Grain Boundaries In Diamond Films On Si(001)

Grain boundaries in [001]-oriented diamond films deposited on Si(001) by microwave-assisted chemical vapor deposition have been investigated in plan-view and cross-section samples using high-resolution electron microscopy. The poly-crystalline diamond films used in this study had large fractions of [001]-oriented grains with typical lateral dimensions of 2 μm at film thicknesses beyond 10 μm. Grains with growth orientations near (001) exhibit generally small-angle orientation deviations between their crystal lattices. Small-angle grain boundaries of symmetric and asymmetric geometry with misorientation angles below 15° are investigated in both [110]- and [001]-directions. It is found that the structures of such small-angle grain boundaries can be described by a dislocation model. These grain boundaries are on average parallel to the {110}-plane and contain in many cases micro-facets parallel to {lll}-planes. Large-angle grain boundaries with tilt angles up to 40° are also observed in interconnected films of smaller thickness. In all cases structural units with large open volumes and additional second phases are not found at the grain boundaries.

Quantitative HRTEM investigation of an obtuse angle dislocation reaction in gold with a CScorrected field emission microscope

We investigate quantitatively the non periodic arrangement of atom columns surrounding an obtuse angle dislocation reaction in gold utilizing a CM200 FEG instrument equipped with a spherical aberration corrector. The in-plane component of the Burgers vector of the observed stair-rod dislocation is ⅙ [110]. Column positions are determined from single lattice images and compared with those from a reconstructed electron exit wave. We find that absolute position measurements of 1–3 pm require knowledge of the defocus to better than 1 nm which can be achieved by a reconstruction of the exit-plane wave. In contrast, a defocus value of 8.9 nm already leads to apparent displacements as large as 35 pm if single lattice images are considered. Such discrepancies are either caused by residual lens aberrations or by the superposition of delocalization effects at interfaces caused by defocusing of the objective lens. Commonly, however, only relative displacements are of interest. In this case the CS corrector improves the interpretability of single defocused lattice images with a remarkable signal to noise ratio which is advantageous for in-situ experiments. As an example for analyzing in-situ experiments we determine displacements recorded in a time resolved experiment of radiation induced atom motion on surfaces.

[Valgus high tibial osteotomy - long-term results]

PURPOSE OF THE STUDY

The aim of the study was to evaluate the long-term results in a group of patients treated by proximal tibial valgus osteotomy.

MATERIAL

A group of 92 high tibial osteotomies performed in the 1985/1994 period were evaluated. All were indicated for primary osteoarthritis. Closing wedge osteotomy was the technique used. Staple-fixed osteotomy was immobilised in a plaster cast for 6 weeks in 44 cases. Osteotomy fixed with a plate in 35 or with a cerclage in 13 cases was immobilised for two weeks.

METHODS

Recurrent intensive pain and walking problems were regarded as a termination of the favourable effect of osteotomy. This was evaluated by the Kaplan-Meier survival analysis. The tibio-femoral angle 5 to 10 degrees of valgus was considered as an optimal deformity correction. The results were compared in relation to complications, correction, duration of immobilisation and patient age.

RESULTS

The mean age of the patients was 59.8 ± 8.7 years (range, 42 to 78). During surgery, medial unicompartmental arthritis, grade II or higher, was recorded in 59 patients (64.1%) and multicompartmental knee arthritis was found in 66 patients (71.7%). The absence of noticeable problems was reported by 80.4% of the patients at 10 years and by 30.4 % at 15 years after osteotomy. Surgery decreased the range of motion from 100 ± 6.9 to 94.5 ± 17.7 degrees flexion (p = 0.04). Poor correction and post-operative complications were found in 21 patients (22.8 %) who also experienced significantly worse outcomes (p = 0.003). Good results after 10 and 15 years were reported by 47.6% and 14.3% of the patients, respectively. Of 71 patients (77.2%) who had good correction and surgery without complications, the osteotomy showed a good effect in 90.1% at 10 post-operative years and in 35.2% at 15 years. A longer immobilisation resulted in significantly worse results (p = 0.04) and a restricted range of motion (p = 0.02). The patients younger than 60 years achieved better results than the elderly patients (p = 0.38), but the difference was not significant.

DISCUSSION

Good results were recorded up to 10 years after osteotomy, although some patients had had worse arthritis than recommended for this procedure. Inadequate correction and complications deteriorated the effect of osteotomy. With the opening wedge technique it is easier to achieve good correction, and stable fixation allows for active physical therapy. Better long-lasting results are achieved with total knee arthroplasty (TKA). However, in young active adults TKA can fail prematurely. Osteotomy can postpone the necessity of this implantation. If TKA is performed after osteotomy, functional outcomes are similar to those after primary implantation.

CONCLUSIONS

Corrective osteotomy is an effective method in patients below 60 years who have an early-stage osteoarthritis of the knee with axial mal-alignment. If the tibio-femoral angle is over-corrected to more than 10 degrees valgus, patelo-femoral pain will ensue. Post-operative active physical therapy is necessary. After bone healing, implants must be removed. Corrective osteotomy has not been overcome by the development of joint replacement techniques, but both methods are complementary in the treatment of osteoarthritis.

