Utilisation des implants biodégradables dans le traitement chirurgical des fractures et au cours des ostéotomies

Résumé L'utilisation de matériaux d'ostéosynthèse biodégradables a l'avantage d'éviter la réintervention pour extraire le matériel. Les biomatériaux de polymères polyglycolides ont été expérimentés sur plus de 3 600 animaux de laboratoire avant leur introduction en pratique clinique. Depuis 1984 nous les avons utilisés comme matériau d'ostéosynthèse dans près de 1 700 cas parmi lesquels 880 cas de fracture malléolaire, 226 cas d'ostéotomie en chevron pour hallux valgus, 65 cas de fracture de la tête radiale et 54 cas de fracture de l'olécrane. Parmi les 800 premiers cas traités par broches biodégradables nous avons obtenu des résultats favorables et sans incidents dans 91 pour cent des cas. Il y eut 7 cas de fixation défaillante nécessitant une réintervention. Il y a eu 7 cas d'infection superficielle et 3 cas d'infection profonde. Nous avons observé la formation d'une collection séreuse sous-cutanée sans influence sur le résultat radiologique ou clinique dans 52 cas (6,5 %). Au vue de ces résultats et compte tenu des avantages économiques et psychologiques des matériaux biodégradables (pas de réintervention), on peut penser que l'usage de biomatériaux rivalise favorablement avec l'usage de matériaux conventionnels dans certains types d'ostéosynthèse.

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Utilization of biodegradable implants in the surgical treatment of fractures and osteotomies

Summary The utilization of biodegradable implants instead of metals in orthopaedic surgery abolishes the need to remove the fixation material. For this study biodegradable rods and screws of self-reinforced polyglycolide, polylactide and lactide-glycolide copolymer were developed and manufactured. The clinical introduction of these implants was preceded by thorough experimental studies with 3 600 animals. From November 1984 the developed biodegradable method of osteofixation was used in 1 700 operations. These included 880 displaced malleolar fractures, 226 chevron-osteotomy for hallux valgus, 65 displaced fracture of the radial head, 54 displaced frature of the olecranon and other fresh fractures or orthopaedic operations. In the first 800 cases operated on using self-reinforced polyglycolide rods the postoperative course was uneventful (91%). Because of failure in the fixation reoperation was needed in 7 cases. A superficial wound infection was observed in 7 cases, deep infection in 3 and transient fluid accumulation in 52 cases (6,5%). Fluid accumulation did not influence the radiological or clinical end-result. The advantages of biodegradable fixation are many-sided. There is a costbenefit and clinical capacity is free for other use, and psychological advantages must be emphasised because removal of implants is not needed. The over all results of this study were considered favourable.

     

Interaction between thiol-modifying agents and P1075, a KATP channel opener, in rat isolated aorta

In vascular smooth muscle, openers of ATP-dependent potassium channels (K _ATP channels), such as P1075 (N-cyano-N’-(1,1-dimethylpropyl)-N’’-3-pyridylguanidine), produce relaxation. In this study we have investigated the effects of thiol-modifying agents on the binding of P1075 and on the ⁸⁶Rb⁺ efflux stimulating and vasorelaxant effects of the opener in rat aortic rings. The increase in ⁸⁶Rb⁺ efflux induced by P1075 was taken as a qualitative measure of K⁺ channel opening. The hydrophilic SH-group-oxidizing substance, thimerosal (1 to 100μM), abolished specific binding of [³H]-P1075 with an IC₅₀ value of 7.6±1.2μM; at 30μM, the half time for inhibition was 38min. Two other thiol-oxidizing agents, PMB (4-hydroxy-mercuribenzoic acid) and DTBNP (2,2’-dithio-bis(5-nitropyridine)), inhibited binding up to 86% and 44%, respectively. The disulphide bond reducing substance, DTT (1,4-dithiothreitol, 0.1 to 1mM), reduced [³H]-P1075 binding by up to 20% and partially reversed the inhibitory effect of thimerosal. In ⁸⁶Rb⁺ efflux experiments, thimerosal (3 to 100μM) concentration-dependently increased basal efflux but inhibited P1075-stimulated tracer efflux with an IC₅₀ value of 7±1μM. The inhibitory effect occurred with a half-time of approximately 8min and was essentially reversed by DTT. In rings precontracted with noradrenaline, thimerosal inhibited the vasorelaxant effect in a noncompetitive manner, shifting the concentration-relaxation curves to the right and reducing maximum relaxation.The data show that oxidation of thiol groups interferes with the binding of the K _ATP channel opener, P1075; concomitantly, the ⁸⁶Rb⁺ efflux stimulating and the vasorelaxant effects are inhibited. Reduction of disulphide bonds by DTT has only minor effects on the action of P1075. Collectively, the results suggest that intact thiol groups are essential for the functioning of the K_ATP channel in rat aorta. The different kinetics governing the inhibition of opener binding and of opener-stimulated ⁸⁶Rb⁺ efflux suggest that the SH-groups involved in the two processes differ in their accessibility to thimerosal and/or in their reactivity. Received: 7 April / Accepted: 9 July 1997     

Computergestützte Charakterisierung von sonographischen Plazentastrukturen

Schlu?folgerungen Aus der Me?wert-Verteilung der Grauwerte im Sonogramm lassen sich Kennwerte berechnen, die eine computergestützte sonographische Reifebeurteilung der Plazenta erm?glichen. Allerdings sind die Verteilungsparameter (Median, Varianz, Schiefe, Exze?) abh?ngig von den Ger?teparametern. Zuverl?ssiger ist die Berechnung von Kennwerten, die sich auf die strukturellen Eigenschaften des Sonogramms beziehen. Bei den hier dargestellten Untersuchungen k?nnen Kennwerte für den Kontrast bzw. für die Ansammlung gleichartiger Grauwerte um einen bestimmten Punkt die sonographische Beurteilung der Plazenta optimieren. Damit erweitern sich die M?glichkeiten für die Zustandsdiagnostik der intrauterinen Lebensbedingungen.     

