Periprosthetic Patellar Fractures

Abstract

The patella is the largest sesamoid bone in the skeleton. Located within an expansion of the quadriceps tendon, the patella allows an increased functional lever arm of the quadriceps and enhances the mechanical advantage of the extensor mechanism of the knee. In addition, it provides an articulating surface with a low coefficient of friction, protects the native and prosthetic knee from trauma, protects the quadriceps tendon and extensor mechanism from frictional irritation, and affects the cosmetic appearance of the knee1. Because of its biomechanical importance, any problems involving the patella or the patellar component of a total knee prosthesis can have a substantial effect on overall knee function. In fact, patellar complications following total knee arthroplasty have been a well-documented source of discomfort and disability2-6. Although infrequent, periprosthetic fractures of the patella remain a challenge for even the most experienced joint reconstruction surgeons. This is largely due to the discouraging results that are common following the treatment of all but nondisplaced patellar fractures. Even with meticulous anatomic fracture reduction, healing, and reconstitution of the extensor mechanism, return to prefracture function is rare7. …