Surgical Technique for Spine and Spinal Nerves
Vol.3 No.1(2001)

Disorders in Thoracic Spine
Staged spinal cord decompression through posterior approach for thoracic
OPLL-myelopathy -- how to resect the OPLL
Shigeru Hirabayashi, M.D., et al
After decompressing and shifting the spinal cord widely at both the cervical and thoracic levels posteriorly with tension-band laminoplasty as the first step, the spinal cord is further decompressed circumferentially at the most affected level by resecting the OPLL as the second step. The operation is performed under MEP control. In the beginning, laminectomy at the affected level is performed, followed by longitudinal durotomy. After the facet joint and the outer cortex of the transverse process have been resected, the thoracic spinal nerves are identified and lifted. By retracting the dura mater medially, the posterolateral surface of the OPLL can be clearly seen. After stripping adhesions between the dura mater and the OPLL, the OPLL is resected piece by piece and finally en bloc. Laminoplasty is performed between the transverse processes using a hydroxyapatite spacer. Even though cerebrospinal fluid leaks, it can be stopped by compressing the skin over the site after sugery.
In conclusion, the purpose of this operation is to prepare in advance a condition in which the spinal cord can be shifted posteriorly, so that the OPLL can be safely resected. As the operative field is shallow, wide, and clear through the posterior approach, the resection of the OPLL and decompression of the spinal cord can be more safely performed.
Application of Intraoperative Ultrasonography and Ultrasonic Osteotome
for Thoracic OPLL
Yasuaki Tokuhashi，MD.，et al.
In order to minimize the risk of iatrogenic cord injury during circum-spinal cord decompression from the posterolateral approach for thoracic myelopathy due to OPLL, intraoperative ultra-sonography and an ultrasonic osteotome were used for eighteen patients. The lesion of OPLL involved 3.7 vertebral bodies on average. In 9 cases it was accompanied by OLF. All patients complained of gait disturbance(Frankel's C, 12 patients; D, 6 patients). The average JOA score was 3.8. After wide laminectomy or resection of OLF, the degree of de-compression of the spinal cord from OPLL was valuat-ed by intraoperative ultrasonography. In case of insufficient decompression with severe palsy, a circum-spinal decompression was performed. The OPLL was cut by the ultrasonic osteotome under ultrasonographic observation. In the patients without severe palsy,posterior stabilization was performed, even if the degree of decompression was insufficient. As a result of ultrasonographic evaluation, posterior decompression was sufficient in 6 patients and insufficient in 12. 7 posterior and 2 anterior circum-spinal decompressions and 3 posterior stabilizations were performed in addition. At final follow-up(average 4 years and 8 months), all the patients were able to walk, although palsy was transiently aggravated in 5 patients and support was required in 12. The recovery rate by JOA score was 52.7%. Considering the preoperativeseverity and absence of worseningat final follow-up, the outcomes were satisfactory. Ultrasonic instruments enabled such operations to be done　weresafer than the usualprodecures.
Diagnosis by imaging and surgical outcome for thoracic arachnoid cyst
Kunihiko Sasai，MD.，et al
To assess the characteristics of the imaging and surgical outcome, six cases of thoracic arachnoid cyst(3 men and 3 women, 33 to 77 years old, mean follow-up 2 years 11 months) who were surgically treated, were retrospectively investigated. Three items(cystic lesion, flow void, and flattened cord) were analyzed on the preoperative imaging(myelogram, CT-myelogram, and MR T2 imaging). In 5 of 6 patients(1 extradural cyst and 4 intradural cysts), arachnoid cyst was confirmed during surgery, and one patient was normal. 1 patient with intradural cyst and 1 patient with extradural cyst were easily diagnosed on myelogram and MR imaging. In 3 of 4 patients, intradural arachnoid cyst could be diagnosed by flattened cord on CT-myelogram and axial view in MR imaging, and they recovered well after surgery. On the other hand, one patient with intradural cyst and arachnoiditis was clinically unchanged. Though intradural arachnoid cysts couldn't always be diagnosed by preoperative imaging, patients with flattened cord on imaging should be surgically treated.
Diagnosis and surgical treatment of thoracic arachnoid cyst
- analysis of 25 cases-Minoru
Hoshimaru，MD.，et al.
