Search

There have been some reports of gross trunnion failure (GTF) in total hip arthroplasty. Here, we report a case of GTF 19 years after bipolar hemiarthroplasty using a 28-mm head with a 14/16 taper bore. Compared to other GTF reports, the current case had some unusual aspects: bipolar hemiarthroplasty, 28-mm head, relatively late-onset, and no apparent findings of metallosis though a severe one was evident. A Computed tomography scout view provided valuable information in evaluating polyethylene, metal head, and neck inside the bipolar cup. The current report suggests a need for concerned regarding short trunnion length which may be associated with GTF.

Incomplete fractures are assumed to occur in the intertrochanteric area as fractures at other sites, but reports of incomplete intertrochanteric fractures (IIFs) are rare. In 1999, Schultz et al. defined isolated greater trochanter fractures (GTFs) as IIFs when intertrochanteric extension is observed on magnetic resonance (MR) images. On multiplanar reformation computed tomography (MPR CT) images acquired for further study of apparently isolated GTFs, we noted incomplete cortical breakage in the intertrochanteric area. We then found that the fracture line was incomplete on plain radiographs in some intertrochanteric fractures. We evaluated IIFs and apparently isolated GTFs using MPR CT and analyzed the fracture patterns of IIFs that were confirmed using MPR CT.Between February 2006 and June 2019, 36 cases of IIF were detected using MPR CT in 36 patients. They were 17 women and 19 men with a mean age of 74.7 years (range, 26-94 years). Plain radiographs and MPR CT images were evaluated by two experienced orthopedic surgeons. In addition, MR imaging was performed in 5 cases.Plain radiographs showed no evidence of fracture in 2 cases, isolated GTF in 7 cases, and IIF in 27 cases. In all cases, incomplete cortical breakage in the intertrochanteric area was confirmed on MPR CT images. Cortical breakage was located in the anterior portion of the intertrochanteric area, whereas the posterior portion remained intact in all cases. The detection rate of cortical breakage was higher on coronal or sagittal images than that on axial images. On MR images of 5 cases, intertrochanteric extensions were found in the medullary space. All extensions originated in the greater trochanter area and extended anteriorly in the axial plane and inferomedially in the coronal plane. On the T1-weighted mid-coronal image, the extension reached or passed the midline in 3 cases, and cortical breakage was detected in only 2 cases.In all cases of IIF, cortical breakage was detected in the anterior portion of the proximal femur, leaving the posterior cortex intact. This finding is notably different from that of intertrochanteric extension (from posterior to anterior) detected on MR images of isolated GTFs.

Most isolated greater trochanter (IGT) fractures are treated conservatively. However, some require surgical fixation although indications for surgery have not yet been established. Many surgeons perform surgical fixation when the intertrochanteric extension crosses the midline on magnetic resonance (MR) images. Nevertheless, for mechanical strength, cortical bone integrity is more important than that of intramedullary cancellous trabeculae. We retrospectively evaluated the clinical usefulness of multiplanar reformation computed tomography (MPR CT) in determining treatment strategies for IGT fractures.We evaluated 99 cases of suspected IGT fractures between October 2004 and December 2019. They were 66 women and 33 men with a mean age of 77 years. The mean follow-up period was 34 months. Most patients were evaluated with plain radiographs, followed by additional imaging study via MPR CT in 65 cases, magnetic resonance imaging (MRI) in 5 cases, and both in 17 cases. Typically, fractures were fixed surgically when a cortical breakage was detected in the intertrochanteric area on MPR CT, while fractures without evidence of cortical breakage on MPR CT were treated conservatively.In 13 out of 82 cases evaluated by MPR CT, incomplete cortical breakage in the intertrochanteric area was detected, of which 10 were treated surgically. The remaining 3 cases were treated conservatively due to patient's refusal, poor medical condition, and failure to detect breakage. Of 69 cases without cortical breakage, 61 cases were successfully treated conservatively. Among the 17 cases evaluated by both MPR CT and MRI, cortical breakage was detected in 3, of which the intertrochanteric extension crossed the midline on the MR image only in 1 case. Of the remaining 14 cases without breakage, the intertrochanteric extension crossed the midline in 5. Among these 5 cases, 3 were treated conservatively.The results suggest that MPR CT is a useful imaging modality for further evaluation of IGT fractures. It was especially valuable in evaluating cortical bone integrity, which may be more critical for fracture stability.

