Yasumitsu Ajiro

Outcome of Treatment for Spinal Metastases Using Scoring System for Preoperative Evaluation of Prognosis

Study Design. Prospective study. Objective. To evaluate our treatment outcome for spinal metastases using our treatment strategy based on prognostic scoring system. Summary of Background Data. In the treatment of spinal metastases, life expectancy is most important, and our scoring system for metastatic spine tumor prognosis has been useful for such prognostic evaluation. Methods. Conservative treatment or palliative surgery was indicated in patients with a predicted prognosis of less than 6 months or in those with multiple vertebral metastases, whereas excisional surgery was performed in patients with a predicated prognosis of 1 year or more, or with a predicted prognosis of 6 months or more, and with metastasis in a single vertebra. One hundred eighty-three patients were prospectively treated according to this principle using our prognostic scoring system, and the outcome was evaluated. Results. The consistency rate between the predicted prognosis from the criteria of the scoring system and the actual survival period was high in patients within each score range (0–8, 9–11, or 12–15), 87.9% in the 183 patients. Only the palliative surgery group (n = 55) showed a significant improvement of the Barthel index between before and after treatment (P < 0.01). The mean maximum Barthel index after treatment in any modality ran parallel to the total scores of our scoring system. Conclusion. The prognostic criteria using our scoring system were useful for the pretreatment evaluation of prognosis irrespective of the treatment modality. In any treatment, the survival period of the patients affected the functional prognosis; therefore, it may be appropriate and realistic to select treatment methods by giving first priority to the life expectancy of patients.

Impact of passive smoking on the bones of rats.

Many epidemiological surveys have identified smoking as a risk factor for osteoporosis, but it is unclear whether smoking has a direct effect on bone metabolism and if such an effect could cause osteoporosis. Therefore, we examined whether smoking causes osteoporosis based on the impact of smoke exposure on the bones of rats. A rat model of passive cigarette smoking was prepared by breeding rats in a cigarette-smoking box for 4 or 8 weeks. Histological changes, micro-computed tomographic (CT) analysis, mechanical bone strength, and bone mineral density of the femur and lumbar vertebrae were examined in these rats and in control rats that were not exposed to smoke. Lower mechanical bone strength was observed in smoke-exposed rats, but these differences were not significant. Significantly lower bone mineral density was found in the femur (P<.01) and lumbar bones (P<.001) of 8-week smoke-exposed rats compared to controls. In a micro-CT scan of lumbar vertebrae, the bone volume, trabecular thickness, trabecular number, and trabecular separation differed significantly between smoke-exposed rats and controls. Histologically, the osteocytes in the smoke-exposed rats were small (approximately 25% of the size in controls), and decreased numbers of marrow cells and osteoblasts (P<.01), as well as a black carbon dust-like substance, were found in the bone of smoke-exposed rats. These results indicate that smoking significantly decreases bone mineral density, which causes osteoporosis, and the organizational changes in the bone suggest a direct effect of smoking on bone structure. Fewer marrow cells were present in the smoke-exposed rats, and a black carbon dust-like substance was observed.

A patient with two re-surgeries for delayed myelopathy due to progression of ossification of the posterior longitudinal ligaments after cervical laminoplasty.

Study Design. Case report. Objective. To discuss the development of delayed myelopathy due to the progression of ossification of the posterior longitudinal ligament (OPLL) after cervical laminoplasty. Summary of Background Data. The progression of OPLL after cervical laminoplasty for the treatment of OPLL is often shown in long-term follow-up; however, few patients with reoperation due to OPLL progression have been reported. Methods. The patient was a 70-year-old male carpenter. At 57-years of age, he underwent open door laminoplasty between C3 and C7 with dome-like laminectomy of C2 for the treatment of myelopathy due to mixed-type OPLL (continuous type at C3–C4 and segmental type at C5). Five years after the initial surgery, the disorder of skilled motor activity in the bilateral hands and ambulatory difficulties recurred as a result of cranial progression of OPLL (between C2 and C4). He underwent laminectomy and posterior fusion between C2 and C5 and returned to work. Four years after resurgery, the same symptoms recurred. Results. CT revealed the progression of OPLL thickness at C5 level and longitudinal progression of OPLL to C6/7. Sagittal view of MRI demonstrated spinal cord compression between C5 and C6/7 because of OPLL at C5 and hypertrophic ligamentum flavum at C5–C6 and C6–C7. Posterior fusion extending up to C7 with laminectomy of C6 and C7 was performed. His symptoms were alleviated and he could walk again. Conclusion. We reported a patient with OPLL who had undergone resurgery twice because of myelopathy due to the progression of ossification. It was important to establish a sufficiently longitudinal and transverse decompression, taking the risk of the unexpected progression of ossification into consideration.

