Incidence of Distal Femoral Periprosthetic Fractures after Total Knee Arthroplasty.

Background: The incidence of distal femoral periprosthetic fractures associated with total knee arthroplasty (TKA) has been reported as 0.3% to 2.5%. This study examined the incidence of distal femoral periprosthetic fractures at one hospital over a 16-year period. We hypothesized that the incidence of these fractures would be lowered after the introduction of lugged femoral implants and insertion of a distal femoral intramedullary bone graft during TKA.

Methods: From 1994 to 2010, 4,943 primary TKAs were performed. Following these TKA operations, 21 distal femoral fractures occurred. The surgical technique and implant design changed during this interval. Lugged femoral implants were introduced in 2000. Intramedullary bone grafting of the distal femoral intramedullary guide hole was introduced in 2002.

Results: The incidence of distal femoral periprosthetic fracture in this series of 4,943 TKA operations was 0.42% (21/4943). Six fractures occurred in 1,236 knees with femoral implants without femoral fixation lugs (0.49%). Fifteen fractures occurred in 3,707 knees with femoral implants with femoral fixation lugs (0.40%). Eight fractures occurred in 1,653 knees that did not have intramedullary bone grafts (0.48%). Thirteen fractures occurred in 3,290 knees that had intramedullary bone grafts (0.40%). Two fractures occurred in 417 knees with lugged femoral implants and no bone graft (0.48%).

Conclusions: In this series, there was no significant difference in the incidence of distal femoral periprosthetic fractures associated with adding fixation lugs to the femoral implant and filling the femoral intramedullary hole with bone graft.