Periprosthetic Patellar Fractures
Neil P. Sheth, MD; David I. Pedowitz, MS, MD; Jess H. Lonner, MD
  • Embedded Image Periprosthetic patellar fractures may be the most common fractures complicating total knee arthroplasty.

  • Embedded Image Clinical and radiographic examinations should be focused on determining the integrity of the extensor mechanism and the fixation of the patellar component.

  • Embedded Image The etiology of periprosthetic patellar fractures is multifactorial and may be classified on the basis of intraoperative or postoperative factors.

  • Embedded Image Minimally displaced fractures with an intact extensor mechanism and patellar component are best treated nonoperatively with a short period of immobilization.

  • Embedded Image Operative treatment of periprosthetic patellar fractures often yields poor results with high complication rates and little functional improvement. Operative intervention should be reserved for fractures associated with extensor mechanism dysfunction and patellar component loosening.

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. …

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