[Purpose] To report a retrospective evaluation of complications and indications of posterior lumbosacral fixation with iliac screws.

[Materials and Methods] We operated on 22 patients and followed them up for an average of 2 years and 9 months (4-77 months), and studied both the clinical and X-ray findings.

[Results] 13cases have been operated for lumbar degenerative disease(8 of them were revision surgeries due to non-union of previous lumbosacral fusion and impairment at the lower adjacent segment of the previous surgery), 5 for trauma, 2 for spinal tumor, and 2 for infectious spondylolitis. Anterior column support of L5/S1 was practiced in all cases except trauma. Loosening of the iliac screws on X-ray was recognized in 7 cases and rod breakage in 1 case, however all were asymptomatic. Removal of the iliac screws was necessary due to skin trauma caused by prominence of the screws in 3 cases and immediately postoperative neurological symptoms due to misplacement of the screws in one case.

[Discussion] The use of iliac screws provided more stability than that of S1 pedicle screws only. The main complication was the prominence of the screw head. There is need to discuss the treatment for the cases of lumbar degenerative diseases.

[Purpose] We studied retrospectively our patients with discogenic low back pain treated by spinal instrumentation.

[Materials & Method] From June 2005 to February 2009, there were eight consecutive patients who were operated by PLIF and PLF with spinal instrumentation for discogenic LBP. They were 1.7％ of a total 463 cases of PLIF performed during the same period in the same institution. There were 5 males and 3 females, with an average age of 46.9 years. The average follow-up period was 18.1 months. PLF was done on two patients and PLIF on six patients. Our criteria of discogenic LBP were ①LBP worsened by flexion ②no neurological deficit, ③ no compression of the dural tube on MRI. When LBP was relieved by as discblock injecting local anesthetic agent into the disc space, LBP was diagnosed disocogenic. The clinical parameters included Oswestry disability index and visual analog scale. Radiographic parameters included so called black disc and Modic change on MRI.

[Results] The average pre and post-operative ODI were 19.8 and 6.6. The average pre and postoperative VAS were 10 and 2.9. All patients showed black disc and three patients showed Modic type 1 change on MRI.

[Conclusion] This study showed satisfactory clinical outcome of patients with discogenic LBP treated by spinal instrumentation. Discoblock using local anesthetic agent was a useful tool for the diagnosis of discogenic LBP.

We describe herniotomy using a spinous process splitting approach and partial laminectomy for central type lumbar disc herniation. Five patients(four men and one woman)who underwent this surgical procedure were reviewed. The patientsʼ age at the time of operation ranged from 36 to 59 years(mean age 48 years). Patients who had central disc herniation on MRI with positive bilateral SLR test were indicated for surgery. Surgical incision was small and clinical results of all patients were satisfactory. Recurrence of disc herniation occurred in one patient although MRI 6 months after surgery revealed disappearance of the herniated mass.

The advantages of this procedure include : ①wide decompression due to the partial laminectomy is obtained. ②Herniated tissues can be enucleated via 4 approaches. ③We can select the transdural approach intraoperatively if necesary. However, the main limitation is the narrow working field for the herniotomy and hence the potential for damage to neural tissues.

Reduction of osteoporotic vertebral burst fractures causes a large defect in the anterior half of the vertebral body. This defect is not easily repaired and brings about a spinal deformity. To prevent the deformity, the defect is filled with Hydroxyapatite (HA) as a certain spacer. Thirty-eight patients were included (52-86 years old). Follow up period was 4 to 137 months(mean；35.0 months). Operating methods were as follows. The Metal working sleeve was carefully advanced into the bone defect of the vertebral body using a single-side postero-lateral approach. HA columns(mm in diameter)were introduced through the sleeve.

Results: There were no complications including neuro-vascular damage. All patients showed complete resolution of low back pain on motion within 27 weeks (mean；5.2 weeks) after surgery. Anterior vertebral height was 30-84% (mean, 48.7%) on admission, and improved 0-56% (mean, 20.8%)at the latest observation (p<0.0001). The estimated area of the bony fragments retropulsed into the spinal canal using CT images was initially 5-43% (mean, 19.8%), and gradually reduced to 5-29% (mean, 13.5%) at the final evaluation (p=0.0038). In conclusion, this operation will become a useful procedure for osteoporotic vertebral burst fractures.

