Objective
The purpose of this study is to evaluate objectively and quantitatively gait improvement after total hip arthroplasty (THA) using a 3-dimensional computerized Vicon motion analyzer.

Method
A preoperative gait evaluation was performed within one month before surgery and two postoperative gait evaluations at 6 months intervals after surgery. Pre- and postoperative gait parameters of 176 patients with unilateral total hip arthroplasty were evaluated and data were compared with those of 56 healthy persons.

Results
1) Single limb support of affected limb increased significantly at postoperative 6 and 12 months compared with preoperative data. 2) The improvements of hip flexion and abduction of affected limb were in almost normal range at postoperative 12 months. 3) Maximal hip flexor moment in terminal stance of affected limb reached to nearly normal level at postoperative 12 months.

Conclusion
A quantitative gait analyzer is a very useful tool to assess objectively the success of THA as substantiated by the results of this study with a significant improvement in all the parameters of gait., Unilateral total hip arthroplasty, Gait analysis, Kinematics of hip joint