Understanding The Mechanisms And Etiologies Of Peroneal Tendon Tears
The peroneals are a set of two tendons that are on the lateral aspect of the leg. The peroneal tendons have two modes of action. They are the main adductors of the foot and provide weak plantarflexion of the foot. The peroneus longus main function is to stabilize the first ray by providing plantar flexory force. The previs tendon which attaches to the base of the 5th metatarsal helps to abduct the foot. Together these further help stabilize the ankle to prevent ankle sprains.
There are 3 main reasons why patients develop peroneal tendonitis issues
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Traumatic injury
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An overuse injury is commonly seen in athletes
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Chronic overload due to foot type/position/mal-alignment
- Traumatic Injury-This can happen due to severe ankle sprain, rapid dorsiflexion on an inverted foot. These injuries can damage the peroneal retinaculum and the tendons themselves. This leads to tears within the tendons and dislocation from the groove within the fibula.
- Overuse Injury- This is commonly seen in athletes and those that have had previous injury to the lateral ankle ligaments. This leads to excess fatigue on the peroneal tendons. Checking for lateral ankle stability is key with these patients.
- Foot type- Anatomical deformities can also lead to overuse of the peroneal tendons. Pes cavus foot types position makes it so that the peroneal are overstretched and overworked. A shallow fibular groove can cause the tendons to dislocate from their normal anatomical positioning and lead to longitudinal tears.
Diagnosing and fixing peroneal Injuries
The physical exam is the most important part of diagnosing peroneal injuries. This is to figure out the reason for injury as described above. Also, we have to remember there are two different tendons and only one or both may be injured. My physical exam starts with evaluating the ankle joint. If the ankle joint is stable then the injury may be due to the overuse of the peroneal helping to stabilize the ankle. Performing the anterior drawer test and taking stress radiographs can help one determine the extent of an ankle injury. Next, we look for anatomical abnormalities such as high arch foot type, shallow fibular groove, Forefoot abduction. How does one foot compare with the other side?
Now we move on to the evaluation of the tendons. Palpate the tendons to decide the actual location of injury (insertional, proximal, mid substance). The use of a handheld ultrasound can be very helpful in visualizing the injury to the tendons. For better visualization, an MRI is extremely helpful in diagnosing the extent of the injury.
Treatment
Non-surgical:
Initial treatment of peroneal pathology starts with a period of rest. Decreasing activity, RICE, Ankle stabilization brace, cam walker boot. This stage is done to help decrease the inflammation and allow for healing to happen. If one fails the initial treatment we start with physical therapy who will work with therapy such as iontophoresis, contrast soaking, stretching, rehab.
Once a patient has failed all conservative treatment we can use amniotic/PRP Injection therapy to help with the repair of the tendons. There is good literature out there showing the support for the use of amniotic injections.
Surgical Treatment:
For those that failed conservative therapy, we can then move on to the surgical intervention. Surgical intervention should be treated similarly to patients with PTTD (posterior tibial tendon dysfunction). Patients will rarely just do better with the repair of the tendon. We need to address the cause, whether that is lateral ligament injury, Pes cavus, shallow grooves in the fibula.
If the patient has Injury to the lateral ankle ligaments, then those will need to be repaired as well. Ankle arthroscopy is also recommended in these patients since these injuries are often associated with talar dome lesions.
If the patient has a pes cavus deformity then depending on the amount of deformity present a reconstruction may be beneficial. A Dwyer osteotomy followed by an elevation osteotomy of the 1st metatarsal may be needed.
Sometimes a tendon transfer may also be necessary if the brevis tendon is overpowering the adductors of the foot. The tendon may be transferred to the cuboid to decrease the adducting force
The fibular groove and the integrity of the superficial peroneal retinaculum need to be evaluated intraoperatively. Multiple techniques are available to deepen the fibular groove along with reinforcing the retinaculum.
Finally, we can now address the Peroneal tendon. This involves getting rid of debriding the injured regions of the tendon. Then the tendon is repaired with a specialized tubularization technique. If the tendon is too torn a tenodesis procedure may be performed. This involved suturing the two tendons together.
Final Thoughts
Treating peroneal tendon injuries is not very straightforward. It requires a systematic algorithm approach. One must treat these injuries in a similar manner like they would PTTD. One has to address the root cause and then come up with a patient-specific treatment plan.
