Shigenobu Satoh

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.

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.

The treatment of osteoporotic-posttraumatic vertebral collapse using the Kaneda device and a bioactive ceramic vertebral prosthesis

Twenty-two patients with neurologic deficit due to delayed posttraumatic vertebral collapse after osteoporotic compression fractures of the thoracolumbar spine underwent anterior decompression and reconstruction with bioactive Apatite-Wollastonite containing glass ceramic vertebral prosthesis and Kaneda instrumentation. Eighteen patients previously had minor trauma that resulted in a mild vertebral compression fracture without any neurologic involvement and were either conservatively treated or not treated at all. Four had no history of back injury. The preoperative neurologic status was incomplete paralysis in all patients. The average age at surgery was 66(53–79) years. The average follow-up was 34 (20–58) months after surgery. All patients had returned to their daily living with neurologic recovery and stable spine. This type of anterior procedure is effective in the osteoporotic patients and there was a very low incidence of instrumentation failure and very low morbidity.

New anterior instrumentation for the management of thoracolumbar and lumbar scoliosis. Application of the Kaneda two-rod system.

Study Design. The Kaneda multisegmental instrumentation is a new anterior two‐rod system for the correction of thoracolumbar and lumbar spine deformities. This system consists of a vertebral plate and two vertebral screws for individual vertebral bodies and two semirigid rods to interconnect the vertebral screws. Clinical results of 25 thoracolumbar and lumbar scoliosis patients treated with this new instrumentation were analyzed. Objectives. To evaluate the efficacy of the new anterior instrumentation in correction and stabilization of thoracolumbar and lumbar scoliosis. Summary of Background Data. Since Dwyer first introduced the concept of anterior spinal instrumentation and fusion for scoliosis, anterior surgery has gradually gained acceptance. In 1976, a useful modification for the anterior spinal instrumentation, which reportedly provided means of lordosation and vertebral body derotation, was described. However, some authors reported a high tendency of the implant breakage, loss of correction, progression of the kyphosis, and pseudoarthrosis as the major complications. To overcome the disadvantages of Zielke instrumentation, the authors have developed a new anterior spinal instrumentation (two‐rod system) for the management of thoracolumbar and lumbar scoliosis. Methods. Anterior correction and fusion using Kaneda multisegmental instrumentation was performed in 25 patients with thoracolumbar or lumbar scoliosis. The average follow‐up period was 3 years, 1 month (range, 2 years to 4 years, 7 months). There were 20 patients with idiopathic scoliosis (13 adolescents and seven adults) and five patients with other types of scoliosis, including congenital and other etiologies. All patients had correction of scoliosis by fusion within the major curve, and for 16 of the 25 patients, the most distal end vertebra was not included in the fusion (short fusion). Radiographic evaluations were performed to analyze frontal and sagittal alignments of the spine. Results. The average correction rate of scoliosis was 83%. Over the instrumented levels, the correction rate was 90%. Preoperative kyphosis of the instrumented levels of 7° was corrected to 9° of lordosis. Sagittal lordosis of the lumbosacral area beneath the fused segments averaged 51° before surgery and was reduced to 34° after surgery. The trunk shift was improved from 25 mm before surgery to 4 mm at final follow‐up evaluation. The average improvement in the lower end vertebra tilt‐angle was 97% in those patients whose lower end vertebra was included in the fusion and 83% in patients whose lower end vertebra was not included in the fusion. Apical vertebral rotation showed an average correction rate of 86%. At final follow‐up evaluation, all patients demonstrated solid fusion without implantrelated complications. There was 1.5° of frontal plane and 1.5° of sagittal plane correction loss within the instrumented area at final follow‐up evaluation. Conclusions. New anterior two‐rod system showed excellent correction of the frontal curvature and sagittal alignment with extremely high correction capability of rotational deformities. Furthermore, correction of thoracolumbar kyphosis to physiologic lordosis was achieved. This system provides flexibility of the implant for smooth application to the deformed spine and overall rigidity to correct the deformity and maintain the fixation without a significant loss of correction or implant failure compared with conventional one‐rod instrumentation systems in anterior scoliosis correction.

Follow-up study of medial facetectomies and posterolateral fusion with instrumentation in unstable degenerative spondylolisthesis.

From 1978 to 1983, 54 consecutive patients with unstable degenerative spondylolisthesis were treated by medial facetectomies and posterolateral fusion with combined distraction and compression rod instrumentation. The average period of follow-up observation was 30 months. Twenty-five patients had a combination of disc herniation or instability, excluding olisthesis. Single-level fusion was performed in 29 patients, two-level in 23, and three-level in two. Preoperative low-back pain in 87.0% and sciatica in 66.7% were reduced to 7.5% and 5.6%, respectively, at follow-up treatment. Preoperative neurogenic intermittent claudication in 63.0% and neurogenic bladder in 11.1% disappeared completely in all patients at follow-up examination. The solid fusion rate was 96.3%. Difference between the values of %-slip and slip-angle before surgery and those at follow-up examination was not statistically significant. Rod breakage occurred in two patients with pseudarthrosis. The overall clinical results were satisfactory relief of clinical symptoms and regression of physical signs, with a high rate of solid fusion.

