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

Abstract

Background: Currently, two-stage revision total hip arthroplasty (THA) 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.

Methods: A retrospective study of consecutive patients who underwent two-stage revision THA 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 for all patients 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.

Results: There were 147 patients who underwent staged revisions for the treatment of PJI identified. The cohort was 59% women who have a mean age of 60 years (range, 25 to 84) and an average follow-up time of 2.7 years (range, 1.0 to 9.1). 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 than patients who did not dislocate (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 (OR [odds ratio] =1.07, 95% CI [confidence interval] 1.01 to 1.13).

Conclusion: 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 increased risk of dislocation following stage 2 reconstruction and should be avoided when possible.