RESUMEN
BACKGROUND This retrospective study used the Harris hip score (HHS) and range of motion (ROM) to compare gait before and after total hip arthroplasty using the modular S-ROM® hip prosthesis in 23 patients treated at a single center. MATERIAL AND METHODS For this study, 23 patients with severe hip deformity, who were treated with a total hip replacement using the S-ROM® modular hip system by DePuy® in the period from 2003 until 2008, underwent a 3-dimensional gait analysis before and after surgery. Values were compared with a validated data set of healthy subjects. Gait analysis took place using 8 infrared cameras (50 Hz), 2 force platforms of Advanced Medical Technology, Inc. (AMTI)®, and the Vicon® 512 system. The HHS and ROM of the hip joint were determined preoperatively and postoperatively. The follow-up period was 16.7±15.2 months. RESULTS A healthy gait pattern is characterized by an even stride length of both legs in relation to body height and relative symmetry of certain gait phases. These characteristics are influenced by the range of motion of the hip joint and by pelvic tilt. Symmetry could be achieved postoperatively in the stance phase and in the single-leg stance phase. However, the gait phases could not normalize. HHS and ROM improved postoperatively. CONCLUSIONS The findings from this retrospective study showed that ROM and HHS significantly improved following THA with the S-ROM® hip prosthesis, but that gait did not completely return to normal.