Dimensionally Stabilized, Very Low Density Fiberboard

In this study, fiberboards with a specific gravity ranging from 0.2 to 0.5 were made using acetylated, steam-treated, and untreated fiber. In all boards, dimensional stability increased as specific gravity decreased from 0.5 to 0.2. Fiberboards made from acetylated fiber were more dimensionally stable than boards made from steam-treated fiber at all specific gravity levels tested. Steam-treated fiberboards resulted in a 15% weight loss of hemicelluloses and some loss of lignin and extractives. Boards with a specific gravity of 0.2 had a low modulus value, which was probably due to poor adhesion between fibers

Dimensional Stability, Decay Resistance, and Mechanical Properties of Veneer-Faced Low-Density Particleboards Made From Acetylated Wood

Veneer-faced low-density particleboards were made using four combinations of control and acetylated veneers and particles. These boards were tested for dimensional stability in both liquid water and water vapor, for decay resistance in standard soil-block tests with Tyromyces palustris and Trametes versicolor, for strength losses during attack by T. palustris, and for mechanical strength in bending-creep and mechanical tests. Boards made from acetylated veneers and acetylated core particles showed excellent dimensional stability in both liquid water and humidity tests and were resistant to attack by both fungi in an 8-week soil-block test. During the 150-day bending-creep test, the totally acetylated boards showed no strength or weight loss during exposure to T. palustris. Modulus of elasticity and modulus of rupture were slightly reduced for totally acetylated boards compared to boards with control veneers and control particles, and internal bond strength was reduced by about 30%. Screw-holding capacity of the totally acetylated boards and boards with control veneers and particles was essentially the same

Difference in Therapeutic Strategies for Joint‐Preserving Surgery for Non‐Traumatic Osteonecrosis of the Femoral Head between the United States and Japan: A Review of the Literature

For patients with non-traumatic osteonecrosis of the femoral head (ONFH), core decompression (CD) and bone grafts (BG) are mainly performed in the West, while osteotomy is found to be predominant in Japan. It is not well recognized how the surgical procedures for joint preservation in patients with ONFH are completely different between the United States and Japan. This paper identifies the contexts and the differences in treatment strategies for ONFH between the two countries. We compared the surgical trends of the two countries over three periods, 1997-2001, 2002-2006, and 2007-2011 (the US data for the third period was 2007-2008), based on a 2014 US paper and a 2013 national publication in Japan. We compared the details of surgery for non-traumatic ONFH under the same conditions in the two reports. For the period 1997-2001, the rates of surgeries for ONFH in the US were as follows: total hip arthroplasty (THA), 86%; CD, 10%; and osteotomy, 0.4%. In Japan, THA was 61%, osteotomy 38%, and CD 0%. For the recent period, 2007-2011 (US 2007-2008), the rate of THA was 91%, CD 6%, and osteotomy 0.1%, in the US, compared to a THA rate of 73%, CD 0%, and osteotomy 26% in Japan. The results for the interim period (2002-2006) were between the old and new data. The use of joint-preserving surgery for ONFH differs greatly between the US and Japan. The first-line joint-preserving surgery was CD in the US and osteotomy in Japan. Each procedure was rarely done in the other country. From about 2000 to 2010, the percentage of THA increased in both countries. The proportion of joint-preserving surgery (CD in the US and osteotomy in Japan) declined. The decrease in joint-preserving procedures may be largely attributed to improved long-term outcomes of THA due to technological advances. There is also a reluctance for young ONFH patients to undergo joint-preserving procedures, such as osteotomy, that require long-term hospitalization

High Subsidence Rate After Primary Total Hip Arthroplasty Using a Zweymüller-type Noncemented Implant With a Matte Surface

