# Biomechanical Analysis of Two Types of Oseointegrated Transfemoral Prosthesis
); [EMAIL_ADDRESS] (A.I.M. ); [EMAIL_ADDRESS] (F.D.S. ); [EMAIL_ADDRESS] (V.N. )1 Department of Engineering, Universita degli Studi di Palermo, 90128 Palermo, Italy; [PERSON].M. ); [EMAIL_ADDRESS] (A.I.M.M. ); [EMAIL_ADDRESS] (A.I.M. ); [PERSON]A.I.M. ); [EMAIL_ADDRESS] (V.N. )1 Department of Engineering, Universita degli Studi di Palermo, 90128 Palermo, Italy; [PERSON].M. ); [EMAIL_ADDRESS] (A.I.M. ); [EMAIL_ADDRESS] (F.D.S. ); [EMAIL_ADDRESS] (V.N. )1 Department of Engineering, Universita degli Studi di Palermo, 90128 Palermo, Italy; [PERSON].M. ); [EMAIL_ADDRESS] (A.I.M. ); [EMAIL_ADDRESS] (F.D.S. ); [EMAIL_ADDRESS] (A.I.M. ); [EMAIL_ADDRESS] (F.D.S. ); [EMAIL_ADDRESS] (V.N. )1 Department of Engineering, Universita degli Studi di Palermo, 90128 Palermo, Italy; [EMAIL_ADDRESS] (A.I.M. ); francesco.disimone@community. oseoseintegrated prosthesis is directly attached to the skeletal system by percutaneous implant surgically inserted in the medullary canal of the residual femur [5; 6] and, as a result, the artificial limb can be directly linked to the skeletal system. In particular, a stem, made of biocompatible material, is inserted into the medullary canal of the residual bone and after the healing period, during which the implant fully integrates with the bone tissue, the external prosthesis can be connected to the femur by a percutaneous abutment. To achieve an optimal osseointegration, the most important aspects are biocompatibility, shape and surface treatment of stem, bone quality and surgical protocol, in addition to a gradual application of load [7]. After the osseointegration has occurred, the patient develops a special condition, called \"osseopereception\" [8]. It allows the patient to feel the weight of the prosthesis and thereby to activate the residual muscles, improving the freedom of movement of patient and thus his quality of life [9; 10; 11; 12; 13; 14; 15]. Patients with OI prosthesis report greater improvement of quality of life and mobility, as well as pain and infection reduction, compared to those with socket-type prosthesis [10; 12; 13; 16; 17]. Currently, two main designs are available for OI transfemoral prostheses: the screw-fixation type and the press-fit one. Both systems are composed of an intramedullary stem (fixture) and a coupling device (abutment) which passes through the soft tissues of the stump to link with the artificial limb [18; 19; 20]. The two systems differ in structure and composition of the intramedullary stem. A press-fit device is composed of a stem covered with a layer of highly porous metal [4; 21] and achieves skeletal integration as a result of bone penetration and ingrowth [22]. A screw-type device, instead, has a threaded titanium stem that is screwed in the medullary cavity and has been developed by adapting the technology used for osseointegrated dental implants. The press-fit device is usually used only for transfemoral amputees [23]; the screw-type system, instead, is used both for transfemoral and transhumeral implants [24]. The OFRA system (Integrum, Molndal, Sweden) is the most representative example of screw-type implants; OPL (Ooseointegrated Prosthetic Limb, Permedica s.p.a., Milan, Italy) and ISP Endo/Exo prostheses (ESKA Orthopaedic Handels, Lubeck, Germany) are the most common press-fit devices. Nowadays, OFRA, ISP and OPL are the most commercially available systems for direct skeletal attachment of external limb prostheses [1]. The procedure to implant these systems consists of the same main stages. Initially, the fixture is surgically implanted into the medullary cavity. At a later stage, after a healing period during which the fixture is maintained unloaded and the bone-implant integration occurs, the abutment is connected to the fixture using a retaining bolt. The healing period varies depending on the type of implant: about 6-8 weeks for the press-fit systems and up to 6 months for the OPRA implants [25; 26].