Vacuum phenomenon as a predictor of kyphosis after implant removal following posterior pedicle screw fixation without fusion for thoracolumbar burst fracture: a single-center retrospective study.

BACKGROUND: Posterior pedicle screw fixation without fusion has been commonly applied for thoracolumbar burst fracture. Implant removal is performed secondarily after bone union. However, the occurrence of secondary kyphosis has recently attracted attention. Secondary kyphosis results in poor clinical outcomes. The purpose of this was to determine predictors of kyphosis after implant removal following posterior pedicle screw fixation without fusion for thoracolumbar burst fracture. METHODS: This retrospective study reviewed 59 consecutive patients with thoracolumbar burst fracture who underwent implant removal following posterior pedicle screw fixation without fusion. Inclusion criteria were non-osteoporotic fracture and T11-L3 burst fracture. Old age, sex, initial severe wedge deformity, initial severe kyphosis, and vacuum phenomenon were examined as factors potentially associated with final kyphotic deformity (defined as kyphotic angle greater than 25°) or loss of correction. Logistic regression analysis was performed using propensity score matching. RESULTS: Among the 31 female and 28 male patients (mean age 38 years), final kyphotic deformity was found in 17 cases (29%). Multivariate analysis showed a significant association with the vacuum phenomenon. Loss of correction was found in 35 cases (59%) and showed a significant association with the vacuum phenomenon. There were no significant associations with other factors. CONCLUSIONS: The findings of this study suggest that the vacuum phenomenon before implant removal may be a predictor of secondary kyphosis of greater than 25° after implant removal following posterior pedicle screw fixation without fusion for thoracolumbar burst fracture, but that old age, sex, initial severe kyphosis, and initial severe wedge deformity may not be predictors.

Development and Achievement of Cervical Laminoplasty and Related Studies on Cervical Myelopathy.

Cervical laminoplasty (CL) is one of the surgical methods via the posterior approach for treating patients with multilevel affected cervical myelopathy (CM). The main purpose of CL is to decompress the cervical spinal cord by widening the narrowed spinal canal, combined with preserving the posterior anatomical structures to the degree possible and preserving the widened space stably. During the development and improvement of spine surgeries including CL, various studies on CM have progressed and useful achievements have been obtained: (1) posterior cervical spine fixation systems that can be used in combination with CL simultaneously have been developed; (2) various materials to stably maintain the enlarged spinal canal have been developed; (3) the main influential factors on the surgical results are the inner factors of the patients, such as the patient's age and the disease duration; (4) various surgical methods to preserve the function of the posterior cervical muscles have been tried to avoid postoperative kyphotic changes of the cervical spine; (5) postoperative complications, such as C5 palsy and axial pain, have been examined, and the countermeasures have been tried; (6) K-line on lateral X-ray films has been applied to evaluate the indication of CL in patients with CM due to ossification of the posterior longitudinal ligament (OPLL) preoperatively; and (7) the method and idea of CL have been adapted to surgeries at the thoracic and lumbar spine. However, some issues remain to be resolved, such as the deterioration of neurological findings, especially in patients with continuous or mixed-type OPLL, the postoperative kyphotic-directional alignment change of the cervical spine, C5 palsy, and axial pain.

Postoperative C5 Palsy: Conjectured Causes and Effective Countermeasures.

