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1.  The effects of surgery on locomotion in elderly patients with cervical spondylotic myelopathy 
European Spine Journal  2013;22(11):2545-2551.
This study aimed to evaluate the effects of surgery on locomotor ability in patients with cervical spondylotic myelopathy (CSM) and compare the results between elderly and younger patients.
A total of 369 consecutive patients who underwent expansive laminoplasty for CSM were prospectively analysed. Patients were divided into two age groups of ≥75 years (elderly group, 76 patients) and <75 years (younger group, 293 patients). Locomotor ability was estimated using part of the functional independence measure (FIM). The sum of gait and stairs items [functional independence measure (locomotion), FIM-L; possible scores, 2–14] and neurological status were estimated using the Japanese Orthopaedic Association (JOA) score (possible score, 0–17). Pre-operative neurological anamnesis was reviewed, and the surgical results of elderly patients with or without co-existing neurological history were evaluated to determine the origin of locomotor disability.
Peri-operative FIM-L and JOA scores were significantly lower in the elderly group than in the younger group, and the opposite was true for improved FIM score. Cerebral infarction and previous lumbar surgery were identified as neurological co-morbidities in the elderly group. However, there was no significant difference in surgical results between elderly patients with and without co-existing neurological disorders.
Decompression surgery can improve locomotor ability and decrease nursing care requirements among elderly patients with CSM. However, other neurological diseases can co-exist in elderly patients, making it difficult to diagnose the origin of locomotor disability. Therefore, detailed peri-operative work-up and timely decompression should be given priority to avoid progression towards fixed locomotor disability.
PMCID: PMC3886528  PMID: 23955371
Cervical spondylotic myelopathy; Laminoplasty; Locomotion; Functional independence measure; Elderly
2.  Predisposing factors for surgical site infection of spinal instrumentation surgery for diabetes patients 
European Spine Journal  2013;22(8):1854-1858.
Diabetes mellitus (DM) is known as an important risk factor for surgical site infection (SSI) in spine surgery. It is still unclear however which DM-related parameters have stronger influence on SSI. The purpose of this study is to determine predisposing factors for SSI following spinal instrumentation surgery for patients with DM.
110 DM patients (66 males and 44 females) who underwent spinal instrumentation surgery in one institute were enrolled in this study. For each patient, various preoperative or intraoperative parameters were reviewed from medical records. Patients were divided into two groups (SSI or non-SSI) based on the postoperative course. Each parameter between these two groups was compared. Univariate and multivariate analyses were performed to determine predisposing factor for SSI.
The SSI group consisted of 11 patients (10 %), and the non-SSI group of 99 patients (90 %). Univariate analysis revealed that preoperative proteinuria (p = 0.01), operation time (p = 0.04) and estimated blood loss (p = 0.02) were significantly higher in the SSI group compared to the non-SSI group. Multivariate logistic regression identified preoperative proteinuria as a statistically significant predictor of SSI (OR 6.28, 95 % CI 1.58–25.0, p = 0.009).
Proteinuria is a significant predisposing factor for SSI in spinal instrumentation surgery for DM patients. DM patients with proteinuria who are likely to suffer latent nephropathy have a potential risk for SSI. For them less invasive surgery is recommended for spinal instrumentation. In this retrospective study, there was no significant difference of preoperative condition in glycemic control between the two groups.
PMCID: PMC3731500  PMID: 23612899
Spinal instrumentation surgery; Surgical site infection; Diabetes mellitus; Proteinuria; Microvascular disease; Diabetic nephropathy
3.  Bone union rate with autologous iliac bone versus local bone graft in posterior lumbar interbody fusion (PLIF): a multicenter study 
European Spine Journal  2013;22(5):1158-1163.
The purpose of this study is to compare bone union rate between autologous iliac bone and local bone graft in patients treated by posterior lumbar interbody fusion (PLIF) using carbon cage for single level interbody fusion.
