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Morio Matsumoto, Kota Watanabe, Takashi Tsuji, Ken Ishii, Masaya Nakamura, Kazuhiro Chiba and Yoshiaki Toyama

Object

The object of this study was to investigate failures after spinal reconstruction following total en bloc spondylectomy (TES), related factors, and sequelae arising from such failures in patients with malignant spinal tumors.

Methods

Fifteen patients (12 males and 3 females, with a mean age of 46.5 years) with malignant spinal tumors who underwent TES and survived for more than 1 year were included in this analysis (mean follow-up 41.5 months). Seven patients had primary tumors, including giant cell tumors in 4 patients, chordoma in 2, and Ewing sarcoma in 1. Eight patients had metastatic tumors, including thyroid cancer in 6 and renal cell cancer and malignant fibrous histiocytoma in 1 patient each. Seven patients without prominent paravertebral extension of the tumor were treated using a posterior approach alone, and 8 patients who exhibited prominent anterior or anterolateral extension of the tumors into the thoracic or abdominal cavity were treated using a combined anterior and posterior approach. Spinal reconstruction after tumor resection was performed using a combination of anterior structural support and posterior instrumentation. The relationship between instrumentation failure and clinical and radiographic factors, including age, sex, history of previous surgery, preoperative radiotherapy, tumor histology, tumor level, surgical approach, number of resected vertebrae, rod diameter, number of instrumented vertebrae, and cage subsidence, was investigated.

Results

Six patients (40%) with spinal instrumentation failure were identified: rod breakage occurred in 3 patients, and breakage of both the rod and the cage, combined cage breakage and screw back-out, and endplate fracture arising from cage subsidence occurred in 1 patient each. All of these patients experienced acute or chronic back pain, but only 1 patient with a tumor recurrence experienced neurological deterioration upon instrumentation failure. Cage subsidence (≥ 5 mm), preoperative irradiation, and the number of instrumented vertebrae (≤ 4 vertebrae) were significantly related to late instrumentation failure.

Conclusions

Late instrumentation failure was a frequent complication after TES. Although patients with instrumentation failure experienced back pain, the neurological sequelae were not catastrophic. For prevention, meticulous preparation of the graft site and a longer posterior fixation should be considered.

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Soya Kawabata, Kota Watanabe, Naobumi Hosogane, Ken Ishii, Masaya Nakamura, Yoshiaki Toyama and Morio Matsumoto

Severe cervical kyphosis requiring surgical treatment is rare in patients with neurofibromatosis Type 1 (NF1). When it occurs, however, dystrophic changes in the vertebrae make surgical correction and fusion of the deformity extremely difficult.

The authors report on 3 cases of severe cervical kyphosis associated with NF1 that were successfully treated with combined anterior and posterior correction and fusion. All patients underwent halo-gravity traction for approximately 1 month prior to surgery to correct the deformity gradually. Posterior correction and fusion were performed with segmental spinal instrumentation consisting of lateral mass screws, lamina screws, pedicle screws, and polyethylene tape for sublaminar wiring. Anterior spinal fusion was performed using a fibula strut to induce solid bone fusion. All patients used a halo vest for postoperative external fixation.

Preoperative CT scans showed dystrophic cervical spine changes, and MR images demonstrated extensive neurofibromas outside the cervical spine in all 3 patients. The preoperative kyphotic angles were as follows: Case 1, 140°; Case 2, 81°; and Case 3, 72°; after halo-gravity traction, the kyphosis angles improved to 50°, 55°, and 51°, respectively; and after surgery, they were 50°, 15°, and 27°, respectively. Solid bone union was observed in all patients at the latest follow-up. All three patients experienced postoperative complications consisting of superficial infection, severe pneumonia, and partial dislocation of the distal fibula graft after removing the halo vest, in one patient each.

Although dystrophic cervical vertebral changes in these patients with NF1 complicated the correction of severe cervical kyphosis, the use of preoperative halo-gravity traction, a combination of spinal instrumentations, an anterior strut bone graft, and postoperative halo-vest fixation made it possible to correct the kyphosis, maintain the correction, and achieve solid bone fusion.

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Kota Watanabe, Toshihiko Hosoya, Tateru Shiraishi, Morio Matsumoto, Kazuhiro Chiba and Yoshiaki Toyama

✓ In conventional laminectomy for lumbar canal stenosis (LCS), intraoperative damage of posterior supporting structures can lead to irreversible atrophy of paraspinal muscles. In 2001, the authors developed a new procedure for lumbar laminectomy, the lumbar spinous process—splitting laminectomy (LSPSL).

