Interplay between surface properties of standard, vitamin E blended and oxidised ultra high molecular weight polyethylene used in total joint replacement and adhesion of Staphylococcus aureus and Escherichia coli.

We have assessed the different adhesive properties of some of the most common bacteria associated with periprosthetic joint infection on various types of ultra high molecular Weight Polyethylene (UHMWPE). Quantitative in vitro analysis of the adhesion of biofilm producing strains of Staphylococcus aureus and Escherichia coli to physically and chemically characterised standard UHMWPE (PE), vitamin E blended UHMWPE (VE-PE) and oxidised UHMWPE (OX-PE) was performed using a sonication protocol. A significant decreased bacterial adhesion was registered for both strains on VE-PE, in comparison with that observed on PE, within 48 hours of observation (S. aureus p = 0.024 and E. coli p = 0.008). Since Vitamin E reduces bacterial adhesive ability, VE-stabilised UHMWPE could be valuable in joint replacement by presenting excellent mechanical properties, while reducing bacterial adhesiveness.

Study of neurinomas with ultrasound contrast media: review of a case series to identify characteristic imaging patterns.

PURPOSE: The aim of this study was to evaluate whether there exists a characteristic distribution pattern of vessels within neurinomas that may be used to characterise this type of lesion by employing a contrast-specific ultrasound technique. MATERIALS AND METHODS: Between January 2003 and May 2010, 66 suspected neurinomas were evaluated according to their sonographic features (solid fusiform mass with well-defined margins located in direct continuity with the nerve that was not always discernible and heterogeneous as a result of the presence of small cystic areas or calcifications). The lesions were examined using a sonographic contrast medium consisting of sulphur hexafluoride microbubbles and equipment with dedicated contrast-specific software [contrast tuned imaging (CnTI)]. Of these lesions, five were excluded from the analysis because the definitive diagnosis was not available (in two cases, the follow-up was still in progress, whereas in the remaining three, there was no follow-up). Our study, therefore, is based on 61 surgically excised lesions that were confirmed to be neurinomas by histology, which is regarded as the gold standard. RESULTS: In 41/61 cases (67.2%), we identified an enhancement pattern that we termed reticular owing to the interweaving of blood vessels, of which two subtypes were identified depending on whether the interwoven vessels were densely or sparsely packed: loose-knit reticular in 18/41, and tight-knit reticular in 23/41. In 20/61 (32.8%) cases, we observed a vascular pattern of diffuse heterogeneous enhancement, which was divided into two subtypes based on the presence of one (7/20) or more (13/20) avascular areas. CONCLUSIONS: Results showed that all neurinomas studied could be divided into two groups according to the type of enhancement pattern observed: reticular or diffuse heterogeneous.

The biological reaction to polyethylene wear debris can be related with oxidation of the UHMWPE cups.

BACKGROUND: Oxidised UHMWPE due to gamma irradiation in air has a greater susceptibility to wear than non-oxidised UHMWPE (ethylene oxide, EtO). AIM: To evaluate, the biological reaction of loose implants with oxidised and non-oxidised PE components. MATERIALS AND METHODS: Ten loose PE cups sterilised by EtO (group 1) and 13 sterilised by gamma irradiation in air (group 2) were studied. PE wear and oxidation were related to biological reaction. RESULTS: Group 1: PE cups had low wear score and no oxidation. In the oldest implants, a few PE particles and macrophages were observed in the interface membrane. Group 2: PE inserts had medium-to-high PE wear score and variable oxidation. In the interface membrane, the number and total area of PE particles were high and variable; giant cells were more numerous than macrophages. CONCLUSION: Junctional tissues around loose oxidised PE components contain more PE debris and giant cells than membranes around PE components that are not oxidised.

A model for the organization of a regional bank for musculoskeletal tissues in Italy.