The subjects were 106 patients whose course could be observed for at least 2 years. The diagnosis was lumbar spinal canal stenosis in 46 patients, herniated lumbar disk in 12 patients and degenerative spondylolisthesis in 51 patients. Single interbody PLIF was done using iliac bone graft in 53 patients and local bone graft in 56 patients. Existence of pseudo-arthrosis on X-P (AP and lateral view) was investigated during the same follow up period.
No significant differences were found in operation time and blood loss. Significant differences were also not observed in fusion grade at any follow up period or in fusion progression between the two groups. Donor site pain continued for more than 3 months in five cases (9 %). The final fusion rate was 96.3 versus 98.3 %.
Almost the same results in fusion were obtained from both the local bone group and the autologous iliac bone group. Fusion progression was almost the same. Complications at donor sites were seen in 19 % of the cases. From the above results, it was concluded that local bone graft is as beneficial as autologous iliac bone graft for PLIF at a single level.
PMCID: PMC3657055  PMID: 23361529
Posterior lumbar interbody fusion; Autologous iliac bone graft; Local bone graft; Fusion rate
4.  Risk factors for a poor outcome following surgical treatment of cervical spondylotic amyotrophy: a multicenter study 
European Spine Journal  2012;22(1):156-161.
Cervical spondylotic amyotrophy (CSA) is characterized by muscle atrophy in the upper extremities without gait disturbance. However, the indications and outcomes of surgical treatment for CSA have not been clarified. The purpose of this study was to determine the risk factors for a poor outcome following surgical treatment of CSA.
Materials and methods
We performed a retrospective review of CSA in patients from 1991 to 2010 through a multicenter study. We collected information regarding age, type of muscle atrophy, preoperative manual muscle test (MMT), duration of symptoms, high-intensity areas on T2-weighted MR images, low-intensity areas on T1-weighted MR images, levels of spinal canal stenosis, cervical kyphosis and surgical procedures (laminoplasty, anterior cervical discectomy and fusion and posterior spinal fusion), and calculated overall risk factors related to a poor outcome following surgery. Univariate analyses and multivariate logistic regression analysis were performed to identify correlates of a poor outcome.
Fifty-nine patients, 95 % male (56 patients), were included in our analysis with a mean age of 59 years (range 32–78 years). Eighteen patients did not improve after surgery. Symptom duration (OR = 1.263), preoperative MMT grade (OR = 0.169) and distal type of CSA (OR = 9.223) were all associated with an increased risk of a poor surgical outcome.
Early surgery is recommended for CSA patients in whom conservative treatment has not been successful. We also recommend surgery for patients who have severe preoperative muscle weakness or have the distal type of CSA.
PMCID: PMC3540303  PMID: 23001450
Cervical spondylotic amyotrophy; Poor outcome; Risk factor; Surgical treatment
5.  Rheumatoid vertical and subaxial subluxation can be prevented by atlantoaxial posterior screw fixation 
European Spine Journal  2012;21(12):2498-2505.
Literature has described a risk for subsequent vertical subluxation (VS) and subaxial subluxation (SAS) following atlantoaxial subluxation in rheumatoid patients; however, the interaction of each subluxation and the radiographic findings for atlantoaxial fixation has not been described. The purpose of this study was to evaluate the effects of two different posterior atlantoaxial screw fixation on the development of subluxation in patients with rheumatoid atlantoaxial subluxation.
Between 1996 and 2006, rheumatoid patients treated with transarticular fixation and posterior wiring (TA) or C1 lateral mass–C2 pedicle screw fixations (SR) in the Nagoya Spine Group hospitals, a multicenter cooperative study group, were included in this study. VS, SAS, craniocervical sagittal alignment, and range of motion (ROM) at the atlantoaxial adjacent segments were investigated to determine whether posterior atlantoaxial screw fixation is a prophylactic or a risk factor for the development of VS and SAS.
