1 Principles top
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.
An additional treatment goal is restoration of function of the knee extensor mechanism and allow early range of motion of the knee.
The knee joint and fracture lines must be irrigated and cleared of blood clot and small debris to allow exact reconstruction.
2 Patient preparation and approach topenlarge
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 topenlarge
Reduction and temporary fixation
The reduction of this fracture requires careful planning.
The largest fragments are reduced and temporary fixed with K-wires.
In frontal/coronal (transverse) fractures, reduction is easier with the knee extended.
Sagittal fractures are more easily reduced with the knee flexed.
Frequently, the use of several K-wires is required to hold smaller fragments to the larger fragments.
Verify the reduction by palpation of the retropatellar surface.
Non-locking 2.4 and 2.7 plates are typically used for the patella. They are small and very malleable which facilitates contouring to the patella surface.
The plates can be used circumferentially around the patella, in a similar fashion to a cerclage wire, or across the surface to resist distraction forces.
Each piece of the comminuted patella will require at least one point of fixation if not more.
The resulting construct should be strong enough for early motion to be started.
Care should be taken to prevent screw penetration into the joint.
Reduction should be verified by careful intraoperative X-ray and finger palpation.
To achieve a satisfactory stability, the combination with multiple techniques including lag screws, lag screws through a plate, and K-wire fixation with or without cerclage may be needed.