Patella fracture after post total knee replacements.

A retrospective study was done to determine the incidence, clinical function, and complications of treatment in a large series of patella fractures after total knee replacement (TKR). Between 1983 and 1996, 4583 primary AGC TKRs done at our institution. One hundred seventy-seven fractures were identified in 135 patients for a fracture incidence of 3.8%. Twenty-two fractures were vertical and had a stable implant and intact extension mechanism (Type 1). Twenty-one fractures had disruption of the extensor mechanism of less than 1 cm (Type 2A). Seventeen fractures had disruption of the extensor mechanism of 1 cm or more (Type 2B). One hundred fourteen fractures had a loose component and an intact extension mechanism (Type 3). Patients treated nonoperatively generally had no extensor lag and had adequate pain and function scores. Patients treated operatively had a high complication rate. Four of nine patients treated with excision of an extruded patella button developed a deep infection. Both patients treated with open reduction internal fixation (ORIF)had a nonunion develop. Surgery on patients with patella fractures has a high complication rate and should be avoided if possible.