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Aims To develop and internally validate a preoperative clinical prediction model for acute adjacent vertebral fracture (AVF) after vertebral augmentation to support preoperative decision-making, named the after vertebral augmentation (AVA) score. Methods In this prognostic study, a multicentre, retrospective single-level vertebral augmentation cohort of 377 patients from six Japanese hospitals was used to derive an AVF prediction model. Backward stepwise selection (p < 0.05) was used to select preoperative clinical and imaging predictors for acute AVF after vertebral augmentation for up to one month, from 14 predictors. We assigned a score to each selected variable based on the regression coefficient and developed the AVA scoring system. We evaluated sensitivity and specificity for each cut-off, area under the curve (AUC), and calibration as diagnostic performance. Internal validation was conducted using bootstrapping to correct the optimism. Results Of the 377 patients used for model derivation, 58 (15%) had an acute AVF postoperatively. The following preoperative measures on multivariable analysis were summarized in the five-point AVA score: intravertebral instability (≥ 5 mm), focal kyphosis (≥ 10°), duration of symptoms (≥ 30 days), intravertebral cleft, and previous history of vertebral fracture. Internal validation showed a mean optimism of 0.019 with a corrected AUC of 0.77. A cut-off of ≤ one point was chosen to classify a low risk of AVF, for which only four of 137 patients (3%) had AVF with 92.5% sensitivity and 45.6% specificity. A cut-off of ≥ four points was chosen to classify a high risk of AVF, for which 22 of 38 (58%) had AVF with 41.5% sensitivity and 94.5% specificity. Conclusion In this study, the AVA score was found to be a simple preoperative method for the identification of patients at low and high risk of postoperative acute AVF. This model could be applied to individual patients and could aid in the decision-making before vertebral augmentation. Cite this article: Bone Joint J 2022;104-B(1):97–102.

Study Design Retrospective comparative study. Objective To evaluate the accuracy of percutaneous pedicle screw (PPS) placement and intraoperative imaging time using dual fluoroscopy units and their differences between surgeons with more versus less experience. Methods One hundred sixty-one patients who underwent lumbar fusion surgery were divided into two groups, A ( n = 74) and B ( n = 87), based on the performing surgeon's experience. The accuracy of PPS placement and radiation time for PPS insertion were compared. PPSs were inserted with classic technique under the assistance of dual fluoroscopy units placed in two planes. The breach definition of PPS misplacement was based on postoperative computed tomography (grade I: no breach; grade II: Results Of 658 PPSs, only 21 screws were misplaced. The breach rates of groups A and B were 3.3% (grade II: 3.4%, grade III: 0%) and 3.1% (grade II: 2.6%, grade III: 0.6%; p = 0.91). One patient in grade III misplacement had a transient symptom of leg numbness. Median radiation exposure time during PPS insertion was 25 seconds and 51 seconds, respectively ( p < 0.01). Conclusions Without using an expensive imaging support system, the classic technique of PPS insertion using dual fluoroscopy units in the lumbar and sacral spine is fairly accurate and provides good clinical outcomes, even among surgeons lacking experience.

Some cases with lumbar degenerative diseases require multi-level fusion surgeries. At our institute, 27 and 4 procedures of 3- and 4-level fusion were performed out of a total 672 posterior lumbar interfusions (PLIFs) on patients with lumbar degenerative disease from 2005 to 2010. We present 2 osteoporotic patients who developed proximal vertebral body fracture after 4-level fusion. Both cases presented with gait disability for leg pain by degenerative lumbar scoliosis and canal stenosis at the levels of L1/2-4/5. After 4-level fusion using L1 as the upper instrumented vertebra, proximal vertebral body fractures were found along with the right pedicle fractures of L1 in both cases. One of these patients, aged 82 years, was treated as an outpatient using a hard corset for 24 months, but the fractures were exacerbated over time. In the other patient, posterolateral fusion was extended from Th10 to L5. Both patients can walk alone and have been thoroughly followed up. In both cases, the fracture of the right L1 pedicle might be related to the subsequent fractures and fusion failure. In consideration of multi-level fusion, L1 should be avoided as an upper instrumented vertebra to prevent junctional kyphosis, especially in cases with osteoporosis and flat back posture.

