Introduction and purpose: Infections of total hip prostheses are one of the most serious complications that beset this procedure. Their incidence in the world literature is of 1%. However this figure rises to 16% in the case of implants secondary to fractures in patients with multiple pathologies. In this study we conduct a descriptive analysis of the qualitative variables after the implementation of an action protocol to address this complication.

Materials and methods: A consecutive series of 694 patients was studied (420 females, 60.52%, and 274 males, 39.48%). Out of these 233 cases were secondary to fractures ( 60 males and 173 females), which meant that treatment was administered as an emergency (in the first 48 hours), and 461 were primary (241 males and 247 females). The variables related to an infection risk were studied, a distinction being made between an acute and a chronic infection based on CCD criteria. In acute cases, surgical cleaning was performed; in subacute cases, a two-stage replacement was chosen and for chronic infections we performed a resection arthroplasty if the two-stage replacement failed.

Results: We performed a frequency and exponential chi square study which yielded 37 cases (5.33%) of implant infection (11 males, 26 females).The most frequently isolated germ was Staphilococus Aureus. 74% of cases treated with surgical cleaning after a diagnosis of acute infection are now infection-free after a two-year follow-up. 60% of subacute cases, where a two-stage replacement was performed, show a satisfactory result. As regards resection arthroplasty, the success of treatment was around 92%,with a p< 0.005 value.

Conclusions: Careful patient selection and early diagnosis are fundamental to obtain good results in the treatment of THP infections.

Aims: The purpose of this study was to describe the histologic adaptation of the femoral artery wall to the strechtening derived from femoral lengthening by callus distraction. Methods: In 32 New Zealand white rabbits a left femoral bone lengthening was carried out with a total distraction of 30% of initial length. The study was divided into eight progressives stages and at the end of each stage both femoral arteries were excised and prepared for light microscopy and ultrastructural analysis. Results: Light microscopy: Changes in the media layer architecture were observed since lengthening of the 15% of the initial length, reaching its maximum by lengthening of 30% of initial length. Six month after the end of the distraction, the media layer still showed morphologic changes compared to the unlengthened group. U.E.: During the greatest distraction period and one month thereafter the Smooth Muscle cells of the media lost its contractile characteristics and greatly increased their syntesis organelles, and mytosis and isolated binuclear cells are observed representing and accelerated cell proliferation. Six months after the end of the distraction the muscular cells returned almost completely to the normal contractile state. Conclusions: The response of the arterial wall against the strechtening is more a regenerative response due to the muscle cells than a reparative response of the connective tissue. This study suggest that with the greatest distraction, and one month later, the muscle cells change from the original contractile phenotype to a synthetic phenotype, that is a prerequisite for cellular proliferation. The return to the original characteristics six months thereafter could support the reversibility of the cellular phenotype opposite to the progressive elongation.