The peroneus longus tendon and the peroneus shortus tendon function to externalize the foot. The belly of the muscle is located in the lateral fascial compartment of the lower leg. The tendon crosses the fibular canal posterior to the lateral ankle in the hindfoot. The fibular canal is anterior to the fibula and posteriorly lateral to the posterosuperior support band of the fibularis muscle. Morphologically, the posterior peroneal groove is a flat, shallow groove in 10% to 20% of the population.
The peroneal muscle support band is divided into two: the superior and inferior. The superior peroneal muscle support band begins at the posterior lateral fibrocartilage margin of the fibula and the posterior peroneal groove and ends at the lateral aspect of the Achilles and Achilles tendons. It serves to deepen the posterior fibular sulcus and is an important structure to stabilize the peroneal muscle. The inferior support band continues with the lateral root of the extensor support band and attaches posteriorly and inferiorly to the lateral aspect of the anterior aspect of the heel. Two fibrous canals are formed above and below the heel slide to anchor the tendon to the lateral wall of the heel.
The peroneus longus tendon passes posteriorly and laterally to the peroneus shortus tendon, with three curves in its course, and the tendon turns at a large angle as it passes the tip of the fibula, before crossing obliquely over the lateral talonavicular process of the heel and ending at right angles to the base of the 1st metatarsal and the medial cuneus medially at the dice tuberosity. Before entering the plantar aspect of the foot, it also passes through the bony groove on the dice bone, where a small appendage is sometimes visible.
The short peroneal tendon, the belly of which is located closer to the distal end than the long peroneal tendon, lies within the fibrocartilaginous canal between the posterior peroneal tendon and the long peroneal tendon, before turning outside the tip of the fibula to the base of the 5th metatarsal. The fourth peroneal muscle may accompany the long and short peroneal tendons in the fibrous canal.
1.Etiology and pathology
Acute peroneal tendon dislocation is often caused by sports injuries, commonly after the tip of the sled is stuck in the snow during skiing, causing extreme plantarflexion and inversion of the foot. The peroneal muscle support band relaxes, forming a tenosynovitis, and the long peroneal tendon squeezes the short peroneal tendon against the cartilaginous edge of the fibula, causing a longitudinal tear. Long-term observation is less likely to see a complete rupture. Tendon dislocation is more likely to occur if the patient has a flat or convex posterior peroneal groove.
Tenosynovitis can develop as a result of synovial tenosynovial stenosis. Stenosing tenosynovitis often occurs in locations where the tendon travels in a different direction. The most common location is posterior to the outer ankle, below the surface of the dice bone at the prominence of the talus. If there is a low peroneal short tendon belly or a fourth peroneal muscle, then the inner diameter of the tendon sheath is relatively reduced, causing tenosynovitis. Acute trauma can also cause tenosynovitis.
Fractures of the fibula and nonunion of the heel bone can cause peroneus longus tendon seed bone pain syndrome (POPS), which occurs in association with the seed bone within the peroneus longus tendon. The etiology is acute versus chronic, seed bone fracture, dichotomous or multichotomous seed bone, wear and tear or rupture of the long peroneal tendon at the adjacent seed bone. Mechanism of acute injury: sudden violence, causing dorsal extension of the foot inversion.
Common peroneal tendon disorders are.
1, acute peroneal tendon dislocation.
2, acute short peroneal tendon tears.
3, long peroneal tendon seed bone pain syndrome (POPS).
There are 3 types according to the degree of injury to the supporting structures that hold the peroneal tendon in place.
Acute peroneal tendon dislocation classification (Equet-Davis typing)
In type I, the supporting band and periosteum are torn away from the outer ankle cortex, forming a pseudopouch (pocket-like gap) that encases the dislocated tendon. In cross section, the position of the tendon at this point slides from posterior to anterior of the short peroneal tendon, but remains contained in the gap formed by the partial tear of the supporting band and periosteum.
In type II, the cartilaginous edge of the fibula is avulsed along with the supporting band and the periosteum.
In type III, the lateral fibular cortex, the cartilage edge of the fibula is avulsed with the supporting band to form a crural fracture (rim fracture).
Grading of short peroneal tendon tear
degree 1, tendon becomes flattened
degree 2, partial thickening, tear less than 25px
3 degrees, full thickness, tear less than 50px
4 degrees, full thickness, tear greater than 50px
Peroneus longus tendon seed bone pain syndrome typology
ⅠAcute seed bone fracture with multifracture seed bone
ⅡPrevious type of injury healed and formed local callus
Ⅲ Wear and partial tear of the long peroneal tendon at the proximal or distal end of the seed bone
Ⅳ straight line rupture of the long peroneal tendon
Ⅴ giant talus protrusion, impingement of the heel bone with the long peroneal tendon or the seed bone
2. History, clinical manifestations and physical examination
Acute and chronic peroneal tendon instability have different clinical manifestations. Acute dislocations often occur during sports, such as skiing or soccer. The dislocated tendon can be palpated and the injury is associated with a popping sound. After the injury the patient will be immobile due to pain in the lateral aspect of the ankle joint. On examination, swelling, tenderness or localized spotting of the posterior aspect of the fibula is noted. Often the injured tendon will return spontaneously, making it difficult to diagnose and often misdiagnosed as an ankle sprain. Resistance valgus activity during plantarflexion of the foot is investigated, triggering dislocation of the peroneal tendon. In addition, resistance to dorsiflexion is associated with pain when dorsiflexion is performed.
