Introduction. Wear of the UHMWPE component is responsible for many TJR failures. It is now well known that oxidation of UHMWPE, induced by radiation sterilisation in air, dramatically increases the wear rate. ASTM regulations for orthopaedic UHMWPE forbids the addiction of any antioxidant to the polymer powder or to fabricated forms. Vitamin E is widely employed as a biocompatible stabiliser in the food and cosmetic industry. Aim of the present study is to evaluate the efficiency of Vitamin E as a stabiliser for prosthetic UHMWPE.

Materials. Virgin UHMWPE samples were obtained from compression moulded slabs (GUR 1020, Perplas). In addiction, compression moulded slabs of GUR 1020 mixed with 500 and 1000 ppm of Vitamin E respectively were also studied. Electron beam irradiation was performed with doses ranging from 50 to 225 kGy, in air, at room temperature. Slices of controlled thickness (0,1–0,3 mm) were microtomed from the blocks and accelerated ageing was carried out in a ventilated oven at 90°C. FTIR spectroscopy were used to monitor changes in the polymer structure after irradiation and ageing. Mechanical properties were evaluated using the small punch test, as described in ASTM F2183-02.

Results. FTIR measurements on the aged samples showed that the addiction of Vitamin E induces a substantial increase in the oxidative stability of UHMWPE. The overall work to failure of original UHMWPE irradiated at 100 kGy was halved after 160 hours of accelerated ageing, due to the developed oxidation. On the other hand, the work to failure of samples with Vitamin E was constant up to 1800 hours of ageing under the same conditions.

Discussion Irradiation of UHMWPE induces C-C and C-H bond scissions, leading to the formation of alkyl radicals. When irradiation is carried out in air, macroal-kyl radicals can react with oxygen to form hydroperox-ides, which in turn decompose giving other oxidation species, mainly ketones and acids, which decrease the molecular mass. Oxidation of the polymer has been found to cause a dramatic deterioration of its mechanical properties. Vitamin E has been shown to be highly efficient against radiation-induced oxidation and therefore it should be recommended as biocompatible stabilizer for orthopaedic UHMWPE, in order to preserve good mechanical properties.

1. Use of OP1: present situation

1.1 Tibial pseudoarthrosis. The work by Friedlander can be considered golden standard about the clinical application. It is a prospective, randomized clinical trial comparing OP-1 with fresh bone autograft. Results of the two techniques are similar under the clinical and radiographical point of view(1). Some cases of very serious pseudoarthrosis treated with OP1 have demonstrated an high percentual of clinical recovery(2). In the I Orthopaedic Clinic of Turin University pseudoarthrosis are treated with Ilizarov technique, not with the autologous transplantation, so Friedlander’s results are not discriminant for the our work.

1.2 Australian study of 163 patients with amputation risk was done an attempt with OP1 application, before of his commercialisation. In these cases the drug demonstrated to be very efficacious(3).

1.3 Concerning the fresh fractures, experience is limited to prospective, randomised, multicenter clinical trial. The conclusions are a reduction of consolidation delay and the number of reoperation in the OP1 treated group versus the not treated one(4).

2. In the I Orthopaedic Clinic of Turin University (UOSD Muscle-Skeletal Traumatology and External Fixation) guide lines for OP1 application are:

2.1 Delayed union of the docking point in pseudoar-throsis of long bones treated with the Ilizarov technique. OP1 is also used if traditional techniques are not suitable for application

2.2 Traditional techniques failure

2.3 First treatment in very difficult cases of limb reconstruction and bone nonunion

3. From 30/09/2002 till 27/09/2004, 19 patients have been treated with OP1. Middle age is 38 years (range 22–65). Before last intervention, middle number of operation is 6,5 (range 3–26) with middle time treatment of 4 years (range 1–31). 12 healed, 5 are under treatment and 2 are failure (osteomyelitis relapse). 10 tibias, 7 femurs, 1 humerus and 1 forearm were treated. The middle time of healing was 4 months (range 2–6).

Healing has been evaluated by clinical and radiographical point of view (handly evaluation of stability, function recuperation and image of bone consolidation). Radiographic images of bone consolidation are not strictly correlated with clinical stability and function recovery.

