1 Introduction top
General consideration
These single plane, intraarticular fractures require anatomical reduction and interfragmentary compression, sufficient to allow early joint motion. The perfection of the articular reduction is usually assessed by an open approach, but where the skills and resources are available, arthroscopically assisted reduction and percutaneous fixation may be considered. The surgeon should be prepared to find additional comminution, not evident until fracture exposure.
Note on approaches
Unless full facilities and expertise for an arthroscopic approach are available to check the closed reduction, prior to percutaneous screw insertion, the standard lateral parapatellar approach is used to give an optimal view of the joint fracture reduction.
2 Patient preparation top
This procedure may be performed with the patient in one of the following positions:
3 Reduction top
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General consideration
Closed reduction and internal fixation (CRIF) is used in minimally displaced, or undisplaced simple, lateral sagittal, partial articular fractures.
Preliminary reduction
As simple, lateral sagittal, partial articular fractures usually result from a valgus force, the application of a varus stress may reduce the fracture. If varus stress alone is not sufficient, a percutaneous clamp, or ball-spiked pusher, may be used to reduce the fracture. Arthroscopy may be helpful to assess the accuracy of the reduction.
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Temporary K-wire insertion
Under image intensifier control, make a stab incision over the lateral aspect of the injured condyle and insert a temporary K-wire, to hold the reduction.
Make sure, that the K-wire does not conflict with the planned screw tracks.
Check of reduction
Check the reduction in two planes using the image intensifier.
4 Insertion of partially threaded 6.5 mm lag screws top
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General consideration
In general, the screws are inserted at points along the midshaft axis of the femur (dashed line). The area distal to the Blumensaat’s intercondylar roof line must be avoided, in order not to violate the notch. In addition, the area of the lateral knee recess should be avoided.
If you need to insert a screw in the area distal to the Blumensaat’s intercondylar roof line, make sure to direct the screw anteriorly, in order to avoid the intercondylar notch.
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Drill screw hole
Make a small 1.2 cm incision. The incision should go through the iliotibial band.
Create a pilot hole using a 3.2 mm drill bit in the direction of the eventual screw insertion.
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Determine appropriate screw length
Insert a depth gauge into the hole, to determine the appropriate screw length. Generally, a screw is chosen which is 5-10 mm short of the medial cortex.
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Tapping
Remove the depth gauge and tap for the 6.5 mm cancellous bone screw under image intensifier control. In all but the densest cancellous bone of young athletes, tap only the near fragment – the screw itself will normally create its own thread in the cancellous bone of the far fragment.
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Screw insertion
Insert the 6.5 mm partially threaded cancellous bone screw and fully tighten. In the case illustrated, the partially threaded screw will have 32 mm of thread, as opposed to 16 mm of thread.
Note: a washer may be used particularly in osteoporotic patients.
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Additional screw insertion
Insert 1 or 2 additional screws in a similar manner, and remove the K-wire.