Sviluppo e valutazione di tecnologie di progettazione e produzione di componenti protesici per atleti paralimpici

A lower-limb prosthetic socket is the custom element interfacing the individual’s residual limb to the distal prosthetic components. It is usually produced by patient-centered facilities following a multi-step iterative process, based on the manual ability of Certified Prosthetists, who produce the socket and assemble it to the distal elements following internal alignment guidelines. The alignment between socket and foot is crucial to allow the person wearing the prosthesis to comfortably use the device, especially in case of running-specific prostheses. The final socket has to guarantee good fit and function while being lightweight and structurally sound to support the activities of daily living relevant to the individual. Despite the socket’s central role in comfort and function, no standards exist to test their structural strength, resulting in a limited knowledge of their mechanical properties, which entails risks of socket failure or over-dimensioning. The primary objective of this thesis was to define the minimum expected safety requirements of lower-limb prosthetic sockets, especially but not limited to sockets for running-specific sport activities, and to design and implement a testing method to verify them. Moreover, given the limited availability of dedicated alignment devices for sport applications, a secondary aim was to design and implement alignment tools and methods to facilitate a systematic and repeatable alignment of a sport socket with respect to its running-specific foot. First, a systematic review of the literature was conducted to collect information about available socket mechanical testing methods. The results showed a limited literature, mostly based on ISO 10328, i.e. the current standard for off-the-shelf prosthetic components that does not include sockets in its scope of this standard. Overall, the results of the review highlighted the necessity of establishing a common guideline for socket mechanical testing. In an effort to find a solution to this problem, the AOPA Socket Guidance Workgroup was formed to provide the prosthetic community with evidence-based recommendations regarding socket structural testing methods. Based on the evidence collected from the review and from the collaboration with AOPA, two test benches for lower-limb prosthetic sockets were designed and implemented at the University of Padua. The first bench adapted the testing methods of ISO 10328 to testing of sockets for the activities of daily living; decisions about the modes of adaptations were made using a worst-case approach. The second bench was designed to test running-specific sockets and allowed reproducing the most critical instants of the stance phase of the sprinting in a test bench environment; these conditions were calculated from kinematics and kinetics data of sprinting of elite paralympic athletes through a biomechanical assessment with force plates and motion capture system. The two benches were applied to various groups of daily-use and running sockets produced at the INAIL Prosthetic Center and allowed proposing a set of practical guidelines for socket construction that maximized socket strength while minimizing weight. With regards to the alignment between socket and foot for sport application, original alignment tools and methods were implemented to establish, assess, transfer and replicate the alignment between sport socket and running foot from temporary to definitive sockets. Finally, this thesis also includes a final section dedicated to sport-specific orthoses. Two case reports of design and assessment of patient-specific orthoses for elite paralympic athletes are presented: an Ankle-Foot Orthosis for long jump for an athlete with spastic hemiplegia, and a pair of hand orthoses for sitting volleyball for an athlete with scleroderma.