Biomedical subjects

T Vidovszky

Publications and source records attributed to T Vidovszky.

11 recordsLinked to original sources

PubMed1996

A differential scanning calorimetry study of retrieved orthopedic implants made of ultrahigh molecular weight polyethylene.

Differential scanning calorimetry (DSC) was used to examine thermal and thermooxidative properties of ultrahigh molecular weight polyethylene (UHMW-PE) of five acetabular components of failed orthopedic implants retrieved at revision of total hip arthoplasty. The results were compared with controls (unimplanted acetabular cups, a 20-year-old slab of UHMW-PE, and raw material). Profiles of exothermic peaks indicated increased levels of oxidation in all retrieved cups. In three retrieved cups, DSC revealed an additional peak of endotherm that was not seen in control samples. The additional endotherm peaks were not artifacts due to oxidation during scanning, heat buildup during cutting of the samples, or the sterilization method after retrieval. The additional peak was associated with the bulk of the polymer that was extracted with hexane. It varied in relative area, depending on its original location of the sample in a cup, implicating local variability in the extent of changes in material property. The distribution of the changes suggests that, during implantation, tissue exposure and friction affected the level of oxidation and degree of crystallinity in the UHMW-PE to a greater degree than did loading alone. Overall results showed that DSC may be a useful tool in evaluating changes in the properties of UHMW-PE orthopedic components in vivo.

Acetabulum↗

PubMed1995

[Spinal epidural abscess].

The aspecific spinal epidural abscess is an uncommon cause of the spinal cord compression. Forty eight patients presented with epidural abscess were operated on during the last 37-year-period in the National Institute of Neurosurgery Budapest. Experiences with the diagnostic methods and the results of the treatment of these patients are analysed. Based on the case history data, preoperative symptoms and operative findings 31 male and 17 female patients (their age ranged from 15-64 years) have been selected in acute, subacute and chronic groups. Localized backpain, acceleration of the blood sedimentation, leukocytosis and fever were significant findings which were followed by sings of radicular or medullary compression. This clinical picture developed rapidly in the acute group. Aspecific abscess most commonly appeared in thoracal or lumbal localisation and was rarely found in the ventral area. Staphylococcus aureus was the causative organism in nearly 100 percent of the cases. Surgery carried out before the onset of the neurological deficits according to proper CSF examination and myelography, proved to be favourable. Early diagnosis and emergency operation led to a significant improvement of the outcome.

Abscess↗

PubMed1993

Histopathological and immunological investigations of synthetic fibres and structures used in three prosthetic anterior cruciate ligaments: in vivo study in the rat.

Three types of prosthetic anterior cruciate ligaments were investigated by enzymatic and histological analysis of the tissue surrounding each implant and immunologically by a cytofluorometric analysis of T-cell populations in the peripheral blood of rats. Two of the prostheses had a braided construction, one made from polyester and the other from high performance polyethylene fibres. The third type also contained high performance polyethylene fibres, but had been manufactured in a knitted construction (Raschel high performance polyethylene). Five specimens from each prosthesis were implanted intraperitoneally in rats by a trocar for different periods of time up to 4 wk. A control group of rats underwent the surgery, but not the implant. No modification in peripheral T-cell populations was induced by the presence of any implant. Whilst the levels of acid phosphatase and esterase activity appeared to have increased slightly following implantation of any of the prostheses, such increases were not highly significant. Histologically, all three materials induced an intense acute inflammatory reaction at 3 d which gave way to a typical chronic response after 4 wk. The only major difference between the prostheses was that after 4 wk the polyester fibres exhibited less inflammation, and the surrounding tissue was more mature, more vascularized and more densely infiltrated with collagen than with the two high performance polyethylene implants. In conclusion, all three devices provided satisfactory biocompatibility in terms of cellular and healing response.

Acid Phosphatase↗

PubMed1993

Fate of ultrahigh molecular weight polyethylene (UHMW-PE) wear debris in patients with hip implants.

The process of ultrahigh molecular weight polyethylene (UHMW-PE) breakdown, started at the articular surface of the cup, continues in small fragments after generation. An assiduous interaction between the UHMW-PE particles and the host cells leads to oxidative changes of the UHMW-PE and to size reduction of the particles simultaneous with transporting them toward, and finally by, lymphatic or blood vessels. The particles are mobilized by means of enzymatic, extracellular matrix-degrading activity of cells that have phagocytosed them or adhered to them. Together, these characteristics indicate an attempt by the natural cellular immunity system to eliminate the implant wear debris. Macrophages are the main effector cells acting as scavengers; however, excessive amount of the wear debris evokes phagocytic activity of cells other than macrophages as well.

Alloys↗

PubMed1979