Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 69
Filter
3.
QJM ; 111(10): 745-746, 2018 Oct 01.
Article in English | MEDLINE | ID: mdl-29660083
4.
Bone Joint J ; 99-B(8): 1047-1052, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28768781

ABSTRACT

AIMS: The aim of this study was to evaluate the effects of using a portable, accelerometer-based surgical navigation system (KneeAlign2) in total knee arthroplasty (TKA) on the alignment of the femoral component, and blood loss. PATIENTS AND METHODS: A total of 241 consecutive patients with primary osteoarthritis of the knee were enrolled in this prospective, randomised controlled study. There were 207 women and 34 men. The mean age of the patients was 74.0 years (57 to 89). The KneeAlign2 system was used for distal femoral resection in 121 patients (KA2 group) and a conventional intramedullary femoral guide was used in 120 patients (IM group). RESULTS: One patient (0.8%) in the KA2 group and 19 in the IM group had an alignment which was > 3° away from the neutral mechanical axis (p < 0.01). The mean deviation from neutral alignment was 1.01° (standard deviation (sd) 1.0°) in the KA2 group and 1.93° (sd 1.7°) in the IM group (p < 0.01). Blood loss was significantly less in the KA2 group compared with the IM group (784 ml (sd 357) versus 1071 ml (sd 310), p < 0.001). CONCLUSION: The KneeAlign2 system provides a technically straightforward method for identifying the femoral head and performing an accurate distal femoral resection at TKA with significantly less blood loss compared with a conventional intramedullary guide. Cite this article: Bone Joint J 2017;99-B:1047-52.


Subject(s)
Accelerometry/instrumentation , Arthroplasty, Replacement, Knee/methods , Knee Prosthesis , Osteoarthritis, Knee/surgery , Surgery, Computer-Assisted/methods , Aged , Aged, 80 and over , Equipment Design , Female , Follow-Up Studies , Humans , Knee Joint/diagnostic imaging , Knee Joint/surgery , Male , Middle Aged , Osteoarthritis, Knee/diagnosis , Prospective Studies , Radiography , Treatment Outcome
5.
QJM ; 109(7): 495, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27247430
6.
Nat Commun ; 2: 594, 2011 Dec 20.
Article in English | MEDLINE | ID: mdl-22186890

ABSTRACT

The study of carrier multiplication has become an essential part of many-body physics and materials science as this multiplication directly affects nonlinear transport phenomena, and has a key role in designing efficient solar cells and electroluminescent emitters and highly sensitive photon detectors. Here we show that a 1-MVcm(-1) electric field of a terahertz pulse, unlike a DC bias, can generate a substantial number of electron-hole pairs, forming excitons that emit near-infrared luminescence. The bright luminescence associated with carrier multiplication suggests that carriers coherently driven by a strong electric field can efficiently gain enough kinetic energy to induce a series of impact ionizations that can increase the number of carriers by about three orders of magnitude on the picosecond time scale.


Subject(s)
Electronics/methods , Electricity , Electronics/instrumentation , Electrons , Infrared Rays , Luminescence , Optical Devices , Photons , Terahertz Radiation , Thermodynamics
7.
Opt Express ; 19(9): 8277-84, 2011 Apr 25.
Article in English | MEDLINE | ID: mdl-21643077

ABSTRACT

We report a terahertz near-field microscope with a high dynamic range that can capture images of a 370 x 740 µm2 area at 35 frames per second. We achieve high spatial resolution (14 µm corresponding to λ/30 for a center frequency at 0.7 THz) on a large area by combining two novel techniques: terahertz generation by tilted-pulse-front excitation and electro-optic balanced imaging detection using a thin crystal. To demonstrate the microscope capability, we reveal the field enhancement at the gap position of a dipole antenna after the irradiation of a terahertz pulse.


