Analysis of retrieved shoulder prostheses

In the last years the number of shoulder arthroplasties has been increasing. Simultaneously the study of their shape, size and strength and the reasons that bring to a possible early explantation have not yet been examined in detail. The research carried out directly on explants is practically nonexistent, this means a poor understanding of the mechanisms leading the patient and so the surgeon, to their removal. The analysis of the mechanisms which are the cause of instability, dislocation, broken, fracture, etc, may lead to a change in the structure or design of the shoulder prostheses and lengthen the life of the implant in situ. The idea was to analyze 22 explants through three methods in order to find roughness, corrosion and surface wear. In the first method, the humeral heads and/or the glenospheres were examined with the interferometer, a machine that through electromagnetic waves gives information about the roughness of the surfaces under examination. The output of the device was a total profile containing both roughness and information on the waves (representing the spatial waves most characteristic on the surface). The most important value is called "roughness average" and brings the average value of the peaks found in the local defects of the surfaces. It was found that 42% of the prostheses had considerable peak values in the area where the damage was caused by the implant and not only by external events, such as possibly the surgeon's hand. One of the problems of interest in the use of metallic biomaterials is their resistance to corrosion. The clinical significance of the degradation of metal implants has been the purpose of the second method; the interaction between human body and metal components is critical to understand how and why they arrive to corrosion. The percentage of damage in the joints of the prosthetic components has been calculated via high resolution photos and the software ImageJ. The 40% and 50% of the area appeared to have scratches or multiple lines due to mechanical artifacts. The third method of analysis has been made through the use of electron microscopy to quantify the wear surface in polyethylene components. Different joint movements correspond to different mechanisms of damage, which were imprinted in the parts of polyethylene examined. The most affected area was located mainly in the side edges. The results could help the manufacturers to modify the design of the prostheses and thus reduce the number of explants. It could also help surgeons in choosing the model of the prosthesis to be implanted in the patient.

Studio retrospettico sul ruolo della strumentazione nei fallimenti meccanici a seguito di Trattamento Chirurgico nelle Scoliosi dell'adulto

The spinal column performs important functions in the body, including the support of the entire weight of the human body, the ability to orientate the head in space, bending, flexing and rotating the body. Diseases affecting the spine are manifold: the most frequent is scoliosis, which often affects the female population. It is often treated surgically with a very high percentage of failures. The aim of the thesis is to study the role of instrumentation in mechanical failures encountered 12 months after surgery in the treatment of scoliosis. For the purposes of the study, we analyzed specific biomechanical parameters. The pelvic angles determine the position of the pelvis, while the imbalance parameters the structure of the body. We infer other parameters by analyzing the characteristics of the implanted instrumentation. Initially, the anatomy is described of the spine and vertebrae, the equipment used and the possible failures that may occur after surgery. Subsequently, the materials and methods used for the analysis of the above-mentioned parameters for the 61 patients are reported. All data are obtained by the observation of pre and post-operative x-rays with a special program, by reading reports from operators and by medical records. In the fourth chapter, we report the results: the overall failure rate is 60.9%; the types of failures that occurred are rupture of bars and rupture of bars simultaneously to PJK. The most influential parameters on results of the progress of the surgery are the type of material used and the BMI. It is estimated a high percentage of failures in patients treated with implants of cobalt chromium alloys (90.0%). According to the results obtained, it is possible to understand the aspects that in the future should be studied, in order to find a solution to the most frequent surgical failures.