Outcomes of Posterior Fusion Using Pedicle Screw Fixation in Patients &#8805; 70 Years With Lumbar Spinal Canal Stenosis

Pedicle screw fixation is frequently used for spinal fusion in elderly patients. The application of pedicle screw fixation for elderly patients with degenerative lumbar disease remains controversial due to problems such as surgical invasion, osteoporosis, and cost performance. Outcomes of spinal fusion using pedicle screw fixation were evaluated in patients older than 70 years with lumbar spinal canal stenosis. Eighty-one patients older than 70 years with degenerative disorders of the lumbar spine were treated with pedicle screw fixation before 1997. They were 70 to 85 years at screw fixation (mean, 74.1 years). The postoperative follow-up period was 3 to 18 years (mean, 8.2 years). The number of fused levels by pedicle screw fixation was 1 to 7 (mean, 2.1), and bone grafting was performed in 19 patients who underwent posterolateral lumbar fusion with posterior lumbar interbody fusion and in 62 (76.5%) who underwent posterolateral lumbar fusion alone. Bone union was radiographically observed in 90.1%. The grade of independence (Independence [Bedridden] Criteria of the Daily Life of the Impaired Elderly) had been rank J (life independence) in all patients 1 year preoperatively, but deteriorated to rank A1 (capable of going out with a helper) in 51.8% of patients and rank B1 (using a wheelchair) in 19.8% immediately preoperatively. The grade of independence was rank J in 85.6% of patients 3 years postoperatively and remained rank J in 40 (87.0%) of the 46 who were alive 10 years postoperatively. Few complications associated with surgical invasion were found, and the grade of independence tended to remain at a high level for 10 years postoperatively.

Algorithms and Planning in Metastatic Spine Tumors

Metastatic spine tumors cause the loss of the supporting function of the spine through vertebral destruction or invade and compress the spinal cord or cauda equine. As a result, metastatic spine tumor causes severe pain, paralysis, or impairment of activities of daily living (ADL). Also, because the finding of metastatic foci in the spine suggests a generalized disorder, life expectancy and treatment options have many limitations. For this reason, treatment is primarily symptomatic, and the major goals in selecting therapeutic modalities are to relieve pain, prevent paralysis, and improve ADL. This article discusses the selection of treatment for metastatic spine tumors and, in particular, the indications for surgical treatment.

Risk Factors of Adjacent Segment Disease after Transforaminal Inter-Body Fusion for Degenerative Lumbar Disease.

Study Design. A retrospective study. Objective. The purpose of this study was to determine the incidence and risk factors of adjacent segment disease (ASD) after transforaminal inter-body fusion (TLIF) for degenerative lumbar disease. Summary of Background Data. ASD is a major complication after spinal fusion. Many reports have been published concerning the risk factors for ASD after TLIF. A number of quantitative relationships to spino-pelvic parameters have been established. A retrospective cohort study was carried out to investigate spino-pelvic alignment in patients with ASD after TLIF. Methods. This study evaluated 263 subjects (150 subjects undergoing floating fusion (FF group), and 113 patients undergoing lumbosacral fusion (LF group)) who underwent TLIF from 2009 to 2012. The mean follow-up period was 37.6 months. Several parameters were measured using pre- and postoperative full-length free-standing radiographs, including lumbar lordosis (LL), sacral slope (SS), pelvic incidence (PI), pelvic tilt (PT), and PI-LL. Multivariate logistic regression analysis was performed to evaluate these parameters as potential risk factors of early onset radiographic ASD. Results. Radiographic ASD was found in 65 cases (43.3%) in the FF group, and 49 cases (43.3%) in the LF group. LL improved by 7.5° and 3.9° in each group respectively after TLIF. However, PT worsened by 6.4° in the LF group. When comparing with ASD positive cases and ASD negative cases, a significant difference in preoperative PT was observed in both FF (P = 0.001) and LF groups (P = 0.0001). Logistic regression analysis and receiver operating characteristic analysis revealed that preoperative PT of more than 22.5° was a significant risk factor of the incidence of ASD after TLIF (P = 0.02; odds ratio: 5.1, 95% CI: 1.62–9.03). Conclusion. Patients with preoperative sagittal imbalance have a statistically significant increased risk of ASD. The risk of ASD incidence was 5.1 times greater in subjects with preoperative PT of more than 22.5°.

C1-C2 intra-articular screw fixation for atlantoaxial subluxation due to rheumatoid arthritis.