Subject(s)
Image Enhancement/instrumentation , Microscopy/instrumentation , Terahertz Imaging/instrumentation , Computer Systems , Equipment Design , Equipment Failure Analysis , Reproducibility of Results , Sensitivity and Specificity
8.
Blood Purif ; 27(3): 253-60, 2009.
Article in English | MEDLINE | ID: mdl-19218793

ABSTRACT

AIMS: The higher ultrafiltration (UF) induces poor outcomes. The impact of higher UF on the volume status was investigated. METHODS: 60 hemodialysis (HD) patients were divided into three groups according to the ratio of total UF to post-dialysis body weight (TUF/PDW) (<3%, 3-5%, > or =5%). ANP, the ratio of extracellular water to total body water and excess fluid mass (ExF/PDW) by bioimpedance spectroscopy, inferior vena cava diameter by ultrasound were measured at the end of HD. The ratio of post-HD blood volume to pre-HD (BVpost/BVpre) and standardized filtration coefficients (Lpst) of the microvasculature in the vicinity of PDW were calculated. RESULTS: Only Lpst and BVpost/BVpre showed significant differences among the three groups. A stepwise multiple linear regression model revealed that BVpost/BVpre was correlated with TUF/PDW, ExF/PDW and Lpst (R = 0.778, p < 0.001), independently. CONCLUSION: Higher UF causes decreases in BVpost/BVpre and Lpst. BVpost/BVpre was determined by TUF/PDW, ExF/PDW and Lpst.


Subject(s)
Blood Volume , Renal Dialysis/methods , Ultrafiltration/adverse effects , Adult , Aged , Aged, 80 and over , Body Water , Electric Impedance , Extracellular Fluid , Extracellular Space , Humans , Middle Aged , Ultrasonography , Vena Cava, Inferior/diagnostic imaging , Water-Electrolyte Balance
9.
J Phys Condens Matter ; 19(40): 406224, 2007 Oct 10.
Article in English | MEDLINE | ID: mdl-22049122

ABSTRACT

We performed optical-pump terahertz-probe measurements of a Mott insulator YTiO(3) and a band semiconductor Si using a laser diode (1.47 eV) and a femtosecond-pulse laser (1.55 eV). Both samples possess long energy-relaxation times (1.5 ms for YTiO(3) and 15 µs for Si); therefore, it is possible to extract terahertz complex conductivities of photoinduced carriers under equilibrium. We observed highly contrasting behaviour-Drude conductivity in Si and localized conductivity possibly obeying the Jonscher law in YTiO(3). The carrier number at the highest carrier-concentration layer in YTiO(3) is estimated to be 0.015 per Ti site. Anisotropic conductivity of YTiO(3) is determined. Our study indicates that localized carriers might play an important role in the incipient formation of photoinduced metallic phases in Mott insulators. In addition, this study shows that the transfer-matrix method is effective for extracting an optical constant of a sample with a spatially inhomogeneous carrier distribution.

10.
J Bone Joint Surg Br ; 88(10): 1327-30, 2006 Oct.
Article in English | MEDLINE | ID: mdl-17012422

ABSTRACT

The shape of the flexion gap in 20 normal knees was evaluated by axial radiography of the distal femur, and the results compared with those obtained in a previous study by MRI. The observed asymmetry was reduced by 29% using radiography, with a mean value of 3.6 degrees (1.5 degrees to 6.3 degrees) compared with that obtained by MRI of 5.1 degrees (2.6 degrees to 9.5 degrees), a mean discrepancy of 1.49 degrees. The results obtained by radiography and MRI showed a strong correlation (r = 0.78). Axial radiography is acceptable for the evaluation of the flexion gap and is less expensive and more comfortable to perform than MRI. Additionally, no metallic artefact occurs when the radiological method is used for assessment after arthroplasty.


Subject(s)
Femur/diagnostic imaging , Knee Joint/diagnostic imaging , Adolescent , Adult , Female , Femur/pathology , Humans , Knee Joint/pathology , Male , Middle Aged , Radiography
11.
J Bone Joint Surg Br ; 86(8): 1133-6, 2004 Nov.
Article in English | MEDLINE | ID: mdl-15568525

ABSTRACT

Varus and valgus joint laxity of the normal living knee in flexion was assessed using MRI. Twenty knees were flexed to 90 degrees and were imaged in neutral and under a varus-valgus stress in an open MRI system. The configuration of the tibiofemoral joint gap was studied in slices which crossed the epicondyles of the femur. When a varus stress was applied, the lateral joint gap opened by 6.7 +/- 1.9 mm (mean +/- SD; 2.1 to 9.2) whereas the medial joint gap opened by only by a mean of 2.1 +/- 1.1 mm (0.2 to 4.2). These discrepancies indicate that the tibiofemoral flexion gap in the normal knee is not rectangular and that the lateral joint gap is significantly lax. These results may be useful for adequate soft-tissue balancing and bone resection in total knee arthroplasty and reconstruction surgery on ligaments.


