Backside Damage Research Articles

Unicondylar Knee Retrieval Analysis

Unicondylar knee arthroplasty (UKA) is considered an alternative to total knee arthroplasty for patients who have arthritis limited to one compartment of the knee. This study examined surface damage of 3 contemporary UKA designs that were retrieved at revision surgery. Two of the UKA designs were fixed bearing and one was mobile bearing. Demographic information was collected, as well as information about the implants used at revision surgery. Articular surface damage was greater in the fixed-bearing designs as compared to the mobile bearing, although the mobile-bearing implants had significantly shorter length of implantation. Backside damage was also graded for the mobile bearing and when combined with articular wear resulted in overall damage scores higher than both fixed-bearing designs. The fixed-bearing designs showed delamination and surface deformation, whereas the mobile bearing had no evidence of these damage modes. However, mobile-bearing components showed other types of wear, and significant wear damage was present on the bearing surfaces of the mobile-bearing implants despite a short time of implantation. At the time of conversion to a total knee arthroplasty, more than 50% of cases required the use of stems, augments, or constrained inserts for the tibial reconstruction. In conclusion, wear modes differed among UKA prosthesis designs. Revision of a UKA to a total knee arthroplasty remains complex with the tibial preparation more complicated than in the primary setting.

Backside Damage Corresponding to Articular Damage in Retrieved Tibial Polyethylene Inserts

Although motion between the polyethylene insert and tibial baseplate is one probable cause of backside wear, articular contact stresses and kinematic conditions may be additional factors. However, comparisons of articular and backside damage patterns are limited. We report the effect of physiologic loading on the modular capture mechanism and distribution of articular and backside surface damage patterns on retrieved tibial components. We evaluated damage patterns on 37 tibial inserts with a full peripheral rim capture mechanism, including six autopsy-retrieved components that were not previously disassembled and were available for mechanical testing. The duration of physiologic loading affected the modular capture mechanism and damage patterns. Backside damage revealed evidence of a mechanical interlock between the polyethylene insert and tibial tray consistent with the measured insert motion. In autopsy components retrieved after 2 to 6 years, inserts with the least motion had the longest duration of in vivo function and the largest backside damage area. The backside damage area and location corresponded to articular damage with damage patterns concentrated on the posterior half of the polyethylene inserts. Substantial differences between the articular and backside damage modes suggest different wear mechanisms exist at the two interfaces during physiologic loading.

Does Neck/Liner Impingement Increase Wear of Ultrahigh-Molecular-Weight Polyethylene Liners?

We explore the hypothesis that repetitive impingement increases wear of ultrahigh-molecular-weight polyethylene inserts. During revision total hip arthroplasty, 113 acetabular components were retrieved and examined for impingement, backside wear, and articular wear. Sixty percent of acetabular liners showed evidence of prosthetic impingement, with moderate or severe damage to the rim in 32%. Moderate or severe backside damage was present in 31%. Backside wear was found in 61% (22/36) of liners exhibiting impingement vs 16% (12/73) of liners without impingement ( P < .0001). The average articular wear rate of liners with moderate/severe impingement damage was 159 ± 42 mm 3/y, compared with 70 ± 21 mm 3/y for liners with no/mild impingement damage ( P = .02). Repetitive impingement frequently occurs after total hip arthroplasty and leads to a multitude of adverse events, including motion between the liner and the acetabular shell.

Does Neck/Liner Impingement Increase Wear of UHMWPE Liners?

Although impingement damage, backside wear, and damage to the femoral bearing surface are common observations of acetabular liners, they have traditionally been studied independently. In this study, we explore the hypotheses that repetitive impingement increases wear of UHMWPE inserts at both the articular surface and the backside surface, potentially compromising the durability and function of the hip replacement. One hundred thirteen acetabular components were retrieved during revision total hip arthroplasty after an average time in situ of 84 months. Each acetabular liner was examined with incident light and inspected for presence, location, and severity of signs of impingement and backside wear. The depth of penetration of the femoral head into the acetabular liner was also measured to calculate articular wear. Sixty percent (68/113) of acetabular liners examined showed evidence of prosthetic impingement, with moderate or severe damage to the rim in 32% (36/113) of components. Significant backside damage was present in 31% (34/109) of components. Moderate or greater backside wear was found in 61% (22/36) of liners exhibiting significant impingement damage vs 16% (12/73) of liners without impingement (P < .0001). The average wear rate of liners with moderate or severe impingement damage was 0.33 ± 0.07 mm/y, compared with 0.19 ± 0.04 mm/y for liners with mild or no impingement damage (P = .03). Repetitive impingement frequently occurs after THR and leads to a multitude of adverse events, including motion between the liner and the acetabular shell leading to backside wear and accelerated wear of the articular surface.

