Background: Leg length discrepancy (LLD) following total hip arthroplasty (THA) is a leading cause of patient dissatisfaction. However, no reports have described the influence of lower limb alignment on LLD after THA. In the present study, we firstly investigated the change in lower limb alignment after THA. Secondly, we determined the influence of lower limb alignment on LLD after THA. Thirdly, we evaluated the influence of LLD in the entire lower leg on the clinical outcomes after THA.
Methods: We followed up with 54 unilateral hip osteoarthritis (OA) patients 1 year after THA. For the radiological assessment of LLD and lower limb alignment, we obtained anteroposterior radiographs of the pelvis and both lower legs in entirety in a standing position before and 1 year after THA. The Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Medical Outcomes Study Short-Form 36-Item Health Survey (SF-36) were also obtained to assess the clinical outcome.
Resuts: The alignment of the affected leg, which was more valgus than the unaffected leg before THA, tended toward varus after THA, and the discrepancy between the lower limb alignments on both sides decreased. However, the alignment discrepancies that remained after THA influenced the LLD measured on the radiograph of the entire lower leg, and this LLD influenced the clinical outcome as measured by the HHS and the WOMAC score.
Conclusions: LLD in the entire lower leg should be corrected for a better clinical outcome after THA.