To describe the surgical experience of spondylectomy and spinal reconstruction for aggressive vertebral hemangioma (VH) induced at the C4 vertebra. No reports have described surgical strategy in cases covering an entire cervical vertebra presenting with progressive myelopathy.A 28-year-old man presented with rapidly progressing skilled motor dysfunction and gait disorder. The Japanese Orthopedic Association (JOA) score was 6. Radiography showed a honeycomb appearance for the entire circumference of the C4 vertebra. Spinal computed tomography and magnetic resonance imaging showed vertebral tumor with extraosseous extension causing spinal cord compression. Results of diagnostic imaging were strongly suggestive of VH. Transarterial embolization of the spinal body branch was performed first to decrease intraoperative bleeding, followed by cervical posterior fixation to stabilize the unstable segment and excision biopsy to obtain a definitive diagnosis. After definitive diagnosis of cavernous hemangioma, two-stage surgery (anterior and posterior) was performed to complete total spondylectomy and 360° spinal reconstruction.Despite multiple operations, JOA scores were 8.5 after posterior fixation, 10.5 after anterior surgery, 11 after final surgery and 16 on postoperative day 90. The patient acquired excellent clinical results without complications and returned to society.The present three-stage surgery comprising fixation, biopsy, and final spondylectomy with circumferential fusion from anterior and posterior approaches may offer a useful choice for aggressive VH covering the entire cervical spine with rapidly progressive myelopathy.

わが国の農業用地下水使用量は年間約33億m3と地下水全使用量の約3分の1を占めており、干ばつ時など非常用としても、重要な水源である。農林水産省では、灌漑用水など農業用水源を確保するため、地表水の導水が困難な地域や地下水利用障害が発生している地域において、地下水開発や保全の調査を進めてきた。その過程で、地下水探査技術の開発研究も併せ行ってきた。安定した量・質等の特性をもつ地下水には、今後もその賦存状況に応じた活用が期待されるため、適正な開発や保全、あるいは管理が求められる。その実現のためには、地下水盆毎の、よりいっそう正確な地下水流動の把握や変動予測、資源評価など、客観的な分析が必要となろう。

2000年から2006年の間に当院で摘出術が必要であった腰椎椎間板ヘルニアは335例あり，そのうち経硬膜的摘出術が必要であった症例は3例であった．これらの3例は正中に大きく突出したもの（1例は硬膜管内へ突出）であり，通常のLove法によるヘルニア摘出は困難であり，経硬膜的ヘルニア摘出を行った．我々は経硬膜的ヘルニア摘出の際，椎弓切除術により棘上靭帯・棘間靭帯を除去した場合，後方支持組織の破綻から生じる術後腰椎不安定性による再発が起こりやすいと判断し，脊椎固定術（PLIFもしくはPLF）の追加が必要と考えている．

脊椎圧迫骨折患者の中には，椎体圧潰による遅発性神経麻痺を来す例や，偽関節となり背部痛が持続する例が存在する．2006年4月から12月までに当科にて治療を行った圧迫骨折症例のうち，不安定性を呈した陳旧性圧迫骨折15例を対象とし，64列マルチスライスCTを用い検討した．男性5例，女性10例，45～83歳（平均72.6歳），受診までの期間1ヶ月～2年（平均約205日），BMD 0.577～1.525g/cm2（平均0.804g/cm2），受傷機転は不明10例，転倒4例，転落1例，罹患部位はTh12 7例，L1 5例であった．椎体内ガス像12例，水分貯留3例，脊柱管内への椎体突出が5例にみられた．マルチスライスCTにて詳細に検討すると，前方要素と後方要素をつなぐ椎弓根基部骨折を12例73％に認めた．持続する腰痛の原因は前方要素の不安定性のみではなく前方と後方要素をつなぐ椎弓根部での不安定性も関与していると考えられた．

