Application of porous PEO/PBT copolymers for bone replacement.

A range of polyethylene oxide/polybutylene terephthalate (PEO/PBT) copolymers (70-30% PEO) was investigated for nonloadbearing bone replacement application. Porous PEO/PBT cylinders (d = 5 mm, h = 7 mm) were implanted transcortically in the diaphyseal femur of 10 goats, and the animals were sacrificed at 3, 6, 9, 12, and 26 weeks. Qualitative evaluation was performed using light and fluorescence microscopy, scanning electron microscopy, and back-scatter electron imaging with an attached X-ray microanalysis system. The percentage of bone ingrowth and the percentage of bone contact in the pore region were quantitatively assessed using undecalcified histological sections. The hydrogel properties of the PEO/PBT copolymers provided a rapid closure of the defect upon press-fit implantation, due to postoperative water uptake and subsequent swelling behavior of the materials. Bridging of the defect by bone and the occurrence of bone bonding were observed 6 weeks postoperatively for the material with the highest PEO content (70/30). For the 60/40 and 55/45 PEO/PBT proportions, union of the defect and bone bonding were observed at 9 and 12 weeks, respectively. The stiffer 40/60 and 30/70 PEO/PBT implants showed bridging of the 5-mm gap after 12 weeks, but did not reveal bone bonding up to 26 weeks. Peripheral fragmentation, mainly in the marrow cavity, was found for the 70/30 material at 12 weeks and had increased at 26 weeks. Degradation was not seen for the other materials. The histomorphometrical data confirmed the microscopical observations and demonstrated a direct relation between PEO content in the PEO/PBT co-polymers, the rate of bone ingrowth, and the amount of bone contact. Porous PEO/PBT copolymers are degradable, bone-bonding elastomeric substrates with favorable handling properties and a high percentage of bone ingrowth (69-78 at 26 weeks). It was therefore concluded that PEO/ PBT copolymers are highly promising materials for bone-replacement surgery.

Bone-bonding behaviour of poly(ethylene oxide)-polybutylene terephthalate copolymer coatings and bulk implants: a comparative study.

A range of poly(ethylene oxide)-polybutylene terephthalate (PEO-PBT) copolymers (70-30% PEO), both as coating on titanium alloy as well as bulk cylinders, was press-fit implanted in the diaphyseal femur of 16 goats. At early survival times (4 wk), a high degree of cortical bone contact was observed for bulk implants using light microscopy and this was confirmed by backscatter electron microscopy. This was attributed to the swelling behaviour of PEO-PBT copolymers. At this stage, bone contact was also revealed for coated implants, but to a lesser extent. At a later stage (12 wk), bone bonding was demonstrated both morphologically and by X-ray microanalysis, at the interface of 70:30 PEO-PBT bulk as well as 70:30 PEO-PBT-coated implants. Bone bonding increased with time (26 and 52 wk) for this PEO-PBT proportion and was also observed for 60:40 and 55:45 implants, although less frequently. For 40:60 and 30:70 PEO-PBT proportions, bone bonding was not shown. Based on these qualitative data, it was not possible to differentiate between coated and bulk implants with respect to bone bonding. This study demonstrated that the application of PEO-PBT elastomers as coatings does not alter the bone-bonding properties. It was therefore concluded that PEO-PBT coatings are beneficial over the bone-bonding but brittle ceramic coatings, due to their flexibility. In addition, the bone-bonding capacities of these PEO-PBT coatings surpass the non-bonding behaviour of currently available flexible coatings.

Interface reactions to PEO/PBT copolymers (Polyactive) after implantation in cortical bone.

