Ground state of the spin-1/2 chain of green dioptase at high fields

The gem-stone dioptase Cu6Si6O18.6H2O has a chiral crystal structure of equilateral triangular helices consisting of Cu-3d spins. It shows an antiferromagnetic order with an easy axis along c at TN = 15.5 K under zero field, and a magnetization jump at HC = 13.5 T when the field is applied along c-axis. By 29Si-NMR measurements, we have revealed that the high-field state is essentially the two sub-lattice structure, and that the component within ab-plane is collinear. The result indicates no apparent match with the geometrical pattern of helical spin chain.Comment: SCES2013, Hongo, Toky

Electron transfer channel in the sugar recognition system assembled on nano gold particle

Existence of 1D spin diffusion in the electrochemical sugar recognition system consisting of a nano-sized gold particle (GNP), a ruthenium complex and a phenylboronic acid was investigated by NMR and muSR. When sugar molecules are recognized by the phenylboronic site, the response of electrochemical voltammetry of the Ru site changes, enabling the system to work as a sensitive sugar-sensor. In this recognition process, the change in the electronic state at the boron site caused by sugar must be transferred to the Ru site via alkyl chains. We have utilized the muon-labelled electrons method and the proton NMR to find out a channel of the electron transfer from the phenylboronic acid site to the gold nano particle via the one dimensional alkyl chain. If this transfer is driven by diffusive spin channel, characteristic field dependence is expected in the longitudinal spin relaxation rate of muSR and 1H-NMR. We have observed significant decrease in the spin relaxation rates with increasing applied field. The result is discussed in terms of low dimensional spin diffusion

発育性股関節形成不全への人工股関節置換術における寛骨臼コンポーネント設置に対するCT-basedナビゲーションシステムの有効性

Purpose: Developmental dysplasia of the hip (DDH) presents a considerable surgical challenge in total hip arthroplasty (THA). Although the usefulness of computed tomography (CT)-based navigation in cup alignment has been reported, few reports have evaluated three-dimensional (3-D) cup positioning against the acetabulum specifically in patients with DDH. The purpose of this study was to evaluate the efficacy of a CT-based navigation system for alignment and spatial positioning of the cup in THA for patients with DDH. Methods: We reviewed 174 DDH THA cases in which CT-based navigation was used, and 75 cases in which a mechanical guide was used as a control group. Postoperative cup alignment and spatial positioning were evaluated by superimposition of a 3-D cup template onto the actual implanted cup using postoperative CT images, with pelvic coordinates matching the preoperative planning. Results: The proportion within the combined target zone (inclination and anteversion) was 97.7% in the navigation group and 61.3% in the non-navigation group. The mean absolute error between the intraoperative record and the postoperative measurement was 1.5° ± 1.3° for inclination and 2.1° ± 1.8° for anteversion in the navigation group. For acetabular cup positioning, the mean discrepancy between the preoperative planning and the postoperative measurements was 1.9+1.6 mm on the transverse axis, 2.8 ± 2.3 mm on the longitudinal axis, and 1.7 ± 1.3 mm on the sagittal axis. Conclusion: THA using a CT-based navigation system achieved quite high accuracy of cup alignment angles and spatial cup positioning in primary THA for patients with DDH

Revision total knee arthroplasty for unexplained pain after unicompartmental knee arthroplasty : a case report

In this report, we present a case of a 64-year-old woman who underwent revision of knee arthroplasty after failed unicompartmental knee arthroplasty (UKA). She underwent UKA (Biomet Oxford Phase 3) for right localized medial knee pain at the age of 53 and the postoperative course had been uneventful. Eight years after UKA, she had right knee pain that gradually worsened. Tenderness was present over the medial femorotibial and patellofemoral (PF) joints. Plain radiograph showed small osteophytes on the intercondylar eminence and in the lateral compartment. However, these findings were not severe. Although several causes of knee pain after UKA have been reported, none of those causes were found in this case, so the diagnosis of unexplained pain was made. We performed knee arthroscopy and it revealed severe osteoarthritis of the PF joint, bone attrition and exposure of subchondral bone of the medial part of the lateral condyle together with severe synovitis. Revision surgery was performed in the same operation. The postoperative course was excellent and the severe knee pain resolved after surgery. Several registries revealed that revision for unexplained pain was more common after UKA than after total knee arthroplasty. We pointed out the possible causes of unexplained pain including pathological conditions, which were present in our case. Revision surgery may be unsuccessful if the cause of failure is not adequately considered

Forearm lengthening by distraction osteogenesis : A report on 5 limbs in 3 cases

Radioulnar length discrepancy causes pain and decreases function of the wrist, forearm, and elbow. Limb lengthening, which has been used in the treatment of various deformities of the forearm, is necessary to restore balance between the ulna and radius. We treated 5 limbs in 3 patients (2 boys, 1 girl ; mean age 9.3 years old) with radioulnar length discrepancy by distraction osteogenesis of either the ulna or radius using external fixators. We dissected the interosseous membrane between the ulna and radius in 3 limbs in 2 cases and did not do so in 2 limbs of 1 case. These cases include 2 cases with hereditary multiple exostoses, and 1 case with multiple epiphyseal dysplasia. The results were investigated and evaluated in this study, using appropriate clinical and radiographic parameters, noting the state of the interosseous membrane, which has an important role in forearm stability. The mean fixation period was 113 days. The mean distraction distance was 22.8 mm. The mean follow-up period was 637.7 days. The mean ulnar shortening and radial articular angle respectively improved from 7.4 mm and 30.2° preoperatively to -0.1 mm and 34.8° postoperatively. Balance between the ulna and radius was restored, and the results showed significant improvements in range of motion of the joints. However, 2 unintended radial head subluxations occurred in 2 limbs without dissection of the interosseous membrane. In addition, a keloid remained in 1 limb due to pin site infection. Forearm lengthening by distraction osteogenesis was useful in our cases. It is important to recognize the function of the interosseous membrane when lengthening is performed by osteotomy of the proximal ulna by gradual distraction with an external fixator

The Posterior Condylar Cartilage Affects Rotational Alignment of the Femoral Component in Varus Knee Osteoarthritis

Rotational alignment of the femoral component in total knee arthroplasty (TKA) is important for patellar tracking and ligament balance. Preoperative planning based on radiography might have a potential risk for over-rotation because these X-ray based measurements can not detect asymmetric cartilage wear on posterior condyle. The purpose of this study is to evaluate the effect of the posterior condylar cartilage of varus osteoarthritic knee on rotational alignment of the femoral component in TKA. We established two different condylar twist angles (CTA) from intraoperative multiplanar reconstruction (MPR) images and intraoperative information of navigation system. The CTA measured by a navigation system that includes the cartilage (4.8±2.0°) was smaller than those measured by MPR images, which does not include the cartilage (6.6±2.1°) (p<0.05). The difference between these two angles that corresponds to the remaining posterior condylar cartilage was 1.7±1.2°. This result demonstrated that the posterior condylar cartilage might lead to over-rotational of the femoral component in varus osteoarthritic knee. Therefore, when determining rotational alignment of the femoral component, surgeons should consider the effect of the remaining posterior condylar cartilage to avoid the over-rotation of the femoral component, especially in severe varus knees