Disrupted extensor mechanism
General considerations
This is a rare injury. It is clinically important if the extensor mechanism is disrupted. Assessment of the extensor mechanism is important to decide if operative treatment is required.
A gap of 2 mm or less can be managed nonoperatively.
These fractures are classified by UCPF as V.34-A.
Greater fracture displacement is associated with retinacular disruption. Patella alta or patella baja might be present. This can be evaluated clinically and with imaging studies.
Etiology
Avulsion fracture of the quadriceps or patella tendon insertion.
Clinical and radiological signs
- Loss of straight leg raise
- Patella alta or patella baja
Imaging
Plain X-rays remain the first line of investigation.
CT Scan can be used to assess the size and position of the fragment.
Comparison with previous X-rays is useful.
