Patients with lumbar vertebral disease inevitably have an orthosis applied to the trunk after surgery until the treated region is stabilized. During this phase, flexion, lateral flexion, and rotation of the trunk are limited, and patients have difficulty putting on and taking off shoes and socks. When sitting straight at a distance from the edge of the bed, these motions cause excess unilateral elevation of the femur, posterior tilt of the pelvis, and bending of the trunk, which may increase the load on the treated region. Lower leg flexion exercises may make it easier to sit straight with the ischium positioned near the edge of the bed. We investigated a method that reduces the load on the lower back caused by the postural strategies adopted when putting on and taking off socks and shoes while sitting straight. Patients elevated each leg individually and touched the ankle of the elevated leg with the ipsilateral index finger. The elevation angle of the femur, flexion angles of the hip and knee joints and trunk, and tilt angle of the pelvis in the sagittal plane were measured. The sitting distance from the edge of the bed was changed and the patients repeated the task. The hip flexion angle did not change with an increase in the distance from the bed's edge. However, the angles of femoral elevation, pelvic inclination, and trunk flexion increased whereas the knee flexion angle decreased. This suggests that an increase in the femoral elevation angle coupled with an increase in the distance from the bed's edge produces a pelvic-femoral rhythm and increases pelvic tilt and trunk flexion angles. The reduction of the knee flexion angle with an increase in the distance from the bed's edge suggests that the space between the bed's edge and lower leg cannot be maintained by backward movement, making knee flexion difficult. The load on the treated region may have been increased by posterior pelvic tilt, which is induced by femoral elevation, and trunk flexion during these motions while sitting straight when the ischium is positioned at a distance from the bed's edge. The results of this study suggest that as a part of early guidance after surgery, it is necessary to instruct postoperative patients with lumbar disease to position the ischium close to the edge of the bed while sitting straight during the activities discussed.
