Masashi Oshima

A revised scoring system for preoperative evaluation of metastatic spine tumor prognosis.

Study Design. A semi-prospective clinical study was conducted. Objectives. To evaluate the accuracy of a revised scoring system predicting metastatic spinal tumor prognosis and the suitability of the subsequent treatment strategy. Summary of the Background Data. We used a scoring system for the preoperative evaluation of the prognosis of metastatic spinal tumors and selected treatment methods for the predicted prognosis. In the previous version of our scoring system, the reliability of the predicting prognosis was 63.3% in 128 patients with metastatic spinal tumors. Methods. The study participants were 164 patients who died after surgery and 82 who died after conservative treatment. Six parameters were used in the revised scoring system. Each parameter ranged from 0 to 5 points, and the total score was 15 points. In principle, conservative treatment or palliative procedures were indicated in patients with a total score of 8 or less (predicted survival period, less than 6 months) or those with multiple vertebral metastases, while excisional procedures were performed in patients with a total score of 12 or more (predicted survival period, 1 year or more) or those with a total score of 9 to 11 (predicted survival period, 6 months or more) and with metastasis in a single vertebra. The selection of treatment modality was followed faithfully according to the criteria of the revised scoring system after 1998. The prognosis predicted by the revised scoring system and the actual survival period after treatment were compared, and the reliability of the prognostic criteria was analyzed for the group subjected to it prospectively after 1998 (n = 118) and for all 246 patients it was applied to retrospectively. Results. The total score for each patient could be correlated with the survival period. This correlation was also observed in each treatment group. The consistency rate between the predicted prognosis from the criteria of the total scores and the actual survival period was high in patients within each score range (0–8, 9–11, or 12–15), 86.4% in the 118 patients evaluated prospectively after 1998, and 82.5% in the 246 patients evaluated retrospectively. Furthermore, a similar result was also observed in both the surgical procedure group and conservative treatmentgroup. The rate of consistency between the predictedprognosis and the actual survival period in each local extension of the lesion was 75% or more in all types, excluding Type 6 in the surgical classification of Tomita et al. Conclusion. The prognostic criteria using the total scores from our revised scoring system were useful for the pretreatment evaluation of metastatic spinal tumor prognosis irrespective of treatment modality or local extension of the lesion.

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.

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.

Vascular injury following microendoscopic lumbar discectomy treated with stent graft placement

The risk of great vessel injury is low in microendoscopic lumbar discectomy applied in a favorable visual field. However, it is important to be aware of the depth of the pituitary rongeur. In this article, the authors report the case of a 55-year-old woman with lumbar disc herniation who underwent microendoscopic discectomy and subsequently presented with an aneurysm and arteriovenous fistula located at the bifurcation of the right common iliac artery. The patient was treated with endoscopic placement of a stent graft and recovered uneventfully.

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.

Evaluation of biomechanical and histological features of vertebrae following vertebroplasty using hydroxyapatite blocks.

Vertebroplasty was performed using hydroxyapatite blocks to examine the course of compressive strength and histological features in a dog model. The vertebral fracture model was prepared by punching a hole in the center of the vertebra and at 4 sites around the vertebra (5 holes in total) from the front side of the vertebra using an air drill and hollowing the holes. Measurements were made on healthy vertebrae, vertebrae from the vertebral fracture model, vertebrae removed from animals immediately after vertebroplasty, vertebrae collected 1 and 2 months after vertebroplasty, and vertebrae untreated for 1 month after vertebral fracture. Histological examinations were also performed 1 and 2 weeks and 1 and 2 months after vertebroplasty with hydroxyapatite blocks. The strength of vertebrae in the fracture model immediately after vertebroplasty was significantly higher than that in the untreated fracture, and the strength of vertebrae 1 month after the procedure was equivalent to that of healthy vertebrae. Histologically, new bone formation was found around hydroxyapatite blocks 2 weeks after the procedure, and strong crosslinking between neighboring hydroxyapatite blocks was found after 1 month.These results suggest that hydroxyapatite blocks may be effective as filling material for vertebral fracture from both biomechanical and histological perspectives.

Risk Factors for Proximal Junctional Fracture following Fusion Surgery for Osteoporotic Vertebral Collapse with Delayed Neurological Deficits: A Retrospective Cohort Study of 403 Patients

Introduction Approximately 3% of osteoporotic vertebral fractures develop osteoporotic vertebral collapse (OVC) with neurological deficits, and such patients are recommended to be treated surgically. However, a proximal junctional fracture (PJFr) following surgery for OVC can be a serious concern. Therefore, the aim of this study is to identify the incidence and risk factors of PJFr following fusion surgery for OVC. Methods This study retrospectively analyzed registry data collected from facilities belonging to the Japan Association of Spine Surgeons with Ambition (JASA) in 2016. We retrospectively analyzed 403 patients who suffered neurological deficits due to OVC below T10 and underwent corrective surgery; only those followed up for　≥2 years were included. Potential risk factors related to the PJFr and their cut-off values were calculated using multivariate logistic regression analysis and receiver operating characteristic (ROC) analysis. Results Sixty-three patients (15.6%) suffered PJFr during the follow-up (mean 45.7 months). In multivariate analysis, the grade of osteoporosis (grade 2, 3: adjusted odds ratio (aOR) 2.92; p=0.001) and lower instrumented vertebra (LIV) level (sacrum: aOR 6.75; p=0.003) were independent factors. ROC analysis demonstrated that lumbar bone mineral density (BMD) was a predictive factor (area under curve: 0.72, p=0.035) with optimal cut-off value of 0.61 g/cm2 (sensitivity, 76.5%; specificity, 58.3%), but that of the hip was not (p=0.228). Conclusions PJFr was found in 16% cases within 4 years after surgery; independent risk factors were severe osteoporosis and extended fusion to the sacrum. The lumbar BMD with cut-off value 0.61 g/cm2 may potentially predict PJFr. Our findings can help surgeons select perioperative adjuvant therapy, as well as a surgical strategy to prevent PJFr following surgery.

