1 Principles topenlarge
In A3 fractures the lateral side has failed in tension.
In the tibia, the medial fracture tends to extend posteriorly and may be a large, separate fragment.
In A3.1 fractures the failure is through the lateral ligament, in A.3.2 fractures there is avulsion of the tip of the lateral malleolus, and in A3.3 injuries there is a transverse fracture through the lateral malleolus but still below the syndesmosis.
As the posteromedial 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 A3.2 and A3.3 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
The posteromedial fracture is fixed with lag screws.
Note on approaches
The two following approaches are used:
If the posterior medial fragment is large, the approach may need to be more posterior to enable reduction and fixation of this fragment.
2 Fixation topenlarge
The posteromedial fracture is fixed with lag screws, which should be inserted perpendicular to the planes of the fracture.
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 as shown in the X-ray. This needs to be confirmed in multiple planes.