Validity and reliability of a novel 3D scanner for assessment of the shape and volume of amputees’ residual limb models

Objective assessment methods to monitor residual limb volume following lower-limb amputation are required to enhance practitioner-led prosthetic fitting. Computer aided systems, including 3D scanners, present numerous advantages and the recent Artec Eva scanner, based on laser free technology, could potentially be an effective solution for monitoring residual limb volumes. The aim of this study was to assess the validity and reliability of the Artec Eva scanner (practical measurement) against a high precision laser 3D scanner (criterion measurement) for the determination of residual limb model shape and volume. Three observers completed three repeat assessments of ten residual limb models, using both the scanners. Validity of the Artec Eva scanner was assessed (mean percentage error <2%) and Bland-Altman statistics were adopted to assess the agreement between the two scanners. Intra and inter-rater reliability (repeatability coefficient <5%) of the Artec Eva scanner was calculated for measuring indices of residual limb model volume and shape (i.e. residual limb cross sectional areas and perimeters). Residual limb model volumes ranged from 885 to 4399 ml. Mean percentage error of the Artec Eva scanner (validity) was 1.4% of the criterion volumes. Correlation coefficients between the Artec Eva and the Romer determined variables were higher than 0.9. Volume intra-rater and inter-rater reliability coefficients were 0.5% and 0.7%, respectively. Shape percentage maximal error was 2% at the distal end of the residual limb, with intra-rater reliability coefficients presenting the lowest errors (0.2%), both for cross sectional areas and perimeters of the residual limb models. The Artec Eva scanner is a valid and reliable method for assessing residual limb model shapes and volumes. While the method needs to be tested on human residual limbs and the results compared with the current system used in clinical practice, it has the potential to quantify shape and volume fluctuations with greater resolution

Variation in Results of Volume Measurements of Stumps of Lower-Limb Amputees:A Comparison of 4 Methods

de Boer-Wilzing VG, Bolt A, Geertzen JH, Emmelot CH, Baars EC, Dijkstra PU. Variation in results of volume measurements of stumps of lower-limb amputees: a comparison of 4 methods. Arch Phys Med Rehabil 2011;92:941-6. Objective: To analyze the reliability of 4 methods (water immersion, computer-aided design [CAD] photometric method, CAD hand scanner, and circumferential measurements) for stump volume measurement in transtibial amputees. Design: Repeated measurements. Setting: General community, ambulatory care. Participants: Transtibial amputees (N=26; mean age +/- SD, 58.7 +/- 11.0y). Interventions: Stump volume of patients with an amputation was measured on 2 occasions, each consisting of 2 sessions. In each session, stump volume was measured by 2 observers using each of the 4 methods. Sequence of observers and measurement methods was determined randomly. Main Outcome Measure: Repeatability coefficients, as a measure for reliability, for each method were calculated, as well as variance components to estimate the influence of measurement conditions on stump volumes measured. Results: Repeatability coefficients varied from 129mL CAD hand scanner to 158mL CAD photometric method. Error variance contributed 12% to the total variance. Methods contributed 36%, method-amputee and occasion-amputee interactions contributed both 25% to the error variance. Conclusions: Repeatability coefficient was lowest for the CAD hand scanner, which indicates the best reliability. Substantial differences existed in stump volumes measured between the 4 methods

Variation in Measurements of Transtibial Stump Model Volume A Comparison of Five Methods

Objective: To determine the right moment for fitting the first prosthesis, it is necessary to know when the volume of the stump has stabilized. The aim of this study is to analyze variation in measurements of transtibial stump model volumes using the water immersion method, the Design TT system, the Omega Tracer system, circumferential measurements, and anthropometric measurements. Design: Nine stump models were measured on two occasions, each consisting of two sessions. In each session, two observers measured the model using each of the five methods. The grand mean volume for each method was calculated. Variance components and their two-way interactions were calculated of the measurement conditions. Repeatability coefficients were calculated for each method. Results: The grand means of the five methods show systematic differences in volume measurements. Error variance was small (6.4%) relative to the total variance. Method and interaction between stump model and method contributed 82.6% to the error variance. Repeatability coefficients of the methods ranged from 45 ml for the Omega Tracer system to 155 ml for the anthropometric measurements. Conclusions: Error variation in measurement results can be attributed for 82.6% to measurement method and interaction between stump model and method. The Omega Tracer system had the smallest repeatability coefficient, indicating that it is the most reliable method