INTRODUCTION: The surface topography is one key factor that affects the initial fixation of prosthesis in total hip arthroplasty (THA). We aimed to evaluate the mid-term results of a Zweymüller-type noncemented femoral implant (Elance stem) that had a matte surface with a target average roughness of 1.0 to 2.5 μm. The prosthesis was subjected to alkali and heat treatments to enhance its bone-bonding property. METHODS: In this retrospective study, 30 THAs (27 patients) done using an Elance stem from September 2012 to October 2014 were evaluated clinically and radiographically for a mean follow-up of 6.3 ± 1.7 years after the index THA. RESULTS: Stem revision was indicated for six hips (20%). The survival rate with stem revision for any reason was 86.4% (95% confidence interval, 68.9%-94.8%) at 5 years. Stem subsidence >5 mm was noted in 17 hips (56.7%). The survival rate with stem subsidence >5 mm as the end point was 46.6% (95% confidence interval, 29.9%-64.2%) at 5 years. CONCLUSION: The Zweymüller-type noncemented stem with a low-roughness matte surface demonstrated a high subsidence rate, although the bone-bonding property was potentially enhanced by the alkali and heat treatments. Surgeons should be aware that an insufficient surface roughness could lead to poor mechanical fixation of the noncemented stem, even with an appropriate stem geometry and surface chemistry

Discrepancy in the Responsiveness to Hip Range of Motion Between Harris and Oxford Hip Scores

Background: The primary objectives of total hip arthroplasty (THA) include mobility improvement and pain relief; however, the correlation between hip range of motion (ROM) and function remains unclear. We aimed to explore how ROM affects hip functions after THA and compare the responsiveness of each component of the modified Harris Hip Score (mHHS) and Oxford Hip Score (OHS) to preoperative and postoperative ROM. Methods: This prospective observational study involved 120 patients who underwent unilateral THA. Univariate regression analyses were performed using the University of California Los Angeles activity score and mHHS and OHS to determine the effects of preoperative and postoperative flex ROM on clinical scores at 12 months. Multivariate regressions were performed to adjust for the confounding effects of patient factors: age, sex, body mass index, and diagnosis. Results: A larger preoperative flexion ROM was associated with a higher score in the mHHS socks component (standardized coefficient [SC] = 0.26, P = .0041) at 12 months; the effect on the OHS socks component was not significant (P = .34). A larger flexion ROM at 12 months was associated with higher scores in the mHHS support (SC = 0.21, P = .026), stairs (SC = 0.35, P = .0002), and socks (SC = 0.32, P = .0007) components but had no significant effect on any OHS component. The effects of ROM on University of California Los Angeles activity score were limited. Conclusions: A discrepancy was noted in the responsiveness to ROM between the two major measurement tools; this difference might be because mHHS and OHS are surgeon- and patient-administered questionnaires, respectively. This discrepancy also suggests that the patients have higher satisfaction than that assumed by the surgeons

Fixation of Compressed Wood Using Melamine-Formaldehyde Resin

Methods to maximize wood hardness and dimensional stability include various combinations of compression, heating, and chemical treatment. In this study, wood was treated with increasing concentrations of a low molecular weight, water-soluble melamine-formaldehyde resin solution (mol wt 380) and compressed while heated. This method achieved a maximum bulking efficiency of 5% and an antishrink efficiency of 45%, showing that the chemical had not completely penetrated the cell wall. Once the wood was treated, its ability to retain the compressed state was tested by immersing wood specimens in water at different temperatures. Specimens treated with an 8% resin solution retained almost complete fixation when soaked in room-temperature water, while those treated with a 25% solution retained fixation in boiling water. Moreover, a 25% solution of resin and a compression of 54% increased hardness from 0.48 to 0.72 MPa

Similarity in Sequential Bilateral Transient Osteoporosis of the Hip

CASE: Three middle-aged men with habitual drinking developed unilateral hip pain and were referred for osteonecrosis of the femoral head (ONFH). Radiographs showed osteopenia, and magnetic resonance imaging (MRI) showed diffuse bone marrow edema (BME). After several months, the patients' symptoms resolved and radiographic images normalized. More than 6 months later, the contralateral side showed the same clinical course. CONCLUSION: Transient osteoporosis of the hip (TOH) resembles ONFH but heals spontaneously. We report 3 rare cases of sequential TOH, similar in that they occurred in middle-aged male habitual drinkers at risk for ONFH, characterized by diffuse BME on MRI and radiographic resolution

Comparison between alkali heat treatment and sprayed hydroxyapatite coating on thermally-sprayed rough Ti surface in rabbit model: Effects on bone-bonding ability and osteoconductivity.

