Hiroshi Taneichi

Complications of Pedicle Screw Fixation in Reconstructive Surgery of the Cervical Spine

Study Design. Retrospective evaluation of complications in 180 consecutive patients with cervical disorders who had been treated by using pedicle screw fixation systems. Objectives. To determine the risks associated with pedicle screw fixation in the cervical spine and to emphasize the importance of preoperative planning and surgical techniques in reducing the risks of this procedure. Summary of Background Data. Generally, pedicle screw fixation in the cervical spine has been considered too risky for the neurovascular structures. There have been several reports describing the complications of lateral mass screw–plate fixation. However, no studies have examined in detail the complications associated with cervical pedicle screw fixation. Methods. One hundred eighty patients who underwent cervical reconstructive surgery using cervical pedicle screw fixation were reviewed to clarify the complications associated with the pedicle screw fixation procedure. Cervical disorders were spinal injuries in 70 patients and nontraumatic lesions in 110 patients. Seven hundred twelve screws were inserted into the cervical pedicles, and the locations of 669 screws were radiologically evaluated. Results. Injury of the vertebral artery occurred in one patient. The bleeding was stopped by bone wax, and no neurologic complication developed after surgery. On computed tomographic (CT) scan, 45 screws (6.7%) were found to penetrate the pedicle, and 2 of 45 screws caused radiculopathy. Besides these three neurovascular complications directly attributed to screw insertion, radiculopathy caused by iatrogenic foraminal stenosis from excessive reduction of the translational deformity was observed in one patient. Conclusions. The incidence of the clinically significant complications caused by pedicle screw insertion was low. Complications associated with cervical pedicle screw fixation can be minimized by sufficient preoperative imaging studies of the pedicles and strict control of screw insertion. Pedicle screw fixation is a useful procedure for reconstruction of the cervical spine in various kinds of disorders and can be performed safely.

Anterior decompression and stabilization with the Kaneda device for thoracolumbar burst fractures associated with neurological deficits

One hundred and fifty consecutive patients who had a burst fracture of the thoracolumbar spine and associated neurological deficits were managed with a single-stage anterior spinal decompression, strut-grafting, and Kaneda spinal instrumentation. At a mean of eight years (range, five years to twelve years and eleven months) after the operation, radiographs showed successful fusion of the injured spinal segment in 140 patients (93 per cent). Ten patients had a pseudarthrosis, and all were managed successfully with posterior spinal instrumentation and a posterolateral arthrodesis. The percentage of the canal that was obstructed, as measured on computed tomography, improved from a preoperative mean of 47 per cent (range, 24 to 92 per cent) to a postoperative mean of 2 per cent (range, 0 to 8 per cent). Despite breakage of the Kaneda device in nine patients, removal of the implant was not necessary in any patient. None of the patients had iatrogenic neurological deficits. After the anterior decompression, the neurological function of 142 (95 per cent) of the 150 patients improved by at least one grade, as measured with a modification of the grading scale of Frankel et al. Fifty-six (72 per cent) of the seventy-eight patients who had preoperative paralysis or dysfunction of the bladder recovered completely. One hundred and twenty-five (96 per cent) of the 130 patients who were employed before the injury returned to work after the operation, and 112 (86 per cent) of them returned to their previous job without restrictions. We concluded that anterior decompression, strut- grafting, and fixation with the Kaneda device in patients who had a burst fracture of the thoracolumbar spine and associated neurological deficits yielded good radiographic and functional results.

transpedicular Screw Fixation for Traumatic Lesions of the Middle and Lower Cervical Spine : description of the Techniques and Preliminary Report

Thirteen patients with fractures and/or dislocations of the middle and lower cervical spine were treated by transpedicular screw fixation using the Steffee variable screw placement system. Postoperative immobilization was either not used or simplified to short-term use of a soft neck collar. Recovery of nerve function and correction of kyphotic and/or translational deformities were satisfactory. All patients had solid fusion without loss of correction at the latest follow-up. There were no neurovascular complications. It was concluded that transpedicular screw fixation is as strong a fixation procedure for the cervical spine as it is for the thoracic and lumbar spine. This surgical procedure is associated with some risks of major neurovascular injuries; however, safety is adequate if the procedure is performed by experienced surgeons using meticulous surgical techniques.

