Gaitography on lower-limb amputees: Repeatability and between-methods agreement

Abstract

Background:: Gaitography is gait parametrization from center-of-pressure trajectories of walking on an instrumented treadmill. Gaitograms may be useful for prosthetic gait analyses, as they can be rapidly and unobtrusively collected over multiple gait cycles without constraining foot placement. However, its reliability must still be established for prosthetic gait.

Objectives:: To evaluate (a) within-method test-retest repeatability and (b) between-methods agreement for temporal gait events (foot contact, foot off) and gait characteristics (e.g. step times, single-support duration).

Study design:: Cohort study with repeated measurements.

Methods:: Ten male proficient prosthetic walkers with a unilateral trans-femoral or trans-tibial amputation were equipped with a pressure-insole system and were invited to walk on separate days on an instrumented treadmill.

Results:: We found better between-methods reproducibility than within-method repeatability in temporal gait characteristics. Step times, stride times, and foot-contact events matched well between the two methods. In contrast, insole-based foot-off events were detected one-to-two samples earlier. Likewise, a similar bias was observed for temporal gait characteristics that incorporated foot-off events.

Conclusion:: Notwithstanding small systematic biases, the good between-methods agreement indicates that temporal gait characteristics may be determined interchangeably with gaitograms and insoles in persons with a prosthesis. However, the relatively poorer test-retest repeatability hinders longitudinal assessments with either method.

Clinical relevance:: Clinical practice could potentially benefit from gaitography as an efficient, unobtrusive, easy to use, automatized, and patient-friendly means to objectively parametrize prosthetic gait, with immediate availability of test results allowing for prompt clinical decision-making. Temporal gait parameters demonstrate good between-methods agreement, but poorer within-method repeatability hinders detecting prosthetic gait changes.

Keywords: Gait; amputees; center of pressure; online event detection; treadmill test.