4. Conclusion:

4.1 The series is strictly observational. However results are satisfying, given the complexity of treated cases. More prospective randomised double blind clinical studies, and drug cost decrease are necessary to extend the indications for OP1 application.

Introduction Sterilisation of UHMWPE prosthetic components by high-energy radiation in air induces an oxidative degradation of the polymer, which may compromise the mechanical performances of the whole implant. Many manufacturers shifted to gas sterilization with EtO and gas plasma or to radiation sterilization in inert atmosphere and with barrier packaging. Aim of the present study was to investigate the relationship between sterilisation method, packaging, oxidation and mechanical properties of current orthopaedic UHMWPE.

Materials 100 sterilised UHMWPE hip, knee, and shoulder components by 19 orthopedic manufacturers were studied. The components were cut in half and sectioned using a microtome into slices of controlled thickness (0,1–0,3mm) which were analysed by FTIR. The UHMWPE packaging was also evaluated by FTIR, in order to correlate the extent of oxidation to the storage conditions. Mechanical properties were evaluated using the small punch test, as described in ASTM F2183-02.

Results The UHMWPE packaging was classified, when possible, into one of the following types; A: PET blister(s) with Tyvek® gas-permeable cover; B: packaging involving a polymeric multilayer bag; C: packaging involving at least one Aluminium foil. Using Type A, air permeable packaging for radiation-sterilized UHMWPE is the equivalent to irradiation in air. Many radiation sterilized implants packaged using Type A materials were severely oxidized. In the case of packaging type B, we detected moderately low oxygen index (OI) in the majority of samples, but an average high hydroperoxide level, even though type B packaging has well-documented oxygen barrier properties. UHMWPE components contained in packaging type C exhibit low OI and hydroperoxide level, due to the impermeable Al foil. The small punch test measurements showed that the oxidised sample exhibit generally diminished mechanical properties. Reductions in the yield load (up to 15%), in the ultimate load (up to 33%) and in the ultimate displacement (up to 21%), compared to the original or EtO sterilised material, have been measured on the majority of the oxidised samples.

Discussion The present results confirm that oxidation has a negative effect on the mechanical properties of UHMWPE. It remains difficult to generalise about the overall effectiveness of barrier packaging at protecting UHMWPE from oxidation, but it is our opinion that a complete absence of sterilisation-induced oxidation can only be guaranteed by gas sterilisation.

Commercial aviation has recognized since long time that the so called “human factor” is the main responsible for the majority of accidents or near-accidents, which are always reported in aviation but almost never in medicine. Therefore I strongly support the idea that we could much learn from aviation in order to cope with the major cause of our accidents. Like airmen, pilots, air traffic controllers and so on, we also make errors. The first step to reduce the burden of our errors is to be able to admit them in order to analyse their causes, which up to now we are unable to do. Only one medical journal, the Lancet, has started to publish our errors. But beware not to make confusion between, complication, negative outcome and medical error.

The “human factor” must not be understood as human error; on the contrary the human factor is related to the majority of accidents, where the human error is only a minor and final cause.

To understand how “human factors” can play a role in determining the “accident”, we must first distinguish between active and latent failures. Active failures are unsafe acts committed by those at the sharp end of the system: the pilot, air traffic controller, anaesthetist, surgeon.

Latent failures arise from fallible decisions, usually taken within the higher levels of the organization or within society at large. A clear example is the crash of the SAS aircraft in Milano Linate with a small aircraft of the general aviation on the same runaway. No ground radar was available and the fog made the rest. But only the “sharp end” of the system, i.e. the traffic controllers paid for their error, not those responsible for not buying the ground radar.

We must develop a new culture of error but this will remain difficult until our legal systems do not change their approach towards negative outcomes. This vicious circle needs to be cut for the benefit of all, patients and doctors.

Aims: to investigate the mechanical properties of a new nanocomposite bone cement radiopacified with Barium Sulfate (BaSu) nanoparticles added at different concentrations, compared to a control cement with the classical BaSu microparticles.