In this new procedure, the spinous process is split longitudinally in the middle and then divided at its base from the posterior arch, leaving the bilateral paraspinal muscles attached to the lateral aspects. Ample working space for laminectomy is obtained by retracting the split spinous process laterally together with its attached paraspinal muscles. After successfully decompressing nerve tissues, each half of the split spinous process is reapproximated using a strong suture. Thus, the supra- and interspinous ligaments are preserved, as is the spinous process, and damage to the paraspinal muscles is minimal.

Eighteen patients with LCS underwent surgery in which this new technique was used. Twenty patients in whom conventional laminectomy was undertaken were chosen as controls. At 2 years, the clinical outcomes (as determined using the Japanese Orthopaedic Association [JOA] scores and recovery rate) and the rate of measured magnetic resonance imaging—documented paravertebral muscle atrophy were evaluated and compared between the two groups. The mean JOA score recovery rates were 67.6 and 59.2%, respectively, for patients treated with LSPSL and conventional laminectomy; the mean rates of paravertebral muscle atrophy were 5.3 and 23.9%, respectively (p = 0.0005).

Preservation of posterior supporting structures and satisfactory recovery rate after 2 years indicated that this technique can be a useful alternative to conventional decompression surgery for lumbar canal stenosis.

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Naobumi Hosogane, Kota Watanabe, Hitoshi Kono, Masashi Saito, Yoshiaki Toyama and Morio Matsumoto

Object

The authors undertook this study to evaluate curve progression, risk factors for curve progression, and outcomes after decompression surgery in patients with degenerative lumbar scoliosis with minimal to moderate curvature.

Methods

Of 852 patients with lumbar canal stenosis treated by posterior decompression surgery, 50 patients had a lumbar curve greater than 10° at final follow-up. These patients were divided into 2 groups according to curve progression during the follow-up period: the P group (11 patients), with a curve progression of more than 5°, and the NP group (39 patients), with a curve progression of 5° or less. The authors compared preoperative parameters in these 2 groups to elucidate risk factors associated with curve progression and other surgical outcomes.

Results

The average lumbar curve progression in the total group of 50 patients was 3.4° ± 3.9° (range −2.0° to 22.0°). In the P group the average curve progression was 8.5°, and in the NP group it was 2.0°. Multivariate logistic regression analysis showed no significant association between curve progression and any of the potential risk factors evaluated (including curve magnitude, decompression method, and degenerative intervertebral disc changes). Spur formation, evaluated with the Nathan classification at the concave side of the curve, tended to be greater in the P group, although the difference was not statistically significant. There was no significant difference in revision surgery rate, and none of the patients required arthrodesis due to curve progression. Clinical outcomes, evaluated with the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire and the Scoliosis Research Society 22-question questionnaire, were also similar in the 2 groups.

Conclusions

Surgical outcomes did not deteriorate in the P group. While curve progression after decompression surgery could not be predicted from the preoperative factors considered, spur formation at the concave side of the curve may be a candidate factor. The results of this study indicate that spinal fixation to halt deformity progression is not always necessary if the patient's pathological condition derives mainly from canal stenosis.

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Morio Matsumoto, Kota Watanabe, Ken Ishii, Takashi Tsuji, Hironari Takaishi, Masaya Nakamura, Yoshiaki Toyama and Kazuhiro Chiba

Object

In this paper, the authors' goal was to elucidate the clinical features and results of decompression surgery for extraforaminal stenosis at the lumbosacral junction.

Methods

Twenty-eight patients with severe leg pain caused by extraforaminal stenosis at the lumbosacral junction (18 men and 10 women; mean age 68.2 ± 8.9 years) were treated by posterior decompression without fusion using a microendoscope in 19 patients and a surgical microscope or loupe in 9 patients. The decompression procedures consisted of partial resection of the sacral ala, the L-5 transverse process, and the L5–S1 facet joint along the L-5 spinal nerve. The following items were investigated: 1) preoperative neurological findings; 2) preoperative radiological findings, including plain radiographs, CT scans, selective radiculography of L-5; 3) surgical outcome as evaluated using the Japanese Orthopaedic Association scale for low-back pain (JOA score); and 4) need for revision surgery.

Results

All patients presented with neurological deficits compatible with a diagnosis of L-5 radiculopathy such as weakness of the extensor hallucis longus muscle and sensory disturbance in the L-5 area together with neurogenic claudication. On plain radiographs, 21 patients (75%) and 17 patients (60.7%) exhibited lumbar scoliosis (≥ 5°) and wedging of the L5–S1 intervertebral space (≥ 3°), respectively. The CT scans demonstrated marked osteophyte formation at the posterolateral margin of the L5–S1 vertebral bodies, and a selective L-5 nerve root block was effective in all patients. All patients reported pain relief immediately after surgery. The mean JOA scores were 11.3 ± 3.8 before surgery and 24.3 ± 3.4 at the time of the final follow-up examination; the recovery rate was 68.6 ± 16.5%. The mean estimated blood loss was 66.6 ± 98.6 ml, and the mean surgical time was 135.3 ± 46.5 minutes. No significant difference in the recovery rate of the JOA scores or in the surgical time and blood loss was observed between the 2 surgical approaches. Four patients underwent revision posterior interbody fusion for the recurrence of radicular pain as a result of intraforaminal stenosis in 3 patients and insufficient decompression of the extraforaminal area in the remaining patient at an average of 19.5 months after surgery.

