Patellar fracture after total knee arthroplasty is a rare yet challenging complication. Patellar fracture can occur as a result of trauma or it may be atraumatic. A multitude of factors can lead to periprosthetic patellar fracture including patient related factors, surgical technique related factors, and implant specific factors. Understanding the etiologic factors leading to atraumatic patellar fractures could result in minimizing complications. We present the results of peri-prosthetic patellar fractures in 12 patients. All type I non-displaced fractures (7 cases) were treated nonoperatively. Surgical treatment was selected for the remaining 5 cases which included resection arthroplasty combined with open reduction and internal fixation of the fracture (3 knees), partial patellectomy (1 knee), and total patellectomy (1 knee). The outcome was excellent in 1 knee, good in 8 knees, and fair in the remaining 3 knees at the latest follow-up. There were 2 reoperations; 1 for disruption of the extensor mechanism and 1 for refracture. One patient developed a superficial wound infection. We reviewed the available literature regarding the etiology, surgical strategies, and outcomes for periprosthetic patellar fracture.
Level of evidence: Therapeutic studies, level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.