Methods: the starting material was Endurance (J& J/ DePuy, USA) bone cement without BaSu; the radi-opacifier particles have been mixed into the cement powder in several different concentrations of 5, 10, 20, 30, 40% of the weight respectively. Two groups were studied: controls, with classical medical grade BaSu particles (average size 1000 nm) and nanocomposites, with nanoparticles (av. size 100 nm). In accordance with the ASTM, an Instron 4201 machine tested a minimum of 6 specimens for each concentration. Tensile tests were performed at cross-head speeds of 1mm/sec, while compression tests were performed at 25,4 mm/sec. Results were statistically analysed.

Results: nanocomposites had higher compressive Yield strength in all groups except 30 and 40% and lower compressive Modulus in all but 5% group (no significant difference). Nanocomposites had higher tensile values in 5%, 10%, and 40% concentrations for Strain-to-failure, yield stress, and Work-of-Fracture, and no significant differences in the other concentrations. Tensile modulus had not statistically significant variations. Higher BaSu concentrations give increases in tensile modulus and decreases in the other tensile properties for both the groups. The nanocomposite outperformed the control in the 5, 10, and 20% groups, while the 30 and 40% groups had no significant differences; all the results were above ASTM requirements.

Conclusions: bone cement has several uses, like joint replacement, filling defects in tumour or revision surgery, and more recently vertebroplasty. These applications require different properties and would have benefits from the possibility to change viscosity, radiopacity, time of polymerisation, mechanical features. Previous studies have demonstrated the improved performances of the new nanocomposite cement at the clinical used concentration of 10%. This study investigated the possibility to augment the concentration of BaSu and therefore the radiopacity and their relative effect on the mechanical properties; the results demonstrated the good compliance of the nanoparticles cement in this field. This would be useful in particular for specific applications such vertebroplasty. Further studies are needed to investigate and determine the ideal fatigue, handling and mixing properties, viscosity and radiopacity.

Aims: To understand why during routine analyses of the physico-chemical properties of retrieved UHMWPE prosthetic components (Pes), it was noticed that some cups, which were directly in contact with bone, evidence a material loss in correspondence with the area adjacent to bone.

Methods: PEs retrieved during revision surgery and stored in formalin prior to observation, have been analysed by Fourier Transform InfraRed (FTIR) spectroscopy and Scanning Electron Microscopy (SEM).

Results: The results of the FTIR analyses did not display appreciable differences compared to those of the majority of the retrieved prostheses. Oxidation of UHMWPE was detected, but it is known to be due to sterilisation with high energy radiation in air, under uncontrolled conditions.

The SEM analyses indicated that the PEs surface which was directly in contact with bone shows an anomalous degradation. The surface looks as it has been corroded or “bitten” and its morphology is significantly different from that of surfaces abraded either in vivo or in vitro.

Conclusions: The results so far obtained seem to indicate that the surfaces, which have been in contact with bone during the implant time, undergo a selective biodegradation process, facilitated by gamma in air sterilisation, and influenced by the biological reactivity of the patient (such as osteclast activation).

Aims: Among the Medical Services complex missions in the context of the Olympic event an important issue is to ensure the basic and emergency health care assistance to the athletes, the Olympic Family members, the Olympic staffs, the IOC members, the media staffs, the spectators and to all of the other persons participating to the Olympic events. The base of this program is of organizing a system able of furnishing a quality standard of care which must not be inferior to the one offered daily to the resident population and at the same time the Olympic event must not impact on the quality of care provided to the resident population. Methods: In Salt Lake City, during the XIX Winter Olympic Games, 11986 medical care have been provided. Among the acute visits there have been 231 athletes injuries with 14 athletes hospitalized and 1023 non-athletes injuries. Results: For an easy manage of the system it has been decided to divide the territory of competence in two areas: the Torino urban area and the alpine area. It will be identiþed, for each area, an ofþce district, responsible for all the territories included. Separate resources for the medical assistance will be implemented in the competition area and in spectator areas. The main instrument of the whole system will be the þrst aid teams, made up of members of the regional health care system, the voluntary services, the alpine and speleological rescue corps of Piemonte, the security and rescue service of the sport centers and any other accredited bodies. The dimension of the area involved, together with the need to guarantee timely rescue, stabilization and hospitalization activities, call for the creation of helicopter bases. Conclusions: The greatness of this project will certainly allow to leave a legacy to the host city which will enrich the quality of the health care organization at the service of the residents not only of structures and buildings but also of knowledge and speciþc experiences.

