Reliability of three different methods for assessing amputee residuum shape and volume: 3D scanners vs. circumferential measurements.

Background: Objective and reliable methods are necessary to monitor and manage amputee residuum shape and volume and design prosthetic residuum-prosthesis interfaces. Portable 3D scanners are potential solutions for digitally recording the amputee residuum characteristics.

Objective: To investigate test-operator reliability when measuring lower limb residuum shape and volume using two different types of 3D laser-free scanners compared with tape measurements generally adopted in clinic.

Methods: Ten lower limb amputees took part in this study. Residuum volume, cross sectional areas, and perimeter lengths were measured by three different operators on three different occasions using two types of 3D scanners (Artec Eva scanner and OMEGA Scanner 3D) and circumferential measurements. Methods: Variance components, intraclass correlation coefficients and intra-rater and inter-rater reliability coefficients were calculated for all measurement conditions.

Results: Residuum volume outputs ranged from 569 to 3115 mL. The factor contributing mostly to the residuum volume error variance was the shape of the residuum (75.85%). Volume intraclass correlation coefficients for both intra-rater and inter-rater reliability exceeded 0.9 for all three conditions. Volume reliability coefficients ranged from 70.68 mL (Artec Eva intra-rater reliability) to 256.85 mL (circumferential measurements inter-rater reliability). Shape relative error reached the highest values for the circumferential measurements (>10% for the cross-sectional areas and >5% for the perimeters).

Conclusions: The Artec Eva scanner resulted in the lowest test-operator reliability coefficients. However, both investigated scanners are a potential alternative for measuring small and macroscopic changes in residuum characteristics.