Spinal arachnoid cysts usually occur in the subarachnoid space dorsal to the thoracic cord. The radiological diagnosis of thoracic arachnoid cysts may be difficult. The purpose of this study is to elucidate the clinical features of thoracic arachnoid cysts and the surgical management of this disorder. Forty-one patients with spinal arachnoid cyst were treated at Ohtsu Municipal Hospital from 1979 to 1999. Twenty-five patients(61%) harbored an arachnoid cyst in the thoracic portion. The mean age of these 25 patients was 40.7 years(range 20-63 years), and they consisted of 15 females and 10 males. All 25 patients underwent resection of the arachnoid cyst. They demonstrated a variety of neurological symptoms such as spastic gait(14 cases), backache(11 cases), and paresthesia of the lower extremities(9 cases). Interestingly, 9 patients had symptoms in the upper extremities although there was no radiological abnormality in the cervical cord. Myelography showed early opacification of a cyst in 16 cases and blockade of CSF flow or delayed clearance of contrast materials in 9 cases. Surgical results were good in 16 patients, fair in 8 and, poor in one.
The Surgical Treatment for Multi-level Thoracic Disc Herniations
Seiichi Sugiyama，MD.，et al.
There have been few surgical reports about symptomatic multi-level thoracic disc herniations and therefore the object of this study is to report the surgical treatment of this disorders. Four patients(1 male, 3 females) suffering from multi-level thoracic disc herniations causing myelopathy underwent surgery. Their ages ranged from 41 to 71 years(average; 62). Magnetic resonance imaging and computed tomographic myelography clearly showed anterior compression of the spinal cord due to multiple herniated discs. The affected disc levels ranged from Th 6 to Th 11 and the mean number of herniated discs was four. All patients were treated by anterior decompression of the spinal cord using a microscope and interbody fusion by rib grafts through a transthoracic approach. Spinal instrumentation was used in two patients. In all cases good clinical results were obtained after surgery. Our operative methods using the transthoracic approach were useful for multi-level thoracic disc herniations, and spinal instrumentation may contribute to prevention of postoperative spinal deformity as well as reduction of recumbency time.
The symptoms of dorsal root ganglia of thoracic spinal nerve.
The investigation of the operated cases.
Kaiji Ohta，MD.，et al.
The author(K.O.) has performed 587 spine surgery operations, among which 120 cases involved only the thoracic spine. This percentage of thoracic spine operations was too high compared with other spine surgeons. We found out that a small OLF could induce severe symptoms. We also discovered that the decompression of the dorsal ganglion of spinal nerves was very important. The pathology remains unclear, but it is certain that the decompression of the nerve root relieves the symptoms.
It is impossible to make a diagnosis by alone radiological study(CT, MRI). We think that clinical signs are important for the diagnosis. Theoretical proofs and objective techniques of diagnosis are necessary.
A Result of Thoracic Interbody Fusion by Posterior Approach
Akira Miyauchi，MD，et al
The purpose of this paper is to report the results of a newly developed technique of posterior decompression and immediate interbody fusion of the thoracic spine, and to discuss its efficacy.　Technically, by removing the laminae and facets bilaterally, the intervertebral disc and anterior pathologies could be removed without neural hazard. The intervertebral space was filled with bone grafts, and pedicle screw fixation was performed.
Materials and Methods: The operation was performed on 18 selected cases, 8 with trauma, 3 with spondylosis, 2 with spinal infection, and 5 with osteoporotic vertebral necrosis. They were followed for a minimum period of 3 months.
Results: All but one, who had postoperative infection, acquired solid union by 11 months postoperatively. There was no neurological complication. This technique proved to be valid as immediate decompression and fusion surgery in selected cases of thoracic pathology such as fracture dislocation, burst　fracture of certain types, localized spinal infection and spondylotic myelopathy. No need for thoracotomy, circumferential decompression and easier acceptance of pedicle screw fixation are the advantages of this technique.
Closing Wedge Osteotomy for Rigid Thracolumbar Kyphosis
Kato Yuji，MD.，et al.
