established without any loosening of the instrument. There has been no recurrence in the thoracic spine.
Laminoplasty of the Axis with Reconstruction of Deep-Layer Nuchal Muscles
Mika HANGAI, et al
Abstract It has been reported that the deep-layer nuchal muscles attached to the spinous process of the axis(or C2 muscles) were regarded as key structures for maintaining the lordotic curvature of the cervical spine. We have newly developed a surgical technique for axis(C2)laminoplasty and reconstruction of C2 muscles, preserving the normal bone-tendon insertion to the spinous process, in addition to the conventional C3-7"French door open”laminoplasty. We have operated on twentyfour patients using this technique and carried out a one-year clinical follow-up and radiological analysis.
Postoperative subjective symptoms around the neck were not different from those after conventional C3-C7 laminoplasty. The C2/C7 angle did not change after the C2 laminoplasty(P=0.81). However, the average C2 inclination tended to anteflex after surgery. The position of the reconstructed C2 spinous process moved 8.6 mm caudally on average. We have experienced 3 cases of non-union.
These results suggest that our new technique is safe and useful. However, it is inadequate for regaining lordotic alignment, which we have achieved after C3-7 laminoplasty. We have therefore increased the number and thickness of the threads. In addition, the suture material has been changed from absorbable to non-absorbable. Further clinical and radiological follow-up is required.
En-bloc Laminoplasty with New APACERAM Spacer
Yukimasa NISHIMURA, et al
Abstract We developed a new model of APACERAM spacer for en-bloc laminoplasty. The purpose of this paper is to present this method and the CT findings after 1 year follow-up.
En-bloc laminoplasty with the new APACERAM spacer was carried out on 21 patients from June 1999. The average age at the time of operation was 64 years, with 13 male patients, and 8 female. In 21 patients, 59 laminae were treated with the new APACERAM spacer. The CT examinations were performed at 6 weeks and 1 year after operation.
No breakage or dislodgment of the APACERAM spacer occurred in any patients up to 1 year after operation. Union of the spacer with the lamina at the facet joint side was observed in all patients, but at the spinous process side it was seen in 26 laminae out of 59(44%).
Our new model of APACERAM spacer has been found useful for the operation of en-bloc laminoplasty.
Posterior Stabilization and Fusion Using Cervical Pedicle Screw System
Akira MIYAUCHI, et al
Abstract A cervical pedicle screw system was applied in selected cases which required rigid cervical spinal fusion. Seventeen patients, 10 with trauma, 2 with metastatic tumor, and 5 with cervical spondylotic myelopathy(3 kyphosis and 2 slippage), were included in this retrospective study. They consisted of 13 men and 4 women, with an average age of 59 years(20-76 years). Seven patients were surgically treated by posterior procedure alone；iliac bone was grafted onto the decorticated lateral masses before the application of the plates. In the other 10 patients, anterior decompression and anterior strut graft followed the posterior procedure with pedicle screw fixation. Neurological deterioration was not observed. Postoperative CT scans revealed that 3 out of 73 screws were malpositioned. Two screws penetrated the medial aspect of the pedicle and 1 the lateral；however, no neurological complication was observed. There was no vascular injury during surgery, nor hardware failure. The advantage of the pedicle screw system is that it obtains solid stabilization, but the disadvantage is the difficulty in evaluation of bone fusion by plain radiographs in cases of posterior surgery alone.
Cervical Interbodies Thread Cage Fusion
Kaiji OHTA, et al
Abstract While plate fusion has long been used at our clinic for treating cervical derangement, last year we adopted threaded cage fusion. The objective of this study is to evaluate the advantages of cage fusion over plate fusion.
The advantages of the system using titanium cages described in this study are the absence of need for harvesting bone from the iliac crest for autografting, and the consequent absence of complications associated with harvesting, as well as less hemorrhage during surgery and shorter surgical time. In addition, the new device system permits patients to walk the day after surgery.
However, though cage fusion is highly advantageous in terms of surgery procedure, complete evaluation of the method requires long-term follow-up. Cage fusion, being less invasive than plate fusion, is more solid and provides a better surgical outcome；is also enables patients to walk the day after surgery. Although long-term observation is required, cage fusion promises to be extremely useful for cervical anterior interbody fusion.