Reliability and Validity of Measurement Tools for Residual Limb Volume in People With Limb Amputations: A Systematic Review

Background Measurements of residual limb volume often guide decisions on the type and timing of prosthetic prescription. To help inform these decisions, it is important that clinicians use measurement tools that are reliable and valid. Purpose The aim of this systematic review was to investigate the reliability and validity of measurement tools for residual limb volume in people with limb amputations. Data Sources A comprehensive search on MEDLINE, EMBASE, CINAHL, Scopus, and Web of Science was performed on July 11, 2016. Study Selection Studies were included if they examined the reliability or validity of measurement tools for residual limb volume, were conducted on humans, and were published in English. Data Extraction Data were extracted from 11 reliability and 4 validity studies and included study characteristics, volumetric estimates, and reliability and validity estimates. The quality of the studies was also rated. Data Synthesis Data from 2 studies (38 participants) indicated good to excellent intrarater (intraclass correlation coefficient [ICC] ≥0.88) and interrater (ICC ≥0.88) reliability and high between-session reliability (coefficient of variation [CV] = 10%) for water displacement volumetry. One study (28 participants) reported excellent intrarater and interrater reliability (ICC ≥0.93) for the circumferential method, and data from 2 studies (19 participants) indicated high between-session reliability for the optical surface scanner (CV ≤9.8%). Three studies (26 participants) indicated good to excellent between-session reliability results for computed tomography (CV = 9.2%–10.9%). One study (7 participants) showed moderate within-session reliability (CV = 50%). Using water displacement volumetry as the gold standard, 2 studies (79 participants) indicated excellent validity for the circumferential method ( r ≥0.92; ICC ≥0.92). All studies reporting measures of reliability or validity were performed with people who had transtibial amputations. Limitations Only studies published in English and in which water displacement volumetry was used as the gold standard were included in this review. The reliability and validity of the quality rating scale used in this review have not been tested. Conclusions On the basis of a limited number of moderate- to high-quality studies with small sample sizes, circumferential and water displacement methods were found to be reliable, and the circumferential method was found to be valid in people with transtibial amputations. There are inadequate data for drawing conclusions about volume measurement methods in people with other types of limb amputations

Clinical utility of pressure feedback to socket design and fabrication

Background: The clinical utility of measuring pressure at the prosthetic socket-residual limb interface is currently unknown. Objectives: This study aimed to identify whether measuring interface pressure during prosthetic design and fabrication results in closer agreement in pressure measurements between sockets made by different clinicians, and a reduction in pressure over areas of concern. It also investigated whether clinicians value knowing the interface pressure during the fabrication process. Study design: Mixed methods. Methods: Three prosthetists designed a complete prosthetic system for a transtibial residual limb surrogate. Standardised mechanical testing was performed on each prosthetic system to gain pressure measurements at four key anatomical locations. These measurements were provided to the clinicians, who subsequently modified their sockets as each saw fit. The pressure at each location was re-measured. Each prosthetist completed a survey that evaluated the usefulness of knowing interface pressures during the fabrication process. Results: Feedback and subsequent socket modifications saw a reduction in the pressure measurements at three of the four anatomical locations. Furthermore, the pressure measurements between prosthetists converged. All three prosthetists found value in the pressure measurement system and felt they would use it clinically. Conclusions: Results suggest that sensors measuring pressure at the socket-limb interface has clinical utility in the context of informing prosthetic socket design and fabrication. If the technology is used at the check socket stage, iterative designs with repeated measurements can result in increased consistency between clinicians for the same residual limb, and reductions in the magnitudes of pressures over specific anatomical landmarks. Clinical relevance This study provides new information on the value of pressure feedback to the prosthetic socket design process. It shows that with feedback, socket modifications can result in reduced limb pressures, and more consistent pressure distributions between prosthetists. It also justifies the use of pressure feedback in informing clinical decisions

Simultaneous measurement of normal and shear stress using fiber bragg grating sensors in prosthetic applications

The interface between the residual limb and the socket of a person with an amputation experiences complex loading conditions during daily activities. Currently, the effect of such loading conditions on tissue health and comfort is poorly assessed. This is largely due to the lack of appropriate sensing technology to facilitate measurement of strains/stresses at this interface. This paper will outline a novel method to simultaneously measure the normal and shear strains using fiber Bragg grating sensors embedded into a foam liner that sits at the prosthetic interface. Furthermore, this method enables the measurement of normal and shear strains when the material properties of the embedding material are unknown. As a validation to the new technique, an application of this process using Pe-Lite foam is presented. A comparison of the derived load based on this process to an applied load measured using a material testing machine is performed. Results show a very good agreement of measured normal and shear strains/stresses for loads below 20 N. However, discrepancies were evident above this load. This paper has provided a proof of concept for using fiber Bragg grating sensors in materials with unknown or inconsistent properties. This method provides a pathway for embedding sensors in prosthetic and orthotic applications

Relationships between self-report and performance-based measures in individuals with lower-limb amputation: alternatives for quantifying gait pathology