Efficacy of posterior decompression and fixation based on ossification-kyphosis angle criteria for multilevel ossification of the posterior longitudinal ligament in the thoracic spine

OBJECTIVE The range of decompression in posterior decompression and fixation for ossification of the posterior longitudinal ligament in the thoracic spine (T-OPLL) can be established using an index of spinal cord decompression based on the ossification-kyphosis angle (OKA) measured in the sagittal view on MRI. However, an appropriate OKA cannot be achieved in some cases, and posterior fixation is applied in cases with insufficient decompression. Moreover, it is unclear whether spinal cord decompression of the ventral side is essential for the treatment of OPLL. In this retrospective analysis, the efficacy of posterior decompression and fixation performed for T-OPLL was investigated after the range of posterior decompression had been set using the OKA. METHODS The MRI-based OKA is the angle from the superior margin at the cranial vertebral body of the decompression site and from the lower posterior margin at the caudal vertebral body of the decompression site to the prominence of the maximum OPLL. Posterior decompression and fixation were performed in 20 patients. The decompression range was set so that the OKA was ≤ 23° or the minimum if this value could not be achieved. Cases in which an OKA ≤ 23° could and could not be achieved were designated as groups U (13 patients) and O (7 patients), respectively. The mean patient ages were 50.5 and 62.1 years (p = 0.03) and the mean preoperative Japanese Orthopaedic Association (JOA) scores were 5.9 and 6.0 (p = 0.9) in groups U and O, respectively. The postoperative JOA score, rate of improvement of the JOA score, number of levels fused, number of decompression levels, presence of an echo-free space during surgery, operative time, intraoperative blood loss, and perioperative complications were examined. RESULTS In groups U and O, the mean rates of improvement in the JOA score were 50.0% and 45.6% (p = 0.3), the numbers of levels fused were 6.7 and 6.4 (p = 0.8), the numbers of decompression levels were 5.9 and 7.4 (p = 0.3), an echo-free space was noted during surgery in 92.3% and 42.9% of cases (p = 0.03), the operative times were 292 and 238 minutes (p = 0.3), and the intraoperative blood losses were 422 and 649 ml (p = 0.7), and transient aggravation of paralysis occurred as a perioperative complication in 2 and 1 patient, respectively. CONCLUSIONS There was no significant difference with regard to the recovery rate of the JOA score between patients with (group U) and without (group O) sufficient spinal cord decompression. The first-line surgical procedure of posterior decompression and fixation with the range of posterior decompression set as an OKA ≤ 23° before surgery involves less risk of postoperative aggravation of paralysis and may result in a better outcome.

Classification and scoring systems for metastatic spine tumors: a literature review

Introduction Accurate evaluation of metastasis and life prognosis is essential for selecting a suitable therapeutic strategy for metastatic spine tumors owing to limitations in treatment options. For this purpose, various classification, evaluation, and scoring systems have been developed. Methods Classification, evaluation, and scoring systems for metastatic spine tumors reported to date were identified by performing a literature search on PubMed. We reviewed the most cited classifications and scorings before 2009, and all classifications and scorings reported after 2010 from the search results. Results Six classifications and 23 scorings were reviewed. The classification/evaluation methods are divided into 1) anatomical classification/evaluation methods, 2) evaluation methods for neurological symptoms/instability, and 3) scoring systems for predicting life expectancy. The first 2 were useful for the planning and evaluation of surgical indications. Scoring systems for life prognosis also permitted rough prediction of the outcomes and were useful for the selection of a suitable treatment. However, variation of the patient background, diversity of adopted prognostic factors, and the absence of scoring systems that could predict the outcome with an accuracy of 90% or higher introduced some limitations. Conclusion The identified classification, evaluation, and scoring systems have been generally useful for treatment strategies. However, we emphasize the necessity of multidisciplinary development and revision of classification and evaluation methods to adapt to the prolongation of survival associated with increased diversity and improvement of treatment options.

Efficacy of HA Block Kyphoplasty for Old Osteoporotic Spine Fractures

We have successfully treated osteoporotic spine fractures for about three years, by using transpedicular kyphoplasty with hydroxyapatite blocks (HA Block: PENTAX) (refer with: Fig. 1), The 13 patients, four men and nine women, ranged from 61 to 86 years in age (mean, 73 years). The mean Visual Analogue Scale (VAS) was 8.5 points before operation, improved to 2.7 points on the next day of operation, and improved significantly to 1.8 points at the final evaluation. The mean deformity rate (Anterior height / Posterior height x 100) was 66.3% before operation, but improved to 91.7% immediately after operation. At the time of follow-up, this rate was 78.6%, indicating that the correction loss was 13.1%. This procedure caused none of serious complications such as neurological disorder and pulmonary infarction. Kyphoplasty with HA blocks may be safe and effective in the treatment of chronic vertebral fractures.