The incidence of femoral component version change in primary THA using the S-ROM femoral component.

Although use of modular femoral components in revision total hip arthroplasty (THA) is widely accepted, many still question the need for modular versatility in primary THA. This study examined a large cohort of primary THA patients implanted with a modular S-ROM femoral component (DePuy Orthopaedics, Warsaw, Indiana) to determine the percentage of hips in which the surgeon changed version of the femoral component to increase the intraoperative stability of the THA construct and/or to maximize hip range of motion without impingement.In a group of 1000 routine, primary THAs, femoral component version was changed in 479 hips (47.9%). This change in rotational position of the femoral stem ranged from 60° retroversion with respect to the position of the sleeve to 80° of anteversion with respect to the sleeve. Ten hips (1%) experienced dislocation within the first 3 postoperative months. There was no difference in the dislocation rate between those patients in which femoral component version was changed versus those in which version was not changed. Statistical analysis showed no correlation between the likelihood of changing stem version and any of the following clinical variables: patient age, sex, diagnosis, or surgeon.The high percentage of straightforward primary THAs in which it was deemed beneficial to change version of the stem combined with the lack of correlation between femoral version change and clinical variables leads us to conclude that the routine use of a stem that allows variable version may be advantageous when compared to a nonmodular stem, as it is not possible to preoperatively determine when changing version will be required.