They are two tendons that are located on the outside of the ankle and together with the tibial tendons (also two) act like the reins of a horse, controlling the lateral movements of the ankle. The peroneal tendons which run along the back of the fibula and are two tendons.
The function of these tendons is to evert the foot (bend the ankle outward). It is attached to the fibula by a ligament-like structure of tissue, called the retinaculum , which prevents dislocation.
The first thing would be to clarify that the most correct way is to call this injury tendinosis (degeneration), since only at the beginning we find inflammatory cells. Tendinitis implies that there is an inflammation in the tendon, while in tendinosis we find a thickening of the tendon, as it is replaced by a disordered poor quality tissue. This usually occurs in response to repetitive and sustained irritation in the tendon, which over the months will change its normal properties. Irritation is normally a mixture of two types of causes; anatomical abnormalities in the foot/ankle + overuse or performing sports activities that involve the tendon on a regular basis. The typical patient is an athlete, withtendency to suffer from ankle sprains and pes cavus, usually with short and powerful calf muscles.
Sustained degeneration over time usually ends up leading to partial or total rupture of the tendons, especially the peroneus brevis.
The causes can be divided into two types; related to sports (incorrect training) and the anatomical causes of each patient.
Sports tendinopathy is common to other tendinopathy such as Achilles tendinopathy and includes:
Among the anatomical or mechanical factors, the most frequently involved are the presence of pes cavus , especially associated with hindfoot varus, this pathology being typical in supinator patients with short gastrocnemius. If we also use soft shoes for the training we do, we will still load the peroneals more. In the case of a history of poorly treated ankle sprain, the stress on these tendons is multiplied.
Peroneal tendinosis produces pain in the posterior and lateral area of the ankle , just in the posterior area of the fibula. At first this pain appears after long distance sessions in runners and not every day. Little by little, if we continue with the same activity, it will interfere with our training until it becomes a very limiting pain, which is aggravated by twisting the ankle.
In addition to pain, it is very common that you notice instability in the ankle , putting the ligaments at risk, since, like any damaged muscle, it stops contracting correctly and the energy goes to the joint stabilizing structures. That is why these patients either have suffered an ankle sprain or are at risk of suffering one in the future. In chronic cases where degeneration has led to partial rupture of the tendon, pain appears with minimal effort or even at rest . That is why, if you are preparing a long-distance event like the Marathon and you start with pain on the outside of your ankle, consult a specialist before the injury can get worse.
Because peroneal tendon injuries are sometimes misdiagnosed and may worsen without proper treatment, prompt evaluation by a foot and ankle surgeon is advised. To diagnose a peroneal tendon injury, the surgeon will examine the foot and look for pain, instability, swelling, warmth and weakness on the outer side of the ankle. In addition, an x-ray or other advanced imaging studies such and MRI may be needed to fully evaluate the injury. The foot and ankle surgeon will also look for signs of an ankle sprain and other related injuries that sometimes accompany a peroneal tendon injury. Proper diagnosis is important because prolonged discomfort after a simple sprain may be a sign of additional problems.
The treatment will be determined by the state of the tendons as well as the causes of the tendinopathy. The majority of peroneal tendinosis will be cured without surgery, performing a combination of changes of habit or changes of the tread along with a specific treatment for the tendon.
For the first objective, the first thing to do is to indicate a time for modifying the activity, changing the jump and the run for bodybuilding and proprioception exercises (see activity section). It is likely that we will temporarily recommend a varus/valgus stabilization splint, which replaces the function of the tendon, allowing flexo-extension and therefore sports activity. This phase can last between 4 and 12 weeks depending on the state of your tendons and will be accompanied by a solution to your support problems, if any, by changing shoes or insoles. After this time, a progressive return to sports discipline will be carried out, doing cross-training sessions., alternating bodybuilding/proprioception with running/jumping.
To favor the healing of degenerative changes in the tendon, currently, biological treatments are the most effective, avoiding the use of anti-inflammatories and corticosteroids, which will only provide a transitory effect with a damaging effect on the tendon. Biological treatments promote the natural healing mechanisms, the most used being platelet-rich plasma (PRP) and Orthokine, although for the peroneal tendons there are still no long-term studies due to the short time these treatments have been used. Surgical treatment is reserved for cases in which we think that the above is not going to be enough.
We reserve surgery for the few cases of patients with any of the following characteristics:
In all cases, we will perform a debridement or cleaning of the damaged tendon tissues as well as the adhesions that may have been created. In the case of partial tears or tears, in most cases we can make a primary repair , without the need to touch other structures. When the rupture is complete, usually of the peroneus brevis, we perform an intervention in which we “connect” the peroneus brevis tendon to the long one, creating a single functioning tendon.
Cases associated with subluxation of the fibulae require a somewhat larger surgery, carving a deeper groove in the posterior part of the fibula together with a repair of the retinaculum.
Sometimes making the groove at the back of the fibula bone deeper allows more room for the tendons and can also help. Lastly, if the tendon is in very poor condition, it may be necessary to remove the tendon and connect the peroneus longus to the peroneus brevis. Only the specific tendon should be addressed. Sometimes both can be compromised.
Peroneal instability or dislocation means that the peroneal tendons jump the fibula when they contract and abnormally pass to the front of the outer ankle. The patient himself notices a snap and sees the jump to the anterior area, suffering from a very unpleasant sensation and pain. The pain is caused by the degeneration that occurs in the tendons, peroneal tendinosis.
The same anatomical and functional factorsthat lead to peroneal tendinosis and produce peroneal degeneration produce peroneal instability or dislocation of the same. The mechanical overload together with the cavo-varus will damage the structure that retains the peroneal tendons in their normal place; the retinaculum. The retinaculum is a band of collagen fibers (similar to a ligament) that hold the two peroneal tendons in position just behind the fibula. These tendons, subjected to chronic irritation, can “win the battle” against the retinaculum and it will be the retinaculum that is damaged, instead of the tendons themselves suffering the injuries/ruptures. The only difference in these patients compared to patients with peroneal tendinosis is the anatomical shape of the fibula. In those who suffer dislocation, the posterior aspect of the fibula, where the cartilage through which the peroneals slide is located, is convex instead of having the normal deep groove. This causes the combination of the factors described above to force the retinaculum and jump towards the anterior area.
For the diagnosis in the exploration, we will perform a maneuver that reproduces the dislocation , we can even see the dislocation directly in the ultrasound, and diagnose other minor conditions such as tendinosis + peroneal subluxation. The treatment, as in tendinosis, involves correcting the causes; training / insoles / bodybuilding.. The need for surgical intervention is much more frequent. This intervention, as I show you in the video, consists of repairing and tightening the damaged retinaculum , frequently associating the carving of a new groove in the posterior part of the fibula , preserving the cartilage.