The mechanical properties of three different bandages and their applicability for fixating patients on positioning aids of operation tables during hip and knee surgery

Arthroplasty is a successful surgical procedure; in 2014, only in Italy, the prosthetic replacement operations achieved the numbers of 175.2901, of which 67.365 are knee’s replacement. A lot of techniques are available for this operation, depending on the positioning of the patient, and lot of used devices too. These are used to immobilize the patient, as the success of the operation depends on the precision of the bone’s cut, although the insertion of the prosthesis. In this thesis, the mechanical properties of three bandages are investigated in laboratory and on cadavers. They are evaluated as a medical bandage to immobilize some parts of the patient during the surgical intervention. The three bandages are the iFix, the peha haft and the Coban; the last one is already used in surgical operations. A morphological analysis is done using SEM and the following mechanical tests are performed: the tensile test, the grab test and the tear resistance test. The morphological test showed the structural properties of the bandages: each one seemed anisotropic, and their fibres are different for every orientation. To find if the iFix is isotropic, the mechanical properties of iFix are investigated for all its orientations, and only in the longitudinal direction it is compared with the other two bandages. The mechanical test’s results return the maximum force, the breaking force and the two elongations associated. The tensile test’s results showed that the iFix had different properties in different orientations, as the longitudinal one should be preferred for its resistance. The three bandages’ comparison evidenced that the iFix was less elastic than the other two: they presented the same maximum and breaking force but different elongations, which were higher for the peha haft and the Coban. The grab test is done with wet samples, and it showed that the iFix didn’t change its properties while the Coban and the peha haft get the maximum and breaking forces decreased. The last test measured the forces in a sample with a cut of 1 cm on its edge: the iFix showed different forces compared with the tensile test’s results, as the tear resistance (maximum force of 60 N) was lower than the tensile resistance (maximum force of 100 N). To prove if the mechanical properties of the bandages are the same applied on human body, a test on cadavers is done. In this case only the iFix and the Coban were used, as the peha haft wasn’t a sterile material, so its usage in such an application is questionable. In this test the sub-bandage pressure is evaluated when a specific traction is applied. The compression is measured with an array of sensors, which are applied on the left leg of the cadaver. The results are shown using colour maps for all the traction’s forces. The two bandages presented different points of high compression, on the tibia for the iFix, and near the ankle for the Coban. Results suggest that the iFix is more rigid than the Coban, and it gives a more stable fixation. These results seem to agree with the ones obtained in the laboratory, so the iFix is better for a stable fixation than the Coban, as it could generate unwanted movement of the foot during the surgery. From our point of view, IFix can be used on lower extremities of the body, as the average pressure was constantly under 10 kPa, and the tests shown its resistance if wet or cut. Our study showed that the iFix gave a stable fixation, which depends on the orientation of the fibres, and it coul