Hiroshi Tamai

High-pressure and high-temperature phase relations in CaSiO3 and CaMgSi2O6 and elasticity of perovskite-type CaSiO3

Abstract Phase transformations in CaSiO 3 and CaMgSi 2 O 6 were studied up to ∼ 50 GPa using both high-pressure in situ X-ray diffraction study and quench experiments. A new intermediate high-pressure and high-temperature phase named CaSiO 3 -III was found in the pressure range from 10 to 13.8 GPa, above which a perovskite-type CaSiO 3 was stable. Both CaSiO 3 -III and perovskite-type CaSiO 3 are unquenchable. The compression curve of perovskite-type CaSiO 3 was determined up to 31.5 GPa at room temperature. Least-squares fitting of the Birch-Murnaghan equation of state gave the following values for the bulk modulations and a zero-pressure volume: K 0 = 325 ± 10 GPa and V 0 = 45.58 ± 0.07 A 3 where d K 0 d P was assumed to be 4. This bulk modulus, however, is very sensitive to the choice of the zero-pressure volume and has large uncertainty. CaMgSi 2 O 6 was found to break down into CaSiO 3 and MgSiO 3 at 17 GPa. CaSiO 3 crystallizes into cubic perovskite-type structure while MgSiO 3 breaks down further into Mg 2 SiO 4 plus SiO 2 . With increasing pressure, the last transforms into ilmenite, and then into perovskite structure, while the coexisting perovskite-type CaSiO 3 remains unchanged. Solubilities of both Ca and Mg in MgSiO 3 and CaSiO 3 perovskites are found to be very low.

The diagnosis of double-crush lesion in the L5 lumbar nerve using diffusion tensor imaging

BACKGROUND CONTEXT A double-crush lesion is a condition in which the lumbar nerve is compressed both medially and laterally in the spinal canal, where diagnosis can be very difficult, and is a factor leading to poor surgical success rates. PURPOSE Diffusion tensor imaging (DTI) was used to determine DTI parameter fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) in both intraspinal column lesions alone and in double-crush lesions. STUDY DESIGN This study used a prospective study. PATIENT SAMPLE Of the 56 cases (mean age: 72.2 years) that underwent laminectomy for lumbar spinal stenosis at our clinic between April 2013 to March, 2015, 10 cases with L5 radiculopathy caused by L4-L5 stenosis (Intraspinal stenosis group (Group I); mean age: 74.7 years), and 5 cases with persistent symptoms caused by L5 foraminal stenosis despite L4-L5 decompression surgery (Double-crush group (Group D); mean age: 77.6 years) were targeted. One patient in Group D was diagnosed through microendoscopic intrapedicular partial pediculotomy and the remaining four cases by nerve root infiltration. Five healthy cases (mean age: 54 years) were studied as controls. OUTCOME MEASURES Intraspinal zone (Iz), nerve root (N), and extraforaminal zone (Ez) were established as the regions of interest, and the L5 nerve FA and ADC values were determined on the affected side. METHODS Diffusion tensor imaging was performed prospectively by 1.5T magnetic resonance imaging before surgery, and DTI parameters of L5 nerve were evaluated in all patients and healthy volunteers. Student t test was used for group comparisons, and a p<.05 was considered statistically significant. RESULTS Fractional anisotropy values (Iz, N, Ez) were 0.415, 0.448, and 0.517, respectively, increasing as sites became more distal. Group I values were 0.335, 0.393, and 0.484, and Group D values were 0.296, 0.367, and 0.360. Compared with the healthy volunteers, Group D had significantly lower Iz (p<.05) and Ez (p<.001) values, while Group I had significantly lower Iz (p<.05) values. In Group D, Ez FA values were significantly lower (p<.001) than in Group I. Apparent diffusion coefficient values (Iz, N, Ez) in the healthy control group were 1.270 mm2/s, 1.151 mm2/s, and 0.937 mm2/s with values decreasing as sites grew distal. In Group I, the ADC values were 1.406 mm2/s, 1.184 mm2/s, and 1.001 mm2/s, while in Group D they were 1.551 mm2/s, 1.412 mm2/s, and 1.329 mm2/s. Compared with the healthy volunteers, Iz (p<.05) and Ez (p<.05) values were significantly higher in Group D. The N (p<.01) and Ez (p<.001) ADC values were significantly higher in Group D than in Group I. CONCLUSIONS Depending on where the nerve was compressed, changes in DTI parameters revealed nerve damage (low FA values and increased ADC) in the intraspinal canal in the Intraspinal Group, and over a widespread area in the Double-crush Group spanning the medial to lateral spinal canal. Our research suggests that in cases where double crush is suspected before surgery, failed back surgery syndrome may be prevented by evaluating DTI images.

