What is Peroneal Tendon Syndromes?
Peroneal tendon disorders cause pain in the back and side of the foot. There are three main types of these disorders: peroneal tendonitis (inflammation), peroneal subluxation (misplacement), and peroneal tendon tears; all these might lead to ankle instability as they often result in a pain on the side of the ankle. The peroneal tendons are in the outer part of the leg and are connected to two muscles – the peroneus longus and the peroneus brevis. These muscles and tendons receive nerve signals from the superficial peroneal nerve and blood from the peroneal artery.
The peroneus brevis muscle starts on the outer side of the end part of the fibula bone and between the muscles, and attaches to the base of the fifth toe bone. On the other hand, the peroneus longus starts at the top part of the fibula bone and the outer side of the shinbone, and connects to the base of the big toe bone and towards the inner edge of the foot. These tendons pass through a protective cover that is located behind the fibula bone, with each tendon having their own protective cover once they pass this bone. They travel through a path bordered by a supporting band of connective tissue, the back part of the fibula bone that has a groove, and a ligament between the heel bone and the fibula bone.
At the level of the ankle, the peroneus brevis tendon is in front and towards the inner side of the peroneus longus tendon. Sometimes, unusual anatomy can lead to a peroneal disorder such as a low lying brevis muscle belly, or the presence of an extra muscle in the foot called the peroneus quartus muscle. The peroneus quartus muscle normally runs from the peroneus brevis to a particular part of the heel bone, and is associated with peroneus brevis tears and displacement.
What Causes Peroneal Tendon Syndromes?
When the peroneal tendons, which are located in your leg and foot, suddenly contract due to an injury, they can get torn. They may also get detached from the part they’re connected to, which is called an avulsion. This is how acute, or sudden, injuries can occur.
If these tendons continue to pop out of place over time — a condition known as chronic subluxation — it can cause inflammation and irritation, leading to tendonitis, which is an inflammation of the tendon. The constant friction of the tendons against the bone located at the backside of the lower leg, the fibula, can also result in longitudinal tears or tears that run along the length of the tendons.
Chronic lateral ankle stability — meaning that the outer part of the ankle has been weakened or loosened over time — can cause the tendons to pop out of place or even tear due to increased movement. This situation can happen if the tendons become lax or loose.
Moreover, the shape or alignment of the ankle and foot can cause abnormal movement of the tendon. For instance, specific anatomical differences in the groove at the back of the fibula, the alignment of the hindfoot, or having a high-arched foot, can lead to these tendons to be more prone to popping out or becoming dislocated.
Risk Factors and Frequency for Peroneal Tendon Syndromes
Peroneal tendon tears often occur in active, young individuals. These tears may be longitudinal (often due to subluxation over the fibula) or transverse. Among these, the peroneus brevis tendon is usually more prone to tears compared to the peroneus longus. However, it’s possible for both tendons to tear concurrently.
- Young, active individuals are most often affected by peroneal tendon tears.
- Tears can be either longitudinal (due to displacement over the fibula) or transverse.
- The peroneus brevis tendon is torn more often than the peroneus longus tendon.
- However, both tendons can also tear together.
- According to a retrospective study, 88% had peroneus brevis tears, 13% had peroneus longus tears, and 37% had combined tears.
Signs and Symptoms of Peroneal Tendon Syndromes
Understanding the history of a patient’s condition is crucial when trying to diagnose disorders of the peroneal tendons. Key details to uncover include when the issue started, what movements or activities make it worse, whether any injuries have occurred, and whether there is any associated swelling. A patient might also describe a snapping or popping feeling at the bone on the outer part of the ankle. Doctors would also inquire about any previous steroid injections or recent use of antibiotics – Fluoroquinolones and steroids can be linked to tendon problems.
During the physical exam, the doctor will inspect the ankle and foot for redness or swelling and test the strength of ankle twisting and foot flexing. The doctor can check the peroneus longus tendon specifically by resisting active eversion – essentially pushing against the turning out of the foot. The patient’s tendons will be felt during ankle movement, and the structure of the back of the foot will be evaluated while the patient is standing. The doctor would also perform the ankle drawer test to assess the stability of the ankle ligaments, and examine the patient for peroneal tendon subluxation when they are laid down with a knee flexed to 90 degrees.
Peroneal tendonitis is often characterized by a slow onset of pain and swelling. There might be a noticeable fluid in the tendon sheath with a crackling sound. The main area of tenderness is typically along the peroneal tendons at the back and bottom of the fibular head. Tendon tears usually cause constant swelling, pain, and a sensation of ankle instability or weakness. If the tendon is out of place, patients may experience painful clicking and popping at the outer ankle bone. Subluxation might become obvious with voluntary foot turning out.
Testing for Peroneal Tendon Syndromes
If your doctor suspects that you may have a problem with your peroneal tendon (the tendon that runs along the outside of your ankle), the first thing they will use is an ankle X-ray. The X-ray will be taken while you are standing to get the best possible view. They will take images from a variety of angles to check for any fractures or alignment issues in your foot. Certain findings on the X-ray might suggest a peroneal tendon injury, such as a pulled away (avulsion) fracture from the base of the fifth toe bone, or bone changes in and around the peroneal tendon area.
Ultrasound, another imaging technique, is a radiation-free, less expensive option that can provide a dynamic view of the tendon’s movement. Additionally, ultrasound can also be used to accurately guide injections, if needed. Studies have shown that ultrasound is excellent at identifying tendon tears – it has a sensitivity (ability to correctly identify a condition) of 100% and specificity (ability to correctly rule out a condition) of 85%.
