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1.  Mid-Term Results of Computer-Assisted Cervical Pedicle Screw Fixation 
Asian Spine Journal  2014;8(6):759-767.
Study Design
A retrospective study.
The present study aimed to evaluate mid-term results of cervical pedicle screw (CPS) fixation for cervical instability.
Overview of Literature
CPS fixation has widely used in the treatment of cervical spinal instability from various causes; however, there are few reports on mid-term surgical results of CPS fixation.
Record of 19 patients who underwent cervical and/or upper thoracic (C2-T1) pedicle screw fixation for cervical instability was reviewed. The mean observation period was 90.2 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 years after surgery. Postoperative computerized tomography was used to determine the accuracy of screw placement. Visual analog scale (VAS) for neck pain and radiological evidence of adjacent segment degeneration (ASD) at the 5-year follow-up were also evaluated.
Mean JOA score was significantly improved from 9.0 points before surgery to 12.8 at 5 years after surgery (p=0.001). The C2-7 lordotic angle of the neutral position improved from 6.4° to 7.8° at 5 years after surgery, but this was not significant. The major perforation rate was 5.0%. There were no clinically significant complications such as vertebral artery injury, spinal cord injury, or nerve root injury caused by any screw perforation. Mean VAS for neck pain was 49.4 at 5 years after surgery. The rate of ASD was 21.1%.
Our mid-term results showed that CPS fixation was useful for treating cervical instability. Severe complications were prevented with the assistance of a computed tomography-based navigation system.
PMCID: PMC4278981  PMID: 25558318
Cervical pedicle screw; Cervical instability; Mid-term results; Adjacent segment degeneration
2.  Comparison of Spinous Process-Splitting Laminectomy versus Conventional Laminectomy for Lumbar Spinal Stenosis 
Asian Spine Journal  2014;8(6):768-776.
Study Design
Seventy-five patients who had been treated for lumbar spinal stenosis (LSS) were reviewed retrospectively.
Invasion into the paravertebral muscle can cause major problems after laminectomy for LSS. To address these problems, we performed spinous process-splitting laminectomy. We present a comparative study of decompression of LSS using 2 approaches.
Overview of Literature
There are no other study has investigated the lumbar spinal instability after spinous process-splitting laminectomy.
This study included 75 patients who underwent laminectomy for the treatment of LSS and who were observed through follow-ups for more than 2 years. Fifty-five patients underwent spinous process-splitting laminectomy (splitting group) and 20 patients underwent conventional laminectomy (conventional group). We evaluated the clinical and radiographic results of each surgical procedure.
Japanese Orthopaedic Association score improved significantly in both groups two years postoperatively. The following values were all significantly lower, as shown with p-values, in the splitting group compared to the conventional group: average operating time (p=0.002), postoperative C-reactive protein level (p=0.006), the mean postoperative number of days until returning to normal body temperature (p=0.047), and the mean change in angulation 2 years postoperatively (p=0.007). The adjacent segment degeneration occurred in 6 patients (10.9%) in the splitting group and 11 patients (55.0%) in the conventional group.
In this study, the spinous process-splitting laminectomy was shown to be less invasive and more stable for patients with LSS, compared to the conventional laminectomy.
PMCID: PMC4278982  PMID: 25558319
Lumbar spinal stenosis; Spinous process-splitting laminectomy; Postoperative low back pain; Paravertebral muscle, posterior approach
3.  Surgical treatment of Klippel–Feil syndrome with basilar invagination 
European Spine Journal  2012;22(Suppl 3):380-387.
Klippel–Feil syndrome (KFS) is a congenital cervical vertebral union caused by a failure of segmentation during abnormal development and frequently accompanies conditions such as basicranial malformation, atlas assimilation, or dens malformation. Especially in basilar invagination (BI), which is a dislocation of the dens in an upper direction, compression of the spinomedullary junction from the ventral side results in paralysis, and treatment is required.