[Venous thromboembolism prophylaxis after total hip arthroplasty]

PURPOSE OF THE STUDY The authors compare the frequency of thromboembolic disease in the patients receiving prophylactic therapy for 10 days with that in the patients having a prolonged course of preventive treatment recommended for up to 35 days after total hip arthroplasty (THA). MATERIAL The group first evaluated comprised patients undergoing total hip replacement in 2005 and 2006 when enoxaparin was administered for 10 days after surgery. Patients with revision THA were not included. The other group included patients operated on in 2008 who received preventive treatment for 35 post-operative days either with enoxaparin for the whole time, or with enoxaparin for 10 days of hospital stay and then warfarin up to the 35th day after surgery. Patients under going revision THA and those taking other prophylactic agents were not evaluated. METHODS The evaluation of the 2005/6 group included retrospective reviews of medical records, questionnaires sent to the patients and information received from their general practitioners. The 2008 group assessment was based on the information obtained at the patient's follow-up visit at 3 months and completed with data from the questionnaires and medical notes. We focused on the records of distal or proximal deep vein thrombosis in lower extremities and of pulmonary embolism including cases with a fatal outcome. Complications associated with pharmacological prevention were also recorded. RESULTS In the 2005/6 group including 478 patients with an average age of 67.2 years, 23 (4.8 %) patients developed thrombo- embolic disease within 3 months of surgery, six patients had pulmonary embolism of which two of them died. The thromboembolic complication developed at a median of 30.5 post-operative days, i.e., after patient discharge from hospital. In the 2008 group comprising 289 patients with an average age of 63.8 years, three patients (1 %) developed thromboembolic disease within 3 months of surgery. Of them, one woman had deep vein thrombosis in relation to a high factor VIII level; and one developed pulmonary embolism with no fatal outcome. Only the minority of patients (6.9 %) continued enoxaparin therapy, the majority (93.1 %) preferred conversion to warfarin after discharge from hospital. Of the total number of 289 patients evaluated, complications associated with prophylactic treatment were recorded in 52 patients (18 %), name- ly, in 35 patients (12.1 %) it was difficult to establish the correct dosage of warfarin, in 13 patients (4.5 %) warfarin caused minor bleeding or dyspepsia and in 4 patients (1.4 %) major bleeding was recorded. DISCUSSION In our study the patients receiving a 10-day prophylactic therapy showed a slightly higher occurrence of thromboembolic disease within 3 months of THA surgery (4.8 %) than the patients reported by Eikelboom et al. (4.3 %). The results of prolonged prophylactic treatment for at least 35 days were similar, thromboembolic disease was found in 1 % of the patients. The development of thromboembolic event was recorded in our study at a median of 30.5 post-operative days, as compared with a median of 17 days in the study by Liebermann et al. In both studies, most of the thromboembolic complications developed after the patients had been discharged from hospital. The majority of patients chose warfarin for prolonged preventive treatment. There was a high complication rate (18 %) due to not finding the correct warfarin dosage or because of its overdose CONCLUSIONS Patients undergoing THA are at high risk of developing deep vein thrombosis. The risk can be markedly reduced by prolonged pharmacological ophylaxis It is recommended that the use of warfarin for this prolonged therapy should be care- fully considered, because its optimal dose is difficult to establish and its overdose may cause serious complications.

Charcot arthropathy of the knee. A case-based review

The diagnosis of Charcot arthropathy in the knee is rare. However, there is an increasing number of diabetic patients, and they are living longer due to improvements in treatment. Because neuropathic arthropathy is a late effect of peripheral neuropathy, we can expect an increasing incidence of neuropathic arthropathy. Total knee arthroplasty is the preferred choice of treatment by patients, although it may also be associated with a high incidence of serious complications. This case report presents a young female with diabetes mellitus and Charcot arthropathy of the knee managed by total knee arthroplasty and a literature review. The report encompasses a 5-year follow-up of the patient, from the first contact after knee distortion through diagnosis of Charcot arthropathy and the performance of total knee arthroplasty with outpatient controls. The diagnosis was established on the basis of the rapid destruction of the medial tibial condyle after knee distortion in a patient with neuropathy. Neuropathic arthropathy was confirmed by histology. The patient refused knee fusion and total knee arthroplasty was performed. The patient quickly achieved a painless, stable knee with a 130-degree range of motion. However, a radiolucent line appeared under the tibial component due to premature weight-bearing. The patient was ordered to refrain from weight-bearing for the next 3 months, and the knee was healed. While the management of Charcot arthropathy in the knee remains controversial, total knee arthroplasty is not a contraindication. Early diagnosis, appropriate choice of implant and operative technique, and long-term weight protection are essential.

