Executive Editor: Rick Buckley, Chris Colton

Authors: Florian Gebhard, Phil Kregor, Chris Oliver

Patella Extraarticular avulsion fracture

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1 Principles top

Treatment goal

The patello-femoral joint is biomechanically very stressed when the knee is loaded. Any compromise of the joint surface is likely to lead to degenerative joint disease.
It is, therefore, highly desirable, in patellar fractures to strive for anatomical reduction of the joint surface and stable fixation. In addition, a treatment goal is restoration of function of the knee extensor mechanism.


Sleeve fractures are very rare and may be very subtle on x-rays as the sleeve remaining within the avulsed tendon is thin and is often not apparent on over-penetrated images, whilst at the same time, the lower pole of the patella may have a virtually normal profile.

2 Patient preparation and approach top


Patient preparation

This procedure is normally performed with the patient in a supine position with the knee flexed 30°.



For this procedure a mid-axial longitudinal approach is used.

3 Reduction and fixation top


Fracture debridement

The knee joint and fracture lines must be irrigated and cleared of blood clots and small debris to allow exact reconstruction.


Reduction and temporary fixation

A Weber clamp is used to reduce the fracture before fixation.


Fixation of avulsion

Insert a partially threaded cannulated screw, with a washer, as a lag screw.

The fixation is checked with an image intensifier in AP and lateral planes.


Neutralization of bending forces

As implant pull-out, or failure, is virtually inevitable, the bending distraction forces must be neutralized by additional patellotibial cerclage or tension band wiring.

Repair any tears of the lateral and medial patellar retinacula with sutures.

v2.0 2019-03-21