Objective: To evaluate the gait of transfemoral amputee patients using a prosthesis with a 4-bar linkage knee joint with either a mechanical swing phase control (Otto Bock 3R20) or a pneumatic swing phase control (Tehlin knee).
Design: Randomized cross-over trial.
Setting: Rehabilitation Department of a university hospital in The Netherlands.
Patients: Twenty-eight subjects with unilateral transfemoral amputation for reasons other than chronic vascular disease; ages between 16 and 65 years and familiar with the use of the Otto Bock 3R20 knee.
Selection procedure: a consecutive sample.
Intervention: The Otto Bock 3R20 was used by the subjects before they entered the study. The patients changed to the Tehlin knee at random either after 1 or 2 assessments with the Otto Bock 3R20.
Main outcome measures: Temporal and kinematic variables in gait analysis (speed recordings were taken before and after the equipment for the measurements of the other parameters was placed on the patients). Subjective scores for comfortable and fast ambulation were obtained by means of 2 questionnaires. Questionnaire A consisted of multiple choice questions (maximum score: 5) and questions using an 8-point rating scale (maximum score: 7). In questionnaire B, the patient was asked to compare the present prosthesis with the previous one.
Results: Fast walking speed in gait analysis was higher with the Tehlin knee than with the 3R20 (without equipment 95% confidence interval (CI) .02-.09 m/sec, with equipment CI .04-.11), while comfortable walking speed was not higher with the Tehlin knee (without equipment CI -.20-.20 m/sec, with equipment CI .00-.05). Symmetry of walking as regards swing phase duration was closer to 100% with the Tehlin knee than with the 3R20 (comf. walking CI 4% to 19%, fast walking CI 7% to 17%). Knee joint range of motion during swing phase was smaller with the Tehlin knee than with the 3R20 (comf. walking CI 1.8 degrees-8.7 degrees, fast walking CI 2.0 degrees-9.5 degrees). Knee flexion duration during swing phase was shorter for the Tehlin knee than for the 3R20 at fast walking speed (CI 6-46msec), while knee flexion duration from and to 10 degrees flexion was shorter for the Tehlin knee at comfortable speed (CI 18-67msec) and fast speed (CI 20-64msec). In questionnaire A the amputees reported the Tehlin knee to be better for fast walking (part A1 CI .01-.52, part A2 CI .13-.98) and in questionnaire B for both comfortable and fast walking.