210 キャビテーション噴流によるバックサイドダメージゲッタリングのC-V特性(材料力学 II,2.学術講演)

210 キャビテーション噴流によるバックサイドダメージゲッタリングのC-V特性(材料力学 II,2.学術講演)

Backside Wear of Miller-Galante I and Insall-Burstein II Tibial Inserts

The objective of this study was to determine if there was a difference in the amount, type, and location of backside wear in the Miller-Galante I and Insall-Burstein II PE tibial inserts. A secondary objective was to determine if backside wear damage in these two designs was a function of clinical factors (patient height, weight, gender, age, and length of time of implantation), shelf life of the PE tibial insert, and tibial component thickness. Backside wear damage was assessed on 24 Miller-Galante I and 11 Insall-Burstein II tibial inserts (implantation time, 0.5-12.4 years). For both groups combined, implantation time was positively correlated to wear damage and to PE peg height into screw holes. The Miller-Galante I group had significantly larger PE pegs than the Insall-Burstein II group. The Miller-Galante I group had significantly more burnishing and larger PE pegs posteriorly than anteriorly. There was no correlation between insert shelf life before initial surgery and backside wear. The thinner the component, the larger the total damage scores in the Miller-Galante I group. This study supports the hypothesis that backside wear of PE tibial inserts may be influenced by design and component thickness and by clinical factors.

Evaluation of the effectiveness of back-side damage gettering in silicon introduced by a cavitating jet

Photocapacitance measurements have been performed to evaluate the electrical effectiveness of gettering by back-side damage, introduced by a cavitating jet into silicon wafers. The silicon wafers, which had their back sides damaged previously in localized areas, were intentionally contaminated and subsequently thermally treated to diffuse the contamination through the wafer. The density of deep levels varied between the areas with back-side damage and those without. The results obtained on back-side damaged areas were closer to those on the original starting material. These results confirm that the back-side damage introduced by a cavitating jet can function as gettering sites.

Wear and surface cracking in early retrieved highly cross-linked polyethylene acetabular liners.

A higher degree of cross-linking has been shown to improve the tribological properties of ultra-high molecular weight polyethylene in laboratory studies; however, its effect on in vivo behavior has not been well established. We investigated in vivo wear mechanisms in retrieved highly cross-linked polyethylene acetabular liners in order to determine if early in vivo wear behavior is accurately predicted by hip-simulator studies. A total of twenty-four liners (twenty-one explanted and one unimplanted highly cross-linked liners and two explanted ethylene-oxide-sterilized non-cross-linked liners) were examined for this study. The average age of the patients was 59.9 years, and the average time in vivo was 10.1 months. Articular surface damage on the front and back sides of the liners was assessed with an optical scoring system. Surface quadrants were assigned a grade from 0 to 3 according to the observed wear mechanisms and the percentage of surface affected. The micromechanisms of liner damage were evaluated with use of scanning electron microscopy. The average front and back-side explant damage scores were 11 (range, 2 to 26.5) and 6.7 (range, 3.7 to 13.3), respectively. There was consistent evidence of early surface deformation and cracking. All explants exhibited some form of surface change, including surface cracking, abrasion, pitting, or scratching. The original machining marks on the liner surface were observed to be either unaltered, drastically distorted, or absent. Highly cross-linked ultra-high molecular weight polyethylene acetabular liners that were retrieved at an average of ten months after implantation exhibited signs of surface damage that had not been predicted by in vitro hip-simulator studies. These devices had not failed clinically as a result of wear. The discrepancy between in vitro and in vivo wear surfaces may be due to variability in terms of in vivo lubrication and cyclic loading or may represent early surface damage mechanisms that are not well demonstrated by long-term simulator studies.