Risk factors and probability of vertebral body collapse in metastases of the thoracic and lumbar spine

STUDY DESIGN The associations between vertebral body collapse and the size or location of the metastatic lesions were analyzed statistically to estimate the critical point of collapse. OBJECTIVES To determine risk factors for collapse, to estimate the predicted probability of collapse under various states of metastatic vertebral involvement, and to establish the criteria of impending collapse. SUMMARY OF BACKGROUND DATA Pathologic vertebral collapse brings about severe pain and paralysis in patients with cancer. Prevention of collapse plays a significant role in maintaining or improving their quality of life. Because no previous study has clarified the critical point of vertebral collapse, however, the optimum timing for prophylactic treatment has been unclear. METHODS The size and location of metastatic tumor from Th1 to L5 were evaluated radiologically for 100 thoracic and lumbar vertebrae with osteolytic lesions. The correlations between collapse and the following risk factors (x1-x4) were determined by means of a multivariate logistic regression model: x1, tumor size (the percentage of tumor occupancy in the vertebral body [% TO]); x2, pedicle destruction, x3, posterior element destruction; and x4, costovertebral joint destruction. RESULTS Significant risk factors were costovertebral joint destruction (odds ratio, 10.17; P = 0.021) and tumor size (odds ratio of every 10% increment in %TO, 2.44; P = 0.032) in the thoracic region (Th1-Th10), whereas, tumor size (odds ratio of every 10% increment in %TO, 4.35; P = 0.002) and pedicle destruction (odds ratio, 297.08; P = 0.009) were main factors in the thoracolumbar and lumbar spine (Th10-L5). The criteria of impending collapse were: 50-60% involvement of the vertebral body with no destruction of other structures, or 25-30% involvement with costovertebral joint destruction in the thoracic spine; and 35-40% involvement of vertebral body, or 20-25% involvement with posterior elements destruction in thoracolumbar and lumbar spine. CONCLUSIONS With respect to the timing and occurrence of vertebral collapse, there is a distinct discrepancy between the thoracic and thoracolumbar or lumbar spine. When a prophylactic treatment is required, the optimum timing and method of treatment should be selected according to the level and extent of the metastatic vertebral involvement.

Correction of cervical kyphosis using pedicle screw fixation systems

STUDY DESIGN This retrospective study was conducted to analyze the clinical results in 30 patients with cervical kyphosis that had been treated using cervical pedicle screw fixation systems. OBJECTIVES To evaluate the effectiveness of a pedicle screw fixation procedure in correction of cervical kyphosis. SUMMARY OF BACKGROUND DATA Correction of cervical kyphosis is a challenging problem in the field of spinal surgery. There have been several reports regarding surgical correction of cervical kyphosis; however, there have been no detailed reports on correction of cervical kyphosis using a pedicle screw fixation procedure. METHODS Thirty patients with cervical kyphosis underwent correction and fusion using cervical pedicle screw fixation. Seventeen of 30 patients with flexible kyphosis (Group I) were managed by a posterior procedure alone. The remaining 13 patients with rigid or fixed kyphosis (Group II) had a combined anterior and posterior procedure. RESULTS The average preoperative cervical kyphosis of 29.4 degrees improved to 2.3 degrees after surgery and was 2.8 degrees at the final follow-up. In Group I patients, preoperative kyphosis of 28.4 degrees improved to 5.1 degrees at the final follow-up. In contrast, preoperative kyphosis of 30.8 degrees in Group II patients improved to 0.5 degree at the final follow-up. Solid fusion was achieved in all patients. There were two patients with transient nerve root complications related to pedicle screw instrumentation. CONCLUSION Cervical kyphosis in 30 patients was effectively corrected using a pedicle screw fixation procedure with no serious complications. Flexible kyphosis with segmental motion can be satisfactorily corrected by a single posterior procedure using pedicle screw fixation. However, circumferential osteotomies combined with a posterior shortening procedure involving a pedicle screw system are required to achieve the best correction of fixed kyphosis by bony union. Cervical pedicle screw fixation is the most advantageous instrumentation in the correction of cervical kyphosis.

A genome-wide association study identifies common variants near LBX1 associated with adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis is a pediatric spinal deformity affecting 2–3% of school-age children worldwide. Genetic factors have been implicated in its etiology. Through a genome-wide association study (GWAS) and replication study involving a total of 1,376 Japanese females with adolescent idiopathic scoliosis and 11,297 female controls, we identified a locus at chromosome 10q24.31 associated with adolescent idiopathic scoliosis susceptibility. The most significant SNP (rs11190870; combined P = 1.24 × 10−19; odds ratio (OR) = 1.56) is located near LBX1 (encoding ladybird homeobox 1). The identification of this susceptibility locus provides new insights into the pathogenesis of adolescent idiopathic scoliosis.