Postoperative C5 palsy (C5 palsy) is defined as de novo or aggravating muscle weakness mainly at the C5 region with slight or no sensory disturbance after cervical spine surgery. The features of C5 palsy are as follows: 1) one-half of patients are accompanied by sensory disturbance or intolerable pain at the C5 region; 2) 92% of patients have hemilateral palsy; 3) almost all palsy occurs within a week after surgery; 4) the incidence is almost the same between the anterior and posterior approaches to the cervical spine; 5) the prognosis is relatively good even in patients with severe muscle weakness. Even now, the precise causes of C5 palsy have not yet been revealed. From the viewpoint of the kinds of nerve tissue involved, the uncertain causes of C5 palsy are divided into two theories: 1) the segmental spinal cord disorder theory and 2) the nerve root injury theory. In the former, the segmental spinal cord, particularly the anterior horn cells, is thought to be chemically damaged because of preoperative ischemia and/or the aggression of reactive oxygen during postoperative reperfusion. By contrast, in the latter, the anterior rootlet and/or nerve root are believed to be mechanically damaged because of compression force and/or distraction force. In this theory, the features of C5 palsy can be well explained from anatomical viewpoints. Additionally, various countermeasures have been proposed, such as the intermittent relaxation of the tension of the hooks to the multifidus muscles during surgery; prophylactic foraminotomy to decompress C5 nerve root; prevention of excessive posterior shift of the spinal cord, which may cause the tethering effect of the nerve root; and prevention of excessive postoperative lordotic alignment of the cervical spine. These countermeasures have been proved effective, and may support the nerve root injury theory as the main conjectured theory on the causes of C5 palsy.

Surgical Treatment for Ossification of the Posterior Longitudinal Ligament (OPLL) at the Thoracic Spine: Usefulness of the Posterior Approach.

Various methods via anterior or posterior approach with or without spinal stabilization have been performed in accordance with the level and configuration of ossification of the posterior longitudinal ligament (OPLL) as the decompression surgery for thoracic myelopathy due to OPLL. Among them, anterior decompression at the middle thoracic level (T4/T5-T7/T8) is especially difficult to perform because of the special anatomical structures, where the spinal alignment is kyphotic and the thoracic cage containing circulatory-respiratory organs exist nearby. Of the anterior decompression procedures at this level, the posterior approach has various advantages compared to the anterior one. In the anterior approach, the procedure is complicated and the effect of decompression of the spinal cord can be obtained only by direct resection or anterior floating of the OPLL. However, complications such as spinal cord injury and dural tear are most likely to occur at that time. On the contrary, in the posterior approach, the procedure is simple, and various options to obtain decompression can be selected from, these are, laminectomy, laminoplasty, dekyphosis surgery, staged decompression surgery (Tsuzuki's method), circumferential decompression via posterior approach alone (Ohtsuka's method), and circumferential decompression via combined posterior and anterior approaches (Tomita's method). Among them, in laminectomy, laminoplasty, and dekyphosis surgery, anterior decompression can be obtained to some extent without performing direct procedure on the OPLL. In Ohtsuka's method, complete decompression can be obtained via posterior approach alone, although it is somewhat technically demanding. It is preferable to drop the shaved down and separated OPLL anteriorly instead of trying to remove it completely to avoid complications, especially in patients with severe adhesion between the dura mater and OPLL.

Enantioselective acylation of 1,2- and 1,3-diols catalyzed by aminophosphinite derivatives of (1S,2R)-1-amino-2-indanol.

A phosphinite derivative that can be easily prepared in two steps from commercially available aminoindanol was found to be an effective catalyst for enantioselective acylation of diols. For the asymmetric desymmetrization of meso-1,2-diols, the corresponding monoester was obtained in up to 95% ee from the reaction in the presence of 5 mol % catalyst.

Clinical factors as predictors of the risk of falls and subsequent bone fractures due to osteoporosis in postmenopausal women.

In Japan, the "bedridden state" is one of the most serious problems the aged face, and it is becoming a social problem. The main causes of the bedridden state are cerebrovascular disorders and bone fractures following falls. The purpose of this study was to predict risk factors for falls and resultant bone fracture due to osteoporosis. We explored mobility parameters for possible fall prevention. In order to examine the correlation between the risk of falling and resultant bone fracture due to osteoporosis, logistic regression analysis was performed between bone mass (independent variable) and various factors dependent variables: body mass index [BMI], body fat percentage, atherogenic index, presence of transformation-related osteoarthritis of knee, presence of transformation-related osteoarthritis of spine, maximum step length, single-leg stance with open eyes, and hip-joint flexion motion angle); predictive factors were then examined. Predictive factors were determined by the stepwise method. Subjects who could not perform the "single-leg stance with open eyes" test had a risk of falling and bone fracture 2.49 times as large as that of subjects who could. The "single-leg stance with open eyes" test may be considered a useful method for the early detection of the risk of falling and bone fracture associated with osteoporosis. As a first step to identify factors predicting the occurrence of falls and bone fractures due to osteoporosis, we intended to discover an indicator that would help to detect incipient osteoporosis.

