Mobilization was much more efficient in the intervention group than in control group from postoperative day 1 (Fig. 1) the results were close to the defined goal, and the differences between groups were statistically significant (P 0.01) during the postoperative days 1 to 4. The activity measured by number of steps walked is shown in Fig. 2. The differences between groups were statistically significant for postoperative days 1 to 6 (days 1 to 5: P 0.01; day 6: P 0.03). The activity correlated significantly to the ambulation time (r 0.52, P 0.0001).