Chronic dislocation of the peroneal tendon may or may not be associated with recurrent injury, and patients often feel tendon entrapment or pain at the posterior aspect of the external ankle, complaining of uncontrolled ankle joint, and unstable peroneal tendon subluxation may be accompanied by instability of the lateral ankle ligament. Light finger pressure on the tendon during the valgus provocation test can cause pain, and palpation can check the extent of the dislocation.
In patients with peroneal tenosynovitis, pain can develop at the tendon during foot valgus. These patients may have a history of fracture, such as a fracture of the heel bone.
Peroneus longus tendon seed bone pain syndrome is classified as acute or chronic. Acute POPS is characterized by acute pain on the lateral aspect of the plantar aspect of the foot. On examination, pressure pain can be palpated at the tip of the fibula, where the long peroneal tendon travels, and the pain can arise against valgus. Saphenous numbness can be complicated at the nerve branch proximal to the tendon. Chronic POPS has the same presentation but often continues to present with symptoms over weeks or months, confusing it with ankle sprains.
3. Imaging manifestations
Acute peroneal tendon dislocation can be found on plain radiographs, when a wafer sign appears from an abnormal violent injury and an avulsion fracture of the posterior lateral fibular cortex. This sign can be more obvious on ankle point x-ray, but it is not visible in 50% of patients. Imaging is not significant for chronic peroneal tendon dislocations, but can be helpful in detecting bone deformity healing in tendinitis. Imaging is diagnostic of POPS with or without lateral foot callus formation in the presence of a fracture of the seed bone of the long peroneal tendon. x-ray findings of proximal displacement of the seed bone indicate a rupture of the peroneal tendon at the distal end of the seed bone. Harris images of the heel axis can be used to examine the heel talonavicular process for hyperplasia.
MRI is not usually used to diagnose acute peroneal dislocations, but can be used to confirm the diagnosis when the foot is too swollen for physical examination to determine whether the dislocation has spontaneously repositioned, and MRI shows fluid in the tendon sheath, which is a good indication of tendon damage. In chronic dislocations or tendinitis, fluid around the tendon may also be seen, and longitudinal tears may be detected. Cross-segmental morphologic analysis of the fibula can be performed to check if the posterior ankle sulcus is flat or too shallow.
4. Treatment
The treatment of acute peroneal tendon dislocation is now controversial. One treatment is cast immobilization of the ankle in plantarflexion for 6 weeks with no weight bearing. This can be effective in 50% of patients. Proponents argue that this saves the patient from unnecessary surgery. However, surgery is 95% effective in treating acute peroneal tendon dislocations and is effective in preventing recurrence. Surgery for acute dislocations is a simpler method of treatment than for chronic dislocations. Contraindications to surgery include: severe systemic or peripheral vascular disease. Chronic subluxation or dislocation of the peroneal tendon should be treated surgically if symptoms develop.
Peroneal tendon tenosynovitis should be treated conservatively first: nonsteroidal anti-inflammatory drugs, local braking, and shoe replacement. The shoe can be raised on the lateral edge of the heel bone to reduce pain. If the patient’s compliance is poor, debridement surgery for tendinitis may be considered.
Impingement signs due to healing bone deformities can be treated with tendon decompression surgery and removal of the bone causing the impingement.
Acute POPS should be braked. Chronic patients with symptoms presenting for more than 1 month may undergo surgery to remove the fibular seed bone and repair the peroneal longissimus tendon. The tendon, if ruptured and retracted, can be sutured together with the short fibular tendon. If the talocrural process is hypertrophied, it can be removed.
Postoperative care
The patient’s stitches are removed, reviewed, and the short leg cast is replaced 14 days after surgery. No weight-bearing on the affected limb for 4 to 6 weeks. After that, the patient will be moved under a joint mobility restrictor. And joint mobility exercises were performed. Peroneal tendon strength exercises were started at 8 weeks, and normal activities were allowed after 3 months. Sports were started after 4 to 6 months.
Prognosis and results
The results after peroneal tendon strengthening were all favorable. Complications such as recurrence of dislocation, saphenous nerve injury, and persistent swelling and pain were seen in approximately 5% of patients.