Peroneal Tendon Subluxation

Tendons are strong white bands of fibrous tissue that connect muscles to bones. As a muscle contracts, it pulls the tendon, which in turn pulls the bone to which it is attached and this carries out the movement of the skeleton.

Tendon subluxation refers to a condition in which the tendon slips out of its normal position during movement; however, it relocates itself back to its normal position. When the tendon fails to relocate itself to its normal position the condition is called tendon dislocation or subluxation.

The peroneal tendons belong to the two peroneal muscles located on the outer side of the lower leg. The two tendons travel downward along the outer side of the ankle, passing behind the outer bump of the ankle. From here the tendons angle forward and pass under the foot where they attach to the lower surface of the bones of the midfoot (metatarsals). As the muscles contract, the tendons pull the foot downward (plantarflexion) and outward (eversion).

This curved course of the tendons is secured by the following anatomical structures:

A sheath surrounds the ligaments as they pass behind the outer bump of the ankle, this sheath is further stabilized by ligaments located both deep (calcaneofibular ligament) and superficial (retinaculum) to it.

In more than 80% of individuals, there is a groove located on the back of the leg bone to accommodate these tendons

A bony ridge may further assist the groove in keeping the tendons in place and preventing their subluxation.

Causes of peroneal tendon subluxation:

Damage to the retinaculum:

This most commonly occurs after an inversion ankle sprain. As the foot twists inwards, the peroneal tendons are stretched forcefully and their pulley-like action can tear the retinaculum fibers. The damaged retinaculum fails to hold the tendons in place, leading to their subluxation.

Moreover, as the foot rolls inwards, other ligaments located on the outer side of ankle also become damaged. The peroneal tendons have to take on their role as well in stabilizing the ankle. This excessive workload may also cause inflammation of the peroneal tendons called peroneal tendonitis and make them more liable to subluxation.

Recurrent ankle sprains may cause instability of the ankle with subsequent peroneal tendon subluxation.

A shallow groove or a small or absent bony ridge may also be the reason behind peroneal tendon subluxation, especially when there is no previous history of ankle sprain.

Symptoms:

  • There is a painful snapping sensation on the outer side of the ankle, as the tendons move out of their place during ankle movement
  • The area is tender
  • Pain while walking on toes or with sideways cutting while running
  • After acute injury, there may also be swelling along with pain in the area

Treatment

Non-Surgical Treatment involves:

Immobilizing the ankle, making sure that the tendons are relocated to their normal position. The immobilization cast is applied for about six weeks.

Surgical Treatment is required in about 50% of cases and it includes the following options:

Repairing the damaged retinaculu

Deepening the groove

Creating a bone block by cutting and reattaching the bone near the lower end of fibula