In this study, we investigated the effect of different surface treatments (hydroxyapatite (HA) coating, alkali heat treatment, and no treatment) on the ability of bone to bond to a rough arc-sprayed Ti metal surface, using rabbit models. The bone-to-implant contacts for untreated, HA-coated, and alkali heat-treated implants were 21.2%, 72.1%, and 33.8% at 4 weeks, 21.8%, 70.9%, and 30.0% at 8 weeks, and 16.3%, 70.2%, and 29.9% at 16 weeks, respectively (n = 8). HA -coated implants showed significantly higher bone-to-implant contacts than the untreated and alkali heat-treated implants at all the time point, whereas alkali heat-treated implants showed significantly higher bone-to-implant contacts than untreated implants at 4 and 16 weeks. The failure loads in a mechanical test for untreated, HA coated, alkali heat-treated plates were 65.4 N, 70.7 N, and 90.8 N at 4 weeks, 76.1 N, 64.7 N, and 104.8 N at 8 weeks and 88.7 N, 92.6 N, and 118.5 N at 16 weeks, respectively (n = 8). The alkali heat-treated plates showed significantly higher failure loads than HA-coated plates at 8 and 16 weeks. The difference between HA-coated plates and untreated plates were not statistically significant at any time point. Thus HA coating, although it enables high bone-to-implant contact, may not enhance the bone-bonding properties of thermally-sprayed rough Ti metal surfaces. In contrast, alkali heat treatment can be successfully applied to thermally-sprayed Ti metal to enhance both bone-to-implant contact and bone-bonding strength

Development of Safety Measures of Bicycle Trafflc by Observation wffh Deep-Leamlng, Drive Recorder Data, Probe Blcycle wlth LIDAR, and Connected Simulators

This research outlines the development of evaluating safety measures for bicycle traffic using state-of-the-art technology, which was started since 2020 as a four-year project. The project is funded by the Commission on Advanced Road Technology in the Ministry of Land, Infrastructure, Transport and Tourism(MLIT). While Japan has a high bicycle modal share of 12% (2010), bicycle-related fatalities are relatively high among other countries in the IRTAD database (2019). Under these circumstances, since 2007, various measures for bicycle traffic measures have been implemented to improve the safe bicycle traffic environment, including the revision of the Road Traffic Act and the formulation of a national plan to promote bicycle use. However, serious accidents involving bicycles are remained in some specific cases. According to the government's traffic accident analysis results (2019), right-hook crash at signalized intersections are one of the most serious types of collision involving bicycles, along with accidents at unsignalized intersections involving vehicles turning left, rear-end collisions, and single vehicle accidents due to off-road deviation. In particular, proactive safety measures are required at signalized intersections along arterial roads, where electric personal mobility vehicles traveling at speeds of up to 20 km/h are expected to share with bicycles in the future. In order to evaluate safety measures for bicycle-vehicle crashes, this project set the following goals. 1) Identify factors influencing near-miss incidents and collisions through analysis of drive recorder data and accident statistical data. 2) Detailed analysis of traffic conditions from the cyclist's perspective using a probe bicycle equipped with a LiDAR sensor. 3) Development of an experimental environment using a connected simulator for evaluation of cooperative driving behavior. 4) Clarification of experimental conditions to evaluate different scenarios and conditions with and without intervention. 5) Proposal of effective interventions to improve crash cases based on experiments