PubMed Health⌕ Search

Biomedical subjects

M Böhler

Publications and source records attributed to M Böhler.

12 recordsLinked to original sources
PubMed2004

Partial ozonation of activated sludge to reduce excess sludge, improve denitrification and control scumming and bulking.

Disposal of sewage sludge is forbidden and agricultural use of stabilized sludge will be banned in 2005 in Switzerland. The sludge has to be dewatered, dried, incinerated and the ashes disposed in landfills. These processes are cost intensive and lead also to the loss of valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Partial ozonation of the return sludge of an activated sludge system reduces significantly excess sludge production, improves settling properties of the sludge and reduces bulking and scumming. The solubilized COD will also improve denitrification if the treated sludge is recycled to the anoxic zone. But ozonation will partly inhibit and kill nitrifiers and might therefore lead to a decrease of the effective solid retention time of the nitrifier, which reduces the safety of the nitrification. This paper discusses the effect of ozonation on sludge reduction, the operation stability of nitrification, improvement of denitrification and gives also an energy and cost evaluation.

Agriculture↗
PubMed2002

Adverse tissue reactions to wear particles from Co-alloy articulations, increased by alumina-blasting particle contamination from cementless Ti-based total hip implants. A report of seven revisions with early failure.

We revised seven alumina-blasted cementless hip prostheses (Ti-alloy stems, cp Ti threaded sockets) with low- or high-carbon Co-alloy bearings at a mean of 20.1 months after implantation because of pain and loosening. Histological examination of the retrieved periprosthetic tissues from two cases in which the implant was stable and three in which the socket was loose showed macrophages with basophilic granules containing metal and alumina wear particles and lymph-cell infiltrates. In one of the two cases of stem loosening the thickened neocapsule also contained definite lymphatic follicles and gross lymphocyte/plasma-cell infiltrates. Spectrometric determination of the concentration of elements in periprosthetic tissues from six cases was compared with that of joint capsules from five control patients undergoing primary hip surgery. In the revisions the mean concentration of implant-relevant elements was 693.85 microg/g dry tissue. In addition to Cr (15.2%), Co (4.3%), and Ti (10.3%), Al was predominant (68.1%) and all concentrations were significantly higher (p < 0.001) than those in the control tissues. The annual rates of linear wear were calculated for six implants. The mean value was 11.1 microm (heads 6.25 microm, inserts 4.82 microm). SEM/EDXA showed numerous fine scratches and deep furrows containing alumina particles in loosened sockets, and stems showed contamination with adhering or impacted alumina particles of between 2 and 50 microm in size.

Aged↗
PubMed2000

Wear debris from two different alumina-on-alumina total hip arthroplasties.

We compared wear particles from two different designs of total hip arthroplasty with polycrystalline alumina-ceramic bearings of different production periods (group 1, before ISO 6474: group 2, according to ISO 6474). The neocapsules and interfacial connective tissue membranes were retrieved after mean implantation times of 131 months and 38 months, respectively. Specimen blocks were freed from embedding media, either methylmethacrylate or paraffin and digested in concentrated nitric acid. Particles were then counted and their sizes and composition determined by SEM and energy-dispersive x-ray analysis (EDXA). The mean numbers and sizes of most alumina wear particles did not differ for both production periods, but the larger sizes of particle in group 1 point to more severe surface destruction. The increased metal wear in group 2 was apparently due to alumina-induced abrasion of the stems. In this study the concentrations of particles in the periprosthetic tissues were 2 to 22 times lower than those observed previously with polyethylene and alumina/polyethylene wear couples.

Adult↗
PubMed2000

Comparison of migration in modular sockets with ceramic and polyethylene inlays.

This study compared migration in 73 cementless total hip arthroplasties (THAs) with either alumina ceramic (n = 23) or polyethylene (n = 50) inlays; prosthesis sockets and stems were identical except for the inlays. After 7 years of follow-up, 5 sockets (4 with ceramic and 1 with polyethylene inlays) had been revised an average of 63.3 months (range: 49-81 months) after implantation, and survival analysis showed a significantly higher revision rate for sockets with ceramic inlays (89 +/- 6%) versus polyethylene inlays (98.2 +/- 1.7%) (P = .032). Migration analysis of the first three postoperative years revealed significantly higher vertical migration in sockets with ceramic inlays (P = .047), in patients aged <60 years (P = .02), and in osteoporotic type C bone (A versus C, P = .0071 and B versus C, P = .0004).

Ceramics↗
PubMed1999

Loss of correction after lateral closing wedge high tibial osteotomy--a human cadaver study.

In 12 human cadaver tibiae, osteotomies were carried out at two levels (2 and 3 cm from the distal joint line) with three different wedges (5 degrees, 10 degrees, 15 degrees) to evaluate the influence of displacement of the osteotomy fragments on areas of cortical contact. In undisplaced osteotomies (medical cortical edges superposed) cortical contact areas formed 28% (level 2 cm) and 40.5% (level 3 cm) of the cortical circumference of the proximal fragments (NS). Wedge angles and levels of osteotomy displayed no statistical differences. In displaced osteotomies cortical contact decreased significantly (P < 0.05). Displacing the distal fragment laterally, medial cortical contact is lost, and weight-bearing leads to revarisation as cancellous bone sustains only 3 MPa, and the measured compressive stresses at the medial edge amounted to 6 MPa on average. Displacing the distal fragment medially leads to a decrease of total cortical contact, too, but at the medial edge of the osteotomy cortical contact areas are still present. As a result of the study, postoperative weight-bearing without additional plaster cast fixation is recommended only in cases with undisplaced fragments.

