Limb amputation is a traumatic event that significantly reduces the ability to perform daily activities, impairs mobility, and lowers quality of life. In Italy, approximately 4 million people live with disabilities, with 1.2 million having motor disabilities. Among lower limb amputees (around 200,000), most are elderly, with amputations due to diabetic or vascular issues. Other groups include middle-aged adults (often victims of workplace accidents) and young individuals (victims of traffic accidents).

Post-amputation rehabilitation mainly involves the use of prostheses, which, however, can cause skin problems due to the socket (the part that anchors the prosthesis to the residual limb). Among patients using a socket, 34-63% develop chronic skin issues and pain. Complications include excessive sweating, sores, abscesses, and irritation. Additionally, daily volume changes in the residual limb and long-term weight fluctuations further complicate the use of conventional prostheses.

In the last two decades, research groups, assisted by experienced surgeons, have worked to develop implant solutions that bypass the socket and address these issues. One such solution is osteointegrated prostheses, which use the principle of osteointegration to anchor the prosthesis directly to the bone of the residual limb. A metal stem is surgically inserted into the medullary canal of the residual limb and fixed through bone growth, establishing a direct connection between the amputated limb and the external prosthesis.

Osteointegrated prostheses are widely accepted worldwide as a valid alternative to socket prostheses, especially for young and active individuals with transfemoral, transtibial, transhumeral, or transradial amputations not caused by vascular issues. The key benefit of osteointegration is the restoration of load alignment along the anatomical and mechanical axis, improving control of the residual limb during walking, as well as overall functional capacity and quality of life. Other advantages include greater stability, enhanced sitting comfort, a wider range of hip movement, faster attachment and detachment of the prosthesis, and improved body perception. Additionally, the direct contact between the metal stem and the bone generates sensory feedback (osteoperception), allowing the patient to better control the amputated limb by perceiving ground contact through vibrations transmitted to the bone. Osteointegration offers the only viable alternative for prosthetic use in patients with a short residual limb, where conventional socket prostheses would not be suitable.

Inclusion Criteria:

• Subjects of both sexes, aged between 18 and 65 years;
• Subjects with unilateral transfemoral amputation, following trauma, tumor, infection, or congenital defect;
• Subjects already scheduled for osteointegrated prosthesis surgery for amputation;
• BMI < 35 kg/m²;
• Difficulty in using the traditional socket prosthesis (pain, reduced mobility, short residual limb, skin infections, ulcers, volume changes in the residual limb);
• Subjects who have signed informed consent and reviewed the study information sheet.

Absolute exclusion criteria:

• Peripheral vascular diseases;
• Pregnancy;
• Rheumatoid arthritis;
• Neurological deficits;
• Amputation of the contralateral limb;
• Active infections;
• Immunodeficiency;
• Comorbidities/concurrent disabilities, general or localized (Multiple Sclerosis, Parkinson's disease, muscle tone disorders, malignant neoplasms, etc.), that may interfere with the study;
• Presence of uncontrolled psychiatric comorbidities;
• Declared or evident cognitive deficits that would impair understanding of the tasks required (MMSE ≤ 24);
• Insufficient degree of cooperation;
• Length of the bone stump (measured from the lesser trochanter to the apex of the stump) less than 15 cm;
• Previous radiotherapy on the amputated limb;
• Ongoing chemotherapy treatments.

Relative exclusion criteria:

• Smoking;
• Uncontrolled diabetes;
• Previous infections;
• Presence of additional joint prostheses on the same limb;
• Osteoporosis with a T-score of -2.5 or lower.