Prosthetic socket design and fit are key for a successful amputee rehabilitation and comfort, directly influencing patient satisfaction and quality of life. However, there is a lack of quantitative data on stump pressure distribution and how it changes over time, which could greatly contribute to the efforts of designers, prosthetists and doctors to improve patient comfort.

This study explores the use of Force Sensitive Resistors (FSRs) to measure and visualize stump pressure distribution, specifically for transtibial prosthetic sockets. The research involves testing an experimental prototype equipped with FSRs on a cyclic loading machine, followed by a comparison of the results with a simulation.

The findings indicate that the highest loads are registered by FSRs positioned at the bottom of the stump and below the knee. Some anomalies were observed, potentially due to specific geometric features of the prototype and the way the load was applied during testing.
Overall, the experimental data suggests that FSRs are effective for measuring stump pressure distribution. However, further testing with increasingly complex load cases is necessary to validate the sensors' reliability.

In conclusion, FSRs demonstrate significant potential for enabling knowledge-based designs focused on patient well-being. Through the course of this project, valuable design insights and requirements for integrating sensors into prosthetic sockets were identified. Moreover, this systematic sensor testing approach can be applied to explore and compare between other pressure sensors.

Slipped capital femoral epiphysis (SCFE) is a condition in adolescents affecting the proximal femur. Increased mechanical forces result in fracture of the growth plate. Factors increasing the mechanical forces include for example obesity and endocrine disorders. As a result of the fracture a shift of the bone shaft towards the femur head occurs, causing mobility issues and pain. A treatment option for these patients is an intertrochanteric osteotomy with plate fixation. Restoring range of motion and pain reduction are the main aims of the surgery.

This intertrochanteric osteotomy alters the femur anatomy, resulting in a mismatch between bone and conventional plate fixation. These plates do not fit to the reconstructed bone, resulting in high chances of plate failure. The best option for these patients is to use patient-specific designed bone plates for femur fixation. Optimal mechanical properties of the patient-specific plate are important in limiting plate failure. These properties are dependent on design parameters, which can be adapted dependent on patient criteria and anatomy. Investigations towards patient-specific bone plates and the optimal design parameters for efficient and stable fracture fixation is lacking.

The focus of this study is on a specific SCFE patient case treated with corrective osteotomy using a patient-specific Ti-6Al-4V plate and screws for bone fixation and stability. A valid numerical model (i.e., finite element analysis (FEA)) is created, with physiological loading corresponding to two leg stance and walking, for an initial designed (ID) patient-specific bone plate to analyse plate performance. Screw configuration analysis and topology optimization of the ID plate were performed to design an alternative topology optimized (TO) plate. Biomechanical experiments with digital image correlation (DIC) techniques were performed for mechanical strength analysis and validation of the finite element model (FEM).

Both ID and TO plate were able to withstand two leg stance loading conditions according to both FEA and experimental testing. For walking loading conditions the ID plate showed instability, which could result in higher probability of failure in the plating construct. Quasi-static compression experiments showed failure in the most lateral proximal screw in all tests. The failure in the screws was caused by high bending moments. Optimization of the ID plate resulted in an alternative plate design in SCFE treatment. The TO plate consisted of six screws, decreasing plate length by 18.1%. The TO plate had a variable thickness, where thickness was increased around the lateral side of the plate compared to the ID plate.

The steps followed in this study to design a patient-specific implant and evaluation plate mechanical behaviour with FEM and additional experimental testing have shown to be adequate in investigating plate performance and can be used in the evaluation of newly designed patient-specific bone plates in SCFE patients.

Integration of the sensory systems inside patient-specific medical devices (e.g., implants or prosthesis) can provide additional measurement data at different time points. This can result in improving the traditional designs of those medical devices, and consequently leading to increasing the patient’s comfort and quality of life. By doing measurements directly on or inside the patient, information can be gathered more specifically, which is important for improving detection and diagnosis. Next to that, it enables better decision-making for therapies, treatments and the allocation of prosthesis, causing improved rehabilitation. Problems with the comfort and fitting of the prosthesis can have a big impact on the life of the patient wearing the prosthetic. If there is lack of comfort, the patient is less likely to wear the device and that could limit the rehabilitation and satisfaction about their life in multiple areas. To get a better insight in the transtibial prosthesis in particular, and possibly solve the problems that occur, measurements can be done at the interface of the patient and the socket of this prosthesis. The data can be used to visualize the problem more accurately and, as a result, the response and treatment process can be chosen in a more precise manner. First, a case study about the lower limb prosthesis was conducted. Several questions will be reviewed, including defining elements of the satisfaction of patients about their prosthesis, what current existing problems with prosthesis are and the reasons of patients why they are not satisfied with their prosthesis. Then, two types of sensors will be used to visualise the problems occurring at the interface of the socket and the residual limb. One type of sensor is the piezoelectric pressure sensor. It is used to map the pressure on the limb inside the socket. Several experiments have been done with an existing 3D printed socket design and the data is compared to a finite element model that predicts stress distributions to validate this model. The model itself was changed on multiple areas to get closer to test conditions and improve model outputs. To be able to improve such models, the test-procedure should be further revised. After that, thermistors were used to measure the temperature within a 3D printed socket. A design for a new socket has been made to actively use the temperature data and cool the residual limb inside the socket when needed. This is done by integrating air-channels within the structure of the 3D printed socket and air is forced through those channels with a power-fan. The design has been validated with several tests and it is improved based on that. Those tests, calculations and estimations have shown that the current design may be able to cool the residual limb when further improved and optimized. In the end, several suggestions and recommendations for improvements were provided. Some of those improvements could be made in the size of the air-channels and the interface between socket and residual limb. Finally, present and potential (ongoing) developments on how to change the patient's condition, as well as how to apply promising developments in innovative ways, will be addressed.