The Bencox M stem is a mid-short type 1 stem with additional unique design features. It has a reduced stem length and a lateral shoulder to facilitate minimally invasive surgery, as well as an angular lateral shoulder and a trapezoidal neck to minimize stem-liner impingement. There have been many mid-term reports on type 1 stems, but no results have been reported so far on this novel design type 1 femoral stem. This study presents the clinical and radiological outcomes of total hip arthroplasty performed with the M stem after a minimum 5-year follow-up.From July 2014 to February 2015, 125 primary total hip arthroplasties using the M cementless femoral stem were performed on 112 patients in our hospital. Among them, 94 patients (106 hips) were eligible for the study and were followed up for more than 5 years. Our primary outcome was clinical results, which were evaluated by the Harris Hip Score (HHS), thigh pain, noise, and other complications. Secondary outcome was radiological outcomes. Seventy-seven hips were evaluated radiologically with attention to implant fixation, migration, loosening of component, degree of stress shielding, radiolucent lines, focal osteolysis, heterotopic ossification, and the evidence of impingement between the stem and liner.The average HHS improved from 54.6 points (range, 24-67 points) to 96.8 points (range, 91-100 points) at the latest follow-up. Three hips (2.8%) had intermittent thigh pain, which was tolerable without medication. Five hips (4.7%) had ceramic-related noise. There were no other complications such as infection, nerve injury, dislocation, or revision. All implants showed radiographic evidence of stable fixation by bone ingrowth without migration. Fifty-seven hips (74%) showed mild femoral stress shielding. Distal cortical hypertrophy was detected in 7 hips (9%), and heterotopic ossification was observed in 17 hips (22%). No implant demonstrated focal osteolysis and notching of the femoral neck or shoulder on radiographs.The minimum 5-year results of total hip arthroplasty performed with the M cementless femoral stem were encouraging clinically and radiologically. A long-term follow-up will be necessary to evaluate its longevity.

We compare electroabsorption modulators (EAMs) with multiple quantum wells (MQWs) based on InGaAs(P)/InP and InGa(Al)As/InAlAs material systems. We carefully choose the quantum-well structures so that the structures based on different material systems have similar band-offset energies and excition-peak wavelengths. Assuming the same light wavelength of $1.55{\mu}m$ , we show the transfer functions of EAMs with each quantum-well structure and calculate the escape times of photogenerated charge carriers. As the heavy-hole escape time of the quantum well based on InGaAs(P)/InP is much longer than those of photogenerated charge carriers of InGa(Al)As/InAlAs, the EAM based on the InGa(Al)As/InAlAs material seems to be more suitable for high-optical-power operation.

We examine the sensitivities of the intrastep-quantum-well (IQW) structure with an InGaAs well to the thickness and composition variations. With the layer variations into account, we evaluate the changes in absorption coefficient as a function of electric field and the subsequent transfer functions of the electroabsorption modulator. It is concluded that the examined IQW structure is rather sensitive to the thickness variation but is robust to the composition variation. This work suggests that the thickness control is very important in actually growing the IQW structure to obtain the desired performance with the IQW.

We report a new high-sensitivity biosensor using athermal TM-mode SOI resonators with bulk and surface detection limits of 4.7×10−7 RIU and ∼100fg/mm2. Simple DFB harmonic dithering feedback techniques obviate spectrometers and tunable lasers.

Shallow-ridge silicon ring resonator sensors designed for high-sensitivity TM mode operation are fabricated on silicon-on-insulator (SOI), demonstrating complete cancellation of thermo-optic effects for aqueous solution operation near 300K.

We show that conventional expressions for spontaneous emission into waveguide modes correctly predict broadband (non-resonant) Purcell enhancement in Slot waveguides. Time resolved photoluminescence measurements on Er-doped ultra-thin 8.3 nm slot channel waveguides corroborate this effect.

We present the enhancement of the link performance of the railio-over-fiber system at 60 GHz. by using the system-on-packagc (SoP) electroabsorption modulator (EAM) module with two-stage low-noise amplifiers (LNAs). When compared with the performance of the link that used the narrow-band EAM module without any pro-amplifier, the RF gain of the link that used the SoP module was increased by 30 dB and the noise figure was reduced by 30 dB with a little sacrifice in dynamic range at an EAM bias point that gave the maximum modulator slope efficiency.

We developed a 60-GHz narrow-band module and a system-on-package (SoP) module in which an RF amplifier and a band-pass filter were integrated. We characterized the analog performance of modules by two-tone intermodulation measurements.

A built-in potential exists in the reflective liquid-crystal-on-silicon (LCoS) microdisplay cell due to the work-function difference between the aluminum and indium–tin-oxide electrodes. As a consequence, the flicker is generated unless the dc offset voltage is applied to compensate the built-in potential. In this paper, we present the experimental result that the dc offset voltage changes with time as the display is operated and the ions are generated in the liquid crystal (LC). To understand the experimental result, we simulate the ion motion in the LCoS cell by considering both the drift and diffusion. We discuss how the ion concentration in the LC affects the screening of the internal electric field in the bulk LC region and subsequently the built-in potential in the LCoS cell. We show that for an ion concentration higher than the value required to fully compensate the initial built-in potential, the polarity of the built-in potential is changed due to the high electric field near electrodes. By matching the experimental and simulation results, we predict how the ion concentration in the LC increases as a function of operation time.