Evaluation of joint laxity against distal traction force upon flexion in cruciate-retaining and posterior-stabilized total knee arthroplasty.

BackgroundSeveral studies have reported varus-valgus stability in the extension position after total knee arthroplasty (TKA). However, few studies have evaluated joint laxity in the flexion position postoperatively. The purpose of the study was to evaluate joint laxity against distal traction force on flexion after cruciate-retaining and posterior-stabilized total knee arthroplasties.MethodsA total of 44 knees (22 knees cruciate-retaining, 22 knees posterior-stabilized) in 40 patients with osteoarthritis were tested in this study. The subjects were seated at a table and their knee joints were fixed at 80° of flexion to avoid overlapping images of condyles and the femoral shaft. Tibial shafts were adjusted to be parallel to the radiographic films, and posteroanterior radiographs were obtained. Flexion stress tests were performed with a distal traction of 100 N at a neutral foot position. Radiographs were obtained at neutral and traction positions. The distance from the perpendicular line of the top of the polyethylene insert to the midpoint on the tangential line of the femoral condyle was measured (joint space distance) at each side.ResultsIn the flexion-neutral position, average joint space distances were 0.1 ± 0.2 mm in cruciate-retaining (CR) TKA knees and 0.2 ± 0.3 mm in posterior-stabilized (PS) TKA knees. With flexion-traction stress tests, the average joint space distances were 0.5 ± 0. 5 mm in CR TKA knees 2.4 ± 1.2 mm in PS TKA knees. Average changes of joint space distances between the two positions were 0.3 ± 0.4 mm (CR TKA) and 2.2 ± 1.5 mm (PS TKA). The changes in joint space distances between neutral and traction positions of PS TKA knees were significantly larger than those of CR TKA knees in flexion stress tests (P < 0.01).ConclusionThe posterior cruciate ligament acted as a stabilizer against distal traction force in the CR-TKA knees. However, the laxity of PS-TKA knees against distal force differed among individual cases.

Total Knee Arthroplasty in a Patient with Bilateral Congenital Dislocation of the Patella Treated with a Different Method in Each Knee

We have operated total knee arthroplasty in a patient with bilateral congenital dislocation of the patella treated with a different method in each knee.

Discrimination between Lumbar Intraspinal Stenosis and Foraminal Stenosis using Diffusion Tensor Imaging Parameters: Preliminary Results

