Revision of a Failed Patellofemoral Arthroplasty to a Total Knee Arthroplasty

Jess H. Lonner, MD

The failure mechanisms most associated with patellofemoral arthroplasty include progressive tibiofemoral cartilage degeneration; patellar pain, catching, or subluxation caused by soft-tissue imbalance; component malposition; and problematic designs. Early trochlear designs had a relatively high tendency for failure related to patellar maltracking. In a study of fifty-six knees that had a patellofemoral arthroplasty, 18% had late failure from tibiofemoral degeneration after a mean duration of follow-up of fifteen years. Therefore, despite the reasonable success of patellofemoral arthroplasty, some patients will ultimately require revision to total knee arthroplasty, particularly given the young age of many of these patients. In his JBJS published study, Jess H. Lonner, MD found the short-term results of total knee arthroplasty were not compromised when revision of a failed patellofemoral replacement was performed. Standard primary total knee arthroplasty components can typically be used for revision of the failed patellofemoral replacement, with predictably good bone support and without the need for supplemental augments, structural bone-grafting, or stems. Condylar support was uncompromised. Unless there is a considerable so-called notch in the anterior cortex of the femur that extends more proximal than the proximal extent of the anterior flange of the femoral component of the total knee replacement, use of a femoral stem augmentation was not necessary. A patellofemoral replacement can be revised to a total knee arthroplasty without difficulty, most often with use of primary implants without stems or augments. Typically, the patellar component can be retained, unless it is worn, loose, or malpositioned, giving support to the primary use of domed all-polyethylene patellar components, which are compatible with most contemporary femoral component designs. The results of total knee arthroplasty do not seem to be compromised by the presence of a prior patellofemoral replacement.

Material Covered

• Indications
• Trochlear Component Removal
• Avoiding Complications

 

Specifications

• Total Run Time: 31:46 minutes
• Catalog Number: 5107
• VJO Publication Date: June, 2009