Component fracture in total knee arthroplasty

The records of 26 patients (27 knees) who sustained a fracture of a total condylar design total knee prosthesis were reviewed. Twenty-five fractures involved the tibial component and two involved the femoral component. Mean time to failure was 8.2 years for tibial components and 7.2 years for femoral components. The overall fracture prevalence rates were 0.33% and 0.03% for tibial and femoral components, respectively. Specific designs had increased fracture rates and revision arthroplasty increased the relative risk. Anatomic limb alignment exceeded 5 of varus or valgus in 24 of 25 knees with tibial component fractures. Lucencies were noted beneath all but one fractured tibial tray. However, 22 of 23 tibial components that had a keel or stem were well fixed distally and subsidence occurred only beneath the fractured portion of the prosthesis. Tibial component fractures are related to revision arthroplasty, prosthesis design, malalignment, and inadequate support beneath the tibial tray with good distal fixation.