Increasing Limb Length During Stage 1 Revision Leads to Higher Rates of Instability Following Stage 2 Revision Total Hip Arthroplasty.

Abstract

Currently, two-stage revision total hip arthroplasty is the gold standard in managing periprosthetic joint infection (PJI) of the hip; however, complications are common, including instability. The purpose of this study was to determine how alterations in limb length during a stage 1 articulating spacer affect dislocation rates of the stage 2 revision. A retrospective study of consecutive patients who underwent two-stage revision total hip arthroplasty for PJI between December 2013 and December 2022 was performed. We measured limb length as the perpendicular distance from the trans-teardrop line to the apex of the lesser trochanter after stage 1 articulating spacer implantation. Independent t-tests and logistic regression were used to compare limb lengths following stage 1 spacers between patients who did and did not dislocate after stage 2 implantation. Overall, 147 patients who underwent staged revisions for the treatment of PJI were identified. The cohort was 59% women who had a mean age of 60 years (range, 25 to 84 years) and an average follow-up time of 2.7 years (range, 1.0 to 9.1 years). The dislocation rates after stage 1 and stage 2 were 3.0 and 11.7%, respectively. Limb length did not impact dislocation rates of the articulating stage 1 spacers (P = 0.71), but patients who sustained a dislocation following stage 2 were lengthened significantly more at stage 1 implantation (8.5 ± 15.9 versus 0.8 ± 11.8 mm, P = 0.033). Additionally, the odds of dislocation after stage 2 increased by 7% with each mm lengthened during stage 1 (odds ratio = 1.07, 95% confidence interval: 1.01 to 1.13). During a stage 1 articulating spacer of the hip, limb length restoration is often disregarded, which can result in overlengthening that may necessitate subsequent shortening during stage 2 reconstruction. This study demonstrates that overlengthening of an articulating stage 1 hip spacer can place the patient at an increased risk of dislocation following stage 2 reconstruction.