Clinical presentation
We present the case of a 38-year-old male patient with KFS and severe BI. Plane radiographs and computed tomography (CT) images showed severe BI, and magnetic resonance image (MRI) revealed spinal cord compression caused by invagination of the dens into the foramen magnum and atlantoaxial subluxation. Reduction by halo vest and skeletal traction were not successful. Occipitocervical fusion along with decompression of the foramen magnum, C1 laminectomy, and reduction using instruments were performed. Paralysis was temporarily aggravated and then gradually improved. Unsupported walking was achieved 24 months after surgery, and activities of daily life could be independently performed at the same time. CT and MRI revealed that dramatic reduction of vertical subluxation and spinal cord decompression were achieved.
Reduction and internal fixation using instrumentation are effective techniques for KFS with BI; however, caution should be exercised because of the possibility of paralysis caused by intraoperative reduction.
PMCID: PMC3641246  PMID: 22926486
Klippel–Feil syndrome; Occipitocervical malformation; Basilar invagination; Surgical treatment
5.  Stable reconstruction using halo vest for unstable upper cervical spine and occipitocervical instability 
European Spine Journal  2011;21(2):295-303.
Upper cervical or occipitocervical disorders such as rheumatoid arthritis present as atlantoaxial subluxation, vertical subluxation of the axis, and subaxial subluxation, which produce myelopathy and severe pain. In such cases, occipitocervical reconstruction surgery may be indicated, and several reports have described reduction of subluxation by fixing the halo vest before this surgery.
The purpose of this study was to evaluate the efficacy of using the halo vest before the surgery for unstable upper cervical spine and for occipitocervical instability.
Twenty-eight patients (9 men and 19 women; mean age, 61.8 years at surgery) who presented with atlantoaxial or occipitocervical fusion were studied. In all cases, the halo vest was fixed in the conscious condition, and subluxation was reduced before the surgery. The mean follow-up period was 45 months. Roentgenologic measurement and clinical evaluation were performed before the surgery and at the final follow-up.
Using the halo vest resulted in significant reductions in the atlantodental interval, the space available for the spinal cord, and the Ranawat value (p < 0.05), and these were maintained until the final follow-up. The mean Japanese Orthopedic Association score significantly improved from 9.5 before surgery to 12.2 at the final follow-up (p = 0.01). Nineteen cases (68%) improved by more than 1 grade by Ranawat’s classification after surgery and 16 cases (57%) maintained the same at the follow-up visit.
Conscious preoperative reduction using the halo vest for occipitocervical disorders is a useful and safe technique.
PMCID: PMC3265589  PMID: 21833572
Occipitocervical disorders; Occipitocervical reconstruction; Halo vest
6.  Cervical Pedicle Screw Fixation Combined with Laminoplasty for Cervical Spondylotic Myelopathy with Instability 
Asian Spine Journal  2012;6(4):241-248.
Study Design
A retrospective study.
To evaluate the surgical results of cervical pedicle screw (CPS) fixation combined with laminoplasty for treating cervical spondylotic myelopathy (CSM) with instability.
Overview of Literature
Cervical fixation and spinal cord decompression are required for CSM patients with instability. However, only a few studies have reported on CPS fixation combined with posterior decompression for unstable CSM patients.
Thirteen patients that underwent CPS fixation combined with laminoplasty for CSM with instability were evaluated in this study. We assessed the clinical and radiological results of the surgical procedures. The Japanese Orthopedic Association (JOA) scoring system was used to evaluate the clinical results. The percentages of sli p, difference in sli p angle between maximum flexion and maximum extension of unstable intervertebrae, and perforation rate of CPS were evaluated.
The mean JOA scores before surgery, immediately after surgery, and at final follow-up were 9.1, 13.3, and 12.6, respectively. The mean percentages of sli p before surgery, immediately after surgery, and at final follow-up were 9.1%, 3.2%, and 3.5%, respectively; there were significant improvements immediately after surgery and at final follow-up. The difference in sli p angle between the maximum flexion and maximum extension of the unstable intervertebrae changed from 9.0° before surgery to 1.6° at the final follow-up. The perforation rate of CPS was 10.9%.
The results suggest that CPS fixation combined with laminoplasty is an effective surgical procedure for treating CSM with instability.
