Mapping lines of non-extension in persons with lower limb amputation to aid comfort-driven prosthetic socket design.

OBJECTIVE: This study aimed to develop a new technique to map the strain field for persons with lower-limb amputations to use for the design of comfortable prostheses. METHODS: Using a DSLR camera with stenciled 2D markers, we demonstrated a technique to measure skin strain around the residual limb of persons with lower limb amputations. We used open-source software programs to reconstruct a series of cloud points derived from the pictures of the marked residual limb into 3D models, then calculated the minimum, maximum, and non-extension lines from directional strain fields. RESULTS: A DSLR camera was successful in capturing 2D markers. The maximum mean principal strain was 68% ± 14%, observed around the patella. The minimum compressive mean principal strain of -31% ± 4% was observed posteriorly in the popliteal region of the knee. Although lines of non-extension (LoNE) appear separate in different participants, they are anatomically located in regions that could be generalized for the design of prostheses. CONCLUSIONS: Marker locations extracted from the video of different poses can be compared to calculate strains from which the position of LoNE can be generated. The use of LoNE could be valuable in reducing discomfort at the socket interface and informing future socket design.

Measuring discomfort-An objective method for quantifying peak pressure discomfort and improved fit in adults with transtibial amputation.

BACKGROUND: Prosthetic socket coupling with the residual limb should be comfortable without causing skin breakdown or excessive pressure. However, users report socket discomfort, and there is a scarcity of objective measurements available to assess this feeling of discomfort. Quantifying the specific pressure may enable clinicians and users to determine and improve comfort levels objectively. OBJECTIVES: (1) To evaluate if a peak pressure reduction assists in resolving wounds, redness, and pain inside prosthetic sockets in people with transtibial amputation. (2) To determine if peak pressures measured inside the prosthetic socket due to external forces could be used to quantify the level of improvement in socket discomfort. DESIGN: In this cohort study, we used a pressure sensor to quantify and facilitate adjustments to the prosthetic socket, correlating this information to the user's socket comfort. SETTING: Outpatient clinic in a tertiary hospital in Singapore. PARTICIPANTS: People (N = 16) with unilateral transtibial lower limb amputation using a prosthesis. INTERVENTIONS: NA. MAIN OUTCOME MEASURES: Peak pressure and socket comfort score (SCS). RESULTS: The peak pressure value showed a statistically significant reduction across all participants following adjustments at a 50% delta change in pressure (p = .001). This was achieved with a mean number of 2.6 ± 1.4 adjustments per participant. Following the adjustments, the paired t-test results showed a mean increase between the first SCS and final SCS was 2.6 (p = .001). CONCLUSION: The wound, redness, and pain resolved in 15 of 16 participants regardless of diabetic status following socket adjustments. Although the peak pressures values did not correlate to the SCS score, the reduction in peak pressure saw significant improvement to the SCS. The use of a portable sensor is a fast and efficient means to quantify adjustments inside the prosthetic socket and could potentially be considered as part of future care delivery.

Identification of Secondary Biomechanical Abnormalities in the Lower Limb Joints after Chronic Transtibial Amputation: A Proof-of-Concept Study Using SPM1D Analysis.

SPM is a statistical method of analysis of time-varying human movement gait signal, depending on the random field theory (RFT). MovementRx is our inhouse-developed decision-support system that depends on SPM1D Python implementation of the SPM (spm1d.org). We present the potential application of MovementRx in the prediction of increased joint forces with the possibility to predispose to osteoarthritis in a sample of post-surgical Transtibial Amputation (TTA) patients who were ambulant in the community. We captured the three-dimensional movement profile of 12 males with TTA and studied them using MovementRx, employing the SPM1D Python library to quantify the deviation(s) they have from our corresponding reference data, using "Hotelling 2" and "T test 2" statistics for the 3D movement vectors of the 3 main lower limb joints (hip, knee, and ankle) and their nine respective components (3 joints × 3 dimensions), respectively. MovementRx results visually demonstrated a clear distinction in the biomechanical recordings between TTA patients and a reference set of normal people (ABILITY data project), and variability within the TTA patients' group enabled identification of those with an increased risk of developing osteoarthritis in the future. We conclude that MovementRx is a potential tool to detect increased specific joint forces with the ability to identify TTA survivors who may be at risk for osteoarthritis.