Subject(s)
Knee Joint/anatomy & histology , Posture/physiology , Adolescent , Adult , Female , Humans , Magnetic Resonance Imaging/methods , Male , Middle Aged , Stress, Mechanical
12.
J Bone Joint Surg Am ; 85(7): 1238-42, 2003 Jul.
Article in English | MEDLINE | ID: mdl-12851348

ABSTRACT

BACKGROUND: Little information is available on the kinematics of the normal knee in deep flexion. The purpose of this study was to use magnetic resonance imaging to analyze the patellofemoral articulation in deep flexion. METHODS: Axial scans were made of the patellofemoral joint of twenty healthy Japanese volunteers with the knee in approximately 90 degrees of flexion, in maximum active flexion (mean [and standard deviation], 140 degrees +/- 10 degrees ), and in maximum passive flexion (mean, 156 degrees +/- 5 degrees ). A fat-suppressed, three-dimensional, fast low-angle shot sequence was used to visualize the articular cartilage. The patellofemoral contact area was determined on sequential images and was reconstructed three-dimensionally. RESULTS: At 90 degrees of flexion, the contact area on the patella was continuous over the medial and lateral facets in fourteen knees and was located in the proximal half of the articular surface. At maximum active and passive flexion, the odd facet engaged in fifteen and eighteen knees, respectively. At maximum passive flexion, the contact area of the lateral facet moved distally and decreased significantly (p = 0.0002). From 90 degrees of flexion to maximum active flexion, the mean total contact area remained constant (3.43 +/- 0.70 and 3.62 +/- 0.72 cm (2), respectively); it then decreased significantly in maximum passive flexion (2.96 +/- 0.78 cm (2), p = 0.04). CONCLUSIONS: The contact area on the patella was divided into two parts (the odd and lateral facets) and moved distally in deep knee flexion. The size of the contact area on the lateral facet significantly decreased in maximum passive flexion.


Subject(s)
Knee Joint/physiology , Magnetic Resonance Imaging , Patella/physiology , Range of Motion, Articular , Activities of Daily Living , Adult , Biomechanical Phenomena , Female , Femur/physiology , Humans , Japan , Knee Prosthesis , Life Style , Magnetic Resonance Imaging/methods , Male , Prosthesis Design , Rotation , Tibia/physiology , Weight-Bearing
13.
J Arthroplasty ; 17(8): 1028-32, 2002 Dec.
Article in English | MEDLINE | ID: mdl-12478514

ABSTRACT

Anthropometric data on proximal tibiae of 100 knees in 80 Japanese patients undergoing total knee arthroplasty were obtained. Anterior-posterior (AP) and medial-lateral (ML) lengths of the tibia were measured on computed tomography scans and intraoperatively on tibial resection surfaces. A special small component is unnecessary, and size variation should focus on ML length of 65 to 75 mm because this includes 90% of women's knees. AP-to-ML ratio had a negative correlation with ML length, indicating that small knees were longer in the AP direction. Most prostheses had AP mismatch up to 5 mm for small women's knees. These data could provide the basis for designing the optimal tibial component for most of the Asian-Pacific population.


Subject(s)
Anthropometry , Knee Prosthesis , Tibia/anatomy & histology , Aged , Aged, 80 and over , Arthroplasty, Replacement, Knee , Asian People , Female , Humans , Japan , Male , Middle Aged , Prosthesis Design
14.
Clin Orthop Relat Res ; (402): 196-201, 2002 Sep.
Article in English | MEDLINE | ID: mdl-12218484

ABSTRACT

The purpose of the current study was to investigate the bone anatomy in determining the rotational alignment in total knee arthroplasty using computed tomography. Axial images of 109 knees in 83 patients with varus osteoarthritis who had total knee arthroplasty were analyzed. On the images of the distal femur and the proximal tibia, a baseline for the anteroposterior axis of each component was drawn based on the epicondylar axis for the femur and the medial (1/3) of the tibial tuberosity for the tibia. The angle between these two lines was analyzed as the rotational mismatch between the components when they were aligned to the anatomic landmarks of each bone. Fifty-four knees (49.5%) had an angle of 5 degrees or greater and 13 knees (11.9%) had an angle of 10 degrees or greater. There was a tendency to align the tibial component in external rotation relative to the femoral component. The results indicated that the landmarks of each bone were the intrinsic cause of the rotational mismatch in knees with varus osteoarthritis. Surgeons doing total knee arthroplasties should be aware of this and check the rotational mismatch between the components. When it is present, the tibial component should be realigned to match the femoral component rotation to minimize problems caused by the mismatch.