Study Design Retrospective observational study. Purpose To examine fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) values of damaged nerves to discriminate between lumbar intraspinal stenosis (IS) and foraminal stenosis (FS) using diffusion tensor imaging (DTI) Overview of Literature It is important in the selection of surgical procedure to discriminate between lumbar IS and FS, but such discrimination is difficult. Methods There were 9 cases of IS, 7 cases of FS, and 5 healthy controls. The regions of interest were established in the lumbar intraspinal zone (Iz), nerve root (N), and extraforaminal zone (Ez). The FA and ADC values were measured on the affected and unaffected sides of the nerves. The FA ratio and the ADC ratio were calculated as the affected side/unaffected side ×100 (%). Results In the Ez, the FA value was significantly lower in FS than in IS (p<0.01). FA ratio was significantly lower in FS than in IS for the Ez (p<0.01). In the Iz, the ADC value was significantly higher in IS than FS (p<0.01). ADC ratio was significantly higher in FS than in IS for the N and Ez (p<0.05). For the Ez, receiver operating characteristic analysis of parameters revealed that the FA values showed a higher accuracy for the diagnosis of FS than the ADC values, and the FA value cut-off value was 0.42 (sensitivity: 85.7%, false positive: 11.1%) and the FA ratio cut-off value was 83.9% (sensitivity: 85.7%, false positive: 22.2%). Conclusions The low FA value in the extraforaminal zone suggests the presence of foraminal stenosis. When the FA value and FA ratio cut-off value were established as 0.42 and 83.9%, respectively, the accuracy was high for the diagnosis of foraminal stenosis. It may be possible to use DTI parameters to help in the discrimination between IS and FS.

Assessment of Clinical Symptoms in Lumbar Foraminal Stenosis Using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire

Objective It is important to develop an easy means of diagnosing lumbar foraminal stenosis (LFS) in a general practice setting. We investigated the use of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) to diagnose LFS in symptomatic patients. Methods Subjects included 13 cases (mean age, 72 years) with LFS, and 30 cases (mean age, 73 years) with lumbar spinal canal stenosis (LSCS) involving one intervertebral disc. The visual analogue scale score for low back pain and leg pain, the JOABPEQ were evaluated. Results Those with LFS had a significantly lower JOA score (p<0.001), while JOABPEQ scores (p<0.05) for lumbar dysfunction and social functioning impairment (p<0.01) were both significantly lower than the scores in LSCS. The following JOABPEQ questionnaire items (LFS vs. LSCS, p-value) for difficulties in: sleeping (53.8% vs. 16.6%, p<0.05), getting up from a chair (53.8% vs. 6.6%, p<0.001), turning over (76.9% vs. 40%, p<0.05), and putting on socks (76.9% vs. 26.6%, p<0.01) such as pain during rest, and signs of intermittent claudication more than 15 minutes (61.5% vs. 26.6%, p<0.05) were all significantly more common with LFS than LSCS. Conclusion Results suggest that of the items in the JOABPEQ, if pain during rest or intermittent claudication is noted, LFS should be kept in mind as a cause during subsequent diagnosis and treatment. LFS may be easily diagnosed from LSCS using this established patient-based assessment method.

Diagnosis of Lumbar Foraminal Stenosis using Diffusion Tensor Imaging

Diagnosis of lumbar foraminal stenosis remains difficult. Here, we report on a case in which bilateral lumbar foraminal stenosis was difficult to diagnose, and in which diffusion tensor imaging (DTI) was useful. The patient was a 52-year-old woman with low back pain and pain in both legs that was dominant on the right. Right lumbosacral nerve compression due to a massive uterine myoma was apparent, but the leg pain continued after a myomectomy was performed. No abnormalities were observed during nerve conduction studies. Computed tomography and magnetic resonance imaging indicated bilateral L5 lumbar foraminal stenosis. DTI imaging was done. The extraforaminal values were decreased and tractography was interrupted in the foraminal region. Bilateral L5 vertebral foraminal stenosis was treated by transforaminal lumbar interbody fusion and the pain in both legs disappeared. The case indicates the value of DTI for diagnosing vertebral foraminal stenosis.