In vivo behaviour of low-temperature calcium-deficient hydroxyapatite: comparison with deproteinised bovine bone

This study aims to evaluate in detail the biological osteoconductive properties of the low-temperature synthetic porous calcium-deficient hydroxyapatite and to compare it with the biological apatite. Bone reactions to granules of similar sizes of the low-temperature hydroxyapatite and commercially available non-sintered deproteinized bovine bone were compared. Two different temperatures were used to fabricate two batches of newly developed porous hydroxyapatite with different carbonate groups content and specific surface area. The histological analysis of specimens with histomorphometry was performed at different time after in vivo implantation. Based on histological analysis, the level of bone formation in the spaces between the implanted granules and through the interconnected pores of all implanted materials within a cortical region (bone area ingrowth 72-85 %) was several-fold higher than within a cancellous bone site (bone area ingrowth 16-28 %) at three and six months after implantation. Within the cancellous bone site, bone coverage of the implanted material at six months was significantly higher in hydroxyapatite material fabricated using low-temperature synthesis and subsequent processing at 150°C than in hydroxyapatite scaffold developed using low-temperature synthesis with subsequent processing at 700°C or deproteinized bovine bone. According to our study, the bioactive properties of the low-temperature calcium-deficient hydroxyapatite are comparable with the biological apatite. The favourable influence of a high specific surface area of a low-temperature calcium-deficient hydroxyapatite on in vivo bone formation was emphasized.

Manganese adlayers on i-Al-Pd-Mn quasicrystal: growth and electronic structure

Pseudomorphic growth of thin elemental metal films is often observed on a variety of crystalline solids. On quasicrystalline surfaces with their complex structure and the absence of translational periodicity, the situation is different since elemental metals do not exhibit quasicrystalline order, and hence the specific interaction between overlayer and substrate is decisive. Here we study the growth of manganese films on an icosahedral i-Al-Pd-Mn alloy with a view to establishing the growth mode and electronic structure. Although we observe an exponential intensity variation of the adlayer and substrate related x-ray photoemission spectroscopy (XPS) peaks, low energy electron diffraction (LEED) shows that Mn adlayers do not exhibit quasicrystallinity. The detailed structure of the Mn 2p core level line reveals considerable electronic structure differences between the quasicrystalline and elemental metal environment. Evidence of a substantial local magnetic moment on the Mn atoms in the overlayer (about 2.8  µ(B)) is obtained from the Mn 3s exchange splitting.

Behaviour of nonresorbable bioactive glass-ceramic implanted into long bone defects: comparison with cancellous allografts

INTRODUCTION

The goal of this retrospective study was to compare the long-term results after implantation of the nonresorbable glass-ceramic material and transplantation of the cancellous allografts into the defects of long bones.

METHOD

The bone cysts were excochleated and filled using granules of glass-ceramic material or cancellous allografts. Clinical, radiographic and scintigraphic examinations of 30 patients were carried out 2-14 years after their surgery.

RESULTS

Though signs of complete incorporation allowing full weight-bearing capacity were observed on plain radiographs, we detected pain in six out of nine patients after diaphyseal implantation of nonresorbable glass-ceramic. We found an increase in (99) (m)Tc-methylene diphosphonate uptake on the delayed images in the area of glass-ceramic implantation, mainly in its diaphyseal location. In patients after bone transplantation, the cancellous allografts were completely integrated and the scintigraphic findings were physiological.

CONCLUSION

The implantation of the nonresorbable glass-ceramic material into the diaphyseal defects of long bones is not suitable based on our study.

Effect of a single dislocation in a heterostructure layer on the local polarization of a ferroelectric layer

We study, on an atomic scale, the influence of a single dislocation in a SrTiO3 sublayer on the local ferroelectric polarization of the neighboring ferroelectric PbZr0.2Ti0.8O3 (PZT) sublayer in an epitaxial SrTiO3/PbZr0.2Ti0.8O3/SrTiO3 three-layer heterostructure. The strain field of the dislocation in the SrTiO3 layer propagates across the interface into the PZT layer and leads to a strong variation of the c-lattice parameter of the PZT layer. Accompanying a strong reduction of the c-lattice parameter, the off-center displacements of the Zr/Ti atoms away from the center of the oxygen octahedra are also strongly decreased, resulting in a decrease of the local spontaneous polarization by up to 48%.

Methotrexate released in vitro from bone cement inhibits human stem cell proliferation in S/G2 phase

Methotrexate (MTX) released from bone cement showed a useful local effect in animal models of bone tumours. However, local toxic reactions such as impaired wound healing were observed in areas surrounding the MTX-loaded implant. Therefore, we hypothesised that MTX released from bone cement would have harmful effects on human mesenchymal stem cells (MSC)-one of the basic components of bone marrow and tissue reparatory processes. Moreover, elution of MTX was calculated from implants prepared either with liquid or powdered MTX. During the 28-day incubation, the cement compounded with liquid MTX showed the highest elution rate of the drug. MTX released from pellets produced a significant decrease in proliferation of MSC as a consequence of a blockade of their cell cycle in the S/G2 phase. These findings indicate impairment of stem cell function in marginal areas surrounding the MTX-loaded cement and may help to explain problems with regeneration of tissues in these locations.