Sexual risk behavior in women with cervical human papillomavirus infection

In a study of 972 women, sexual characteristics of 66 women with a cervical human papillomavirus infection (CHPI) were compared to the remaining study population. Among a number of sexual variables that were significantly correlated with CHPI were number of lifetime sexual partners, short partnerships, many recent partners, infidelity, casual travel sex, sexual début abroad, oral and anal sex, and sexual abuse. In multifactorial analyses four variables remained significantly correlated with CHPI, i.e., number of lifetime sexual partners, casual travel sex, sexual début abroad, and infidelity. It is concluded that CHPI shows most of the epidemiological characteristics of a sexually transmitted disease.     

A novel technique of ab interno glaucoma surgery: follow-up results after 24 months

Purpose It was the aim of this study to investigate the efficacy, longevity, and safety of a new ab interno intervention for the treatment of primary open-angle glaucoma (POAG). Methods The previously described method of radiofrequency-mediated “sclerothalamotomy ab interno” was applied in 53 eyes of consecutive patients with POAG between April 2002 and July 2002. Average preoperative intraocular pressure (IOP) was 25.6±2.3 mmHg (range 18–48 mmHg). Sclerothalamotomies were carried out with a custom-made high-frequency dissection 19 G probe (tip 0.3×1 mm) applying bipolar current with a frequency of 500 kHz (tip temperature 130°C). Results After a follow-up period of 24 months, the average IOP was 15.0±1.6 mmHg (range 11–20 mmHg) (p<0.005). The average number of topical agents was 2.6±1.0 (range 1–5) preoperatively. Twenty-four months after surgery such agents were used in only five (9.6%) eyes and the average was 0.21±0.53 (range 0–2). Transient IOP elevation was observed in 12 of 53 eyes (22.6%) postoperatively. In all cases elevated IOP could efficiently be controlled with topical medication. In general, IOP dropped continuously over the course of the 6 months following surgery and then remained constant. Conclusions This study indicates that sclerothalamotomy ab interno is a safe and efficient surgical method for the treatment of POAG. Long-term results clearly demonstrate the longevity of IOP reduction.     

Exogenous Modulation of TGF-β1 Influences TGF-βR-III-Associated Vascularization during Wound Healing in Irradiated Tissue

BACKGROUND AND PURPOSE: Following preoperative radiotherapy prior to ablative surgery of squamous epithelial cell carcinomas of the head and neck region, wound-healing disorders occur. Previous experimental studies showed altered expression of transforming growth factor-(TGF-)beta isoforms following surgery in irradiated graft beds. Altered levels of TGF-beta(1) are reported to promote fibrosis and to suppress vascularization during wound healing, whereas expression of TGF-beta receptor-III (TGF-betaR-III) is associated with vascularization. The aim of the study was to analyze the influence of anti-TGF-beta(1) treatment on TGF-betaR-III-associated vascularization in the transition area between irradiated graft bed and graft. MATERIAL AND METHODS: Wistar rats (male, weight 300-500 g) underwent preoperative irradiation of the head and neck region with 40 Gy (four fractions of 10 Gy each; n = 16 animals). A free myocutaneous gracilis flap taken from the groin was then transplanted to the neck in all rats. The time interval between operation and transplantation was 4 weeks. Eight animals received 1 micro g anti-TGF-beta(1) into the graft bed by intradermal injection on days 1-7 after surgery. On days 3, 7, 14, 28, 56, and 120, skin samples were taken from the transition area between transplant and graft bed and from the graft bed itself. Immunohistochemistry was performed using the ABC-POX method to analyze the TGF-betaR-III and E-selectin expression. Histomorphometry was performed to analyze the percentage and the area of positively stained vessels. RESULTS: A significantly higher expression of TGF-betaR-III was seen in the irradiated and anti-TGF-beta(1)-treated graft bed in comparison to the group receiving preoperative irradiation followed by transplantation alone. The percentage of TGF-betaR-III positively staining capillaries from the total amount of capillaries in the anti-TGF-beta(1)-treated graft bed was higher than in the group irradiated only. The total area of capillaries was also higher in the TGF-beta(1)-treated group. CONCLUSION: Neutralizing of TGF-beta(1) activity in irradiated tissue undergoing surgery leads to a higher expression of TGF-betaR-III and increased vascularization. TGF-betaR-III seems to be associated with newly formed blood vessels during neovascularization in wound healing.     

Endovaskuläre Brachytherapie als neue Therapieoption zur Prophylaxe der Rezidivstenose nach peripherer Katheterintervention

The therapeutic concept of irradiation of the vessel wall for prevention of restenosis after endovascular procedures is based on increasing knowledge about the pathophysiology of the process leading to restenosis. There is until now only a limited number of studies concerning the use of brachytherapy (BT) in the peripheral circulation, which is in contrast to the already large experience in the coronary circulation. In the peripheral trials the radiation dose was administered by a remote afterloader using a gamma source. According to the available data, vascular BT is a promising technology with the potential to reduce the restenosis rate. The Vienna-2-Trial was the first randomised study to demonstrate the efficacy of endovascular BT for prophylaxis of restenosis after femoropopliteal percutaneous transluminal angioplasty. However, we have to await further supportive data from ongoing clinical trials before definitive recommendations can be given. Currently, endovascular BT seems already justified in patients with recurrent interventions or after long-segment femoropopliteal angioplasty because of the high risk of restenosis in these patients. The next years will demonstrate the ultimate role of endovascular BT in comparison to the rapidly evolving field of drug-eluting stents.