Closing wedge osteotomy, by the modified Eggshell procedure(Heinig) was performed for a 41-year-old female with post-traumatic rigid kypho-scoliosis after neglected dislocation of T11/12, with neurological deficit of the lower extremities. The radiogram showed 45 kyphosis and 15 scoliosis. After pediculectomy of T12 using a T-saw, the lateral wall of the T12 vertebral body was exposed. T12 intravertebral cancellous bone was removed, creating a thin cortical or eggshell rim on transpedicular approach, with 30°open posteriorly and 15°on the left-sid. After inserting a pedicle screw, the thin posterior cortical wall of the T12 vertebral body was pushed anteriorly by an impactor. Correction was performed using a 2 rod setting of T10-T11 and L1-L2. 23 degrees correction in the sagittal plane and 4 degrees in the frontal plane were safely obtained.
A Case of Spinal Reconstruction Using Cage for Symptomatic Extraosseous Thoracic Hemangioma
Masaki Mori，MD.，et al.
Most vertebral hemangiomas are asymptomatic. We treated a case symptomatic extraosseous thoracic hemangioma by spinal reconstruction using a cage. The patient was a 68-year-old female. Chief complaints were back pain and numbness of the right leg. Plain radiographs of the 11th thoracic vertebra demonstrated characteristic vertical striations. MRI and CT scan showed spinal cord compression by extraosseous tumor extension. Several feeding vessels of the tumor were shown by angiography. On transpedicular biopsy, the histological diagnosis was cavernous hemangioma. Embolization of the feeding vessels was performed with coils before surgery. Laminectomy and subtotal vertebrectomy were done by single posterior approach. Reconstruction of the spine was performed with a titanium cage with autograft and pedicle screw system. Operative time was 8 hours and blood loss was 658ml.
Five months after operation, stabilization of the spine was established without loosening of the cage and pedicle screws. Clinical symptoms were improved.
By preoperative embolization of feeding vessels, the amount of hemorrhage during surgery was minimized. Laminectomy and subtotal vertebrectomy by single posterior approach were performed. Rigid stabilization of the spine was obtained by the titanium cage with autogenous bone graft and pedicle screw system. Radiation therapy was not used because of the absence of malignancy and the subtotal resection of the T11 vertebra.
Spinal Infection
Postoperative MRSA Infection in Spinal Instrumentation
Kenichi Watanabe，MD.，et al.
Postoperative MRSA infection is one of the most serious complications of spinal
instrumentation surgery. This presentation reports the author's own experience of six cases and discusses problems and treatments. The diagnosis was established in four patients within two weeks, in one patient in two months and in one patient in more than six months. Osteomyelitis developed in two patients and septicemia developed in three patients, of whom one patient died of DIC, following by multi-organ failure. Debridement and washing were done in all cases, continuous irrigation in one case, closed wound method in three cases, open wound method and dressing change in four cases and removal of instrument in five cases. One to four re-operations were performed in each patient. It took 10 months at the longest for wound closure.
Delay in the diagnosis of MRSA infection may lead to osteomyelitis, sepsis and endotoxic shock, followed by DIC. Therefore once infection is suspected, needle aspiration or needle biopsy is mandatory to obtain culture for early diagnosis. Removal of instruments, open method and dressing change and secondary closure of wound are the recommended procedures.
The Methods and Complications of Spinal instrumentation
for Active Infectious Spondylitis
K. Arai，MD.，et al.
Spinal instrumentation for active infectious spondylitis usually achieves good results, but there are some patients who suffer an eventful course after this operation. 36 patients received single-stage posterior instrumentation for fusion with anterior curettage and bone graft, and five of them had complications after the operation. These were recurrent kyphosis caused by failure at the bone-instrument interface(n=3), and aggravation or prolongation of infection(n=2). The failures at the bone-instrument interface were due to displacement of screws(n=2) and fracture of the vertebral body(n=1). The former is thought to have been caused by osteoporosis or severe scoliosis, which placed excessive stress on the screws. In the latter, the residual vertebral body after curettage was too small to support the titanium mesh. Aggravation of infection was caused by misdiagnosis; tuberculosis was not detected at the first operation. The reason for the prolonged infection is not clear, but it is possible that the use of the titanium mesh for anterior fusion may have had some role.
These complications suggest that the patients with severe osteoporosis or scoliosis and those with large lesions of the vertebral body may require technical devices and fixation at more levels.