Placing the drain tube in the proper position with minimally invasive spinal surgery is difficult, because of the small incision and narrow working space. We report a new method to place the drain tube in the proper position for microendoscopic decompression to avoid postoperative epidural hematomas. After microendoscopic decompression, adrain passer€whose shape had been improved to be straight as a thin dechamps was inserted percutaneously through the silk thread.
Then let the tubular retractor carefully in along the outer wall of it. The drain tube (10 Fr.) was pulled out to the outside of the body with the drain passer by passing it through the silk thread.
Finally, the proper position and the length of the drain tube was confirmed with a microendoscope.
The conventional method to place the drain tube for spinal posterior decompression is performed by penetrating the trocar from the operative field. However, the small skin incision in microendoscopic surgery makes it difficult to pull out the drain tube through the deep muscle layer. Drain tubes which are pulled out superficially tend to be uncontrolled. Our method enables surgeons to pull out the drain tube from the deeper layer and to place it at the intended position, and does not need any special surgical instruments or techniques.

[Objective] To investigate the incidence of facet cysts after hemi-laminotomy of the lumbar spine.

[Method] The subjects were 57 patients who underwent magnetic resonance imaging (MRI) after hemi-laminotomy of the lumbar spine between July 2006 and July 2009. Among the patients, 42 had lumbar canal stenosis and 15 had lumbar spondylotic listhesis.

[Result] Facet cysts were observed in 10 patients. The cysts occurred on the approach side in 6 patients and the opposite side in 4. Four patients had radicular pain, 2 had low back pain, 1 had both radicular and low back pain, 1 had vesico-rectal disturbance,and 2 had no symptom. We classified them into 3 groups according to the size [measurement of width (mm)×length (mm) as an approximate value] of the cyst on MRI：large (>40mm 2;4 patients),medium (20-39mm 2;2 patients),and small (<20mm 2;4 patients). The severity of their symptoms was correlated to the size of the cyst. Eight patients underwent MRI twice after the surgery. In 5 patients,the cysts disappeared during the follow-up period.

[Conclusion] A facet cyst developing after hemi-laminotomy of the lumbar spine must be considered as one of the causes of postoperative deterioration.

Percutaneous endoscopic lumbar discectomy (PELD) is a new surgical procedure for disc herniation in Japan, and is often used as a minimally invasive technique. Currently the procedure is not mature and the surgical instruments are not sophisticated.

This report highlights the clinical outcome and problems of PELD for 35 patients with lumbar disc herniation. JOA score improved from 15.2 pre-operatively to 25.5 post-operatively. The complications were damage of to the exiting nerve root and root branch, and leakage of the cerebrospinal fluid. I experienced recurrence in 2 cases.

[Objective] The microscopic translaminar approach is the less invasive procedure to upward or foraminal lumbar disc herniations compared with the standard interlaminar approach. The purpose of this study is to evaluate the efficacy and the clinical outcomes of this procedure.

[Methods] Between December 2008 and January 2010, 7 patients underwent the microscopic translaminar approach. There were 2 males and 5 females with an average age of 48.9 (32-68) years old. The level of lesions was L3/4 in 1, L4/5 in 2, and L5/S1 in 4 cases. The type of lesions was foraminal in 4 and upward in 3 cases.

[Results] Appreciation of the pinched exiting nerve roots, herniotomy, and nucleotomy were all performed as the standard interlaminar approach in all 7 cases. Follow-up period ranged from 3 to 12 months postoperatively. All cases improved with the average recovery rate 63.7% on JOA scale, and no complications nor recurrences were reported.

[Discussion and Conclusions] The advantages of this approach are preservation of the facet joints and capability of an extension of the laminectomy to every direction without inducing of extreme instability. The translaminar approach is thought to be useful in selective cases.

