Energy cost during ambulation in transfemoral amputees: a knee joint with a mechanical swing phase control vs a knee joint with a pneumatic swing phase control.

The aim of the study was (i) to evaluate the preference of transfemoral amputees for a 4-bar linked knee joint with either a mechanical swing phase control or a pneumatic swing phase control, and (ii) to compare the energy expenditure in transfemoral amputees using a prosthesis with a mechanical swing phase control with that of the same amputees using a prosthesis with a pneumatic swing phase control. The study included 28 unilateral transfemoral amputees amputated for reasons other than chronic vascular disease. All patients had a prosthesis with a knee joint with mechanical swing phase control (the Otto Bock 3R20) before entering the study. The amputees changed their knee joint to one with pneumatic swing phase control (the Tehlin knee joint) at random either after the first or second assessment. The amputees were asked for their preference at the second and third assessments. The energy expenditure while walking at speeds of 2 and 3 km/h was measured at each assessment. After having tried both knee joints, 19 patients preferred the Tehlin knee, 6 patients preferred the Otto Bock 3R20, and 3 patients had no preference. The energy expenditure measurement showed that walking with the Tehlin knee required more energy than walking with Otto Bock 3R20. Because of the limited number of patients included in the study and the fact that a double-blind design was impossible to achieve, conclusions should be drawn with caution.