Patella

2. It is important to fully evaluate patella fractures on the AP x-ray as well as
the lateral x-ray. The AP x-ray demonstrates the number of fragments and
vertical splits in the sagittal plane that are not visible on the lateral x-ray.

3. It is important to fully evaluate patella fractures on the AP x-ray as well as
the lateral x-ray. The AP x-ray demonstrates the number of fragments and
vertical splits in the sagittal plane that are not visible on the lateral x-ray.

4. Lateral radiograph demonstrating complete separation of
the patella with loss of extensor mechanism.

5. A vertical midline incision is performed over the patella.

6. After coming through subcutaneous tissue, the patella
fracture is immediately evident. The clot and cancellous
bone edges are cleaned.

7. A lamina spreader demonstrates the fracture site.

8. The articular surface of the patella and trochlear groove are
evident upon flexion of the knee.
PATELLA ARTICULAR
SURFACE
TROCHLEAR
GROOVE
PROXIMAL DISTAL

9. RETINACULAR TEAR
With displaced patella fractures there are concomitant
retinacular tears medially and laterally.

10. TROCHLEA
PATELLA ARTICULAR
SURFACE
After complete debridement and cleaning of the fractures, a
cannulated screw guidewire can be placed retrograde through
the fracture site, close and parallel to the articular surface.

11. The drill is then used also in a retrograde fashion.

12. The saggital plane split is seen when the distal fragment is flexed.
This fracture is fixed with a transverse lag screw that will not
interfere with the cannulated screws.

13. Using a clamp, the fracture is reduced.

14. Using a clamp, the fracture is reduced.
FRACTURE
REDUCTION

15. A second clamp is necessary in this
case to maintain the reduction.

16. Closeup of the complete reduction,
using several clamps.

17. After the reduction is complete, the K-wires are visualized in the
lateral and AP planes, which are used to evaluate not only the
guidewire placement but also the reduction.

18. Lateral and AP views. Notice that the lag screw is placed
between the inferior lateral and inferior central fragment,
but does not extend into the fragment on the medial side, as
this would interfere with the placement of the K-wire.

19. The two cannulated screws are placed over the guidewires. These
screws must be large enough to enable the tension band to be placed
through them.

20. Each manufacturer is different; the surgeon must be confident that
the cannulation of the screw will accommodate the cable or wire system.

21. The screw should be placed such that it is short of the end of the
bone. This is to avoid the cable or wire system from being injured
by the sharp threaded end of the screw.

22. The cable system is introduced through one screw looped around
anteriorly, then placed in the same direction through the second
screw.

23. The two ends are pulled through a connector and underneath
the clamp, which remains in place during the tightening.

24. In this case the Dahl-Miles system is used and the tightener
is connected to the two free ends after a fastener is attached.

25. Lateral X-Ray

26. AP x-ray demonstrating the tightening
of the cable grip system.

27. After the wire is sufficiently tightened and crimped
in place, it is trimmed very close to the sleeve.

28. The retinaculum is then carefully repaired on both the
medial and lateral sides to afford stability and additional
support to the reconstruction.

29. Closeup of the final reconstruction.

30. Lateral radiograph demonstrating the reduction. Notice that the
screw tips are shy of the cartilage on the patella. The cable grip
system wraps around the bone and is not making a sharp angle
at the tip of the screw.

31. AP x-ray demonstrating the reconstruction using the cannulated
screws to fix the central distal fragment and the medial distal fragment
back to the proximal fragment. The distal lateral fragment is held with
a lag screw. After fixation, the knee is brought to a complete range of
motion to confirm stability and repeat radiographs are obtained.