The mean follow-up was 7.2 years (4–12). No statistically significant difference was observed among the patients treated with either of the procedure during the follow-up period. Of 34 patients who underwent posterior atlantoaxial screw fixation, SAS was observed in 26.5 % during the follow-up period; however, VS was not observed. Postoperative C2–7 angle, and Oc–C1 and C2–3 ROM were significantly different between patients with and without postoperative SAS. The incidence of SAS was 38.9 % for TA and 12.5 % for SR; statistically significant differences were observed in the postoperative C1–2 and C2–7 angles, and C2–3 ROM.
Atlantoaxial posterior screw fixation may be an appropriate prophylactic intervention for VS and SAS if the atlantoaxial joint develops bony fusion following physiological alignment. Compared to TA, SR provided optimal atlantoaxial angle and prevented lower adjacent segment degeneration, thereby reducing SAS.
PMCID: PMC3508217  PMID: 22825632
Rheumatoid arthritis; Atlantoaxial subluxation; Vertical subluxation; Subaxial subluxation; Posterior screw fixation
6.  Primary spinal cord tumors: review of 678 surgically treated patients in Japan. A multicenter study 
European Spine Journal  2012;21(10):2019-2026.
To clarify the relative frequency of various histopathological primary spinal cord tumors and their features in Japanese people and to compare this data with other reports.
Primary spinal cord tumor surgical cases from 2000 to 2009, which were registered in our affiliated hospital database were collected. We examined age at surgery, sex, anatomical location, vertebral level of the tumor, and pathological diagnosis in each case.
Of the 678 patients in our study, 377 patients (55.6 %) were males and 301 patients (44.4 %) were females (male/female ratio 1.25). The mean age at surgery was 52.4 years. Of these tumors, 123 cases (18.1 %) were intramedullary, 371 cases (54.7 %) were intradural extramedullary, 28 cases (4.1 %) were epidural, and 155 cases (22.9 %) were dumbbell tumors. The pathological diagnoses included 388 schwannomas (57.2 %), 79 meningiomas (11.6 %), 54 ependymomas (8.0 %), 27 hemangiomas (4.0 %), 23 hemangioblastomas (3.4 %), 23 neurofibromas (3.4 %), and 9 astrocytomas (1.3 %). The male/female ratios for schwannomas, meningiomas, ependymomas, hemangiomas, hemangioblastomas, neurofibromas, malignant lymphomas, and lipomas are 1.4, 0.34, 1.3, 1.5, 2.3, 1.3, 2.7 and 2.3, respectively.
This is the first published research in English on the epidemiology of primary spinal cord tumors in Japanese people. Similar to other reports from Asian countries, our data indicates a higher male/female ratio overall for spinal cord tumors, a higher proportion of nerve sheath cell tumors, and a lower proportion of meningiomas and neuroepithelial tumors compared to reports from non-Asian countries. Data in the current study represent the characteristics of primary spinal cord tumors in Asian countries.
PMCID: PMC3463691  PMID: 22581192
Spinal cord tumor; Epidemiology; Tumor location; Schwannoma; Meningioma
7.  Complications and outcomes of posterior fusion in children with atlantoaxial instability 
European Spine Journal  2011;21(7):1346-1352.
Atlantoaxial instability (AAI) is an uncommon disease in children. Surgical treatment of pediatric patients with AAI poses a challenge to spine surgeons because of the patients’ immature bone quality, extensive anatomical variability, and smaller osseous structures. In this study, the authors report complications and outcomes after posterior fusion in children with AAI.
The authors reviewed medical records of patients 13 years old and younger with AAI who underwent posterior fusion in the Nagoya Spine Group hospitals, a multicenter cooperative study group, from January 1995 to December 2007. We identified 11 patients who underwent posterior fusion, and analyzed their clinical outcomes and complications. To determine if vertical growth within the construct continued after posterior fusion, in three patients at 5 or more years following occipito-cervical (O-C) fusion, intervertebral disc heights and vertebral heights between the fused and non-fused levels were compared on the final follow-up.