Surgical treatment using posterior instrumentation for infectious spondylitis
Futoshi Suetsuna，MD.，et al.
12 patients with infectious spondylitis treated using posterior instrumentation(PI) were reviewed. There were 7 males and 5 females with an average age of 61 years. 4 patients had wiring fixations in cervical spine(CS) and 8 patients had pedicle screw fixations in thoraco-lumbar spine(TLS). Clinical diagnosis involved 4 cases with tuberculous spondylitis and 8 cases with pyogenic spondylitis. All cases showed improvement of kyphotic angle. There were one case with loss of correction of 2 degrees in CS and 2 cases with an average loss of correction of 3 degrees in TLS. Failure of instruments was seen in one case having breakage of one pedicle screw. Pre and post operative cultures showed specific bacterias except two cases. The average post operative recovery rate was 78%. Bone fusion was obtained in all cases. In PI for infectious spondylitis , applications of wiring in CS and pedicle screw in TLS produced enough correction of kyphotic deformity and maintenance. It was useful to apply the continuous irrigation for cases having infections to posterior elements of the spine. We think that there is an indication of using PI for infectious spondylitis to obtain the correction of kyphotic deformities and early postoperative rehabilitation.
Experimental prulent infection of the intervertebral disc
Yasuhiro Iwasaku，MD.，et al.
The intervertebral disc has no blood supply and is considered to have less resistance to bacteria than other tissues. A Bacterial solution was incubated for 24 hours at 37℃ and at the time of inoculation the bacterial count had increased to between 107 and 108 organisms per ml. They were calculated by dilution and pour plate techniques. This paper reports the ensuring experimental discitis. One microliter of three kinds of bacterial solution(Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa) was inoculated separately into a disc of young adult Wistar rat tails by microsyringe for gas chromatography. Three weeks after inoculation, the discitis was observed by histology and softex roentgenogram. Softex showed discitis as narrowing of the disc space, destruction of the endplate and sclerotic change of the disc adjacent to the affected disc space. The discitis was then evaluated by softex. Infectious doses 50(ID-50) were evaluated for three kinds of bacteria(Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa). ID-50 scores were 65 bacteria for Staphylococcus aureus, 820 for Staphylococcus epidermidis and 49 for Pseudomonas aeruginosa. Experimental subcutaneous abscess or osteomyelitis was induced by a minimum amount of 160 bacteria. The disc was then vulnerable to bacterial infection.
Surgical management for chronic low back pain
Lumbar spinal fusion for lumbar disc herniation and spinal canal stenosis
Sadaaki Nakai,M.D.
Posterior herniotomy is the common technique for surgical treatment of lumbar disc hernia, but in certain conditions, interbody fusion is indicated. This study was made in order to see the subjective outcome of posterior lumbar interbody fusion(PLIF) and posterior herniotomy for lumbar disc hernia. The subjects were thirty-nine patients with lumbar disc hernia who were treated with PLIF, and 326 who were treated with posterior herniotomy. Subjective evaluation of symptoms and the degree of patient satisfaction were done by questionnaire. The parameters for assessment were: how each patient scored their symptoms one year after surgery and at the time of the survey; whether the patient had changed jobs because of residual symptoms after surgery; how satisfied the patient was with the results of surgery; and whether the patient required medication because of residual symptoms after surgery.
An average score of 37% of the 39 patients rated subjective symptoms after PLIF as less severe at the time of study than at 1 year after surgery. In response to the question as to the degree of satisfaction with surgery, 36% of patients responded that they were satisfied, and 64% said that they were moderately satisfied. A total of 70% did not need to change work because of postoperative symptoms, and medication for residual symptoms was occasionally required by 50.
Low Back Pain after 360 Degrees Lumbar Fusion Using Pedicle
Screwing and Titanium Cages
Yuji Yoshida, M.D., et al
Postoperative low back pain was studied two years after surgery in 63 patients who were operated upon by decompression and 360 degrees fusion using pedicle screwing and titanium cages for degeneration of a lumbar disc. 63.5% of patients had complained of low back pain. Comparison was made between the group with and without low back pain in various conditions. It was found that the patients with polyaxial screws and cylinder type cages had significantly less low back pain. The possible　causes of post　instrumentation low back pain are discussed.
