The "Distal Femoral Replacement Downgrade": Technique of Using Bicondylar Femoral Cones With a Hinge Total Knee Arthroplasty Revision in Patients Who Have Massive Distal Femoral Bone Loss as an Alternative.

BACKGROUND

Massive femoral bone loss with collateral insufficiency in revision total knee arthroplasty is often managed with distal femoral replacement (DFR), but this procedure sacrifices bone stock and carries notable risks. We described outcomes of a bone-preserving alternative (the "DFR downgrade") that pairs bicondylar, metadiaphyseal-engaging femoral cones with a hinge construct.

METHODS

We performed a retrospective review of consecutive patients who underwent revision total knee arthroplasty using a "DFR downgrade" technique for severe femoral bone loss between February 2016 and July 2024. There were 20 patients (mean age, 69 years (range, 58 to 86); 65% men) included, with a mean follow-up of 14.5 months (range, 0.9 to 43.7). Indications were aseptic loosening in 75%, infection in 10%, ligamentous instability in 10%, and arthrofibrosis in 5%. Demographics, Anderson Orthopaedic Research Institute classification, operative details, postoperative complications, and clinical and radiographic outcomes were collected. The Kaplan-Meier method was used to estimate reoperation-free and rerevision-free survivorship. Femoral bone loss was classified as Anderson Orthopaedic Research Institute (IIA in 10%, IIB in 30%, and III in 60% of cases.

RESULTS

Survivorship free from revision for aseptic loosening was 100% at one and two years. Survivorship free from any rerevision was 85.1% at one and two years. Survivorship free from any reoperation was also 85.1% at one and two years. There were three knees that required reoperation: one for a periprosthetic femoral fracture revised to a DFR; one for infection treated with two-stage revision and reimplantation of a DFR downgrade construct; and one for patellar button exchange after an implant recall.

CONCLUSIONS

In patients who have severe femoral bone loss and condylar compromise, a "DFR downgrade" consisting of a bicondylar cone-hinge construct achieved favorable survivorship. While further study is warranted, this appears to be a pragmatic, bone-preserving alternative to DFR.