Distraction Rod Instrumentation with Posterolateral Fusion in Isthmic Spondylolisthesis: 53 Cases Followed for 18???89 Months

Fifty-three cases of isthmic spondylolisthesis were treated with distraction rod instrumentation and posterolateral fusion with or without nerve root decompression, and they were followed for an average of 39 months. Thirty-one cases without neurologic deficit were treated with instrumentation and fusion only. In 22 cases of predominant sciatic pain with neurologic deficit signs, nerve root decompression and instrumentation with fusion were conducted. The results showed a 90.6% solid union rate with satisfactory clinical improvement. Realignment of the vertebral displacement such as reduction of olisthesis and widening of the olisthetic disc spaces was obtained to some extent. No serious complications were encountered.

Pathologic features of spinal disorders in patients treated with long-term hemodialysis.

Study Design. Pathologic features of hemodialysis‐associated spinal disorders were evaluated using preoperative radiographic images and histologic findings of the spinal lesions resected during surgery. Objectives. To investigate the pathology of hemodialysis‐related spinal disorders and to determine the role of amyloidosis in the establishment of severe destruction of the spine. Summary of Background Data. The pathologic events leading to hemodialysis‐associated spinal disorders are poorly understood. The distribution of amyloid deposits in the spine also has not been clarified. Methods. Twenty patients with hemodialysis‐associated spinal disorders were investigated regarding pathologic features of neural compression and spinal destruction. Preoperative radiographic images such as plain radiography, tomography, computed tomography, magnetic resonance imaging, and scintigraphy were assessed for the existence of an intracanal mass, hypertrophy of the ligamentum flavum, and destructive changes of the spinal components. Histologic examination also was conducted by light microscopy and scanning electron microscopy to determine the distribution pattern of amyloid deposits in the spinal components. Results. Six patients with no destructive changes in the spine showed spinal canal stenosis. In the cervical spine, a main factor associated with spinal canal stenosis was the presence of intracanal amyloid deposits in three patients. In the lumbar spine, a main factor associated with spinal canal stenosis was hypertrophied ligamentum flavum in three patients. Destructive changes of the facet joints, intervertebral disc, and vertebral body were seen in the other 14 patients. Amyloid deposits were densely distributed at the enthesis of capsular fibers to the bone and in anular tears in the intervertebral discs. Vertebral end plates were destroyed by penetration of amyloid granulation into the vertebral body. Osteoclast activity in the destroyed vertebral bodies was enhanced, with no evidence of new bone formation. Conclusions. Amyloid deposits played an important role in the progression of spinal destruction and severe instability.

Reconstruction of an iliac crest defect with a bioactive ceramic prosthesis

SummaryBetween June 1987 and December 1990, an iliac crest prosthesis made of bioactive apatite- and wollastonite-containing glass ceramic (A-W·GC) was used in 60 patients for the reconstruction of the iliac crest defect after harvesting autogenous tricortical iliac bone graft. The clinical results of this prosthesis were satisfactory. No patients felt spontaneous pain in the reconstructed area, and 93% of the patients had no tenderness there. In the radiological evaluation at the final follow-up, no apparent “radiolucent clear zone” was detected at the prosthesis-iliac bone junction in 98% of the patients. Excellent new bone formation between the prosthesis and the iliac crest was also noticed in 96% of the patients. The A-W·GC iliac crest prosthesis was beneficial for reconstruction of the iliac crest defect.

FREE VASCULARISED FIBULAR STRUT GRAFT FOR ANTERIOR SPINAL FUSION

A vascularised fibular strut graft was used for anterior spinal fusion in 16 patients with spinal kyphosis. The procedure was abandoned in three because of difficulty in establishing a vascular anastomosis and in one because the grafted fibula dislodged two days after operation. One patient died after five days. Of the 11 remaining patients, there were seven males and four females. Their ages at the time of operation averaged 30.9 years (12 to 71). The number of vertebrae fused averaged 6.7 (5 to 9) and the length of fibula grafted averaged 10.9 cm (6.5 to 18). Average follow-up was 54 months (27 to 84). Bone union occurred at both ends of the grafted fibula in all 11 patients, with an average time to union of 5.5 months (3 to 8). We did not see a fracture of the grafted fibula. Two patients had postoperative complications; the graft dislodged in one and laryngeal oedema occurred two days after operation in the other. A vascularised fibular strut graft provides a biomechanically stable and long-standing support in spinal fusion because the weak phase of creeping substitution does not take place in the graft.

Results with Zielke instrumentation for idiopathic thoracolumbar and lumbar scoliosis.

Thirty-one patients (23 adolescent, eight adult) underwent spinal fusions with Zielke instrumentation for idiopathic thoracolumbar and lumbar scoliosis. Their curves averaged 55.2 degrees. In most patients the length of fusion did not extend beyond the major curve. Correction of scoliosis was 82% in adolescents and 59% in the adults. The kyphotic component of the curves was corrected from an average of 21 degrees to 8 degrees. Correction of the spinal vertebra rotation was 46% in the adolescent patients. The tilt angle of the vertebra at the lower end of the curve was reduced significantly. The fusion rate was 93.5%. Two of the adult patients developed pseudarthrosis. Major complications were not encountered. The Zielke instrumentation system in the management of idiopathic thoracolumbar and lumbar scoliosis offers the advantages of a relatively good correction and minimal segment fusion.