Hidehiro Itoh

Cervical pedicle screw insertion: assessment of safety and accuracy with computer-assisted image guidance.

We used a commercially available computer-assisted image-guidance system for cervical pedicle screw insertion in both the laboratory and in a preliminary clinical setting. Nine plastic cervical spine models (C2-C7) were used in the laboratory test. The StealthStation was used to create the preoperative plan for each screw such that it would be inserted down the center of the pedicle, parallel to the long axis. Using a light-emitting diode-equipped drill guide, 2-mm holes were drilled in 108 pedicles. A total of 108 pedicle holes were drilled. The mean trajectory deviation from the surgical plan in the axial plane was 1.7+/-1.7 degrees (range, 0 to 8 degrees), and the mean deviation of the position of the hole was 1.7+/-0.6 mm (range, 0.1 to 2.9 mm). Eighty-three drill holes (76.9%) were contained within the pedicles, whereas partial cortical perforation was noted in 25 pedicles (23.1%). In the clinical setting, 36 cervical pedicle screws were inserted in nine patients using the image-guided system. Within the limits of imaging artifact, all 36 pedicle screws appear to have been inserted accurately by postoperative computed tomographic examination. No neurologic or vascular complications were encountered.

Experimental spinal fusion with use of recombinant human bone morphogenetic protein 2.

STUDY DESIGN Posterolateral lumbar spinal fusion with use of recombinant human bone morphogenetic protein 2 (rhBMP-2) was tested in rabbits by implanting composites of rhBMP-2 and collagen carrier. OBJECTIVES To examine the bone-formation-inducing activity of rhBMP-2 and find the optimal amount of rhBMP to add to a collagen carrier to constitute bone-formation-inducing implants to be substituted for bone graft in posterolateral spinal fusion in rabbits. SUMMARY OF BACKGROUND DATA In animal models, rhBMP-2--impregnated collagen has been successfully used for posterolateral spinal fusion, indicating that it is a potential substitute for the autogenous corticocancellous bone graft currently used most routinely in posterolateral lumbar spinal fusion. METHODS Nine rabbits were divided into three equal groups. The bilateral L4-L5 transverse processes were exposed, and collagen strips impregnated with rhBMP-2 (10, 50, or 200 micrograms) were placed on the left transverse processes, and collagen strips alone were inserted on the right. All rabbits were killed 24 weeks after surgery. The implanted sites were assessed for new bone formation and bony fusion by radiography and histologic examination. RESULTS New bone formation was noted in intertransverse spaces on the left side of all rabbits except one (10 micrograms rhBMP-2). Twelve weeks after implantation, no new bone formation was seen on the right side of all animals. The newly formed bone masses were significantly larger in the 50-microgram and 200-microgram rhBMP-2 groups than in the 10-microgram rhBMP-2 group (P < 0.01), but there was no significant difference between bone formation in the 50-microgram and 200-microgram groups (P = 0.647). CONCLUSIONS The rhBMP-2/collagen composite implant was an effective bone graft substitute for achieving posterolateral spinal fusion. When combined with a collagen carrier, the optimal rhBMP-2 dose for achieving posterolateral spinal fusion seemed to be approximately 50 micrograms per segment in rabbits.

Early-phase enhanced inflammatory reaction after spinal instrumentation surgery.

Study Design. The erythrocyte sedimentation rate, C-reactive protein, white blood cell count, and body temperature were measured prospectively in patients after two types of spinal surgery without complications and three cases of infection after spinal instrumentation surgery. Objectives. To investigate the effects of instrumentation on postoperative inflammatory reaction, and to describe early detection of postoperative wound infection. Summary of Background Data. In thoracic and abdominal surgery as well as hip arthroplasty, C-reactive protein has proved more valuable than erythrocyte sedimentation rate for early detection of postoperative infectious complications. It has not yet been established, however, how inflammatory parameters change after surgery when spinal instruments have been inserted into the body. Methods. For this study, two groups of patients were examined: a control group that underwent spinal decompression surgery without instrumentation (n = 36) and another group that underwent spinal decompression and fusion surgery with spinal instrumentation (n = 37). The erythrocyte sedimentation rate, C-reactive protein, white blood cell count, and body temperature were recorded 1 day before surgery and on days 0 to 4, 7, 11, 14, 21, 28, and 42 after surgery. Results. Inflammatory indexes (i.e., C-reactive protein, erythrocyte sedimentation rate, white blood cell count, and body temperature) were significantly higher for the surgery with instrumentation than for the spinal decompression surgery without instrumentation. Multiple regression analysis showed that C-reactive protein and erythrocyte sedimentation rate peaks significantly correlated with the use of instrumentation (C-reactive protein:P = 0.000257, erythrocyte sedimentation rate:P = 0.000132). In the patients with infection after spinal instrumentation surgery, C-reactive protein, white blood cell count, and body temperature started to increase again 4 to 11 days after surgery. The elevation of erythrocyte sedimentation rate levels was prolonged. Conclusions. Erythrocyte sedimentation rate and C-reactive protein display a significantly higher reaction after spinal surgery with instrumentation. Renewed elevation of C-reactive protein, white blood cell count, and body temperature after postoperative days 4 to 7 may be a critical sign of postoperative infection.