The bone reaction at the interface of a range of PEO/PBT copolymers (Polyactive) after press-fit implantation in the diaphyseal femur of 20 goats was investigated. The animals were sacrificed at 1, 4, 12, 26, and 52 weeks. Undecalcified histologic sections were prepared, evaluated qualitatively, and quantified with the aid of an image analysis system. The percentage of bone contact was determined morphometrically for all PEO/PBT proportions; for the 70/30 ratio, the percentage of calcification of the material surface and of bone-bonding (defined as a continuum at the light microscopic level between calcification within the material surface and bone tissue) were also assessed. PEO/PBT copolymers possess hydrogelic properties, and a direct relation has been established between water-uptake and PEO content. The swelling behavior of all PEO/PBT substrates resulted in a high degree of bone contact (over 95%) at early stages. From the 12-week survival time onward the 70/30 revealed higher percentages of bone contact (over 80%) when compared with the other ratios (60/40, 55/45, 40/60, and 30/70). This difference was statistically confirmed 1 year postoperatively. The materials with the higher PEO contents showed the highest amounts of calcification, which is reflected by the rate of bone-bonding (70% of bone-bonding for the 70/30 at 52 weeks). Calcification and bone-bonding were not observed for 40/60 and 30/70 proportions. The quantitative results confirmed the relation between PEO content, water-uptake, calcification, and bone-bonding. It was furthermore demonstrated that PEO/PBT copolymers initially establish a high degree of bone contact, whereas the bone-bonding properties, especially of the 70/30, accomplish a long-term implant fixation.

Interfacial behavior of PEO/PBT copolymers (Polyactive) in a calvarial system: an in vitro study.

Polyactive, a polyethylene oxide/polybutylene terephthalate (PEO/PBT) copolymer, has been reported to display bone-bonding behavior. Although a detailed description of the in vivo bone/Polyactive interface is available, the underlying bone-bonding mechanism is still largely unknown. In this in vitro study, a calvarial envelope method has been adopted to reproduce the in vivo bone-bonding phenomenon and subsequently to obtain information on the biological effect of varying PEO/PBT segment ratios. The following PEO/PBT ratios were examined: 70/30, 60/40, 55/45, 40/60, and 30/70. Light microscopy (LM) and scanning (SEM), transmission (TEM), and backscatter electron microscopy (BSE), as well as X-ray microanalysis (XRMA), were employed. Within the period of analysis (3 weeks), an intimate contact between mineralized deposition and the 70/30, 60/40, and, to a lesser extent, the 55/45 surface was observed. Calcified areas developed within the surface of these PEO/BPT proportions during the culture period. Needle-shaped crystals from the mineralized tissue compartment and from calcified areas within the materials surface were intermingled at the interface, providing a morphologic continuity. A cellular layer was interposed with the mineralization front and the noncalcified 40/60 and 30/70 substrates. Apparently, the percentage of PEO is important for calcification within the near surface of the polymer. This relation is such that the higher the PEO content in PEO/PBT ratios, the more rapid the calcification. The occurrence of material calcification is considered to be largely responsible for the subsequent interfacial interactions. The calvarial envelope culture method allows not only reproduction of the in vivo bone/Polyactive interface, but also a relatively rapid differentiation within the range of PEO/PBT ratios.(ABSTRACT TRUNCATED AT 250 WORDS)

[The significance of body temperature, sedimentation, C-reactive protein, leukocyte count and differential for the diagnosis of infections in an internal medicine emergency department]. / De betekenis van lichaamstemperatuur, bezinking, C-reactief proteïne, leukocytenaantal en -differentiatie voor de diagnostiek van infecties op een eerstehulpafdeling voor inwendige geneeskunde.

The value of body temperature, erythrocyte sedimentation rate (ESR), C-reactive protein, white blood cell count and differentiation for the diagnosis of infections in patients in the first aid department of internal medicine, was investigated. Forty-six infections were observed in 260 patients (prevalence 18%). Patients with fever had a fourfold increased chance to have an infection. In a patient with fever and an increased ESR the chance to have an infection was 91%, with fever and a normal ESR 33%. In the absence of fever the chance to have an infection was 14% if the ESR was increased and 7% if normal. White blood cell count and differentiation, like C-reactive protein in addition to body temperature were of no use for the diagnosis of infections.