Design and development of a novel 3D-printed non-metallic self-locking prosthetic arm for a forequarter amputation.

BACKGROUND: Upper limb, in particular forequarter amputations, require highly customised devices that are often expensive and underutilised. OBJECTIVES: The objective of this study was to design and develop a comfortable 3D-printed cosmetic forequarter prosthetic device, which was lightweight, cool to wear, had an elbow that could lock, matched the appearance of the contralateral arm and was completely free of metal for a specific user's needs. STUDY DESIGN: Device design. TECHNIQUE: An iterative user-centred design approach was used for digitising, designing and developing a functional 3D-printed prosthetic arm for an acquired forequarter amputation, while optimising the fit and function after each prototype. RESULTS: The cost of the final arm was 20% less expensive than a traditionally-made forequarter prostheses in Singapore. The Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) 2.0 survey was administered, with results indicating that the 3D-printed arm was preferred due to its overall effectiveness, accurate size, ease of use and suspension. However, durability had a lower score, and the weight of the arm was 100 g heavier than the user's current prosthesis. The technique described resulted in a precise fitting and shaped forequarter prosthesis for the user. Using the user's feedback in the iterations of the design resulted in improved QUEST survey results indicating the device was effective, easy to use, perceived as lighter and more secure than the user's traditionally-made device. CONCLUSION: A fully customised cosmetic forequarter prosthesis was designed and developed using digital scanning, computer-aided design modelling and 3D printing for a specific user. These technologies enable new avenues for highly complex prosthetic design innovations.

Leveraging Digital Technology to Overcome Barriers in the Prosthetic and Orthotic Industry: Evaluation of its Applicability and Use During the COVID-19 Pandemic.

BACKGROUND: The prosthetic and orthotic industry typically provides an artisan "hands-on" approach to the assessment and fitting of orthopedic devices. Despite growing interest in digital technology for prosthetic and orthotic service provision, little is known of the quantum of use and the extent to which the current pandemic has accelerated the adoption. OBJECTIVE: This study's aim is to assess the use of digital technology in prosthetics and orthotics, and whether its use can help overcome challenges posed by the current COVID-19 pandemic. METHODS: A web-based survey of working prosthetists, orthotists, and lower limb patients was conducted between June and July 2020 and divided into three sections: lower limb amputees, prosthetist and orthotist (P&O) currently using digital technologies in their practice, and P&O not using any digital technology. Input was sought from industry and academia experts for the development of the survey. Descriptive analyses were performed for both qualitative (open-ended questions) and quantitative data. RESULTS: In total, 113 individuals responded to the web-based survey. There were 83 surveys included in the analysis (patients: n=13, 15%; prosthetists and orthotists: n=70, 85%). There were 30 surveys excluded because less than 10% of the questions were answered. Out of 70 P&Os, 31 (44%) used digital technologies. Three dimensional scanning and digital imaging were the leading technologies being used (27/31, 88%), primarily for footwear (18/31, 58%), ankle-foot orthoses, and transtibial and transfemoral sockets (14/31, 45%). Digital technology enables safer care during COVID-19 with 24 out of 31 (77%) respondents stating it improves patient outcomes. Singapore was significantly less certain that the industry's future is digital (P=.04). The use of virtual care was reported by the P&O to be beneficial for consultations, education, patient monitoring, or triaging purposes. However, the technology could not overcome inherent barriers such as the lack of details normally obtained during a physical assessment. CONCLUSIONS: Digital technology is transforming health care. The current pandemic highlights its usefulness in providing safer care, but digital technology must be implemented thoughtfully and designed to address issues that are barriers to current adoption. Technology advancements using virtual platforms, digitalization methods, and improved connectivity will continue to change the future of health care delivery. The prosthetic and orthotic industry should keep an open mind and move toward creating the required infrastructure to support this digital transformation, even if the world returns to pre-COVID-19 days.