Gettering of Cu in Silicon Wafer by Using Cavitation Impacts

A novel gettering method using cavitation impacts is presented. Gettering is very important technique for IC manufacturing. Silicon wafers used as a substrate for semiconductors are often exposed to contamination during the device processes. If crystal defects are intentionally introduced into back-side of silicon wafer, metal impurities such as Cu and Fe in the wafer are trapped in the defects and gather into the region during heat cycles. As a result, the zone near the surface of the wafer that is used as active device region is kept off unwanted impurities. This technique is called gettering. In this paper, to introduce backside damage, which is one of the gettering techniques, cavitation impacts are utilized. Cavitation bubbles produce high-pressure impacts upon collapsing. The suitable damage can be introduced by controlling the intensity of cavitation impacts. The high speed submerged water jet with cavitation, i.e., a cavitating jet, was used to cause cavitation impacts. The cavitating jet can introduce backside damage without the use of particles, as in shot blasting that is popular technique. In order to confirm the gettering effectiveness of the damage introduced by a cavitating jet, an experimental study was carried out. The silicon wafer treated by the cavitating jet was intentionally contaminated with solution of Cu(NO3)2. The wafer was then thermally treated. The surface was observed after etching that makes defects on the surface observable. On the surface of the wafer having no gettering effectiveness, defects which were induced by contamination are observed. If the wafer has gettering effectiveness, defects are not observed on the surface. Gettering effectiveness of the damage introduced by the cavitating jet was shown.

Back Side Damage Gettering of Cu Using a Cavitating Jet

The effectiveness of the back side damage introduced by a cavitating jet to getter contamination in silicon has been demonstrated. Back side damage required for gettering has been introduced successfully into a silicon wafer, utilizing impacts caused by the cavitating jet. A wafer, which had previously been back side damaged in a selected area, was intentionally contaminated and submitted to a thermal treatment. The effectiveness of gettering was confirmed by the observation of etch pits on the surface, induced by the intentional contamination, other than in regions below which there was back side damage. No etch pits were observed in regions with back side damage.

キャビテーション噴流により導入したバックサイドダメージの評価(技術OS3-1 半導体デバイス,技術OS3 電子・情報機器と材料力学)

キャビテーション噴流により導入したバックサイドダメージの評価(技術OS3-1 半導体デバイス,技術OS3 電子・情報機器と材料力学)

Optical analysis of surface changes on early retrievals of highly cross-linked and conventional polyethylene tibial inserts

Retrieved tibial liners of highly cross-linked and conventional polyethylene were examined for articular and backside surface damage. Surfaces were graded for pitting, machine-mark loss, scratching, abrasion, delamination, and embedded debris. Whereas no difference existed in the damage score for the 2 groups, the highly crosslinked group showed significantly less elimination of machine marks. Wear, surface plastic deformation, or a combination, could account for the damage on these components. Only 1 of the highly crosslinked polyethylene inserts was available for destructive testing. That insert was melted to activate the shape memory, and thus differentiate, between wear versus plastic deformation. Nearly all changes on the articular and backside surfaces disappeared upon melting, and original machining marks reappeared, suggesting that the surface changes for that component were primarily the result of plastic deformation and not material removal.

Study of silicon backside damage in deep reactive ion etching for bonded silicon-glass structures

For devices of bonded silicon and glass structures fabricated by deep reactive ion etching (DRIE), it is important to avoid damage at the silicon sidewall and backside during through-wafer etching in order to ensure reliability of devices. The silicon damage caused by charge accumulation at the glass surface is inhibited by means of an electrically conducting layer patterned onto the glass and connected with the silicon. In this study, indium tin oxide films were applied in order to identify the positions of silicon damage in the structural layout without destruction of samples. From the results, we report that there exists silicon damage caused by charge accumulation at the silicon islands divided by DRIE and we present important rules for mask layout when utilizing this method.