Conclusions

Extraforaminal stenosis at the lumbosacral junction is a rare but distinct pathological condition causing L-5 radiculopathy. Decompression surgery without fusion using a microendoscope or a surgical microscope/ loupe is a feasible and less invasive surgical option for elderly patients with extraforaminal stenosis at the lumbosacral junction.

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Tomohiro Hikata, Kota Watanabe, Nobuyuki Fujita, Akio Iwanami, Naobumi Hosogane, Ken Ishii, Masaya Nakamura, Yoshiaki Toyama and Morio Matsumoto

OBJECT

The object of this study was to investigate correlations between sagittal spinopelvic alignment and improvements in clinical and quality-of-life (QOL) outcomes after lumbar decompression surgery for lumbar spinal canal stenosis (LCS) without coronal imbalance.

METHODS

The authors retrospectively reviewed data from consecutive patients treated for LCS with decompression surgery in the period from 2009 through 2011. They examined correlations between preoperative or postoperative sagittal vertical axis (SVA) and radiological parameters, clinical outcomes, and health-related (HR)QOL scores in patients divided according to SVA. Clinical outcomes were assessed according to Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores. Health-related QOL was evaluated using the Roland-Morris Disability Questionnaire (RMDQ) and the JOA Back Pain Evaluation Questionnaire (JOABPEQ).

RESULTS

One hundred nine patients were eligible for inclusion in the study. Compared to patients with normal sagittal alignment prior to surgery (Group A: SVA < 50 mm), those with preoperative sagittal imbalance (Group B: SVA ≥ 50 mm) had significantly smaller lumbar lordosis and thoracic kyphosis angles and larger pelvic tilt. In Group B, there was a significant decrease in postoperative SVA compared with the preoperative SVA (76.3 ± 29.7 mm vs 54.3 ± 39.8 mm, p = 0.004). The patients in Group B with severe preoperative sagittal imbalance (SVA > 80 mm) had residual sagittal imbalance after surgery (82.8 ± 41.6 mm). There were no significant differences in clinical and HRQOL outcomes between Groups A and B. Compared to patients with normal postoperative SVA (Group C: SVA < 50 mm), patients with a postoperative SVA ≥ 50 mm (Group D) had significantly lower JOABPEQ scores, both preoperative and postoperative, for walking ability (preop: 36.6 ± 26.3 vs 22.7 ± 26.0, p = 0.038, respectively; postop: 71.1 ± 30.4 vs 42.5 ± 29.6, p < 0.001) and social functioning (preop: 38.7 ± 18.5 vs 30.2 ± 16.7, p = 0.045; postop: 67.0 ± 25.8 vs 49.6 ± 20.0, p = 0.001), as well as significantly higher postoperative RMDQ (4.9 ± 5.2 vs 7.9 ± 5.7, p = 0.015) and VAS scores for low-back pain (2.68 ± 2.69 vs 3.94 ± 2.59, p = 0.039).

CONCLUSIONS

Preoperative sagittal balance was not significantly correlated with clinical or HRQOL outcomes after decompression surgery in LCS patients without coronal imbalance. Decompression surgery improved the SVA value in patients with preoperative sagittal imbalance; however, the patients with severe preoperative sagittal imbalance (SVA > 80 mm) had residual imbalance after decompression surgery. Both clinical and HRQOL outcomes were negatively affected by postoperative residual sagittal imbalance.

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Masaya Nakamura, Osahiko Tsuji, Kanehiro Fujiyoshi, Kota Watanabe, Takashi Tsuji, Ken Ishii, Morio Matsumoto, Yoshiaki Toyama and Kazuhiro Chiba

Object

The optimal management of malignant astrocytomas remains controversial, and the prognosis of these lesions has been dismal regardless of the administered treatment. In this study the authors investigated the surgical outcomes of cordotomy in patients with thoracic malignant astrocytomas to determine the effectiveness of this procedure.

Methods

Cordotomy was performed in 5 patients with glioblastoma multiforme (GBM) and 2 with anaplastic astrocytoma (AA). A Kaplan-Meier survival analysis was performed, and the associations of the resection level with survival and postoperative complications were retrospectively examined.