Negative outcomes, accidents and complications are unavoidable. In surgery as in aviation a major role is played by human factors contributing to 30 to 90 per cent of accidents. However in aviation accidents and near-accidents are investigated and all errors are reported.

Surgical errors and near-accidents are never reported nor investigated and no lesson can be learned.

Aims: A prospective multicentric study was carried out in patients having metal-on-metal METASUL components to check if the concentration markers of chromosomal damage (Sister Chromatid Exchanges (SCEñs) and Micronuclei (Mni) and that of Co, Cr, Ni and Mb in the body ßuids are affected by the implant of METASUL components within 6 months. Methods: 30 patients were enrolled homogeneous as to the exposition to mutagenic agents. Observation times were pre-op., 7 days, 2 months, 6 months; blood and urine samples were taken at each observation time, and the markers of chromosomal damage (blood) and the ion concentration (blood and urine) were measured. Results: measurements showed a 2-fold increase of Co in blood, a 10-fold increase of Co in urine, a 1.5-fold increase of Cr in the blood and a 3-fold increase of Cr in the urine at a follow-up of 6 months from the operation; the Ni blood concentration was also increased at the 7 day check-up. The study cohort did not show any modiþcation in the frequency of markers of chromosomal damage at any of the observation times. The amount of the SCEñs and Mni recorded at all the observation times did non correlate with each other nor with any of the ion levels measured in the blood and in the urine. Conclusions: the implant of prostheses with METASUL components determines an increase in the concentrations of mainly Co and Cr in blood and urine, but that this increase has no genotoxic effects on the peripheral lymphocytes in the selected group at a follow-up of 6 months.

The choice of treatment for open fractures is conditioned by the care of bone and soft tissue. Grade I open fractures can be treated as closed fractures, according to the centre’s protocol. In Grade II open fractures skin wounds must be left open, and the suture should be delayed for at least a week. Most authors perform fixation by means of intramedullary nails.

In our opinion, external fixation is the best choice in these cases. The skin cannot be closed in Grade III open fractures, and the basic point of treatment is adequate surgical debridement. The fixation must be done by external fixation. To achieve the treatment in an emergency situation, the device to be used must be quick and simple like a monolateral device that can be changed into a more complex one, such as an Ilizarov.

The Ilizarov technique uses distractional osteogenesis that can fill bone and soft tissue loss without further bone or soft tissue grafting.

Following these general guidelines, each district has its own particular approach to treating open fractures. Internal fixation by DCP plates is always indicated for forearm fractures. For a humerus fracture, simple direct shortening and external fixation can fill bone loss. Patients with fractures of the femur usually have multiple injuries. The problem is to provide a quick fixation in order to allow for easier intensive care. External fixation is the most indicated technique.

The choice of treatment for open fractures is conditioned by the care of bone and soft tissue. Grade I open fractures can be treated as closed fractures, according to the centre’s protocol. In Grade II open fractures skin wounds must be left open, and the suture should be delayed for at least a week. Most authors perform fixation by means of intramedullary nails.

In our opinion, external fixation is the best choice in these cases. The skin cannot be closed in Grade III open fractures, and the basic point of treatment is adequate surgical debridement. The fixation must be done by external fixation. To achieve the treatment in an emergency situation, the device to be used must be quick and simple like a monolateral device that can be changed into a more complex one, such as an Ilizarov.

The Ilizarov technique uses distractional osteogenesis that can fill bone and soft tissue loss without further bone or soft tissue grafting.

Following these general guidelines, each district has its own particular approach to treating open fractures. Internal fixation by DCP plates is always indicated for forearm fractures. For a humerus fracture, simple direct shortening and external fixation can fill bone loss. Patients with fractures of the femur usually have multiple injuries. The problem is to provide a quick fixation in order to allow for easier intensive care. External fixation is the most indicated technique.