Genetic variants in GPR126 are associated with adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is the most common pediatric skeletal disease. We previously reported a locus on chromosome 10q24.31 associated with AIS susceptibility in Japanese using a genome-wide association study (GWAS) consisting of 1,033 cases and 1,473 controls. To identify additional AIS-associated loci, we expanded the study by adding X-chromosome SNPs in the GWAS and increasing the size of the replication cohorts. Through a stepwise association study including 1,819 cases and 25,939 controls, we identified a new susceptibility locus on chromosome 6q24.1 in Japanese (P = 2.25 × 10−10; odds ratio (OR) = 1.28). The most significantly associated SNP, rs6570507, was in GPR126 (encoding G protein–coupled receptor 126). Its association was replicated in Han Chinese and European-ancestry populations (combined P = 1.27 × 10−14; OR = 1.27). GPR126 was highly expressed in cartilage, and the knockdown of gpr126 in zebrafish caused delayed ossification of the developing spine. Our results should provide insights into the etiology and pathogenesis of AIS.

Traumatically induced vertebral artery occlusion associated with cervical spine injuries : Prospective study using magnetic resonance angiography

Study Design. A prospective study using magnetic resonance angiography (MRA) on a consecutive cohort of patients with cervical spine injuries. Objective. To investigate clinical and radiographic features of vertebral artery injury/occlusion associated with nonpenetrating cervical spine trauma. Summary of Background Data. With the popularization of MRA, vertebral artery injury has been a common complication of cervical spine trauma. However, detailed clinical features such as restoration of blood flow in occluded vessels and collateral circulation have not been fully evaluated. Methods. During a 2-year period, 64 consecutive patients with cervical spine fractures and/or dislocations were prospectively evaluated for patency of the vertebral artery and collateral circulation. Extracranial and intracranial MRAs were conducted at initial injury and follow-up. Results. Vertebral artery occlusion occurred in 11 patients, including 10 with unilateral and 1 with bilateral. Only the patient with bilateral occlusion was symptomatic but had no permanent neurologic deficit as a result of brain ischemia. He had complete circle of Willis, which provides sufficient collateral blood supply from anterior circulation. Follow-up MRAs revealed restoration of blood flow in occluded vessel(s) in 3 patients. All of them had compressive injuries. Conclusions. The incidence of traumatically induced vertebral artery occlusion was 17.2%. The potential for blood flow restoration was higher in compressive injuries than in distractive injuries. The mechanism of occlusion in compressive injuries is likely to be vasospasm or minor artery dissection, which may cause reversible occlusion because vessels are subjected to relatively minor stretching in compressive injuries. Vertebral artery occlusion was rarely symptomatic because of sufficient collateral blood supply through not only contralateral vertebral artery but also the circle of Willis.

Lack of association between adolescent idiopathic scoliosis and previously reported single nucleotide polymorphisms in MATN1, MTNR1B, TPH1, and IGF1 in a Japanese population.

Adolescent idiopathic scoliosis (AIS) is a spinal deformity most commonly arising in apparently healthy girls around puberty. AIS has a strong genetic predisposition. Several genetic associations between AIS and single nucleotide polymorphisms (SNPs) have been reported; common SNPs in the genes for matrilin 1 (MATN1), melatonin receptor 1B (MTNR1B), tryptophan hydroxylase 1 (TPH1), and insulin‐like growth factor 1 (IGF1) are reported to be associated with AIS in Chinese. However, these associations have not been replicated so far. To confirm the associations, we compared these SNPs with AIS predisposition and curve severity in a population of Japanese females consisting of 798 AIS patients and 1,239 controls. All the subjects were genotyped using the PCR‐based Invader assay. We found no association of any of the SNPs with AIS predisposition or curve severity. Considering the statistical power and sample size of the present study, we concluded that these SNPs are not associated with either AIS predisposition or curve severity in Japanese.

Replication study of the association between adolescent idiopathic scoliosis and two estrogen receptor genes.

Adolescent idiopathic scoliosis (AIS) is a common disorder with a strong genetic predisposition. Associations between AIS and common single nucleotide polymorphisms (SNPs) in estrogen receptor genes have been reported. rs9340799 in the gene for estrogen receptor α (ESR1) is reported to be associated with curve severity in Japanese and with AIS predisposition and curve severity in Chinese. In addition, rs1256120 in the gene for estrogen receptor β (ESR2) is reported to be associated with AIS predisposition and curve severity in Chinese. However, the sample sizes of these previous studies were small, and the associations of these SNPs have not been replicated. To examine the association between AIS and estrogen receptor genes, we investigated the association of rs9340799 and rs1256120 with AIS predisposition and curve severity using a large Japanese population, consisting of 798 AIS patients and 637 sex‐matched controls. We found no association of either SNP with AIS predisposition or curve severity in the Japanese population. Considering the statistical power of the present study and the limitations of the previous reports, we conclude that the associations of rs9340799 and rs1256120 with AIS predisposition and curve severity are negative.