Preoperative CT examination for accurate and safe anterior spinal instrumentation surgery with endoscopic approach.

The purpose of this article is to introduce a new procedure for the surgical planning of thoracic anterior spinal instrumentation via endoscopy. For accurate and safe anterior screw insertion via the endoscopic approach, we devised a surgical plan based on the preoperative chest computed tomography (CT) findings obtained with radiographic markers. Using this method, we performed endoscopic thoracic spinal instrumentation surgery in 14 patients. Nine patients underwent anterior endoscopic correction and fusion of idiopathic scoliosis by Cotrel-Dubousset instrumentation, and five patients underwent anterior endoscopic spinal fixation with instrumentation. The accuracy of screw insertion was evaluated postoperatively by CT scanning. One interbody fusion cage and 53 screws were inserted in the 14 patients using endoscopy. Postoperative CT scans revealed that the screws were all accurately inserted without any neurologic complications. In conclusion, using this novel procedure for surgical planning based on CT findings obtained with radiographic markers, anterior screws can be inserted safely and accurately via an endoscopic approach.

Surgical treatment with instrumentation for severely destructive spondyloarthropathy of cervical spine.

Nine patients with severely destructive spondyloarthropathy and marked neurologic deficits associated with dialysis-related amyloidosis underwent posterior decompression and fusion by means of instrumentation at our institute. All patients showed segmental kyphosis, six patients vertebral ankylosis, and eight patients spondylolisthesis. Spondylolisthesis at two levels was noted in three patients. Of the 11 levels of spondylolisthesis in all, 9 were proximally adjacent and 2 were distally adjacent to vertebral ankylosis. All patients underwent posterior decompression and multisegment fusion with autogenous iliac bone. From three to five spinal segments were fixed. Seven patients underwent posterior fusion by means of a pedicle or lateral mass screw between levels C3 and C7, one patient between C3 and C6, and one between C3 and T1. The clinical rate of improvement at the final follow-up was 74.3%. Though complete stability could not be achieved in three patients, the results were rated as good. No postoperative neurologic deterioration has been observed in this series, nor did any patients die immediately after surgery or during the postoperative follow-up period. As anterior long-span surgery might be too invasive for hemodialysis patients, we think that posterior decompression and fusion may well be a reasonable and effective strategy for severe hemodialysis-associated cervical spondyloarthropathy with neurologic deficits. To achieve complete stability, 360° fusion with both anterior and posterior fixation with instrumentation may be required for these patients.

Multilevel subtotal corpectomy and interbody fusion using a fibular bone graft for cervical myelopathy due to ossification of the posterior longitudinal ligament

A retrospective study of the outcomes of multilevel anterior decompression and interbody fusion for cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL) was performed to both investigate the long-term results and assess the cause of late deterioration. Twenty-seven patients (mean age, 58.1 years) underwent this procedure and were followed for at least 5 years. The severity of the clinical symptoms was described using the scoring system for cervical myelopathy proposed by the Japanese Orthopaedic Association (JOA score). The average preoperative JOA score was 7.7, and the score at final follow-up was 13.4 with a recovery rate of 62.0%. A delayed deterioration was attributed to a thoracolumbar lesion other than a compromising alteration of the cervical spine. Consequently, this method of treatment for OPLL could stop the progress of ossification and keep a physiological cervical alignment and thus provide good long-term results.

Neurogenic bladder in patients with cervical compressive myelopathy

We examined the urinary disturbances in 56 consecutive patients with cervical compressive myelopathy using the latest International Continence Society classification. Of the 56 patients with cervical compressive myelopathy, 29 (52%) had some urinary subjective complaints, whereas the remaining 27 (48%) had none. Urologic examination indicated that 8 of these 29 (28%) patients with urinary complaints had urologic disorders other than neurogenic bladder. Of the remaining 21 patients, only 6 (25%) were judged to have neurogenic bladder on urodynamic study. Urodynamic study may be of limited value in diagnosing urinary disturbance in cervical myelopathy. Further, four cases (83%) showed underactive bladder activity in voiding phase, and only one case (17%) showed overactive bladder activity in filling phase. These results were contrary to those of previous studies indicating that cervical compressive myelopathy is associated with overactive bladder activity in filling phase. There were no significant differences in motor or sensory Japanese Orthopedic Association scores between the patients with and without urinary complaints. However, the patients with urinary complaints had significantly longer durations of myelopathy and delayed motor evoked potential latencies than those without urinary complaints. After surgery, 19 of the 21 (90%) patients with urinary complaints showed recovery from urinary disturbance. Operations in patients with cervical myelopathy were also effective against urinary disturbance. Urinary complaints may be an indication for surgical treatment despite the results of urodynamic study.