Paper Transport in Duplex Color Radiation Fusing, Continuous and Flash

We had reported earlier (NIP 18) the use of high intensity continuous radiation and pulsed radiation for color independent radiant fusing. We had found that there is a potential if special developed sharp melting dry ink is used.At duplex fusing of sheet substrates with electrophotographic engines of duplex loop type the paper passes twice the fusing station with the risk of reheating the first image above softening point. We have analyzed different methods of paper feeding in the fusing area: With radiant fusing the heating time is relatively long with the risk of backside damage. Thus a non-contact paper feeding in the heating zone followed by a non contact paper feeding in the following cooling zone is required.At flash fusing the energy is incorporated into the surface for short time intervals only and backside problems are not expected. To prove this we evaluated the time dependant backside temperature of the substrate after flash fusing with a fast pyrometer. We could prove that backside image artifacts of toner back side layers in full color printing start well above the flash energy density necessary for fusing. Thus conventional contact paper transport means like Kapton&#xAE; belts are sufficient for duplex color flash fusing of sheet materials.

シリコン/ガラス構造におけるDeep-RIEプロセスの開発

For devices with bonded silicon and glass structures fabricated by deep-RIE, it is important to avoid damage at the silicon backside and sidewall during through-wafer etching in order to ensure reliability of devices. The silicon backside damage is caused by charge accumulation at the glass surface. This paper reports the novel method to avoid the processing damage occurred in silicon structures of accelerometers by means of an electrically conducting layer patterned onto the glass and connected with the silicon. The positions of silicon damage in the structural layout were identified without destruction of samples by using transparent indium tin oxide (ITO) films as the electrically conducting layer. From the experiments, it was found that there exists silicon damage caused by charge accumulation at the silicon islands isolated by deep-RIE and we present important rules for mask layout when utilizing this method. Finally, the improved results of shock tests are briefly shown.

A method to evade silicon backside damage in deep reactive ion etching for anodically bonded glass–silicon structures

Due to the microloading effect, an overetch in through-wafer etchings by deep reactive ion etching (DRIE) has to be considered in the fabrication of glass–silicon structures, which results in damages of the silicon surfaces exposed to an ion bombardment. This paper reports on a new method, in which a metal layer is located on the glass surface and electrically connected with the silicon substrate. Although, structures are overetched for a long time, the silicon surfaces remain intact. The results show interdependency between the position of the metal layer on the glass surface and the gap separating the silicon and glass surfaces.

306 キャビテーション噴流によるシリコンウェーハへのバックサイドダメージの導入(学生賞セッションII)

306 キャビテーション噴流によるシリコンウェーハへのバックサイドダメージの導入(学生賞セッションII)

Evaluation of mechanical damage by high resolution x-ray diffraction and minority carrier recombination lifetime in silicon wafer

In Czochralski silicon wafers, the effect of mechanical back side damage was systematically analyzed by x-ray diffuse scattering and minority carrier recombination lifetime measurements. X-ray section topography and wet oxidation/preferential etch methods were also employed. A liquid honing method was used to induce mechanical damage, and the damage grade was varied by controlling process parameters. A high resolution x-ray analysis of the samples was carried out before and after heat treatment at 1100 °C for 60 min. The magnitude of diffuse scattering was analyzed quantitatively by integrating the excess intensity of diffuse scattering into a reciprocal space map and its correlation with the mechanical damage was examined. As the grade of mechanical damage increased, the degree of diffuse scattering increases and minority carrier recombination lifetime decreases, suggesting the generation of more defects. We discuss other experimental results from the viewpoint of the structure–property relationship.

On Point Defect Gettering by Back-Side Damage in the Si-SiO&lt;sub&gt;2&lt;/sub&gt; System

On Point Defect Gettering by Back-Side Damage in the Si-SiO&lt;sub&gt;2&lt;/sub&gt; System

Relaxation-Induced Gettering of Metal Impurities in Silicon: Microscopic Properties of Effective Gettering Sites

ABSTRACTSome gettering processes like internal gettering or backside damage gettering base on heterogeneous precipitation of metal impurities at defects in pre-de ter mined parts of silicon wafers during cooling from high temperatures. We consider microscopic properties of effective heterogeneous nucleation sites for cobalt, nickel and copper impurities from the fundamental point of view of suicide precipitate formation. We follow the basic concept that such gettering sites are defects which allow fast precipitation, i.e. which remove kinetic limitations known from homogeneous precipitation of these impurities at small supersaturation. For Co and Ni it follows that distorted lattice sites in the core of dislocations may establish high incorporation rates of interstitial atoms into suicide particles, whereas for Cu sinks for silicon self-interstitials are suitable gettering sites.