Thirty-three patients with cervical stenotic disorders were treated by unilateral open-doo laminoplasty with titanium miniscrews and miniplates. The more affected unilateral side of the laminae was exposed by a paramedian approach to avoid injury of the nuchal ligament after the 4- cm midline incision. The spinous processes were cut and retracted. Almost all of the ligaments and muscles in the contralateral side were left intact. Four millimeter-wide gutters and contralateral hinges near the intervertebral joint were made by a 3-mm diamond burr. The opened laminae and retracted spinous processes were fixed with titanium miniplates with 6 holes fasten by 4 titanium miniscrews using in each lamina. In 22 operations, HA spacers(mm wide and mm long)with a hole through which the titanium miniplates had been passed, were used. The mean operative time of 33 operations was 177 minutes. The mean enlargement of the minimum spinal canal diameter was 50.9%. The mean recovery rate using the Japanese Orthopaedic Association Scoring by the Hirabayashiʼs Method was 45.8%. Only 3 patients (9.1%) reported postoperative axial neck pain. Our method for unilateral open-door laminoplasty seems to give sufficient decompression and tight fixation of laminae, and is less invasive to posterior supporting elements of the cervical spine.

Antero-lateral partial vertebrectomy (ALPV) is microsurgery in which a high-speed drill is used just medial to the transverse foramen to excise about 1/3 ofthe vertebral body for reliefofanterior compression ofthe cord and nerve roots. Fifteen patients with progressively deteriorating cervical myelopathy due to anterior compression associated with ossification of the posterior longitudinal ligament (OPLL) in the narrowed cervical canal were treated with multilevel ALPVs and implantation ofbeta-tricalcium phosphate (ß-TCP) into the sites ofthe ALPV. All ß-TCPs blocks had been absorbed and replaced by newly formed bone between 6 and 12 months after implantation, resulting in remodeling of the affected vertebral body. The pedicles on the side of the ALPVs were reconstructed during regeneration of the affected vertebrae. The vertebral foramen was expanded in the anterior direction at the levels ofthe ALPVs and physiological size ofthe cervical cord was restored. The cervical curvature remained unchanged at the latest follow up. A certain degree of cervical mobility was preserved in all fifteen patients at the latest follow up. Use of ß-TCP for repair and regeneration after ALPV was successful and led to multilevel decompression in this series.

In double-door laminoplasty of the cervical spine, we pass a round needle with two threads attached through the holes made in the opened laminae. This procedure can be troublesome due to the deep operative field and fragile laminae. We present new threads that can be easily passed through the laminae which were designed by Olympus Terumo Biomaterials and were devised by us.

The concept of the thread are ①it can be passed through easily without causing any damage to the laminae, ②it can be used without needles, ③ it is non-absorbable, flexible and not-too slippery, and ④it is inexpensive and secure.

The latest type, by the name ofÈSUGUTORUÉ, consists of 2 polyester threads of different colors, the ends of which(about cm)are twisted and united by thermal treatment. After the threads have been passed through the laminae, the ends of each thread can be easily unbound and the threads are tied respectively to secure the spacers to the laminae.

[Purpose] In order to improve the surgical results of ACF subsidence of cages was studied by FEA and roentgenographic evaluation.

[Materials & Methods] Number of ACF patients was 58. Mean age of patients was 50.1 years. Follow-up period was 11 to 53 months. Cases included cervical disc herniation, cervical myelopathy and OPLL. Three types of cages: cylinder type, box type (lordosis constant or lordosis adjustment) were evaluated by roentgenographic measurement and FEA. There were 49 one-level-fusions and 9 two-level-fusions. CT DICOM data of patients was installed into 3D modeling. Finite element mesh was generated and it was analyzed using Msc. Marc. The one level fusion group and two level fusion group were compared.

[Results] In one-level-fusions, subsidence occurred more frequently in cylinder type than in box type. Subsidence occurred more frequently in two-level-fusions than in one-level fusions, FEA revealed stress distributed mainly at the anterior side of vertebral body and at the sharp edges of cages.

[Discussion] FEA showed cylinder cages induced more stress distribution at the anterior part of the vertebral body, which explained why cylinder cages had shown a higher incidence of subsidence than box cages. In order to minimize subsidence of cages to prevent kyphotic alignment of the cervical spine, the following points were considered important； ①large contact area of cages against endplates. ②Cornical shape of cages with round anterior edge.