Subject(s)
Arthroplasty, Replacement, Knee/adverse effects , Bone Malalignment/etiology , Osteoarthritis, Knee/surgery , Aged , Aged, 80 and over , Female , Femur/diagnostic imaging , Humans , Male , Middle Aged , Osteoarthritis, Knee/diagnostic imaging , Patella , Radiography , Rotation , Tibia/diagnostic imaging , Treatment Outcome
15.
FEBS Lett ; 509(3): 382-8, 2001 Dec 14.
Article in English | MEDLINE | ID: mdl-11749960

ABSTRACT

The induction of apoptosis by cell cycle regulator molecules under conditions optimal for exponential growth was examined in rat pheochromocytoma PC12 cells by overexpression of cyclins and cyclin-dependent kinases (cdks). By flow cytometry and by immunofluorescence, only cells overexpressing cdk4 or cyclin D1 underwent apoptosis, which was not associated with G1-arrest. Cdk4 kinase activity was significantly higher in cdk4-, or cyclin D1-expressing cells. Furthermore, induction of apoptosis by cdk4 was abrogated by co-transfection of p16(INK4), or dominant negative cdk4. These results suggest that upregulation of cdk4 kinase activity is a primary and critical mediator of apoptosis in PC12 cells under physiological conditions.


Subject(s)
Apoptosis , Cyclin D1/metabolism , Cyclin-Dependent Kinases/metabolism , Proto-Oncogene Proteins , Animals , Bromodeoxyuridine/metabolism , Cell Size , Cyclin D1/genetics , Cyclin-Dependent Kinase 4 , Cyclin-Dependent Kinase Inhibitor p16/metabolism , Cyclin-Dependent Kinases/antagonists & inhibitors , Cyclin-Dependent Kinases/genetics , Flow Cytometry , Fluorescein-5-isothiocyanate , G1 Phase , Gene Expression , Genes, Dominant , Mutation , PC12 Cells , Rats , Time Factors
17.
Clin Orthop Relat Res ; (391): 210-7, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11603671

ABSTRACT

The effect of posterior cruciate ligament resection on the tibiofemoral joint gap was analyzed in 30 patients with varus osteoarthritis of thee knee who underwent total knee replacement. The medial soft tissue was released and the bone cut was made without preserving the bone segment of the tibia to which the posterior cruciate ligament was attached. Then the medial and lateral joint gaps in full extension and 90 degrees flexion were measured before and after the posterior cruciate ligament was resected using a tensioning device. After the resection, the flexion gap significantly increased in the medial and the lateral sides (4.8 +/- 0.4 and 4.5 +/- 0.4 mm, respectively, mean +/- standard error) compared with those seen in the extension gap (0.9 +/- 0.2 and 0.8 +/- 0.2 mm). There was no significant difference between the changes in the medial and lateral gaps. The mean value of the flexion gap was 2 mm smaller than the extension gap before the resection and 1.7 mm larger after the sacrifice. Overall, posterior cruciate ligament resection resulted in an increase in the flexion gap and made space for approximately 3-mm thicker polyethylene. The flexion gap can be controlled selectively with posterior cruciate ligament release.


Subject(s)
Femur , Knee Prosthesis , Osteoarthritis, Knee/surgery , Posterior Cruciate Ligament/surgery , Tibia , Aged , Aged, 80 and over , Equipment Design , Female , Femur/physiopathology , Humans , Male , Middle Aged , Osteoarthritis, Knee/physiopathology , Physical Examination/instrumentation , Range of Motion, Articular , Tibia/physiopathology
18.
J Arthroplasty ; 16(6): 784-9, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11547378

ABSTRACT

Results of total hip arthroplasties with a modified cementing technique using hydroxyapatite were evaluated. Femoral and acetabular components were inserted with cement after hydroxyapatite granules (phi = 100-300 microm). The study group comprised 268 hips in 232 patients. The diagnosis was osteoarthritis in 197 patients. After a mean follow-up of 10.3 years, 5 patients died and 30 patients were lost to follow-up, leaving 218 hips (197 patients; mean age, 58.2 years) for evaluation. Three hips were revised because aseptic (1) and septic (2) loosening of acetabular components. Six other sockets were defined as radiologically loose, and no femoral component was loose. Osteolysis was identified in 2 femora and 0 acetabula. The overall loosening rate was 3.2% for acetabular components and 0% for femoral components. These results show that the loosening rate of cemented total hip arthroplasty components, especially the acetabulum, is reduced markedly with this modified cementing technique.


