Distal Femoral Replacement for Revision Total Knee Arthroplasty in Nononcologic Indications: A Single-Institution Outcomes Study.

Abstract

Background: Distal femoral replacement (DFR) is a salvage procedure to manage massive bone loss in total knee arthroplasty (TKA). Few studies report midterm (five to 10 years) to long-term (> 10 years) outcomes of DFR for nononcologic indications. The purpose of this study was to report the implant survival of DFRs in nononcologic TKA for the entire cohort and by indication, as well as patient-reported clinical outcomes.

Methods: We retrospectively identified all DFR performed for nononcologic indications from 2002 to 2021 at our institution. There were three patients who had less than a 2-year follow-up who were excluded (no revisions after DFR). There were 45 DFR included who had a mean follow-up of 6.6 years (range, 2.0 to 17.2). The mean age was 75 years (range, 53 to 94), the mean body mass index was 29.2 (range, 19.2 to 52.4), and 64.4% were women. Indications for index DFR were mechanical TKA failure (40.0%), periprosthetic fracture (33.3%), and periprosthetic joint infection (26.7%). There were 14 (31.1%) patients who underwent revision after index DFR. Reasons for the first revision were infection (seven), fracture (three), hinge dislocation (two), loosening (one), and extensor mechanism rupture (one). All DFRs were rotating hinge designs with fully cemented stems. Kaplan-Meier analysis was used to determine all-cause revision-free Survival and patient-reported outcomes were collected.

Results: The revision-free survival for the entire cohort was 74.6% at 5 years and 60.2% at 10 years. By indication for index DFR, six of the 12 infection patients, five of the 18 mechanical failure patients, and three of the 15 fracture patients underwent revision. Differences in revision-free survival by indication were not statistically different (P = 0.221). At the final follow-up, the mean Oxford knee score was 25 (range, five to 40), with 69% patient satisfaction.

Conclusions: A DFR for nononcological indications is associated with high revision rates. Midterm (5 to 10 years) and long-term (10 years) revision-free survival is poor and patient satisfaction is modest. Differences in survival by indication for DFR were not statistically significant. DFR remains a valuable salvage procedure, but patients need to be counseled on the expected outcome.