[Conclusions] Cylinder cages had a higher incidence of subsidence due to the higher concentration of stress at the anterior part of vertebral body than box cages.
FEA was useful to evaluate subsidence of cages after anterior cervical fusion.

[Objective] Once instability of the atlantoaxial joint has been detected, the goal of surgery is to reduce pathological subluxation, decompress neural elements and maintain vertebral column alignment. The surgical technique of internal fixation and fusion at the atlantoaxial joint is presented with emphasis on Goel-Harms method.

[Patients and Methods] A total of 23 patients with atlantoaxial instability (17 males and 6 females), who underwent surgery over the past 7 years were included. The age of the patients ranged from 3 to 80 years old. Patients were classified dependant on their etiology into trauma (7) ; rheumatoid arthritis or degeneration and (9) and congenital (7). The preferred technique was the Goel-Harms method. In the cases of retroodontoid pseudotumors with chronic atlantoaxial instability, the posterior C1 arch was resected and combined with posterior fusion.

[Results] No patients demonstrated neurological deterioration after surgery. All patients with retroodontoid pseudotumors demonstrated neurological recovery with gradually diminishing pseudotumors. Revision surgeries were performed in 2 cases of non-union.

[Conclusion] To avoid surgical complications, reduction and internal instrumented fixation of the atlantoaxial joint and bone fusion techniquse are key elements for successful surgery.

Spinal schwannoma accounts for about 20-45% of all spinal tumors, in which upper cervical schwannomas account for 5%. Upper cervical schwannomas typically grow mainly in the epidural space and form a dumbbell shape. Due to this reason, the C1/2 level might have a wide interlaminar window without an intervertebral foramen rather than a cervical level.

[Cases] We had three cases of schwannoma at C1/2 whose ages were 69, 62 and 71 years; two patients were male and one was females. Two patients presented with myelopathy and the remaining patient had cervical pain. One case was complicated with NF2. CT showed laminar erosions of C1 and C2 in all cases. All three patients easily underwent almost total removal with minor bleeding. In two cases, there was a main epidural mass with a small intradural lesion. One case was a dumbell shaped mass.

[Conclusion] The fundamental operative technique for C1/2 schwannomas is debulking and removal of the tumor in the capsule of epidural mass. This avoids intractable bleeding from the venous plexus surrounding the vertebral artery, and furthermore identifies the affected dural sleeve and dural penetration point of the vertebral artery. The next step is removal of the intradural tumor and cutting of the root. These steps should make the operation easier.

[Purpose] We report 3 cases of thoracic ossification of the ligamentum flavum (OLF) associated with lumbar disease. In this study, we discuss some problems, particularly in their diagnosis and treatment.

[Case Reports] The three patients were males of age 72, 66 and 72. All patients presented with numbness in the lower extremities and gait disturbance. One suffered from spastic gait, and two had intermittent claudication. Bilateral patella tendon reflex (PTR) was exaggerated in two patients while unilateral PTR was exaggerated in one patient. Radiological study revealed OLF at lower thoracic levels, with increased signal intensity of the cord on T2-weighted MRI. Associated lumbar diseases were L5 isthmic spondylolisthesis in one case, and L3/4, L4/5 lumbar canal stenosis (LCS) in two cases respectively. Only one case, whose cause of symptoms was thoracic OLF, underwent exclusive thoracic decompression. The other two cases, whose cause of symptoms were both thoracic and lumbar lesions, underwent thoracic and lumbar decompression. All three patients showed improvement in their neurological symptoms after surgery, and new symptoms did not appear.

[Discussion] Because OLF has a strong predilection for the lower thoracic spine and its symptoms are similar to LCS, it is advised to examine both the lumbar spine and the lower thoracic spine in patients who present with lower extremity radiculopathy/myelopathy. In patients with radiologically defined thoracic spine ossification of the ligamentum flavum associated with lumbar disease, neurological findings play an important role in determining the responsible site. However, it is thought that such judgments are often difficult, and simultaneous surgery should be considered in such cases.

Surgical removal of the facet cyst, facet joint preservation is important for prevention of postoperative instability. We removed the cyst through opposite side approach for preserving the facet joint.

