Assessment of sit-to-stand activity in below knee amputees and its relationship with knee extensor torque

The purpose of the study was to investigate the sit-to-stand (STS) activity in below-knee amputees (BKA), as well as the relationship between STS activity and knee extensor torque (KET) of the amputated limb. A total of 12 BKA (man, mean age 35.58±10.48 years) and 19 healthy subjects (control group; man, mean age 30.47±7.27 years) were included in the study.The Balance Master System (Version 8.1) employed to assess STS. Participants were asked to stand up as fast as possible from sitting position according to the test protocol. Weight transfer time, postural sway velocity, weight bearing asymmetry and rising index were measured. Quadriceps femoris (QF) muscle strength was assessed with a handheld dynamometer. KET was calculated by multiplying QF muscle strength and lever arm length. The QF muscles strength of the sound limb was measured at the same level with amputated side (Position 1, P1) and measurement was repeated from the proximal point of malleolus (Position 1, P2).Weight bearing transfer time was found similar in BKA and control group (p>0.05). Postural sway velocity and weight bearing asymmetry were greater (p<0.05); rising index was lower in BKA compared to control group (p<0.05). It was found that more weight was taken on the sound limb than amputated limb in patients with BKA (p<0.05). QF muscle strength of the amputated limb was lower than the sound limb and as well as the control group (p<0.05). The KET of the amputated limb was similar to KET of the sound limb at P1 (p>0.05), while it was lower compared to KET of the sound limb at P2 (p<0.05), and control group (p<0.05).It was found that BKA demonstrated more postural sway, exerted less force and bear more weight on the sound limb during STS activity and it was concluded that these parameters were not related with the KET of the amputated limb.