Nontraumatic lumbar vertebral compression fracture as a risk factor for femoral neck fractures in involutional osteoporotic patients

Abstract: To screen a potential risk factor for femoral neck fracture, we characterized lumbar vertebral fractures in 120 patients with femoral neck fractures (19 men, 101 women; mean age, 78.7 years) by investigating the frequency of patients with lumbar vertebral fracture, the number of vertebral fractures per patient, and the severity of deformity of the fractured vertebral bodies. These findings were compared with data gathered from a population of age- and sex-matched control patients (20 men, 89 women; mean age, 77.6 years) who had no evidence of femoral neck fracture. The heights of the anterior and posterior walls together with the midpart of the lumbar vertebrae were measured on lateral radiographs to identify fractures. The extent of height loss in the fractured vertebrae was calculated for each group. The incidence of patients with vertebral compression fractures was significantly higher in the femoral neck fracture group than in the control group (65.0% vs 41.1%). In terms of age, the difference in the incidence of vertebral fractures in the two groups was greater in the less aged (60–79 years old) than in the more aged (>80 years old) population. The mean number of lumbar vertebral fractures was also significantly greater in the femoral neck fracture group than in the control group (1.59 ± 1.39 vs 0.75 ± 1.19; P < 0.001). The incidence of more deformed vertebral fractures, which were defined as a vertebral height loss of more than 50%, was also significantly higher in the group with femoral neck fracture than in the control group (23.0% vs 7.3%). Based on these results, we concluded that multiple and more severely deformed vertebral fractures might represent a high risk for femoral neck fracture, particularly in patients less than 79 years of age. Care measures that encompass fall prevention and protection of proximal femurs in addition to drug therapy for osteoporosis should be recommended to individuals in this category.

Anterior thoracic spinal fusion in dogs by injection of recombinant human bone morphogenetic protein-2 and a synthetic polymer

The purpose of this study was to achieve spinal fusion in the absence of bone graft material using a new, injectable, and semi-liquid synthetic polymer (polylactic acid polyethylene glycol [PLA-PEG] block copolymer) containing recombinant human bone morphogenetic protein-2 (rhBMP-2). Twenty-seven skeletally mature beagles underwent anterior thoracic spinal fusion at T9–T10. Group I (n = 9) was injected with 1 mL of PLA-PEG block copolymer carrier alone into space under the vertebral pleura and the anterior longitudinal ligament. Group II (n = 9) was injected with 1 mL of PLA-PEG carrier containing 500 &mgr;g of rhBMP-2. Group III (n = 9) was injected with 1 mL of PLA-PEG carrier containing 1000 &mgr;g of rhBMP-2. In the Group I animals, no evidence of new bone formation was noted at the implanted sites both radiographically and histologically. In contrast, all of the nine animals in Group III showed new bone formation in 12 weeks, and four of the nine animals in Group II showed bony mass at the injected sites. However, vertebral bony fusion was incomplete despite the significant amount of new bone formation in both groups that showed new bone formation. In addition to resulting in improvements in the surgical procedure, injection of rhBMP-2 and a synthetic polymer is useful for bone formation for spinal fusion.

Anterior surgery with short fusion using the Zielke procedure for thoracic scoliosis : focus on the correction of compensatory curves

Anterior instrumentation is recommended to correct idiopathic thoracolumbar or lumbar scoliosis through short fusion within the major curve. Only a few reports exist of anterior surgical correction for thoracic scoliosis. This study assessed the results of Zielke instrumentation for thoracic curve and analyzed the three-dimensional correction of deformity, especially correction of the uninstrumented compensatory curve. Seventeen patients, who had undergone selective thoracic correction and fusion using the Zielke procedure to treat thoracic scoliosis, had been followed for at least 3 years. Three-dimensional correction was evaluated radiographically. Furthermore, three-dimensional back deformities were evaluated using a topographic body scanner. Twelve patients with a single thoracic curve and five with a double curve were all female, with a mean age of 14.6 years. The preoperative main thoracic curve was 54.8 degrees +/- 10.5 degrees (range, 40-78 degrees), and it was 23.8 degrees +/- 10.5 degrees (range, 7-40 degrees) at the final follow-up examination (p < 0.0001). The average correction rate of the main curves was 56.6%. By correcting the thoracic curve, the upper and lower compensatory curves were corrected spontaneously without surgical instrumentation, with average correction rates of 45.1% and 50.2%, respectively. The average correction loss of the main curve was 2.3 degrees. The hump angle measured using a topographic body scanner decreased from 12.8 degrees +/- 4.5 degrees to 8.4 degrees +/- 4.3 degrees after surgery (p = 0.0001). Of the three patients in whom the rod broke up, only one showed a correction loss of 10 degrees; however, bony fusion was obtained. Anterior short fusion for thoracic scoliosis appears to offer significant correction, stabilization, and spontaneous correction of the compensatory lumbar curve without limiting lumbar motion.