The socio-economic conditions in many developing countries impede widespread general use of the assets of biomedical technology. In orthopedics this becomes evident from the large-scale, though illegal, reuse of osteosynthesis plates and screws. Scientific research into the issue of the safe reuse of osteosynthesis materials from a biological point of view has never been done. Therefore the aim of this study is to determine whether plates and screws after simple cleaning, applying means which are available in developing countries, are safe from a biological point of view. Cleaning methods evaluated include a toothbrush, water, detergent and bleach. X-ray photoelectron spectroscopy analysis of cleaned surfaces and water contact angle measurements indicate that application of these methods yield surface characteristics similar to those of new, sterilized plates. If desired, bleach can be applied without affecting the surface properties of the materials.

Subsequently, the reactivity of a mammalian monolayer in response to a used screw (ISO-10993-5) and endotoxin release (USP 27-NF 22) was evaluated, showing that all screws tested are non-cytotoxic with endotoxin release within the requirements of the FDA. This study shows that reuse is not necessarily unsafe from a biological point of view.

The combination of Ultra High Molecular Weight Polyethylene (UHMWPE) as tibial substitute components paired with cobalt chrome alloy as femoral substitute components are the most common materials widely used in knee replacement applications. Wear mechanism effect on UHMWPE material is one of the leading factors that cause failure of this application.

In this study, the effects of loading in creating wear product and the influence of wear mechanism to alter material wear factor of the UHMWPE was investigated after Pin on Plate Unidirectional Reciprocating Movement Wear Test. This study use a die drawn GUR 1120 UHMWPE pin paired with nitrogen based-ion implantation of cobalt chrome alloy and utilize 25% bovine serum plus 75% distilled water as lubricant.

The materials were paired in a Pin on Plate Wear Test with sliding unidirectional reciprocating movement and subsequently loaded with 353 N and 462 N of force resulted in 9MPa and 12MPa contact pressure with constant friction velocity of 116.5 mm/s.

After the test, there was significant difference of wear product and wear factor subsequent to the loading process with a total of 35 km distance covered and 25 mm average gait length. From the 353 N loaded forces there was 1,075 mm3 of wear product volume created and 4.4 × 10-8 average wear factor observed, while in the 462 N force application there had been no wear product volume and wear factor resulted during the observation. The result of this study demonstrated that greater load produce lesser wear product and wear factor of the die drawn UHMWPE.

Polymerized material such as Ultra High Molecular Weight Polyethylene (UHMWPE) is commonly used as a bearing cushion with titanium alloy, austenistic stainless steel, ceramic and cobalt chrome alloy to be used for the tibial and femoral components in knee replacement application. As a biomaterial product these substances must comprise a wear resistance capacity.

This study was conducted to observe the wear product and wear factor of the die drawn GUR 1120 UHMWPE that was rubbed against nitrogen based-ion implantation of cobalt chrome alloy (irradiated at 100 Kev for 90 min) and employment of bovine serum in various concentration as lubricant.

The wear mechanism was tested with the application of bovine calf serum pre-conditioned similar to synovial fluids in human knee. The experiment was tested with a Pin on Plate Unidirectional Reciprocating Movement with various lubricant protein concentrations applied. The ‘A’ lubricant is a serum with protein concentration of 19.3 g/L and the ‘B’ lubricant is a serum with protein concentration of 30 g/L; these lubricants were then compared after the reciprocating movement test with constant load of 180 N force, 116.5 mm/s constant friction velocity and 25 mm average gait length with total of 35 km distance covered.

This study showed that protein concentration augmentation would decrease the wear factor up to 300%. This value was derived after increasing the protein concentration of the lubricant (from 19.3 g/L to 30 g/L) which then altered the wear factor from 5.12×10-7 mm3/Nm to 1.71×10-7 m3/Nm respectively.