I saw a nice elderly female with anterior knee pain after tripping on the curb and falling to her knees. Here is her knee X-ray:
The AP and lateral knee radiographs demonstrate a non-displaced transverse patellar fracture. Sometimes these can be difficult to see on AP and lateral films. Another view that can sometimes be helpful is the “sunrise” view of the patella.
Most patella fractures are managed non-operatively. If, however, the patella fragments are displaced more than 3-4 mm on xray there is a higher chance of retinacula compromise requiring operative repair (1). Clinically if the patient cannot maintain their knee in extension against gravity this is concerning for retinacular tear.
This patient has a high chance, despite age, of having a good outcome with non-operative management (she had intact extensor mechanism of the knee).
1. Wheeless’ Textbook of Orthopedics. http://www.wheelessonline.com/ortho/fractures_of_the_patella
Author: Russell Jones, MD