A retrospective multidimensional comparison of microprocessor and mechanical knee users: Analysis of quality of life and satisfaction with the prosthesis.

BACKGROUND: Despite the demonstrated greater efficacy of microprocessor knees (MPK) over mechanical knees (MK), the latter is still widely used by persons with transfemoral amputation. Besides motivations related to local insurance policies, quality of life (QoL) and satisfaction with the prosthesis play a key role in user preference. OBJECTIVE: The aim of this study is to compare QoL and satisfaction in a large sample of MPK and MK users and to assess how these outcomes are explained by clinical and demographic characteristics. STUDY DESIGN: Retrospective study. METHODS: The study was conducted on 75 MPK and 60 MK users. Quality of life was assessed using the EuroQoL Five Dimensions and the EuroQoL Visual Analog Scale questionnaires. Satisfaction was assessed with the Satisfaction with Prosthesis questionnaire. All 3 instruments were self-administered. Univariate and multivariate regression analyses were conducted thereafter. RESULTS: The difference in satisfaction between MPK and MK users was not statistically significant. Significant differences were observed instead for QoL. From the univariate regression analysis, 6 factors were significant predictors of QoL and satisfaction. On multivariate analysis, the number of significant factors was reduced to 3, namely knee type, age at the first prosthesis, and experience with prosthesis. Type of knee and age at the first prosthesis significantly predicted QoL scores, explaining 12% of EuroQoL Five Dimensions and 25% of EuroQoL Visual Analog Scale variances. Age at the first prosthesis and experience with prosthesis predicted Satisfaction with Prosthesis scores in the multivariate model, explaining 25% of the variance. CONCLUSIONS: MPK affects QoL but not satisfaction, which is positively driven by patients' experience with prosthesis and negatively affected by the age at the time of the first prosthesis.

A digital process to replicate the socket-foot alignment in below-knee running specific prostheses.

A well-fitting socket and a fine-tuned foot alignment are crucial elements in a running-specific prosthesis to allow Paralympic athletes with below-knee amputation to express their full competitive potential. For this reason, once a satisfactory socket-foot configuration is established after dynamic alignment, it is fundamental to reproduce the same conditions when constructing the definitive carbon fiber socket, and when renewing or constructing a back-up prosthesis, without dismantling the original. In addition, to cope with emerging needs of the athlete, it would be beneficial to implement fine-tuning adjustments of the alignment in a very controlled manner. At present, this requires elaborate bench procedures, which tend to be expensive, time consuming, prone to manual errors, cumbersome in use and most often require damaging or disposing of the current socket. In this study, we propose an original CAD/CAM workflow that allows replicating the desired socket-foot configuration for below-knee sprinting prostheses, as well as performing socket adaptations and introducing fine-tuning adjustments to the alignments. The workflow is exemplified with reference to two case studies involving elite Paralympic runners with transtibial and partial foot amputations, respectively.

A Workflow for Studying the Stump-Socket Interface in Persons with Transtibial Amputation through 3D Thermographic Mapping.

The design and fitting of prosthetic sockets can significantly affect the acceptance of an artificial limb by persons with lower limb amputations. Clinical fitting is typically an iterative process, which requires patients' feedback and professional assessment. When feedback is unreliable due to the patient's physical or psychological conditions, quantitative measures can support decision-making. Specifically, monitoring the skin temperature of the residual limb can provide valuable information regarding unwanted mechanical stresses and reduced vascularization, which can lead to inflammation, skin sores and ulcerations. Multiple 2D images to examine a real-life 3D limb can be cumbersome and might only offer a partial assessment of critical areas. To overcome these issues, we developed a workflow for integrating thermographic information on the 3D scan of a residual limb, with intrinsic reconstruction quality measures. Specifically, workflow allows us to calculate a 3D thermal map of the skin of the stump at rest and after walking, and summarize this information with a single 3D differential map. The workflow was tested on a person with transtibial amputation, with a reconstruction accuracy lower than 3 mm, which is adequate for socket adaptation. We expect the workflow to improve socket acceptance and patients' quality of life.

Static strength of lower-limb prosthetic sockets: An exploratory study on the influence of stratigraphy, distal adapter and lamination resin.

Knowledge about the mechanical properties of lower-limb prosthetic sockets fabricated with resin infusion lamination and composite materials is limited. Therefore, sockets can be subject to mechanical failure and over-dimensioning, both of which can have severe consequences for patients. For this reason, an exploratory study was conducted to analyze the effect of stratigraphy (layup and fibers), matrix (resin) and mechanical connection (socket distal adapter) on socket static strength, with the objectives of: 1) implementing a mechanical testing system for lower-limb prosthetic sockets based on ISO 10328:2016 and provide the mechanical design of the loading plates, 2) apply the testing system to a series of laminated sockets, and 3) for each type of distal adapter, identify the combinations of stratigraphy and matrix with acceptable strength and minimum weight. Twenty-three laminated sockets were produced and tested. Sixteen met the required strength, with ten exhibiting an excessive weight. Among the remaining six, four combinations of stratigraphy and resin were identified as best option, as they all overcame ISO 10328 P6 loading level and weighted less than 600 g. The selected stratigraphies had limited or absent amount of Perlon stockinettes, which seems to increase weight without enhancing the mechanical strength. Sockets based on Ossur MSS braids and connector show the best compromise between strength and weight when the amount of carbon braids is halved.