[Case presentation] A 72-year-old male visited our hospital due to recurrent pain in both buttocks. MRI revealed L1/2 right facet cyst. Cystectomy was performed due to recurrent pain. Opposite side approach, using the same technique as bilateral decompression through a unilateral approach, was used for preservation of the facet joint. The stem of facet cyst was confirmed without facetectomy.
The pain disappeared after surgery.

[Discussion] Facet cysts can cause pain and neurological symptoms. Traditionally, the affected side approach was applied to remove the cyst, but this approach sometimes results in facetectomy. However, facetectomy often causes postoperative instability using the opposite side approach with the same technique as bilateral decompression from unilateral approach, there is no need to remove the facet joint. This approach is therefore useful for preservation of the facet joint.

[Objective[] We evaluated our clinical outcome for spinal metastases using posterior decompression and stabilization.

[Methods] Forty-three patients(24 men and 19 woman, aged 42-79 years；mean, 61.8 years) with metastatic spinal tumors underwent posterior decompression and stabilization from January 2001 to December 2008. The survival rate after surgery, pain relief, improvement of paralysis (Frankel classification), and ADL were evaluated.

[Results] In all patients, the survival rate was 44.2% at 6 months, 32.6% at one year, and 16.3% at two years. In 24 patients who survived over 6 months, the pain relief, improvement of paralysis, and ADL were 91.7%, 79.2%, and 79.2%, respectively. On the other hand, in 19 patients who died of cancer less than 6 months after surgery, the pain relief, improvement of paralysis and ADL were 89.5%, 15.8% and 15.8%, respectively.

[Conclusion] Regarding improvements of paralysis and ADL, posterior decompression and stabilization surgery was less effective in patients who survived less than 6 months compared with those who survived over 6 months. However, this surgery was effective for pain relief regardless of the survival period.

We report two cases of comparatively rare spinal epidural cyst, managed surgically with recapping laminoplasty. A 49-year-old and a 37-year-old male presented with lower back pain and weakness of the lower limbs. In both cases, MRI showed cystic lesions occupying the spinal canal and displacing the spinal cord anteriorly. CTM revealed compression of the spinal cord and thinning of the pedicles and laminae. We removed the epidural cysts under recapping laminoplasty using a Tsaw and sutured defects on the dura. Postoperative courses were good and there is no sign of recurrence.

Even though spinal epidural cysts are benign, it is necessary to remove the cysts in cases where there is a neurological deficit or invasion of vertebra.

T-saw laminoplasty is safe and effective technique to remove large epidural cysts and to securely close dural defects that communicate with the subarachnoid space.

Lumbar degenerative kypho-scoliosis(LDKS)is accompanied by multiple narrow discs,rigid deformity with osteophytes and degenerative hypertrophy of facet joints,osteoporosis and spinal erector muscle atrophy with sagittal and／or coronal imbalance. Anterior and posterior release is necessary for good correction. We treated it less invasively by multi-level PLIF technique with short fusion. Posterior release was done by total facetectomy,and anterior release by cutting the annulus at the concave side through the inside of the disc. Reconstruction of the spinal column was done using wedge-shaped intervertebral cage and pedicle screw fixation system,and augmented sublaminar taping at the ends of fixation for osteoporotic spine. Bone grafting was done by using excised local bone chips.

[Object] The purpose of the present study was to evaluate the efficacy of calcium phosphate cement(CPC)augmentation in minimally invasive surgery-transforaminal (posterior) lumbar interbody fusion (MIS-TLIF/PLIF)for patients with osteoporosis.

[Methods] 35 patients with osteoporosis who had undergone MIS-TLIF/PLIF augmented with CPC for degenerative lumbar disease were followed for more than six months and were included in the study.

[Results] There was no implant failure or pseudoarthosis, although clear zone surrounding PS was observed in five patients(16%)with one level and in two patients (50%) with two level lumbar interbody fusion.Asymptomatic CPC leakage observed in ten patients (29%).

[Conclusion] CPC augmented percutaneous pedicle screw fixation for instrumentation of the osteoporotic spine can be performed safely, and increases the bone union rate.However, careful attention to surgical technique is necessary to prevent complications related to CPC leakage.