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When is surgery necessary?
So you’re taking your dog out for a walk, enjoying the night air, when suddenly the dog lunges for the bushes. Your shoulder is snapped into tension, and your ankle rolls over the edge of the sidewalk. You hear a sickening “SNAP!” Suddenly, your ankle will no longer carry your weight. The pain is excruciating. It didn’t seem like such a hard roll. How in the heck could you have broken your ankle?
At the ER, an x-ray is taken. Sure enough, you have a crack in a bone on the outside of your ankle, the fibula. Are you going to need an operation or not? How is that decision made?
In order to figure out why ankle fractures sometimes require surgery and other times do well without surgery, an understanding of the anatomy of the ankle is necessary. The ankle is made of three bones, the tibia, the fibula, and the talus. Together, the fibula and the tibia create the roof of the ankle joint. They surround the talus on three sides, creating an extremely stable hinge joint. The stability is both the strength and the weakness of this joint.
These three bones are held together and their motion is guided by their ligaments. On the inside of the ankle, the deltoid ligament spans the gap between the medial malleolus of the tibia and the talus. On the outside, the lateral ligament complex stabilizes the fibula to the talus, and keeps the ankle from rolling over or spraining. Perhaps most important are the ligaments that bind the tibia and the fibula, stabilizing the roof of the ankle, the syndesmotic ligaments.
The stability of this joint makes it extremely resistant to arthritis. While arthritis without underlying injury is extremely common in the hip and knee, it is very rare in the ankle. However, after injury, any loss of stability or congruence in the ankle joint is often followed by rapidly progressive arthritis. Why? The pressure distribution between the tibia and the talus is distorted by even small degrees of malalignment. This distortion leads to an even wear in the damaged ankle.
So the goal of fracture treatment is to strictly restore the alignment and the stability of the ankle joint. This is the most reliable way of ensuring that the ankle will function in as normal a manner as possible. It is therefore critical that the intra-articular portions of the fracture are exactly opposed. It is also extremely important that the ligaments, especially the syndesmotic ligaments, are stabilized completely, so they can heal at proper length. This includes ensuring that the fibula’s length is precisely reestablished.
Two similar ankle fractures, but the one on the right (B.) requires surgery. Why?
To illustrate this, we will look at two very similar fractures, both of them potentially unstable. In case A (these are x-rays looking at the ankle from front to back), the fibula is broken at the level of the ankle joint (blue bracket) and a small portion of the medial malleolus (green arrow) is torn off along with the deltoid ligament. However, the ankle joint itself is in its normal position (red lines). Although this injury has the potential to fall out of alignment, scientific investigations have shown that this rarely happens. It is safe to treat this injury in a cast with close observation.
In case B, the fibula is also broken at the level of the ankle joint (blue bracket) and a small portion of the medial malleolus is torn off along with the deltoid ligament (green arrow). However, in this example, the ankle joint has been very slightly thrown out of proper alignment (incongruent red lines). It is likely that if this injury were allowed to heal in this position, the result would be a painful joint which would rapidly progress to arthritis. It was my judgment therefore that this patient would do better with surgical stabilization or placement of metallic plates and screws to realign and stabilize the joint.
This is only one common fracture pattern. Many patterns of ankle fracture exist and each requires its own approach.
As in many parts of medicine, there is still a great deal of controversy regarding the fine points of decision-making in treating ankle fractures and many surgeons will disagree on the best way to treat a specific fracture. Hopefully, this article will give you some idea of how these decisions are made.
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