While various surgical procedures have been developed for the treatment of atlantoaxial subluxation due to rheumatoid arthritis, C1-C2 intra-articular screw fixation was developed to reduce intraoperative injuries to vertebral arteries. The purpose of this study was to report the therapeutic outcome of this procedure, which was followed for >2 years. Preoperative symptoms were alleviated in all patients. Only 1 patient with subaxial canal stenosis underwent additional laminoplasty during follow-up. All patients with class IIIA or milder neural deficit according to Ranawats classification showed improvement to class I or II. There were no surgery-related complications or incidents, including injuries to vertebral arteries. Bone union was observed in all patients. No change was observed in the reduced atlas-dens interval during follow-up. The atlantoaxial angle was -6 degrees to 30 degrees (average, 19.4 degrees) at follow-up, and was >or=30 degrees after surgery (fusion in an overextended position) in only 1 patient. Although postoperative deterioration of cervical alignment was observed in 4 patients (18.2%), there was no additional surgery due to deterioration of cervical alignment. With no surgery-related complications or incidents, this procedure could be a safe and acceptable option for atlantoaxial subluxation due to rheumatoid arthritis.

Follow-up of patients with delayed union after posterior fusion with pedicle screw fixation.

Study Design. A retrospective study. Objective. To investigate the long-term course of patients with delayed union after posterior fusion with pedicle screw fixation (PS) for degenerative lumbar disease. Summary of Background Data. There have been few studies on the long-term course of patients with delayed union after posterior fusion with PS. Methods. The subjects were 48 patients (54 discs) with delayed union 2 years after PS, who showed no or only mild symptoms, and could be observed for 3 years or longer thereafter. All had received an autograft using iliac bones, and the method was posterior lumbar interbody fusion in 12 disc levels and posterolateral lumbar fusion in 42 disc levels. Delayed union occurred in 28 disc levels with neurologically responsible lesions (Group A) and in 26 disc levels at the ends of multilevels fusions (Group B). Serial changes in radiographic and clinical findings were evaluated. Results. In Group A, bone union was observed more than 2 years after surgery in 10 disc levels of 9 patients (34.6%). In Group B, bone union was observed in 4 disc levels of 4 patients (18.2%). In the bone union group of both groups, the mean maximum postoperative intervertebral range of motion was significantly smaller than that in the persistent delayed union group (P < 0.05). The disc height generally decreased with time, but the decrease was significantly larger in the bone union group (P < 0.05). In both groups, clinical results were excellent or good in 100% of patients. No significant difference was noted between the bone union and persistent delayed union groups. Conclusion. Bone union occurred more than 2 years after posterior fusion with PS in about 30% of patients with delayed union. Its occurrence was related to the intervertebral range of motion and disc height. Firm bone union was not necessarily essential for good clinical results.

Conservative follow-up after epidural abscess and diskitis complicating instrumented metal interbody cage.

There have been few reports on the imaging diagnosis and treatment of infection of interbody cages used in posterior lumbar interbody fusion. Even in a patient undergoing posterior lumbar interbody fusion using a metal cage, magnetic resonance imaging (MRI) might be able to diagnose epidural abscesses and diskitis when titanium alloy implants are used. When infection of the instrumented cage is diagnosed, emergency debridement with or without removal of implants, including the cage, appropriate wound closure, and the administration of potent antibiotics is the standard treatment. This article describes the conservative follow-up of a patient with epidural abscess and diskitis following instrumented posterior lumbar interbody fusion using a metal cage without surgical intervention. A 40-year-old man had undergone instrumented posterior lumbar interbody fusion at the L5/S1 level approximately 1 year previously. He suddenly developed a fever (temperature, 38 degrees C) and severe lower back pain without apparent cause. Late infection was suspected from his symptoms and laboratory findings, and a wide spectrum antibiotic was administered. On MRI, the low and high signal areas near the end-plate of L5/S1 were detected by T1- and T2-weighted imaging, respectively, and an abscess was noted around the cage. We recommended debridement as treatment; however, he refused further surgical intervention by reason of symptomatic remission. Therefore, wide spectrum antibiotics were continued. Fortunately, no lower back pain has recurred. Examination by MRI during the clinical course clarified the presence and disappearance of an epidural abscess and diskitis. Although the outcome of this case was fortunate, this conservative treatment is unusual, and is not recommended as standard treatment.

A novel pedicle screw with mobile connection: a pilot study.

To prevent adjacent disc problems after spinal fusion, a pedicle screw with a mobile junction between the head and threaded shaft was newly developed. The threaded shaft of the screw has 10 degrees mobility in all directions, but its structure is to prevent abnormal translation and tilting. This screw was evaluated as follows: (1) endurance test: 106 times rotational stress was applied; (2) biological reactions: novel screws with a mobile head and conventional screws with a fixed head were inserted into the bilateral pedicles of the L3, L4, and L5 in two mini pigs with combination. Eight months after surgery, vertebral units with the screw rod constructs were collected. After CT scan, the soft and bony tissues around the screws were examined grossly and histologically. As a result, none of the screws broke during the endurance test stressing. The mean amount of abrasion wear was 0.0338 g. In the resected mini pig section, though zygapophyseal joints between fixed-head screws showed bony union, the amount of callus in the zygapophyseal joints connected with mobile-head screws was small, and joint space was confirmed by CT. No metalloses were noted around any of the screws. Novel screws were suggested to be highly durable and histologically safe.