Development and characteristics of a synovial-like interface membrane around cemented tibial hemiarthroplasties in a novel rat model of aseptic prosthesis loosening.

OBJECTIVE: Aseptic prosthesis loosening (APL) is related to the formation and aggressive growth of a synovial-like interface membrane (SLIM) between prosthesis and bone. However, investigation of the early phases of SLIM development in humans presents major difficulties. This study was undertaken to develop and characterize the usefulness of a novel animal model of APL that is based on an established model of defined exercise in a running wheel by Wistar rats that have been subjected to intracranial self-stimulation (ICSS). METHODS: Cemented tibial hemiarthroplasties were implanted into the left knees of 7 male Wistar rats. After 2 weeks, exercise in a running wheel was started in all rats, with a running-load of 2 hours/day for 5 days/week. Six months postoperatively, the knee joints were removed, decalcified, and embedded in paraffin. Histologic evaluation on hematoxylin and eosin-stained sections was performed to investigate the development of a SLIM and the presence of cement debris particles. To characterize the SLIM on a molecular level and investigate growth-regulating factors, the expression of transforming growth factor beta (TGFbeta) and the anti-apoptotic molecule Bcl-2 was analyzed by immunohistochemistry. RESULTS: Although the prostheses appeared mechanically stable after 6 months, the development of SLIM with areas of bone resorption was seen in all samples. Resembling human SLIM, these membranes consisted of loose fibrous tissue, with cement debris particles located particularly at sites originally attached to the prostheses. Immunohistochemistry studies revealed the expression of TGFbeta and Bcl-2 in all specimens. Interestingly, staining for TGFbeta and Bcl-2 was restricted to areas where the SLIM were attached to bone. In contrast, there was only negligible expression of both proteins at sites adjacent to the prostheses. CONCLUSION: Our findings demonstrate that the ICSS Wistar rat model constitutes a feasible tool for studying early stages of APL, and specifically the effect of defined running exercise on SLIM formation. The results further suggest that both cellular proliferation, as stimulated by TGFbeta, and altered apoptosis contribute to early stages of SLIM formation. The expression patterns of TGFbeta and Bcl-2 indicate that the growth of the SLIM is initiated and promoted from the bone rather than from the prosthesis.

[Illumination conditions of visually impaired people under private domestic circumstances - clinical study on 91 patients]. / Die Beleuchtung des Leseplatzes im privaten Wohnbereich Sehbehinderter - Eine klinische Studie an 91 Sehbehinderten.

BACKGROUND: The illuminance and quality of illumination are important factors for visually impaired people to improve contrast sensitivity and reduce glare sensitivity at domestic reading places. The ability of visually impaired people to read can often be improved by simple strategies. At the onset of multiple ophthalmic diseases an optimum of lighting is often the tool of choice to restore reading capability. PATIENTS AND METHODS: 91 visually impaired people were included in this study. 76 were equipped with optical reading tools and 15 used a television reading aid. The illumination conditions of reading places were investigated. This included measurements of illuminance and information about the light source and localization, direction of light and modelling. The understanding of the importance of optimal illumination was judged by a graded scale from 1 - 5. RESULTS: Twenty-two of the 76 visually impaired people equipped with optimal reading tools were using an extra reading place. All others used livingroom or kitchen tables as their preferred reading place. 10 % of the reading places had a illuminance of above 5000 lx, whereas 63 % had less than 500 lx. Incandescent lamps dominated as artificial light sources. In 60 % of all reading places ceiling light sources were predominant. Only 40 % of the patients used an additional reading place illumination. For television reading aids the ceiling light caused a decrease of contrast sensitivity in 1 % - 7 %. If questioned, 90 % of the patients were highly sensitive to problems of good illumination of their reading places. This is, as our study revealed, in contrast to the conditions under which most of the visually impaired people read. CONCLUSIONS: Domestic reading places revealed considerable deficits concerning the illumination. Most visually impaired people do not realize this problem. Ophthalmologists, opticians, low-vision-, orientation- and mobility-trainers are recommended for rehabilitation.

[At home utilization of low-vision aids by the visually impaired]. / Nutzungshäufigkeit vergrössernder Sehhilfen im Wohnbereich von Sehbehinderten.

BACKGROUND: The increase of life expectancy causes a rising number of partially sighted. Therefore our Department of Ophthalmology has founded a laboratory for partially sighted 7 years ago. To optimize patient care, the results were now reinvestigated. MATERIALS AND METHODS: For the present study, 125 patients were selected by geographical aspects (home nearby clinic) from the lab's pool. After a 3 month minimum period of using the low-vision aid (LVA) patients were visited at their homes. Near visual acuity, distance visual acuity, magnification, and contrast sensitivity were studied under domestic and optimized conditions of illumination. Patients were interviewed in detail to investigate their habits of LVA use. RESULTS: An overall number of 94 patients (66 females and 28 males) could be evaluated. The most patients were between 80 and 84 years old. Vision impairment was attributable mostly to macular degeneration (55%) and diabetic retinopathy (21%). Visual acuity and contrast sensitivity decreased during the period of investigation. 79% of the patients had a unsatisfactory domestic illumination (< 1000 lx). Only 23% of the patients used their LVA at a fixed location. Main field of using LVA was reading (68%). The LVA were rarely used for writing and other fields of practice. 76% of LVA were used daily, more than 50% for a maximal duration of 1 h/d. Magnifiers were preferably used for short-time activities. Closed circuit television systems (CCTV) had a very good acceptance. Telescopes were characterized by a very high rate of rejection. The number of non-used LVA was approximately a fifth. Reasons were decreased visual acuity, impractical handling, missing introduction by delivering optician (54%) as well as unsatisfactory illumination. CONCLUSIONS: Improved patient care can be obtained by regular check-up visits (6 months), enhanced illumination, low-vision training, home visits, multi-disciplinary care and modified prescription of LVA.