Background Surgical debridement is often required to treat spinal infections. Successful surgery requires accurate localization of the active infections, however, current imaging technique still requires surgeons’ experience to narrow the surgical fields to achieve less invasive procedures. Purpose To investigate the use of F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for successful surgical planning. Material and Methods Nine patients with suspected spinal infection underwent magnetic resonance imaging (MRI) and FDG-PET/CT before surgery to locate active foci of infections. The spinal structures were divided into seven compartments at each intervertebral disc level for a total of 315 compartments investigated. The same classification system was used to design operating fields for histological correlation. Results FDG-PET/CT diagnosed fewer compartments as active infection (34 compartments, 10.8%) than MRI (62 compartments, 19.7%, P = 0.002). Surgical exploration was performed in 49 compartments, and demonstrated active infection in 25 compartments. The sensitivity / specificity of FDG-PET/CT was 100% / 79%, respectively, which was superior to those of MRI, 76% / 42%. Foci of active infection showed hypermetabolic activity with a SUVmax of 7.1 ± 2.6 (range, 3.0–12.7). Receiver operating characteristic (ROC) analysis indicated an optimal threshold for active spinal infection at a SUVmax of 4.2, corresponding to a sensitivity of 90.3% and specificity of 91.2%. Conclusion FDG-PET/CT demonstrated limited areas of abnormality allowing accurate delineation, and is thus useful to narrow the surgical fields. Since overall diagnostic accuracy of FDG-PET/CT was superior to that of MRI, FDG-PET/CT is a useful technique to narrow the surgical field for successful less invasive surgery.

サヘル地帯では, 気候変動や人間活動の影響によって砂漠化が進行している. 本調査は砂漠化防止対策の一環として, 水資源の賦存形態を把握し, その開発について検討したものである.調査地域は, ニジェール, ブルキナファソ両国にまたがるゴルビ川流域である. 流域の降雨は5～9月の雨季にのみ認められ, 年間降雨量は200～1,200mmである. 河川は季節河川であり, 流出は6月に始まり10月上旬に終わる. 年間流量は平均2.6億m3である. 流域の河川は流域面積によって流出状況の区分ができる. 帯水層は大きく三つに区分でき, 先カンブリア時代の花崗岩・変成岩中の基盤岩帯水層, 第三紀のコンチネンタルターミナル層中の第三紀帯水層, および第四紀河床堆積物中の沖積帯水層である. この地下水は年間を通して利用できる. 流域の水循環をタンクモデルによって推定すると, 蒸発散が66%, 河川流出が5%, 地下浸透が29%である.このような水資源の特性を考慮すると, 乾季では地下水やダム貯留水の利用, 雨季には地表水や地下水を利用するのが有効である. 具体的には堰や地下水の涵養をかねた低ダムの築造や, 各帯水層を対象とした井戸開発である.

Infectious Spondylitis: Characteristics of Geriatric Patients and Significance of Surgery The goal of this study is to identify the characteristics and common problems of geriatric patients with infectious spondylitis and to explore possible solutions for them.

In this paper, we propose a method for generating roles by redistribution of reward between agents in reinforcement learning of multiagent system. In the proposed method, there are two kinds of reward; (1) reward obtained from environment when agents reach the goal and (2) reward received from other agents. Agents can learn actions to work cooperatively with other agents by the reward received from other agents, and the roles of agents are generated. In the proposed method, agents can decide how much reward to which agent to give from the obtained reward by using the history that records actions at the time when the change of environment are recognized. We carried out computer experiments for two tasks; (1) path finding problem and (2) transportation problem, and confirmed that roles of agents are generated by redistribution of reward between agents in the proposed method. Moreover, we confirmed that the proposed method can learn as similar as when the designer decides conditions for redistribution of reward.