The initial surgeries were C1–C2 fusions in six patients and O-C fusion in five patients. Successful fusion ultimately occurred in all patients, however, the complication rate related to the operations was high (64%). Complications included neurologic deterioration, pedicle fracture with pedicle screw insertion, C1 posterior arch fracture with lateral mass screw insertion, perforation of the skull with a head pin placement, and fusion extension to adjacent vertebrae. Two patients required reoperation. The mean fixed and non-fixed intervertebral disc heights on the final follow-up were 2.6 and 5.3 mm, respectively, showing that the disc height of the fixed level was less than the non-fused level. Each vertebra lengthened similarly between fused and non-fused levels except for C2 which had a lower growth rate than the other vertebrae.
A high complication rate should be anticipated after posterior fusion in children with AAI. Careful consideration should be paid to pediatric patients with AAI treated by screw and/or rod systems. After posterior fusion in pediatric patients, each vertebra continued to grow, in contrast the disc height decreased between fused levels.
PMCID: PMC3389100  PMID: 22113532
Atlantoaxial instability; Posterior fusion; Os odontoideum; Down syndrome; Complications; Children
8.  Percutaneous Pedicle Screw Fixation of a Hangman's Fracture Using Intraoperative, Full Rotation, Three-dimensional Image (O-arm)-based Navigation: A Technical Case Report 
Asian Spine Journal  2012;6(3):194-198.
Surgical treatment of a hangman's fractures is technically demanding, even when using the standard open procedure. In this case report, a type II hangman's fracture was treated by percutaneous posterior screw fixation, without a midline incision, using intraoperative, full rotation, three-dimensional (3D) image (O-arm)-based navigation. A 48-year-old woman was injured in a motor vehicle accident and diagnosed with a unilateral hangman's fracture associated with subluxation of the C2 vertebral body on C3. After attaching the reference arc of the 3D-imaging system to the headholder, the cervical spine was screened using an O-arm without anatomical registration. Drilling and screw fixation were performed using a guide tube while referring to the reconstructed 3D-anatomical views. The operation was successfully completed without technical difficulties or neurovascular complications. This percutaneous procedure requires less dissection of normal tissue, which may allow earlier recovery. However, further validation of this procedure for its effectiveness and safety is required.
PMCID: PMC3429610  PMID: 22977699
Pedicle screw; Percutaneous; Minimally invasive; Hangman's fracture; Three-dimensional image-based navigation
9.  Clinical and radiographic outcomes of posterolateral lumbar spine fusion in humans using recombinant human bone morphogenetic protein-2: an average five-year follow-up study 
International Orthopaedics  2008;33(4):1061-1067.
The objectives of this study were to determine whether recombinant human bone morphogenetic protein-2 (rhBMP-2) can be used as the sole stimulator of osteogenesis with success equal to an autologous graft in posterolateral lumbar fusion (PLF) at the same level and to describe the progress until bone union. This study included 11 patients who underwent PLF of L4-5. On the right side, only rhBMP-2, for which polylactic/glycolic acid (PLGA) was used as a carrier, was used, whereas, on the left side, autogenous bone was used. The bone union rate was 73 and 82% at 12 and 24 months after surgery, respectively, on the right BMP side, while the rate on the autogenous bone side was 91%. There was no statistically significant difference in the bone union rate. rhBMP-2 can be used as the sole source of osteogenesis with success equivalent to an autologous graft of the PLF.
PMCID: PMC2898963  PMID: 18581064
10.  Indirect posterior decompression with corrective fusion for ossification of the posterior longitudinal ligament of the thoracic spine: is it possible to predict the surgical results? 
European Spine Journal  2009;18(7):943-948.