Cadaver↗
PubMed1994

Ten-year results of cemented Weller-type total hip arthroplasties. Analysis using different definitions of failure.

The first 100 consecutive cemented Weller-type total hip arthroplasties carried out between 1976 and 1977 were reexamined. Clinical analysis of 43 implants with more than 10 years follow-up showed that results were excellent in 21 patients (49%), good in 13 (30%), fair in 7 (16%) and poor in 2 (5%). Radiographic analysis revealed 33 (87%) stable femoral and 31 (81%) stable acetabular components. Statistical survivorship analysis of all 100 implants produced a probability of reoperation of 6.2%, a probability of radiographic implant loosening of 28.2% and a probability of radiographic loosening with clinical symptoms of 7.6%. The definition of failure should be "radiographic loosening of the prosthesis with clinical symptoms" because this evaluation seems to have the best clinical relevance. Concerning the fact that the cement fixation was not performed to today's standard, the results after more than 10 years with this total hip system (Weller long stem) are sufficient.

Adult↗
PubMed1991

Girdlestone's modified resection arthroplasty.

Thirty-three patients were operated for septic (n = 20) and aseptic (n = 13) loosening of their hip prostheses using Girdlestone's operation over 10 years. An average of 46.6 months later, 22 of these patients were given a follow-up examination. Clinical evaluation according to Harris showed an improvement in mean values from 25 to 53 points, which can be attributed mainly to a marked reduction in pain, as function remained poor and the patients still depended on walking aids. The infection ceased in 92% of the patients with septic prosthesis loosening.

Aged↗
PubMed1987

Survival analysis of an uncemented ceramic acetabular component in total hip replacement.

Follow-up examinations of 67 implants of cement-free ceramic sockets show the need for an exact definition of failure, to warrant comparable evaluations of results. Statistical survival analysis offers the possibility of presenting both the incidence of failures and the dates of their occurrence. If only revision surgery with removal of the socket is considered to be a failure, our material shows the "survival quota" of the ceramic socket after 8 years to be 96.7% +/- 2.2%. If radiological signs of loosening are included in the evaluation of failures, the "survival quota" of the stable implants is reduced to 81.9% +/- 6.9%.

Acetabulum↗
PubMedDate not supplied

[Gonarthrosis and empyema in geriatric patients. Combined synovectomy and KTEP implantation procedure].

ISSUE: Is a one stage procedures with open synovectomy and implantation of cemented knee endoprostheses in patients with empyemas of the knee and concomitant osteoarthritis suitable to reduce morbidity and increase early mobility? METHOD: Three female patients (age [symbol: see text] 88 yrs.) with acute empyema of arthritic knee joints (Pathogen: Staph. aureus) were treated with open synovectomies and implantations of cemented TKA's in a one stage procedure at mean 3 days (1-6) after admission. After 4.6 months (3-6) we carried out the last clinical and radiographic examination and after 15 months (11-21) a telephone questionnaire. RESULTS: The mean operation time was 2.4 hrs. (2-3), the perioperative blood loss at mean 1040 cc (800-1180 cc) and patients received 4 units blood (4-5). Parenteral antibiotics were administered for at mean 21 days (18-25 d). 33 days (27-39) after surgery the patients could be discharged, all of them ambulated with a walker, the operated joints had no signs of infection and blood parameters i.e. leucocyte count, crp and ESR dropped. At the time of the latest follow up examination there were neither clinical nor radiographic any signs that infections recurred. Two patients ambulated with crutches, one still with a walker. The HSS-Score increased from preop. 54 pts. up to 80 pts. at the follow up. CONCLUSION: Due to our results, a one stage procedure with open synovectomy and implantation of cemented total knee endoprostheses seems to be a considerable alternative for the treatment of geriatric patients suffering from knee empyema and severe osteoarthritis.

Aged↗
PubMedDate not supplied

[Prognosis of hip endoprostheses after disorders of wound healing].

41 draining sinuses after THR were treated by debridement without exchanging the implants. Positive bacterial cultures were obtained in 23 patients-the ilio tibial tract was found open in 19 cases (82%). The bacterial cultures were negative in 18 patients-the ilio tibial tract was found open in 7 cases (38%). Revisions took place 21 days (9-43) after primary implantation. At the time of the follow up (0 72 months postoperatively) 7 patients had been revised (8-97) because of recurrence of infection. The results of debridements of contaminated sinuses depend on the ilio tibial tract. Revisions were successful in three out of four paces with an intact, and only in eight out of nineteen cases with an open ilio tibial tract. Besides proper bacterial investigation preoperative sinograms give useful information about the prognosis of revision. In cases with positive bacterial cultures debridements should be done very early to eradicate infection without removing the implants.

Aged↗
PubMedDate not supplied

[5 years' experiences with the Gersthof polyethylene peg-anchored acetabulum].

The acetabular socket "Model Gersthof" is a spheric polyethylene component which can be anchored cement-free by means of three symmetrically arranged pegs at the outside. Between July 1979 and October 1986, 1316 implants of cement-free sockets were performed at our own department. The evaluation of the socket was based on the criterium of radiological instability (= aseptic loosening). After five years of observation, this design-oriented evaluation of success shows a survival of 92% +/- 2.9%.

Acetabulum↗