Numerous outcome measures are used to assess the functional status of individuals with lower-limb amputation. The multitude of available measures, combined with the multidimensional concept of functional status, complicates the selection of appropriate outcome measures for use with this population group. This thesis explored the relationships between a variety of outcome measures frequently used with lower-limb amputees, including quantitative gait analysis. It also developed methods for quantifying outcomes usually obtained from complex and costly technologies usingsimple and clinically appropriate measures. Eight unilateral, transfemoral amputees, twelve unilateral, transtibial amputees and 28 age- and gender- matched able-bodied controls completed the Short-Form 36, Prosthesis Evaluation Questionnaire (only amputee groups), timed-up-and-go test (TUGT), six-minute walk test (6MWT), three-dimensional gait analysis, and energy expenditure analysis. Gait deviation was summarised effectively using gait summary measures derived from waveform techniques, such as the Gait Deviation Index (GDI) and the Gait Profile Score; overall kinematic deviation was largely a result of altered sagittal hip and knee kinematics.Regression techniques and diagnostic analyses demonstrated it was possible to quantify overall kinematic deviation using the 6MWT, time-to-stand, self-reported stair ambulation ability and age. The strength of the 6MWT as a proxy for energy expenditure analysis was explored further. Physiological responses measured during the 6MWT demonstrated at least two minutes of continuous walking was required to establish homeostatic conditions for heart rate, oxygen consumption and oxygen cost. It was recognised that the energy cost of walking was a function of cardiorespiratory fitness and gait efficiency, which was largely determined by changes in knee kinematics on the prosthetic side and pelvic obliquity patterns. The impact of gait deviation on patient satisfaction was also explored, although significant correlations between these variables were not detected. Rather, self-reported ambulation was a significant correlateof satisfaction. Discordance between self-report ambulation and gait deviation was identified in 10% of the sample. Reasons for this discordance were investigated. The 6MWT was found to be an effective proxy for quantifying overall gait deviation and assessing the energy cost of walking, both of which were consequent to altered hip flexion/extension, knee kinematics during stance and pelvic obliquity

Clinical utility of pressure feedback to socket design and fabrication

The International Society for Prosthetics and Orthotics 2019. Background: The clinical utility of measuring pressure at the prosthetic socket-residual limb interface is currently unknown. Objectives: This study aimed to identify whether measuring interface pressure during prosthetic design and fabrication results in closer agreement in pressure measurements between sockets made by different clinicians, and a reduction in pressure over areas of concern. It also investigated whether clinicians value knowing the interface pressure during the fabrication process. Study design: Mixed methods. Methods: Three prosthetists designed a complete prosthetic system for a transtibial residual limb surrogate. Standardised mechanical testing was performed on each prosthetic system to gain pressure measurements at four key anatomical locations. These measurements were provided to the clinicians, who subsequently modified their sockets as each saw fit. The pressure at each location was re-measured. Each prosthetist completed a survey that evaluated the usefulness of knowing interface pressures during the fabrication process. Results: Feedback and subsequent socket modifications saw a reduction in the pressure measurements at three of the four anatomical locations. Furthermore, the pressure measurements between prosthetists converged. All three prosthetists found value in the pressure measurement system and felt they would use it clinically. Conclusions: Results suggest that sensors measuring pressure at the socket-limb interface has clinical utility in the context of informing prosthetic socket design and fabrication. If the technology is used at the check socket stage, iterative designs with repeated measurements can result in increased consistency between clinicians for the same residual limb, and reductions in the magnitudes of pressures over specific anatomical landmarks. Clinical relevance: This study provides new information on the value of pressure feedback to the prosthetic socket design process. It shows that with feedback, socket modifications can result in reduced limb pressures, and more consistent pressure distributions between prosthetists. It also justifies the use of pressure feedback in informing clinical decisions

Transtibial prosthetic socket fitting: Australian prosthetist perspectives on primary challenges, management strategies, and opportunities for workflow and technological innovation

Background: Following transtibial amputation, a custom-built socket is the most common interface between the prosthesis and residual limb. Desire from both prosthetists and prosthesis users for improved socket fitting processes have been well documented. However, there is currently limited information available about prosthetists’ experiences of how prosthetic manufacturing workflow can contribute to socket fit problems. Objectives: This study aims to determine how socket fit problems are currently detected and managed by prosthetists and to identify challenges, management strategies, and opportunities for workflow and technological innovation during prosthesis manufacture and socket fitting. Study design: Mixed-method (quantitative and qualitative) survey. Methods: An online survey was developed and piloted in consultation with members of the Australian Orthotic Prosthetic Association. The final 25-question survey was distributed through their membership database. Mixed methods were used to analyze survey items. Qualitative items were grouped and coded under themes relating to challenges, management strategies, and opportunities. Quantitative data were analyzed using nonparametric descriptive methods. Results: Twenty-three respondents with a range of experience completed the survey. Seven of eight major Australian states/territories were represented. Primary workflow stages presenting challenges with limited strategies/solutions available to the prosthetists were roll-on liner selection, mold or cast modifications, communication with the client, and check socket fitting. Suggested solutions included improved socket–limb interface monitoring technology. Conclusions: This study provides the first insights into prosthetist-identified challenges and limitations at different stages of the socket workflow and presents a starting point for more targeted research into innovation that may assist in these processes

Validation of a Custom Interface Pressure Measurement System to Improve Fitting of Transtibial Prosthetic Check Sockets

Achievement of fit between the residual limb and prosthetic socket during socket manufacture is a priority for clinicians and is essential for safety. Clinicians have recognised the potential benefits of having a sensor system that can provide objective socket-limb interface pressure measurements during socket fitting, but the cost of existing systems makes current technology prohibitive. This study will report on the characterisation, validation and preliminary clinical implementation of a low cost, portable, wireless sensor system designed for use during socket manufacture. Characterisation and benchtop testing demonstrated acceptable accuracy, behaviour at variable temperature, and dynamic response for use in prosthetic socket applications. Our sensor system was validated with simultaneous measurement by a commercial sensor system in the sockets of three transtibial prosthesis users during a fitting session in the clinic. There were no statistically significant differences between the sensor system and the commercial sensor for a variety of functional activities. The sensor system was found to be valid in this clinical context. Future work should explore how pressure data relates to ratings of fit and comfort, and how objective pressure data might be used to assist in clinical decision making