To investigation of the outcomes of indirect posterior decompression with corrective fusion for myelopathy associated with thoracic ossification of the longitudinal ligament, and prognostic factors. Conservative treatment for myelopathy associated with thoracic ossification of the longitudinal ligament (OPLL) is mostly ineffective, and treatment is necessary. However, many authors have reported poor surgical outcomes, and no standard surgical procedure has been established. We have been performing indirect spinal cord decompression by posterior laminectomy and simultaneous corrective fusion of the thoracic kyphosis. Twenty patients underwent indirect posterior decompression with corrective fusion, and were included in this study. The follow-up period was minimum 2 years and averaged 2 years and 9 months (2–5 years 6 months). Operative results were examined using JOA scoring system (full marks: 11 points) and Hirabayashi’s recovery rate, as excellent (100–75%), good (74–50%), fair (49–25%), unchanged (24–0%) and deteriorated (i.e., decrease in score less than 0%). Cases in which the spinal cord is floating from OPLL on intraoperative ultrasonography were defined as the floating (+) group, and those without floating as the floating (−) group. In addition, we used compound muscle action potentials (CMAP) as intraoperative spinal cord monitoring and the cases were divided into three groups: Group A, no change in potential; Group B, potential decreased, and Group C, potential improved. The mean pre- and postoperative JOA scores were 6.2 and 8.9 points, respectively, and the recovery rate was 56%. The outcome was rated excellent in three, good in eight, fair in six, unchanged in two, and deteriorated in one. The mean preoperative thoracic kyphosis measured 58°, and was corrected to 51° after surgery. On intraoperative ultrasonography, 12 cases were included in the floating (+) and 8 in the floating (−) groups; the recovery rates were 58 and 52%, respectively, showing no significant difference between the recovery rates of the two groups. Regarding intraoperative CMAP, the outcome was excellent in one, good in seven, fair in four, and unchanged in one in Group A; fair in one, unchanged in one, and deteriorated in one in Group B, and excellent in two and good in one in Group C. The recovery rates were 50, 48 and 68.3% in Groups A, B and C, respectively, showing that the postoperative outcome was significantly poorer in Group B. Although indirect posterior decompression with corrective fusion using instruments obtained satisfactory outcomes, not all cases achieved good outcomes using this procedure. We consider that additional application of anterior decompressive fusion is preferable when improvement of symptoms occurs not satisfactory after indirect posterior decompression with corrective fusion using instruments. Intraoperative spinal cord monitoring of CMAP demonstrated that the spinal cord was already impaired during the laminectomy via the posterior approach. Concomitant intraoperative monitoring of CMAP to avoid impairment of the vulnerable spinal cord and corrective posterior spinal fusion with indirect spinal cord decompression is recommendable as a method capable of preventing postoperative neurological aggravation.
PMCID: PMC2899584  PMID: 19347374
Ossification of the posterior longitudinal ligament; Thoracic myelopathy; Spinal cord monitoring; Intraoperative ultrasonography
11.  The relationship between the type of destructive spondyloarthropathy and its 10 years ago cervical spine alignment 
European Spine Journal  2009;18(6):900-904.
The objective of this retrospective study was to analyze the relationship between the type of destructive spondyloarthropathy (DSA) and its 10 years ago cervical spine alignment. DSA was reported as a serious complication of long-term hemodialysis. Although previous reports in regard to risk factor of DSA dealt with the period of hemodialysis and the patient’s age upon commencement of hemodialysis, we could not find any reports of the relationship between the type of DSA and its 10 years ago cervical spine alignment. In 96 DSA patients who were the subjects of our study, 8 patients were defined as stage 1, 39 patients as stage 2, 5 patients as stage 3 type A, 11 patients as stage 3 type B, and 33 patients as stage 3 type D. The C2/C7 angle of stage 3 type B was statistically low. The number of the abnormal local cervical alignment was larger in stage 3 types A and B. Multivariate analysis revealed that the risk factors of stage 3 types A and B were the C2/C7 angle and the existence of local abnormal alignment. Fifty-four patients were symptomatic due to DSA and treated at our hospital. Forty-four patients were treated conservatively with medications, physiotherapy, or wearing cervical brace. Ten patients underwent surgical treatment. The loss of physiological lordosis of cervical spine promoted the progression of DSA. Furthermore, the number of the abnormalities of local cervical alignment was statistically larger in stage 3 types A and B; they were the crucial factor promoting the progression of DSA stage 3 types A and B.
PMCID: PMC2899660  PMID: 19350288
Destructive spondyloarthropathy (DSA); Hemodialysis; Cervical spine

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