Evaluation of an instrument-assisted dynamic prosthetic alignment technique for individuals with transtibial amputation

Background: A prosthesis that is not optimally aligned can adversely influence the rehabilitation and health of the amputee. Very few studies to date evaluate the effectiveness and utility of instrument-assisted alignment techniques in clinical practice. Objectives: To compare an instrument-assisted dynamic alignment technique (Compas) to conventional methods. Study design: In a crossover study design, dynamic prosthetic alignments were provided to nine individuals with unilateral transtibial amputations to compare conventional and instrument-assisted alignment techniques. Methods: The instrument-assisted technique involved a commercially available force and torque sensing dynamic alignment system (Compas). Cadence, pelvic accelerations, and socket moments were assessed. A custom questionnaire was used to gather user perceptions. Results: No differences between alignment techniques were found in global gait measures including cadence and pelvic accelerations. No significant alignment differences were achieved by examination of angular changes between the socket and foot; however, significantly higher below-the-socket moments were found with the instrument-assisted technique. From the questionnaire, six amputees had no preference, while three preferred the conventional alignment. Conclusion: The use of Compas appears to produce similar alignment results as conventional techniques, although with slightly higher moments at the socket. Clinical relevance This study provides new information about the clinical utilization of instrument-assisted prosthetic alignment techniques for individuals with transtibial amputation.