Subject(s)
Arthroplasty, Replacement, Hip , Bone Cements , Durapatite , Osteoarthritis, Hip/surgery , Aged , Aged, 80 and over , Arthroplasty, Replacement, Hip/instrumentation , Female , Follow-Up Studies , Humans , Male , Middle Aged , Osteolysis/diagnostic imaging , Osteolysis/surgery , Prosthesis Design , Prosthesis Failure , Radiography , Reoperation , Surgical Instruments
19.
J Biomech ; 34(8): 1031-7, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11448695

ABSTRACT

The relationship between the coefficient of friction and pH value or protein constituents of lubricating fluid, together with viscosity, were studied within a bearing surface model for artificial joint, ultra-high molecular weight polyethylene (UHMWPE) against stainless steel (SUS), using a mechanical spectrometer. Four lubricants were tested in this study: sodium hyaluronate (HA), HA with albumin, HA with gamma-globulin, and HA with (L)alpha-dipalmitoyl phosphatidylcholine ((L)alpha-DPPC). The coefficient of friction between UHMWPE and SUS in HA with albumin or HA with gamma-globulin varied from 0.035 to 0.070 depending on angular velocity and pH. The coefficient of friction in HA or HA with (L)alpha-DPPC varied from 0.023 to 0.045 depending on angular velocity and pH. The variation in pH for HA with albumin had a large effect on the coefficient of friction at low range of angular velocity with viscosity independence. The variation in pH for HA with gamma-globulin had a large effect on the coefficient of friction with viscosity dependence at high angular velocity. The addition of (L)alpha-DPPC showed a small effect on the coefficient of friction at low angular velocity. This study confirms that the presence of albumin in the lubricant promotes pH dependence and viscosity independence of the tribological properties at low speed while the presence of globulin promotes pH and viscosity independence at low speed and promotes pH and viscosity dependence at high speed in the lubrication of UHMWPE against SUS. This study supports the clinical hypothesis that the effect of constituents and pH changes in periprosthetic fluid for the lubrication is a clue toward resolving many complications after total joint replacement.


Subject(s)
Hyaluronic Acid/chemistry , Joint Prosthesis , 1,2-Dipalmitoylphosphatidylcholine/chemistry , Albumins/chemistry , Friction , Humans , Hydrogen-Ion Concentration , Lubrication , Polyethylenes , Stainless Steel , Statistics as Topic , Viscosity , gamma-Globulins/chemistry
20.
J Biomed Mater Res ; 58(2): 167-71, 2001.
Article in English | MEDLINE | ID: mdl-11241335

ABSTRACT

The purpose of this study was to evaluate the mechanical and chemical characteristics of gamma-irradiated, cross-linked polyethylene after long-term service in vivo. Two gamma-irradiated ultra high molecular weight polyethylene (RCH 1000, molecular weight: 10(6)) total hip replacement sockets were retrieved at 15 and 16 years after implantation. Mechanical and chemical characteristics of the sockets were evaluated in comparison with nonirradiated sockets. Significant surface oxidation occurred in the nonirradiated sockets; up to 75% of that seen in the irradiated ones. The mechanical properties of the irradiated sockets were not subject to increased deterioration in the presence of high free radical content. The cross-link was stable and was retained for a long period both in vivo and in ambient air. These data indicate that gamma-irradiated polyethylene was not subject to increased oxidative degradation during long-term service in vivo and confirmed the usefulness of this material as an articulating surface in total hip replacement.


Subject(s)
Arthroplasty, Replacement, Hip , Biocompatible Materials , Polyethylene , Cross-Linking Reagents , Gamma Rays , Humans , Prostheses and Implants
SELECTION OF CITATIONS
SEARCH DETAIL
...