Review Question - QID 219857

This patient was revised to a distal femoral replacement following a periprosthetic fracture of primary TKA components (Figure A). Those with primary TKA implants experience lower revision rates and greater survivorship for re-revision secondary to aseptic loosening, compared to those revised with revision TKA components or those who have already undergone ORIF (Figure C) (Answer 1).

Distal femoral replacements (DFR) function as salvage options for complex primary and revision total knee arthroplasty (TKA). DFR implants are used for various indications, including oncologic reconstruction, native or periprosthetic distal femoral fracture, and severe bone loss and instability in primary and revision TKA. Immediate fixation and the ability to weight-bear following the surgery serve as distinct advantages for these challenging patient populations, who often exhibit advanced age and multiple comorbidities. Although these constructs reliably improve patient pain and functionality, the aforementioned benefits come with the risk of high complication and revision rates, with the literature suggesting those with previous revisions (arthroplasty or ORIF) portending the highest risk for subsequent complications/revisions following their revision to DFR.

Chalmers et al. reviewed their series of 49 patients who underwent distal femoral replacement (DFR) for a periprosthetic femur fracture. The authors categorized patients with prior revision TKA or ORIF of primary components as the "revision cohort." Patients with a history of previous surgery (revision TKA or ORIF) before DFR had a 5.3× higher risk of re-revision compared to patients with primary implants only. Furthermore, survivorship free from re-revision for aseptic loosening at 5 years in the primary and revision cohort was 93% and 53%, respectively. The authors conclude that DFR performed in the setting of failed primary components has significantly better survivorship than patients who suffered fractures with revision components or prior ORIF surgery.

Wyles et al. identified 144 DFRs performed for native or periprosthetic femoral fracture, staged treatment of periprosthetic joint infection, and aseptic TKA loosening. They found increased reoperation rates among patients who were revised to DFR for aseptic TKA loosening or periprosthetic joint infection compared to those with periprosthetic or native femoral fractures. Overall, the 10-year cumulative incidences of revision for aseptic loosening, all-cause revision, and any reoperation were 17.0%, 27.5%, and 46.3%, respectively. Based on these results, the authors conclude that revision of TKA to DFR should be reserved as a salvage procedure.

Figure A shows a periprosthetic fracture in the setting of primary total knee arthroplasty components. Figure B demonstrates the post-op radiographs after revision surgery to DFR. Figure C shows a new periprosthetic fracture in the setting of a previous ORIF.

Incorrect Answers:
Answers 2-5: Patients with revision components, or those who have undergone prior distal femur fracture ORIF, experience higher revision rates than those with only primary components in the setting of periprosthetic fractures revised to PFRs. Survivorship free from re-revision for aseptic loosening is also higher among these patients.