Recent advances in magnetic resonance neuroimaging of lumbar nerve to clinical applications: A review of clinical studies utilizing Dffusion Tensor Imaging and Diffusion-weighted magnetic resonance neurography

Much progress has been made in neuroimaging with Magnetic Resonance neurography and Diffusion Tensor Imaging (DTI) owing to higher magnetic fields and improvements in pulse sequence technology. Reports on lumbar nerve DTI have also increased considerably. Many studies have shown that the use of DTI in lumbar nerve lesions, such as lumbar foraminal stenosis and lumbar disc herniation, makes it possible to capture images of interruptions of tractography at stenotic sties, enabling the diagnosis of stenosis. DTI can also reveal significant decreases in fractional anisotropy (FA) with significant increases in apparent diffusion coefficient (ADC) values in compression lesions. FA values have higher accuracy than ADC values. Furthermore, strong correlations exist between FA values and indications of neurological severity, including the Japanese Orthopedic Association (JOA) score, the Oswestry Disability Index (ODI), and the Roland-Morris Disability Questionnaire (RDQ) in patients with lumbar disc herniation-induced radiculopathy. Most lumbar DTI has become 3T; 3T MRI has made it possible to take high-resolution DTI measurements in a short period of time. However, increased motion artifacts in the magnetic susceptibility effect lead to signal irregularities and image distortion. In the future, high-resolution DTI with reduced field-of-view may become useful in clinical applications, since visualization of nerve lesions and quantification of DTI parameters could allow more accurate diagnoses of lumbar nerve dysfunctions. Future translational studies will be necessary to successfully bring MR neuroimaging of lumbar nerve into clinical use.

Influence of Skeletal Muscle Mass and Spinal Alignment on Surgical Outcomes for Lumbar Spinal Stenosis

Study Design Retrospective observational study. Purpose We considered the relationship between spinal alignment and skeletal muscle mass on clinical outcomes following a surgery for lumbar spinal stenosis (LSS). Overview of Literature There are no reports of preoperative factors predicting residual low back pain following surgery for LSS. Methods Our target population included 34 women (mean age, 74.4 years) who underwent surgery for LSS. Prior to and 6 months after the surgery, systemic bone mineral density and lean soft tissue mass were measured using dual-energy X-ray absorptiometry. Skeletal muscle mass index (SMI) was calculated as the sum of the arm and leg lean mass in kilograms divided by height in meters squared. The spinal alignment was also measured. Clinical outcomes were evaluated using the Japanese Orthopedic Association scoring system, leg and low back pain Visual Analog Scale, and Roland–Morris Disability Questionnaire (RDQ). Additionally, we examined the bone mineral density, skeletal muscle mass, and spinal alignment before and after the surgery. We used the Spearman correlation coefficient to examine the associations among clinical outcomes, preoperative muscle mass, and spinal alignment. Results Sarcopenia (SMI <5.46) was observed in nine subjects (26.5%). Compared with normal subjects (SMI >6.12), RDQ was significantly higher in subjects with sarcopenia (p =0.04). RDQ was significantly negatively correlated with SMI (r =−0.42, p <0.05). There was a significant positive correlation between postoperative RDQ and pelvic tilt (PT; r =0.41, p <0.05). SMI and PT were significantly negatively correlated (r =−0.39, r <0.05). Conclusions Good postoperative outcomes were negatively correlated with low preoperative appendicular muscle mass, suggesting that postoperative outcomes were inferior in cases of decreased appendicular muscle mass (sarcopenia). Posterior PT due to decreased limb muscle mass may contribute to postoperative back pain, showing that preoperatively reduced limb muscle mass and posterior PT are predictive factors in the persistence of postoperative low back pain.

Long-Term Results After TKA for Charcot Disease

The clinical results of 8 patients (12 knees) with Charcot disease (mean age, 63.6 years) who had undergone total knee arthroplasty (TKA) were studied retrospectively 6–13 years after the operation. All the procedures had been performed using cementless fixation of the femoral and tibial components, except for 4 joints. Revision had been the reason for 3 patients, tibial polyethlene insert delamination for 1, and tibial component loosening for 2 patients. None of the patients who underwent cementless TKA required revision. Survival rate was 91.7% at 5 years and 70.7% at 10 years. Cementless TKA was shown to be a reliable and effective means of treating the Charcot knee.