However, "early mobilization" was not defined consistently in previous study. Some authors recommend patients to get out of bed and ambulate on the day of operation while others define as getting out of bed more than 2 hours on day of operation and up to 8 hours on second post-operative day. (Wolk, Meissner et al. 2017) The inconsistency in definition is partly due to the inability to quantify patients' mobility which is usually self-reported by patients and is subjective.(Eva van der Meij 2017) This is especially true for elderly patient in whom preoperative mobility varies significantly between individuals. For this reason, the approach of early mobilization in elderly should be goal directed and individualized according to their preoperative mobility and functional status.