The national and local need for human tissues to be used in transplants is a high one, and constantly growing. Human, scientific and financial resources involved in guaranteeing safe and high-quality tissues as defined by the national guidelines for musculoskeletal tissue banks are considerable. For this reason we need to find adequate solutions to the problem of guaranteeing sufficient availability of tissues with the lowest cost possible for supply. The Piedmont Region Musculoskeletal Tissue Bank, which is located in an Azienda Ospedaliera, has been organized to guarantee the quality of its tissues via biological validation and scientific-clinical coordination; it makes use of the collaboration of removal centers that send tissues taken from the central bank for certification and identifies several centers for preservation; it collaborates with a bank of national importance for tissue processing. The publication of regulations and tariffs based on cost analysis improves the procedures.

The integration of vascular surgical techniques with oncological surgical protocols in the treatment of soft tissue sarcomas of the limbs.

Soft tissue tumors, involving the vascular bundle, require a particular surgical approach: oncological and vascular surgical techniques must be integrated in order to perform a limb-saving surgery with adequate margins. Thirty-six soft tissue sarcomas of the thigh and popliteal region were treated from June 1999 to September 2002. Nineteen cases involving the vascular bundle were analysed and placed in two groups according to imaging and clinical information: Group A, 14 patients, with tumors close to femoral vessels without adventitial infiltration, and Group B, 5 patients, with vascular infiltration. Group A was treated with vascular blunt dissection performing adventitial excision. Group B was treated with vascular "en-bloc" resection and reconstruction. Imaging and clinical information together with surgical techniques, strategies and complications were analysed in order to plan the surgical approach in neoplastic vascular bundle involvement.

Echocolor Power Doppler with contrast medium to evaluate vascularization in lesions of the soft tissues of the limbs.

PURPOSE: Echocolor Power Doppler with contrast medium forms a non-invasive vascular image; the purpose of the study is to evaluate the effectiveness in differentiating benign and malignant tumors in the soft tissues of the limbs. MATERIAL AND METHOD: Echocolor Power Doppler with contrast medium was used to study 80 patients with swelling in the soft tissues of the limbs: there were 54 benign lesions, 22 sarcomas, and 4 aggressive desmoid fibromatoses. RESULTS: Were identified 4 patterns of wash-in and wash-out curves that could be correlated to the histological diagnosis: type I was present in 85% of benign lesions, type III in 91% of malignant lesions and in 3.7% of the benign ones, type II in aggressive fibromatoses, anomalous type in 4 benign lesions and 2 sarcomas; the curve was absent in 2 benign lesions. CONCLUSIONS: Power Doppler Echocolor with contrast medium can become a useful method to be associated with traditional imaging methods in the differential diagnosis of swelling of the soft tissues of the limbs.

Oxidation of orthopaedic UHMWPE.

Retrieved EtO sterilised acetabular cups usually show much less degradation than gamma-ray sterilised cups. Some of our retrieved EtO sterilised cups did, however, reveal unexpected bulk oxidation. It was observed that this oxidation was always accompanied by whitening of the material. This whitening was found to be due to a break-up of the compression moulded material into its original particles. It was noticed that there was no oxidation in all parts, where the break-up and whitening appeared. The oxidation did, however, occur exclusively in the parts where there was a badly consolidated material. Upon examining shelf aged, unsterilised samples, it was found that the degradation was also present here. This shows that the observed phenomenon is not due to the service in vivo and that it must originate from the processing step. Just as for the retrieved samples, the shelf aged cups only showed oxidation in the bulk and not at the surface. It was concluded that the material used for the cups had been badly fused together during the compression moulding and that the machining had created a bad stress situation in the cups leading to a break-up of the particles. The mechanism that initiates the oxidation is not known, but it is believed that the distribution depends on how the internal stresses have acted to break up the structure. In the areas where the particles have been separated, there is probably a higher availability of oxygen than what is normally observed in UHMWPE.

In vivo UHMWPE biodegradation of retrieved prosthesis.

Sixty-two ultra high molecular weight polyethylene prosthetic components (PEs) (31 tibial plateaux and 31 cups), sterilised by gamma rays or ethylene oxide (EtO), were retrieved after 1-12 years depending on different medical reasons and were studied by FTIR spectroscopy with derivatisation of oxidised species. Esters, acids and hydroperoxides were found under the surface of the EtO sterilised PEs up to 2 mm depth. The behaviour of gamma ray sterilised PEs is more complex due to the oxidation following the sterilisation process. Ester and acid formation might arise from the diffusion of components of synovial liquid or from the oxidation process, whereas hydroperoxide formation is thought to be due to the oxidation. Abrasion and delamination process is discussed considering the topological distribution of degradation products.