Anterior Screw Fixation of a Odontoid Fracture with a Cannulated Screw System Using X-Tube and Radiance Illumination System
S. Yagi，MD.，et al.
We reviewed the results of trans-sacro-lumbar arthrodesis(TSLA). Sixteen patients who had various grades of isthmic spondylolisthesis were operated on. The extent of slippage, as defined by Meyerding, was Grade I in 8 patients, Grade II in 7 and Grade IV in one. The loose arch of the fifth lumbar vertebra was removed, and this was followed by laminectomy of the sacrum. Hollow screws packed with autogenous cancellous bone were then inserted from the sacrum to the fifth lumbar vertebra. The average operating time was 167 minutes. The average blood loss was 240ml. The recovery rate averaged 75%. No motion was detected on dynamic lateral radiographs in any of the patients. TSLA provides immediate good stability for the lumbosacral segment, because hollow screws are inserted across the disc space. TSLA is less invasive to paraspinal tisses and, is therefore associated with less postoperative pain.
En-bloc Laminectomized Reset using Sagittal Bone Saw
Toshinori Tamada，MD.，et al.
Laminectomy is a basic technique in posterior lumbar surgery. Additional facetectomy is a completing technique for spinal nerve root decompression. En bloc laminectomized reset is a reconstructive technique without bone autograft or spinal instrumentation. We report a new surgical technique of en bloc laminectomy using a sagittal bone saw.
Seventeen cases of en bloc laminectomized reset included 10 of osteoplastic hemilaminectomy and 7 of total laminectomy. The sagittal bone saw has replaced the T-saw as a new surgical instrument for osteotomy. Osteoplastic hemilaminectomy involves osteotomy of the pars interarticularis, while total laminectomy regains bilateral osteotomy of the laminae.
Ten cases of lumbosacral radiculopathy at the exiting nerve root underwent complete decompression by osteoplastic hemilaminectomy, including 6 of 5th foraminal encroachment and 4 of sequestrated disc with upward foraminal migration, while 7 cases of intracanal lesion underwent complete resection by total laminectomy, including 4 cases of lumbar spinal stenosis, 2 of intradural spinal tumor, and one of sequestrated disc with dorsal migration.
In conclusion, all spinal nerve roots and their surroundings were microsurgically safe from injury by the sagittal bone saw used for osteotomy. This instrument has a more useful design for en bloc laminectomy.
A new decompression technique for lumbar spine when "fenestration
is so difficult that laminectomy should be selected"
Takashi Yamazaki，MD.，et al.
When the laminar width is narrow and the facet is steep, fenestration surgery for lumbar spinal canal stenosis is technically demanding. A new decompression technique for such cases has been developed. This technique consists of(1)cutting half of the spinous process to as L shape, conserving the supraspinous ligament.(2)decompression and(3) returning the spinous process to its original position. Moving the spinous process temporarily gives the operator a good visual field and makes it easy to use surgical instruments such as the osteotome. The characteristic of this technique compared with that used by other authors is that this procedure was done at every segment　which needed decompression. This was applied to 14 patients. Superficial infection occurred in one case, but no major complications or disruption of the reconstructed spinous processes occurred. The clinical results were the same as those performed previously by us. This technique brings a better visual field and better handling of instruments than fenestration, with the same extent of conservation of the posterior elements.
Cervical spine
Selective peripheral denervation of the sternocleidomastoid
and the posterior cervical group muscles for treatment of spasmodic torticollis.
Hiroshi Takahashi，MD.，et al.
Selective peripheral denervation of the muscles of the sternocleidomastoid　and the posterior cervical group was performed according to Bertrand's method in 27 cases with idiopathic spasmodic torticollis or dystonia. In the former group, satisfactory results were obtained in 92%.
For denervation of the sternocleidomastoid, the peripheral accessory nerves were identified first posterior to the sternocleidomastoid, all branches were exposed and denervated, and the muscle itself was sectioned. As for the muscles of the posterior cervical group, extradural section of the roots of C1 and C2 was performed, combined with denervation of the posterior primary divisions(rami) of the C3 to C6 roots. In cases with spasmodic torticollis of rotatory type, denervation of the sternocleidmoastoid of the affected side and the posterior cervical muscles on the other side was performed. If a retrocollic component was observed, bilateral denervation of the posterior cervical muscles was carried out. In cases with laterocollis, denervation of the sternocleidomastoid on the concerned side and of the ipsilateral posterior cervical group was carried out. This method was effective for cases with idiopathic spasmodic torticollis. However, it was only partially effective in cases with generalized dystonia, and one patient needed additional pallidotomy.