Catalytic asymmetric desymmetrization of cyclic meso-1,3- and 1,4-diols by a phosphinite derivative of quinidine.

Asymmetric monobenzoylation reactions of cyclic meso-1,3- and 1,4-diols were catalyzed by a phosphinite derivative of quinidine to afford the corresponding monobenzoylated diol with good yield and enantioselectivity. [reaction: see text]

Effect of dentures wearing on motor reaction time and balance function in elderly people.

OBJECTIVE: To investigate the influence of dentures wearing on the parameters of physical fitness, particularly on agility and balance function in elderly people. DESIGN: A case control study. SETTING: Motohachiohjimachi, Hachiohji, Tokyo, Japan. METHODS: Motor reaction time was measured in the presence and absence of dentures in the subjects who were 1) in a sitting position and lifted the lower limbs as fast as possible in response to a stimulus (Sitting Group) and those who were 2) in a standing position and jumped upright as fast as possible in response to a light stimulus (Jumping Group). The effects of dentures wearing on balance function were investigated by comparing the measured values of static and dynamic body sway. RESULTS AND CONCLUSIONS: Light-reaction time was not significantly influenced by dentures wearing in Sitting Group performing a light body movement that required little muscular force. In a relatively heavy body movement that required agility (i.e., jumping from the standing position), the reactivity changed depending on the muscular force; which might result in the difference of the reactivity due to dentures wearing (i.e., t-test showed a significant difference in the light-reaction time under clenching posture between with and without wearing dentures (p < 0.01)). No significant difference was observed in body sway under clenching posture between with and without wearing dentures.Therefore, we assumed that reaction speed varied depending upon dentures wearing.

Asymmetric borane reduction of prochiral ketone using chiral bis(alpha, alpha-diphenyl-2-pyrrolidinemethanol) carbonate.

Chiral bis(alpha, alpha-diphenyl-2-pyrrolidinemethanol) carbonate (DPP(2).H(2)CO(3)) is a useful asymmetric auxiliary for the asymmetric borane reduction of prochiral ketones. Chiral DPP(2).H(2)CO(3) is recoverable from the reaction and directly reusable for the reaction. The intermediate of KUR-1246, which we are developing as a new uterine relaxant, was synthesized using the methodology.

Y-931, a novel atypical antipsychotic drug, is less sensitive to oxidative phenomena.

The oxidation behavior of Y-931, a potent atypical antipsychotic drug, was compared with that of clozapine and olanzapine. In two enzymatic systems (horseradish peroxidase (HRP)/glutathione (GSH) and HRP/H(2)O(2)/GSH) which generate thiyl radicals, clozapine markedly strengthened the electron paramagnetic resonance (EPR) signal for the radical. Olanzapine, Y-931 and the major metabolites (compounds 1-3) had no or minimal effect on the intensity of this signal. In addition, the redox potential values for the three derivatives were in accord with the EPR spin trapping results. In toxicological experiments in human leukocytes, a concentration-dependent toxicity was observed when neutrophils were incubated with clozapine (1-10 micromol/l) and H(2)O(2) (1 mmol/l). However, Y-931 and olanzapine did not show remarkable toxicity under the conditions.

Halogenovinyl Sulfones. 6.(1) Synthesis of Condensed Heterocycles by Diastereoselective Intramolecular Diels-Alder Reactions of Sulfonyl-Substituted Trienes.

Sulfonyl trienes having a chiral center on the allyl carbon of the diene moiety were prepared from L-amino acid as chiral building blocks. Intramolecular Diels-Alder reaction of the sulfonyl trienes having E-geometry on the diene moiety proceeded on the si-face and exo-selectively to give cis-isoindoles as a sole product in good yields. But using the sulfonyl trienes having Z-geometry on the diene part, the ratio of the diastereomers of the products decreased to about 80:20. The observed stereoselectivity can be explained by calculations with semiempirical and ab initio methods.