How do they tear?
Most commonly the peroneal tendons tear by fraying. They are placed under repetitive stress and have tears within the tendon that slowly tear apart.
Symptoms are not always clear. Since tendons themselves have no nerves inside them, pain is often transmitted to other areas. Tendons connect muscle to bone. The muscle has good nerve input and sometimes people feel cramping pain in the side of the leg (often at night after a lot of activity). The insertion on the bone has great nerve supply so sometimes people have pain on their 5th metatarsal bone on the outside (lateral side) of the foot.
Why do people tear the tendon?
- Acute Dislocation (unusual)
- Overuse (most common)
How to Treat?
Acute dislocation and tears have an abysmal response to non-surgical treatment. In fact, I usually refuse to do it in almost all circumstances. Treating it non-surgically leads to further tearing and can make the tendon irreparable. It also causes intense scaring in the back of the ankle and the instability is never fixed. Because these rare cases can potentially result in permanent damage, I routinely get the patient to surgery quickly.
I also see many patients with incomplete treatment. They have undergone isolated peroneal tendon repairs and they have recurrent pain or MRI documented recurrent tears.
It can be very challenging to determine ankle ligament instability in a patient with peroneal tendon tearing. The pain from the tear can cause spasm and difficulty relaxing to permit a good ligament stress test. Even knowing how to do the right ligament stress test is hard. I am acutely sensitive to this exam as I practice it every day on every patient that walks in the office.
The real question everyone has is why the tendons have problems in the first place. The ankle has several sources of stability. The bony structure is a mortise (like a door) and it is intrinsically stable on flat ground going straight, while the ligaments give mechanical stability for side to side and rotational forces.
When you sprain the ankle severely, the ligaments heal at an extended length and the peroneal tendons must take up the slack so to speak. They work overtime as the secondary dynamic stabilizers.
When they tear and begin to become dysfunctional, instability and pain becomes an even bigger problem than before. Sometimes the instability doesn’t become evident until the tendons tear and other times it is evident soon after the sprain. Regardless, if and when it causes a functional problem, it needs to be fixed.
I get frustrated when I hear that patients “stopped playing basketball” or “stopped going for my daily walk” because they couldn’t do it anymore. This is an easily solved problem with a surgery that lasts less than an hour. Patients are walking on the ankle in a cast by day 1, in a boot by day 18, and in an ankle brace starting physical therapy by 4-6 weeks post-op. Then, it’s just a matter of how hard they work at it to get better, but most athletes begin training by 8 weeks and most people are back to heavy labor by 3-4 months.