Percutaneous cervical disc decompression using Ho:
YAG laser under the endoscopic control(Ho:YAG EPCDD)
Yuichiro Nishijima，MD.，et al.
The purpose of this report is to describe percutaneous cervical disc decompression using Ho:YAG laser under endoscopic control(Ho:YAG EPCDD) and to show the results in 22 patients with cervical disc herniation.
The patients with cervical disc herniation were selected according to the following conditions.
1. The clinical symptom was only radiculopathy.
2. The pain was not controlled with 3 months of conservative treatment.
3. MRI showed contained disc herniation.
We also sometimes performed Ho:YAG EPCDD for patients who were unsuitable for general anesthesia because of pulmonary and/or heart failure. A patient who was afraid of receiving open surgery to the neck was also selected. We prefer this technique for patients with cervical disc herniation at the adjacent level after interbody fusion.
Postoperative results were graded following the Owada criteria. They were graded as excellent when the symptom had disappeared; good when the symptom was improved without any medical intervention; fair when the symptom was slightly improved but still needed some medical aid; and poor when the symptom showed no change or was worsened. There were 5 patients in the excellent group, 10 patients in the good, 4 patients in the fair and 3 patients in the poor. The success rate was 68 % when Ho:YAG EPCDD was considered to be successful in the patients graded as excellent and good. There was no complication such as contamination on neurological damage.
Cervical open door laminoplasty with hydroxyapatite beads
in combination with spinoplasty
Shun-ichi Kihara, et al.
Thirty-five patients with cervical spondylotic myelopathy and OPLL underwent cervical open door laminoplasty with hydroxyapatite beads in combination with spinoplasty during the period from May 1999 to May 2000, as described below. Briefly, the left side of the laminae were exposed from the lower part of C2 to the upper part of Th1, and the spinous processes were then cut and detached together with the nuchal ligament from the laminae. We generally opened the door on the left side and made the hinge on the right side. Using two angled curettes, the laminae were slowly lifted on the open side and fixed with hydroxyapatite beads(5mm). After that, the tips of the the spinous processes, which had been detached from the laminae, were tied up to them. All patients showed remarkable neurological improvement after surgery, with JOA scores from 6.25 to 13.46 on the average. We consider that preservation of the posterior cervical supporting component is useful for the preservation of lordosis.
Instrumentation & complication
The concept and acoring of adjustability of spinal instruments
Shigeo Sano，MD
The concept of adjustability of spinal instruments is described and the adjustability score is calculated numerically. The adjustability is defined as the degree of freedom which allows the rod be fixed to the pedicle screws without changing their direction and alignment. There Six three-dimensional displacements of the screws were made. Adjustability was assessed by determining how much of each displacement the instrument could handle. The adjustability score was calculated for all 6 displacements. The adjustability scores were as follows. For the instruments with direct connection, VSP was 2.0 and the screw-rod system was 3.0. For the instruments with lateral connectors, with single use of lateral connector, Isola was 3.5, TSRH 3.5, Mirage 3.5, CD-Horizon 4.0, USS 4.0, Liberty 4.0, Synergy 4.5 and Isola twister 4.5, and with double use of lateral connectors, Liberty was 6.0. For the polyaxial screw systems, CD was 4.5, Synergy 4.5, and Moss-Miami 4.5. For the combined use of lateral connector and poly-axial screw, CD was 6.0 and Synergy 6.0. For the semi-rigid systems, Diapason was 4.0 and ASD rod system 6.0. Adjustability is an important parameter for characterizing instruments and is useful for instrument selection.
Biomechanical Interbody Fusion With Interbody Fusion Cage
Yoshisada Sato，MD.，et al.
This study investigated the biomechanical rigidity of Anterior Interbody Fusion(ALIF) with an interbody fusion cage. The objectives of the study were to clarify the changes of segmental rigidity after anterior insertion of interbody cages.
