The peroneal retinaculum is a thin band of tissue that helps hold the peroneal tendons behind the fibula at the outside of the ankle. There are actually two distinct peroneal retinaculums; the “superior peroneal retinaculum” and the “inferior peroneal retinaculum.” The one you actually care about if you’re having popping and clicking and pain at the outside of the ankle is the superior peroneal retinaculum.
This is the one that actually gets torn in patients that have severe ankle sprains and develop popping and clicking and or swelling at the outside of the ankle. Both of the peroneal tendons at the outside of the ankle sit behind the fibula in a groove known as the “retromalleolar groove.” The superior peroneal retinaculum simply helps hold the tendons in the groove.
There are a couple of different reasons why people can have peroneal tendons that pop and click at the end of the fibula at the ankle. The most common reason is that the ankle becomes injured such as in an ankle sprain.
The peroneus brevis tendon starts at the peroneus brevis muscle and continues down the back of the leg behind the fibula before it curves around the end of the fibula and then attaches to the base of the fifth metatarsal bone. This tendon is the only one that can actually fire and pull the foot back under the leg when you start to roll your ankle in the most common kind of ankle sprain.
Sometimes when you roll your ankle your peroneus brevis tendon attempts to pull the foot back under the leg so forcefully that the tendon will actually slide forward around the fibula and rip the superior peroneal retinaculum. Once the ankle sprain heals, one or both of the peroneal tendons can have a tendency to flip back and forth around the edge of the fibula.
This condition is often referred to by physicians as peroneal subluxation or dislocating peroneal tendons.
In Figure 1 you can see that the peroneal retinaculum is intact and holding the peroneal tendons behind the fibula bone in the retromalleolar groove at the outside of the ankle.
Figure 2 illustrates a torn peroneal retinaculum allowing the peroneal tendons to slide forward and out of the retromalleolar groove. As the tendons slide back and forth around the edge of the fibula bone they make a popping clicking sound.
Another less common cause of peroneal subluxation is related to the shape of the fibula bone itself. Sometimes the groove is not even present. Figure 3 is a cross-section through the leg at the level of the ankle. In this image there are three illustrations of different possible shapes of the fibula. You can see that the 1st (most common) option is where the fibula groove is actually concave. This deep groove helps to hold the tendons in place because there’s a natural depression in the back of the fibula bone. The 2nd option is where there is not much of a groove at all. And the 3rd option is where the back of the fibula bone is convex instead of concave.
In both of the second two options it is possible that the peroneal tendons can flip back and forth across each other simply because there isn’t very much room between the bone and the peroneal retinaculum.
The noise that you hear and sensation you feel is actually the tendons flipping back and forth across each other. This can cause pain and swelling. It can also cause chronic irritation of the tendons which might lead to splitting or tearing of the tendons.
There are some conservative treatments which might help the tendons to calm down and heal. But the surgery that is most often performed to treat these problems involves surgical reconstruction of the peroneal retinaculum and surgical deepening of the groove at the back of the fibula.
Dr. Christopher Segler, D.P.M. is board certified, American Board of Podiatric Medicine. He advises runners, triathletes and active young adults about the best way to stay active when ankle injuries don’t heal. He travels often to accommodate patients with complicated injuries in San Francisco, Houston, and Hawaii. He also provides remote consultations via Skype for injured expat patients living abroad who need expert advice, but cannot readily access a true ankle expert while overseas. If you have a question about a complicated ankle injury that just isn’t getting better, you can reach him directly at 415-308-0833