1165 The Effect of Stem Length on Stem Alignment: A Comparison of the 125mm and 150mm Exeter V40 Stems

Aim The Exeter V40 hip replacement stem is available in two lengths – 125mm and 150mm. The 150mm stem has been the standard for decades, however, the 125mm stem is a new option which may be more suited to certain femoral shapes. The aim of this study was to assess whether inserting a shorter stem (125mm) would affect stem alignment. Method This was a prospective cohort of 70 patients undergoing cemented total hip replacement at the Golden Jubilee National Hospital, a high-volume national arthroplasty centre. Patients were randomly assigned either the 125mm or the 150mm stem. The post-operative pelvic radiographs were evaluated for stem position. The angle between the midline of the stem and the anatomical axis of the femur was measured. Patient demographics were evaluated for any effect on stem alignment. Results Stems were positioned in significantly increased relative varus in the 125mm group (3.53° varus) compared to the 150mm group (2.21° varus) (p=0.009). Other factors such as BMI, surgeon, sex, and side of operation had no correlation to the stem position in either group. Conclusions There was a greater incidence of varus malalignment observed in the group undergoing THR using the shorter 125mm Exeter stem. This was statistically significant, but the clinical significance was not evaluated as part of this study, which will be investigated in future research.