Fracture of the patella following total knee arthroplasty

The charts of 21 patients (22 knees) with significant radiographic changes of the patella after total knee arthroplasty were reviewed. The average patient age was 73 years, and average follow-up after arthroplasty was 7.3 years. Lateral release, fat pad excision, quadriceps tendon release, and previous surgery were implicated in the etiology of fracture of the patella. Five cases had type 1 pattern (sclerosis, fragmentation, and no fracture), 5 cases had type 2 pattern (undisplaced fracture and fragmentation), and 12 cases had type 3 pattern (displaced fracture and fragmentation). Type 1 and 2 patterns required no surgical treatment and were rated good to excellent according to the Hospital for Special Surgery Disability Score Sheet. Patients with a type 3 pattern who did not undergo surgery were rated poor to fair, while patients with a type 3 pattern who underwent surgical treatment (patellectomy, removal of the patellar component, or excision arthroplasty for infection) were rated good. Patellectomy is the treatment of choice for patients with displaced fractures of the patella. A classification system for the pattern of patellar changes is proposed.