Moreover, if further evaluation is needed, Magnetic Resonance Imaging (MRI) can be used. MRI imaging offers a detailed view of the tendons without risking any radiation exposure. MRIs have been found to have 83% sensitivity and 75% specificity for identifying tears in the peroneus brevis tendon, a specific peroneal tendon at the ankle. The results can show fluid buildup around the tendons, any interruptions in the tendons, swelling of the bone, or any abnormal bone shapes.
Lastly, a Computerized Tomography (CT) scan might be used. While CT scanning does involve radiation exposure, it provides clearer images of the bones which can detect any possible abnormal bone shape that may be causing the tendon problem. A CT scan becomes especially useful if X-rays suggest a possible fracture, or if there are specific bone morphologies that need to be accurately assessed for management purposes.
Treatment Options for Peroneal Tendon Syndromes
Non-surgical Treatment
If you have a problem with your peroneal tendons (the tendons on the outside of your ankle), non-surgical treatments can often help to improve symptoms. These treatments may include anti-inflammatory medicines, applying ice packs, rest and avoiding weight-bearing, and physical therapy. Your doctor may recommend immobilizing your ankle with a cast or controlled motion boot, or suggest changes to your footwear, such as using a lateral heel wedge to relieve pressure on the tendons.
If these initial methods don’t lead to any improvement, a steroid injection around the peroneal tendon sheath (the protective layer that surrounds the tendon) might help with pain and assist doctors in confirming your diagnosis. A different type of injection, called a PRP (platelet-rich plasma) injection, might also be considered. PRP therapy has been shown to improve function in some patients with tendon disorders.
Usually, you would try these non-surgical treatments for 4 to 6 months. It can take this long for the inflammation to go down and symptoms to improve.
Surgical Treatment
When non-surgical treatments are not enough, surgery might be needed. The type of operation recommended depends on the exact nature of your peroneal tendon problem.
If you have inflammation in the peroneal tendons (peroneal tendonitis), surgical options include cleaning out the inflamed tissue and removing the synovium (a layer of tissue that lines the joints and tendon sheaths). These procedures can be done either through a traditional open surgical approach or using a camera on a scope (arthroscopy).
If the peroneal tendons are moving out of place (subluxating or dislocating), the goal of surgery is to fix any damage and ensure the tendons move smoothly. In some cases, a fracture might have caused the tendon problem. If so, this would need to be fixed. Other procedures might involve reshaping the fibular groove (where the tendons run), correcting foot alignment, or rerouting the peroneal tendons. There are also procedures that use a piece of bone to keep the tendons in place.
If the peroneal tendons are torn, the treatment again depends on the severity and type of tear. Partial tears of less than 50% might involve cleaning out and reshaping the tendon. If the tear is complete and recent, the two ends of the tendon might be stitched together. In cases of chronic or severe tears, other techniques might be used, including grafting (using donor tissue to reconstruct the tendon).
What else can Peroneal Tendon Syndromes be?
If you’re experiencing pain or discomfort in your ankle or foot, there could be several possible causes. These might include:
- An ankle sprain
- Rheumatoid arthritis
- A calcaneus (heel bone) fracture
- A fracture in the os peroneum, a small bone in the foot.
In addition to these conditions, certain injuries can be associated with problems in the peroneal area (the outside of your calf). These can include:
- Tears in the lateral ankle ligament (the ligaments on the outside of the ankle)
- Lateral ankle instability (a condition where the ankle easily gives way)
Also, patients who have a varus heel (a condition where the heel points inward) may be more likely to have Charcot-Marie-Tooth disease, a genetic condition that affects nerves.
What to expect with Peroneal Tendon Syndromes
If you have a tear in your Peroneal tendon, it’s good to know that the results after surgery are generally very positive. This includes both improvement in pain levels and being able to resume usual activities. For instance, one study by Saxena showed an 87% rate of return to sport after surgery for this type of injury.
In a different review by Dombek that looked back at past cases, an impressive 98% of patients were able to get back to their full routine of activities about 13 months after surgery for Peroneal tendon tears.
The results are also encouraging when the problem is tendon subluxation (when the tendon slips out of place). Saxena’s research showed everybody in their study was able to get back to their sport after having the superior retinacular ligament repaired (this ligament holds the tendons in place). So, despite your injury, with effective surgical treatment, you can look forward to a good chance of a full recovery.
Possible Complications When Diagnosed with Peroneal Tendon Syndromes
There have been instances of a condition called peroneal compartment syndrome following the sudden tearing or rupture of the peroneus longus tendon.
After undergoing surgery to repair a torn tendon, there are possible complications. These primarily include the tendon re-tearing or the persistence of symptoms. According to Dombek’s findings, these complications occur in about 10% of patients.
Typical Complications:
- Peroneal Compartment Syndrome after peroneus longus tendon rupture
- Re-tearing of the tendon post-surgery
- Persistent symptoms after surgery
Preventing Peroneal Tendon Syndromes
Peroneal tendon disorders are a medical issue that can lead to pain on the outside of your ankle. These disorders basically come in three forms: tendonitis, subluxation, and tears. Tendonitis refers to inflammation of the tendon, subluxation means the tendon is slightly dislocated or moved from its usual place, and tears are when the tendon has been ripped or damaged.
If these conditions aren’t identified or properly treated, it could lead to ongoing pain or instability in your outer ankle. This means you might experience discomfort regularly or feel like your ankle is unstable or unsteady.