Oxidation in orthopaedic UHMWPE sterilized by gamma-radiation and ethylene oxide.

Ten new polyethylene prosthetic components (PEs), ethylene oxide (EtO)- and gamma-sterilized, were studied by means of infrared (IR) analysis in order to evaluate oxidation. Using attenuate total reflection infrared spectroscopy the authors demonstrate that all samples show surface oxidation, formed during processing and shaping, related to mechano-degradation. By means of Fourier transform infrared (FTIR) microscopy and derivatization techniques, the EtO-sterilized PEs present different behaviour in comparison to the gamma-radiated. The former show low levels of depth oxidation that could be related to the degradation which occurred during preparation of slices for IR analysis. The gamma-sterilized PEs show higher oxidation levels, variable from sample to sample, on the surface and in the bulk. The authors demonstrate that oxidation is described both by carbonyl species distribution and by hydroperoxide concentration. The hydroperoxides could be responsible for oxidative PEs ageing in in vivo service. The different oxidation levels and distribution could depend on the conditions of gamma-sterilization, in particular on the rate of the dose absorbed, not previously reported for ready-to-implant PEs. Chain scission of gamma-radiated UHMWPE, estimated by IR analysis, results in reduction of molecular weight and consequently in less abrasive resistance. The scheme of UHMWPE oxidation due to gamma-sterilization demonstrates the inhomogeneous distribution of reactive species in PEs responsible for the unpredictable performance in vivo.

Screw sockets: survivorship analysis after eight years.

A comparative analysis of the radiographic results of 111 screw sockets (65 tapered and 46 hemispherical cup sectors) was made to evaluate both their behaviour over a period of time and the validity of their use today. The follow-up was performed on average 42 months after the implant. Overall survivorship shows a high risk of failure during the fourth year and a greatly increased rate of failure after the sixth year. Comparison of the survival curves of the two types of acetabular component revealed no significant differences. The two types considered were, however, of different sizes: the implanted taper sockets were on average 6.6 mm larger than the comparable hemispherical cup sector acetabular components, thus involving a greater loss of acetabular bone.

Total knee replacement: surgical technique and instrumentation.

The surgical technique and instrumentation of four systems of total knee replacement, two with intramedullary and two with extramedullary alignment systems, are discussed. The differences between the instrumentations, their advantages and disadvantages, and the basic "philosophy" of each technique are compared in four "crucial" operative stages, determinant for the final result: the anteroposterior and distal femoral osteotomies, the tibial osteotomy, and the mechanical axis. In expert hands the two systems are equally reliable. In our experience, the extramedullary system with the tensor is more versatile. The stages are more dependent on the surgeon than on the instruments, and the tensor enables the surgeon to control and balance the level of osteotomy and the soft-tissue release every time. The intramedullary femoral alignment system seems simpler: each step is a direct consequence of the previous one, except the first step, which is, of course, entrusted to the experience of the surgeon. The fact that each stage is predetermined may reduce the chances of error in less skilled hands.

Experience with bipolar prosthesis in femoral neck fractures in the elderly and debilitated.

Eighty-eight bipolar Bateman hip endoprostheses for medial femoral neck fractures were implanted. The average age of the patients was 75 years. Intrahospital results proved the morbidity and mortality rates to be well within acceptable limits. Thirty patients were followed during periods of 12-74 months (median, 33 months). According to Charnley evaluation, mobility was excellent and very good in 20 patients (86%). Good function was present in 63% of patients. The majority of patients belonged to category C as defined by Charnley. Mild pain was present in 19 patients (63%); in only two cases, involving severe rheumatoid arthritis, pain was clearly related to sinkage. Radiographically, no visible protrusion or socket wear was present. Periarticular ossification occurred in 19 patients, but this did not impair function.