PMCID: PMC3530698  PMID: 23275807
Cervical spondylosis; Myelopathy; Instability; Cervical fixation
7.  A Case of Pyogenic Spondylodiscitis Caused by Campylobacter fetus for Which Early Diagnosis by Magnetic Resonance Imaging Was Difficult 
Asian Spine Journal  2012;6(4):274-278.
The purpose of this case report was to report a rare case of pyogenic spondylodiscitis caused by Campylobacter fetus. A 37-year-old male presented with fever and low back pain. By lumbar magnetic resonance imaging (MRI), no abnormal finding was observed at the first presentation. However, low back pain was aggravated, and fever did not improve. Thus, lumbar MRI was repeated on the 26 day after the onset of symptoms, showing abnormal signals at vertebrae and disc spaces, and pyogenic spondylitis was diagnosed. The possibility of pyogenic spondylodiscitis should be taken into account if a patient presents with low back pain and fever, and areas of low signal intensity on a T1-weighted MRI should be carefully examined. When initial MRI does not reveal abnormal findings, repeated MRI after one or two weeks or, more favorably, immediate gadolinium enhancement MRI, are important for patients who have persistent low back pain and fever.
PMCID: PMC3530702  PMID: 23275811
Resonance imaging; Campylobacter fetus
8.  Computer-assisted C1-C2 Transarticular Screw Fixation "Magerl Technique" for Atlantoaxial Instability 
Asian Spine Journal  2012;6(3):168-177.
Study Design
A retrospective study.
To evaluate the surgical results of computer-assisted C1-C2 transarticular screw fixation for atlantoaxial instability and the usefulness of the navigation system.
Overview of Literature
We used a computed tomography (CT)-based computer navigation system in planning and screw insertion in Magerl's procedure, which provides the most rigid atlantoaxial fusion, to avoid risk of vertebral artery (VA) tear by avoiding high-riding VA during screw insertion.
Twenty patients who underwent atlantoaxial fusion under the CT-based navigation system were studied. The mean observation period was 33.5 months. The evaluated items included the existence of VA stenosis by preoperative magnetic resonance angiography, surgical time, blood loss volume, Japanese Orthopaedic Association (JOA) score and Ranawat's pain criteria before surgery and at final follow-up, postoperative screw position evaluated by CT, and bony fusion.
The mean operation time was 205 minutes, with the mean blood loss volume of 242 ml. The mean JOA score was 11.6 points before surgery and 13.7 at final follow-up. Occipital and/or cervical pain presented before operation was remitted or resolved in all patients. Evaluation of screw insertion by CT revealed correct penetration to atlantoaxial joints, with a perforation rate of 2.6%. There was no complication, including VA tear, and all patients who were followed-up during one year or more after surgery achieved bony fusion. Some subjects who appeared inappropriate for surgery from CT images were assessed as eligible for surgery based on the evaluation results obtained using the navigation system.
It was demonstrated that the CT-based navigation system is an effective support device for Magerl's procedure.
PMCID: PMC3429607  PMID: 22977696
Atlantoaxial joint; Atlantoaxial instability; CT-based computer navigation system; C1-C2 transarticular screw fixation
9.  Surgical resection without dural reconstruction of a lumbar meningioma in an elderly woman 
European Spine Journal  2009;18(Suppl 2):232-235.
Meningiomas of the spine occur in the thoracic spine in approximately 80%, followed in frequency by the cervical and lumbar regions. The treatment of spinal meningiomas is complete surgical resection. As intraspinal meningiomas are almost always adherent to the dura, extensive dural resection or diathermic treatment of the dural attachment is usually performed to prevent tumor recurrence. The authors present the case of lumbar spinal meningioma in 82-year-old woman. Successful resection with preservation of the dura mater using the technique of Saito et al. (Spine 26:1805-1808, 2001) is described: After lumbar laminectomy a small incision was made in the surface of the spinal dura. The dura mater was separated into its inner and outer layers, and the tumor was resected with inner layer alone, preserving the outer layer. The outer layer is simply closed to achieve a watertight seal. The pathologic diagnosis was metaplastic (osseous) meningioma. Almost full recovery of the neurologic deficit was attained. Neither complication nor tumor recurrence has occurred in the 5 years since surgery. Dural preservation during surgical resection of spinal meningioma obviates the need for dural reconstruction and should reduce surgical morbidity. However, the patient should be followed long-term to watch for recurrence.