Ten frozen and thawed juvenile pig cadaveric lumbar L3-4 and L4-5 osteoligamentous spines were used. The segmental rigidity and laxity after implantation of the interbody cages were studies and the direction of placement and the number of cages was compared. Mechanical properties were determined by testing lumbar vertebral motion segments in flexion, extension, lateral bending and torsion. The five simulated conditions were(A) intact,(B) a single cage placed centrally and anteriorly,(C) a single cage placed laterally,(D) a single cage placed anterolaterlly and(E) two cages inserted anteriorly.
In the Student T test, there were no significant effects of ALIF(surgery) on the configuration for any of the loading modes. The rigidity of the(D) group was greater than that of the intact condition for all loading modes.
On comparison of the sagittal and lateral bending and torsion, rigidity was greatest with the two cages inserted anterior.
Application of an ultrasonically activated scalpel(Harmonic
Scalpel) in spinal surgery except an endoscopic approach
Yoshitaka Ishizaki，MD.，et al.
Purpose: Endoscopic techniques have recently been applied to the field of spinal surgery and the ultrasonically activated scalpel system has become indispensable to endoscopic surgery. We employed an ultrasonically activated scalpel in spinal surgery except an endoscopic approach to determine its effect on the surgical approach.
Materials: The ultrasonically activated scalpel technique was employed for spinal surgery in which hematorrhachis was most likely to occur; surgery included cervical laminoplasty, especially reoperation, and posterolateral lumbar spinal fusion.
Methods: While the ultrasonically activated scalpel enables hemostasis and incision into soft tissue, to be performed, thermal tissue damage is less than that with ordinary bipolar or monopolar electrocautery. We therefore applied the ultrasonically activated scalpel primarily to detach the soft tissue from the bone adjacent to the nerves. We used a dissecting hook as the scalpel blade.
Results: The ultrasonically activated scalpel device could safely detach soft tissue from the bone adjacent to the nervous system with little subsequent bleeding. The device was valuable in cases of reoperation after cervical laminoplasty.
Conclusion: The ultrasonically activated scalpel system was safely applied and was of value in spinal surgery without an endoscopic approach.
The titanium dura closer is useful in dural injury
during discectomy in high level lumbar disk hernia
Eiichiro Honda，MD.，et al.
Purpose) When dural injury occurred at a deep level during an operation such as discectomy, we found that dural closing by suture caused more tearing of the dura, and was difficult and time-consuming. We now report that the disposable titanium dura closer was very useful in this situation regarding convenience, facility and low rate of complications such as CSF leakage.
Case) The patient, a 62-year-old male, complained of pain in the right anterior thigh and intermittent claudication for half a year. Neurological examination revealed pain and weakness along the L3 nerve root and poor dorsiflexion of the right foot. MRI showed right centrolateral disk extrusion at L2/3, and myelography and CTM showed a thick superior facet on the right side of L4 and poor appearance of the right L5 nerve root. The operation was performed in the following order. The right L5 nerve root was decompressed and the interlaminar window of L3/4 on the right was enlarged, and finally discectomy at L2/3 was carried out from the right side, where the isthmus was removed. At the far medial point, the dura was injured, and the nerve root broke out. The dura was opened widely and the nerve root replaced. The dural defect was covered with Goatex and closed with the titanium dura closer. The clinical course was favorable.
Conclusion) It is difficult to perform dural suture at a deep level because the working space is narrow. The titanium dura closer looks like a skin stapler, adapted to micro-operation. Under the microscope, it is conventional and applicable also to vascular anastomosis.
Endoscope & Spine surgery
Early clinical results of MicroendoscopicDiscectomy(MED)
Motonobu Natsuyama,M.D., et al.
Lumbar disc herniation is a quite common pathology in orthopedics. Percutaneous discectomy remains somewhat controversial. It has limited indications and has not proven to be as effective as conventional or microscopic discectomy. Smith and Foley developed a new minimally invasive procedure for lumbar disc disease, Microendoscopic Discectomy(MED), in 1995. We started MED from October 1998. The purpose of this report is to present the early clinical results 　and complications.