Upper-Limb Exoskeleton Design for Firefighter

Every day, firefighters are involved in emergency response tasks, which are both physically and psychologically exhausting. According to the National Fire Protection Association (NFPA), the number of firefighters who are injured or die while performing their job is incredibly high. When firefighters are injured, they must follow a rehabilitation therapy program to physically recover and depending on the severity of their injuries they may not fully recuperate at all. If they sustain a permanent injury that they cannot recover from, they may be out of work for the rest of their career. This research focuses on studying and developing a special device, known as an exoskeleton, aimed at assisting and preventing potential injuries among firefighters. Nowadays, the usage of human exoskeletons is becoming more common in a variety of fields. In fact, it is currently being researched and developed for soldiers, athletes, and critical care patients around the world. Most of the existing exoskeletons have been developed for the assistance of the lower human body. The research that I have done in my thesis instead relates to mobility of the upper body. Many of the existing exoskeletons have been analyzed and compared to each other and the human body, such as the study of human arm parts and their movements around three principal joints: shoulder, elbow, and wrist. The correct design of the shoulder exoskeleton join is still a big challenge for designers because of the complexity of biomechanical human movements. The exoskeleton must fit perfectly to the human body, otherwise it could be harmful for both the recovery and the safety of the user. The goal of this thesis is to design an upper-body arm exoskeleton worn by firefighters and develop and test a PID control system to prevent the risk of injuries while performing their job.

Biopolyester fibers for sustainable and biocompatible applications

The rising of concerns around the scarcity of non-renewable resources has raised curiosity around new frontiers in the polymer science field. Biopolymers is a general term describing different kind of polymers that are linked with the biological world because of either monomer derivation, end of life degradation or both. The current work is aimed at studying one example of both biopolymers types. Polyhydroxibutyrate (P3HB) is a biodegradable microbial-produced polymer which holds massive potentiality as a substitute of polyolefins such as polypropylene. Though, its highly crystalline nature and stereoregularity of structure make it difficult to work with. The project P3HB-Mono take advantage of polarized Raman spectroscopy to see how annealing of chains with different weights influence the crystallinity and molecular structure of the polymer, eventually reflecting on its mechanical properties. The technique employed is also optimal in order to see how mesophase, a particular conformation of chains different from crystalline and amorphous phase, develops in the polymer structure and changes depending on temperature and mechanical stress applied to the fiber. Polycaprolactone (PCL) on the other hand is a biodegradable fossil-fuel polymer which has biocompatibility and bio-resorbability features. As a consequence this material is very appealing for medical industry and can be used for different applications in this field. One interesting option is to produce narrow and long liquid filled fibers for drug delivery inside human body, using a traditional technique in an innovative way. The project BioLiCoF investigates the feasability of producing liquid filled fibers using melt-spinning techniques and will examine the role that melt-spinning parameters and liquids employed as a core solution have on the final fiber. The physical analysis of the fibers is also interpreted and idea on future developments of the trials are suggested.

Analysis of fragmentation cross sections of GSI 2021 data for the FOOT experiment

Hadrontherapy is a medical treatment based on the use of charged particles beams accelerated towards deep-seated tumors on clinical patients. The reason why it is increasingly used is the favorable depth dose profile following the Bragg Peak distribution, where the release of dose is almost sharply focused near the end of the beam path. However, nuclear interactions between the beam and the human body constituents occur, generating nuclear fragments which modify the dose profile. To overcome the lack of experimental data on nuclear fragmentation reactions in the energy range of hadrontherapy interest, the FOOT (FragmentatiOn Of Target) experiment has been conceived with the main aim of measuring differential nuclear fragmentation cross sections with an uncertainty lower than 5\%. The same results are of great interest also in the radioprotection field, studying similar processes. Long-term human missions outside the Earth’s orbit are going to be planned in the next years, among which the NASA foreseen travel to Mars, and it is fundamental to protect astronauts health and electronics from radiation exposure .\\ In this thesis, a first analysis of the data taken at the GSI with a beam of $^{16}O$ at 400 $MeV/u$ impinging on a target of graphite ($C$) will be presented, showing the first preliminary results of elemental cross section and angular differential cross section. A Monte Carlo dataset was first studied to test the performance of the tracking reconstruction algorithm and to check the reliability of the full analysis chain, from hit reconstruction to cross section measurement. An high agreement was found between generated and reconstructed fragments, thus validating the adopted procedure. A preliminary experimental cross section was measured and compared with MC results, highlighting a good consistency for all the fragments.