PMCID: PMC2899553  PMID: 19219468
Dural preservation; Elderly; Lumbar spinal meningioma; Minimally invasive; Surgical treatment
10.  Perforation Rates of Cervical Pedicle Screw Insertion by Disease and Vertebral Level 
Different perforation rates for cervical pedicle screws by disease are expected in relation to bone quality and pedicle morphology; however, no report comparing pedicle screw perforation rate by disease had previously been published. This study investigated the perforation rates of pedicle screws inserted to cervical pedicle by disease and vertebral level using a CT-based navigation system.
Fifty-three patients who underwent cervical pedicle screw insertion using CT based navigation system were studied. Diseases included rheumatoid arthritis (RA) (24 cases), destructive spondyloarthropathy (DSA) (10), cervical spondylotic myelopathy (CSM) (9), spine tumor (6), and cervical spondylotic myelopathy associated with athetoid cerebral palsy (CP) (4). Screw perforation rates for cervical pedicle screws were studied. Major perforation was defined as perforation 50% of screw diameter or more.
Major perforation rate by disease from C3 to C7 was as follows: spine tumor (0/24, 0%), RA (2/59, 3.4%), DSA (3/65, 4.6%), CP (2/20, 10.0%), and CSM (6/40, 15.0%). There were no clinically important complications such as vertebra arterial injury, spinal cord injury, or nerve root injury caused by any screw perforation. Major perforation rate by vertebral level was: C2(2/30, 6.7%), C3(4/49, 8.2%), C4(6/43, 14.0%), C5(1/32, 3.1%), C6(1/41, 2.4%), and C7(1/45, 2.2%), showing highest rate for C4, followed by C3.
Cervical pedicle screw perforation rate by disease was higher in CSM compared to RA and DSA. The perforation rate by vertebral level was higher for C4 and C3, in this order.
PMCID: PMC2864428  PMID: 20448816
Cervical pedicle screw; image guidance; perforation rate.
11.  Computer-assisted screw insertion for cervical disorders in rheumatoid arthritis 
European Spine Journal  2006;16(4):485-494.
To reconstruct highly destructed unstable rheumatoid arthritis (RA) cervical lesions, the authors have been using C1/2 transarticular and cervical pedicle screw fixations. Pedicle screw fixation and C1/2 transarticular screw fixation are biomechanically superior to other fixation techniques for RA patients. However, due to severe spinal deformity and small anatomical size of the vertebra, including the lateral mass and pedicle, in the most RA cervical lesions, these screw fixation procedures are technically demanding and pose the potential risk of neurovascular injuries. The purpose of this study was to evaluate the accuracy and safety of cervical pedicle screw insertion to the deformed, fragile, and small RA spine lesions using computer-assisted image-guidance systems. A frameless, stereotactic image-guidance system that is CT-based, and optoelectronic was used for correct screw placement. A total of 21 patients (16 females, 5 males) with cervical disorders due to RA were surgically treated using the image-guidance system. Postoperative computerized tomography and plane X-ray was used to determine the accuracy of the screw placement. Neural and vascular complications associated with screw insertion and postoperative neural recovery were evaluated. Postoperative radiological evaluations revealed that only 1 (2.1%; C4) of 48 screws inserted into the cervical pedicle had perforated the vertebral artery canal more than 25% (critical breach). However, no neurovascular complications were observed. According to Ranawat’s classification, 9 patients remained the same, and 12 patients showed improvement. Instrumentation failure, loss of reduction, or nonunion was not observed at the final follow-up (average 49.5 months; range 24–96 months). In this study, the authors demonstrated that image-guidance systems could be applied safely to the cervical lesions caused by RA. Image-guidance systems are useful tools in preoperative planning and in transarticular or transpedicular screw placement in the cervical spine of RA patients.
PMCID: PMC2229817  PMID: 17024400
Cervical spine; Image guidance; Rheumatoid arthritis; Cervical pedicle screw; Transarticular screw

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