Abstract: BACKGROUND: In recent years, total hip arthroplasty has been widely developed, and most patients have achieved satisfactory results at the initial stage. However, complications after total hip arthroplasty in clinical practice were still a major problem for doctors and patients, and the excellent implant position has become the key to evaluate the replacement effect.    
OBJECTIVE: To investigate the influence of different implant position of short-stemmed prosthesis on hip arthroplasty, and to provide guidance for doctors' surgical implementation. 
METHODS: The full cycle gait simulation was carried out by using human dynamics software to obtain the load-bearing conditions of hip joint. The finite element model of hip joint replacement was established by simulating different implantation locations, that is, the position of human strength line and the position of internal and external deviation of 3° and 5°. The stress changes of femur and short-stemmed prosthesis and the strain changes of polyethylene liner in different total hip arthroplasty models were calculated and analyzed. 
RESULTS AND CONCLUSION: (1) In gait, the joint force and angle of the hip joint changed periodicity with time 1.17 s a period, and the total joint force reached a peak value of about 700 N at 0.4 s. (2) No matter how the angle of internal and external deviation changes, the stress value of the lower part of the lesser trochanter and the lateral end of the femur were higher than those of the position of the human physical line, and internal deviation had a greater impact on the stress of the femur than external deviation. (3) The maximum tensile and compressive stress of the prosthesis was lower than that of the internal and external deviation. (4) The maximum compressive strain of polyethylene liner was the smallest at 3° external deviation, reaching 2 198 με. The maximum compressive strain at other angles was higher than that at the human physical line. The maximum value reached 7 348 με at 5° internal deviation, which was 2.08 times as high as that of position of the human physical line, it would aggravate the liner wear. (5) In total hip arthroplasty, different implant position will have a great impact on the mechanical environment of femur, prosthesis and liner. During the operation, the prosthesis should be as close as possible to the human physical strength line. 

Key words: hip, short-stemmed prosthesis, total hip arthroplasty, gait simulation, human force line, stress, finite element analysis