1 Principles topenlarge
In A2 fractures the lateral side has failed in tension, and there is a fracture on the medial side which may be vertical or oblique.
In A2.1 fractures the failure on the lateral side is through the lateral ligament, in A2.2 fractures there is avulsion of the tip of the lateral malleolus, and in A2.3 injuries there is a transverse fracture through the lateral malleolus but still below the syndesmosis.
As the medial fracture is an intra-articular injury, it should be fixed anatomically.
Order of fixation
The choice of fixing the medial or lateral side first may be dictated by the surgeon's preference.
Choice of implant – Lateral fixation
The difference between an A2.2 and A2.3 fracture is the size of the lateral fragment.
If the fragment is large enough, it may be held with a plate and screws from the lateral side,
In osteoporotic bone the fixation may be more secure if locking plates are used.
Anatomic plates are available, and their lower profile may reduce postoperative discomfort due to prominent hardware.
If the fragment is too small, or there is concern about the quality of the bone, it may be better to fix it with K-wires and a tension band wire.
Choice of implant – Medial fixation
Medial malleolar fractures are usually fixed with lag screws. Oblique fractures may benefit from additional support with a buttress plate.
Note on approaches
The two following approaches are used:
2 Fixation topenlarge
Most medial fractures are fixed with lag screws, which should be inserted perpendicular to the plane of the fracture.
In simple transverse fractures, or in patients with good quality bone and fracture morphology in which stable reduction can be achieved, lag screw fixation is usually sufficient.
Oblique fractures are fixed with lag screws perpendicular to the plane of the fracture.
In a vertical fracture, provided the fragment is large enough and the bone quality is good enough, two or even three lag screws on their own may be sufficient.
In vertical fractures, with a tendency to displace due to shearing forces, or if there is any concern about the strength of fixation, further support may be achieved with a buttress plate.
This may be a short plate over the apex of the fracture, with the lag screw(s) inserted inferior to the plate.
Alternatively, a longer plate may be used, with the lag screw(s) inserted through the distal end of the plate.
In fractures when the quality of the bone and the size of the bone are large enough for good fixation to be obtained with plate and screws, this is the preferred method of fixation.
If the fragment is too small, or the bone is of poor quality, tension band wiring is preferred.
3 Check of osteosynthesis top
Check the completed osteosynthesis by image intensification.
Make sure the intra articular components of the fracture have been anatomically reduced.
Make sure none of the screws are entering the joint. This needs to be confirmed in multiple planes.