Materials : We performed MED on 40 patients from October 1998 to October 2000 for lumbar disc herniation. Males were 25, females were 15, and the mean age was 38 years(22~56). In one patient the affected disc level was L2/3, in 22 L4/5, in 15 L5/S, and in two L4/5/S.
Methods: We investigated the period of hospital stay, period of post-operative hospital stay, period before return to normal temperature, frequency of post-operative. NSAIDs, operation time, blood loss, period before beginning to walk, JOA score, period before return to work or school, and complications.
Results: The mean hospital stay was 17.9 days, the mean post-operative hospital stay. 9.7 days, period before return to normal temperature 1.3 days, frequency of post-operative. NSAIDs 1.1 times. The mean operation time was 105 minutes,(65m.~ 180m.). The mean blood loss was 9.7+-18.5 Gm.( uncountable~ 120Gm.). All patients began to walk one day postoperatively. The mean JOA score was improved from 10.7+-3.8preop. to 27.6+-0.9 4w. postop, to 28.1+-0.7 12w. postop.. The mean period before return to work or school was 22.3 days. In one case, we observed liquorrhea, and the damaged dura had to be repaired.
Conclusion: MED is a minimumlly invasive and effective procedure for the treatment of lumbar disc herniation. Postoperative bed rest is short, and the period of return to work or sporting activity can be minimized.
Evaluation on scopic position in MicroEndoscopic discectomy
Hiroaki Nakamura，MD.，et al.
The purpose of this paper is to describe the feasible position of the MED scope during the operative procedure.
(Methods) A test pattern which has three circles divided by four lines was made. In the center of the test pattern, a tubular retractor was set, leaving a space of 2-3mm. The visual field was investigated, depending on the position of the scope.
(Results) when the angled scope was situated in the right lower part of the retractor, objects nearer to the scope looked bigger compared with the left upper part. Because of this, the circle seemed to be warped. This phenomenon was apparent in the right lower and peripheral part within the tubular retractor. In the left upper part, the circumference with 24mm of the diameter which was outside the tubular retractor could be visualized. Therefore, only an angled instrument such an angled curette could reach the end of the visual field.
(Conclusion) Taking these characteristics of the angled scope into consideration, the removal of part of the lamina and yellow ligament can be minimized.
Laparoscopic Resection of a bony spur of the fifth lumbar
vertebral body impinging on the fifth lumbar nerve. A case report
Morio Matsumoto，MD.，et al.
This is a case report of laparoscopic resection of a bony spur of the L5 vertebral body impinging on the fifth lumbar nerve. A 65-year-old female had been suffering from severe left leg pain for three months. Neurological examination suggested that her symptoms were due to L5 nerve root disturbance. Myelograms showed no abnormality within the spinal canal, while CAT scan demonstrated a large bony spur on the anterolateral part of the L5 vertebral body. Temporary but complete pain relief was obtained by selective L5 nerve root block. The diagnosis of fifth lumbar nerve lesion due to the spur was established and the patient underwent laparoscopic resection of the spur. Under laparoscopic visualization, a transperitoneal approach was made to reach the front of the L5-S1 intervertebral disc. After retracting the left common iliac artery and vein laterally, the spur was resected. The pain disappeared immediately after surgery, and the patient had had no recurrent leg pain at a follow-up two years after surgery. Since this disorder is rare, an optimal surgical method has not yet been determined. In this case, a good surgical outcome was obtained by minimally invasive laparoscopic spur resection. This procedure can be a surgical option for this rare condition.
Direct subdiaphragmatic approach to L1, L2 vertebrae under
video-associated endoscopy
Kenji Endo，MD.，et al.
This paper introduces a new endoscopic approach, the subdiaphragmatic direct approach, to the thoraco-lumbar junction. With this approach, we can treat vertebral fractures of L1 and L2 with a very small incision and without costal resection. The subjects were 4 patients(one man and three women) who underwent interbody fusion(Th12 and L1 in two, and L1 and L2 in two) under video-assisted endoscope. There were no complications and the time of hospitalization was within 8 days. The operation time was 135.75±14.17(mean±SD) min. The bleeding during the operation was 247±134.3g. Using the subdiaphragmatic approach, we avoided the need for special repair of the diaphragm after the operation by this minimally invasive surgery. The polyaxial screws can make the endoscopic spinal fusion technique safer and easier.