Results

Cordotomy was performed in a single stage in 2 patients with GBM and in 2 stages in 3 patients with GBM and 2 patients with AA. In the 2 patients with GBM, cordotomy was performed 2 and 3 weeks after a partial tumor resection. In the 2 patients with AA, the initial treatment consisted of partial tumor resection and subtotal resection combined with radiotherapy, and rostral tumor growth and progressive paralysis necessitated cordotomy 2 and 28 months later. One patient with a secondary GBM underwent cordotomy; the GBM developed 1 year after subtotal resection and radiotherapy for a WHO Grade II astrocytoma. Four patients died 4, 5, 24, and 42 months after the initial operation due to CSF dissemination, and 3 patients (2 with GBM and 1 with AA) remain alive (16, 39, and 71 months). No metastasis to any other organs was noted.

Conclusions

One-stage cordotomy should be indicated for patients with thoracic GBM or AA presenting with complete paraplegia preoperatively. In patients with thoracic GBM, even if paralysis is incomplete, cordotomy should be performed before the tumor disseminates through the CSF. Radical resection should be attempted in patients with AA and incomplete paralysis. If the tumor persists, radiotherapy and chemotherapy are indicated, and cordotomy should be reserved for lesions growing progressively after such second-line treatments.

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Lawrence G. Lenke

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Guanyu Cui, Kota Watanabe, Ken Ishii, Yoshiaki Toyama, Kazuhiro Chiba and Morio Matsumoto

A butterfly vertebra is a congenital anomaly often associated with a series of syndromic diseases and is often recognized incidentally without any presenting symptoms. The authors report the case of a 13-year-old girl with lumbar scoliosis and mild spondylolisthesis associated with a butterfly vertebra at L-6 causing radiculopathy. The L-5 and L-6 nerve roots were entrapped at the intervertebral foramina between L-5 and the butterfly vertebra (L-6) and between L-6 and S-1 in the concave side. To decompress and preserve the two nerve roots, correct the deformity, and obtain a solid bone fusion, surgery involving the thorough removal of the facet joints between L-5 and L-6 and between L-6 and S-1 in the concave side was performed, with a partial resection of the butterfly vertebra and the placement of a titanium mesh cage between the L-5 and S-1 pedicles dorsal to the nerve roots. Complete pain relief and correction of the deformity with solid bone fusion was obtained after a 2-year follow-up period.

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Kota Watanabe, Morio Matsumoto, Takashi Tsuji, Ken Ishii, Hironari Takaishi, Masaya Nakamura, Yoshiaki Toyama and Kazuhiro Chiba

Object

The aim in this study was to evaluate the efficacy of the ball tip technique in placing thoracic pedicle screws (TPSs), as compared with the conventional freehand technique, in both a cadaveric study and a clinical study of patients with adolescent idiopathic scoliosis. Although posterior spinal surgery using TPSs has been widely applied, these screws are associated with the potential risk of vascular, pulmonary, or neurological complications. To further enhance the accuracy and safety of TPS placement, the authors developed the ball tip technique.

Methods

After creating an appropriate starting point for probe insertion, a specially designed ball tip probe consisting of a ball-shaped tip with a flexible metal shaft is used to make a guide hole into the pedicle. Holding the probe with the fingertips while using an appropriate amount of pressure or by tapping it gently and continuously with a hammer, one can safely insert the ball tip probe into the cancellous channel in the pedicle.

In a cadaveric study, 5 spine fellows with similar levels of experience in placing TPSs applied the ball tip or the conventional technique to place screws in 5 cadavers with no spinal deformities. The incidence of misplaced screws was evaluated by dissecting the spines. In a clinical study, 40 patients with adolescent idiopathic scoliosis underwent posterior surgery with TPS placement via the ball tip or conventional technique (20 patients in each treatment group). The accuracy of the TPS placements was evaluated on postoperative axial CT scanning.

Results

In the cadaveric study, 100 TPSs were evaluated, and the incidence of misplaced screws was 14% in the ball tip group and 34% in the conventional group (p = 0.0192). In the clinical study, 574 TPSs were evaluated. One hundred seventy-one intrapedicular screws (67%) were recognized in the conventional group and 288 (90%) in the ball tip group (p < 0.01). In the conventional and ball tip groups, the respective numbers of TPSs with a pedicle breach of ≤ 2 mm were 20 (8%) and 15 (5%), those with a pedicle breach of > 2 mm were 32 (13%) and 9 (3%; p < 0.01), and those located in the costovertebral joints were 32 (13%) and 7 (2%).

Conclusions

In both cadaveric and clinical studies the ball tip technique enhanced the accuracy of TPS placement as compared with the conventional freehand technique. Thus, the ball tip technique is useful for the accurate and safe placement of TPSs in deformed spines.