Registering a methodology for imaging and analysis of residual-limb shape after transtibial amputation

Successful prosthetic rehabilitation following lower-limb amputation depends upon a safe and comfortable socket-residual limb interface. Current practice predominantly uses a subjective, iterative process to establish socket shape, often requiring several visits to a prosthetist. This study proposes an objective methodology for residual-limb shape scanning and analysis by high-resolution, automated measurements. A 3-D printed analog residuum was scanned with three surface digitizers on 10 occasions. Accuracy was measured by the scan-height error between repeat analog scans and the computer-aided design (CAD) geometry and the scan versus CAD volume. Subsequently, 20 male residuum casts from ambulatory individuals with transtibial amputation were scanned by two observers, and 10 were repeat-scanned by one observer. The shape files were aligned spatially, and geometric measurements were extracted. Repeatability was evaluated by intraclass correlation, Bland-Alttuan analysis of scan volumes, and pairwise root-mean-square error ranges of scan area and width profiles. Submillimeter accuracy was achieved when scanning the analog shape using white light and laser scanning technologies. Scanning male residuum casts was highly repeatable within and between observers. The analysis methodology technique provides clinical researchers and prosthetists the capability to establish their own quantitative, objective, multipatient datasets. This could provide an evidence base for training, long-term follow-up, and interpatient outcome comparison, for decision support in socket design.