Foot Drop Treatment (Tendon Transfer)

What is foot drop?

Foot drop occurs when the muscles and tendons that pull the foot up are no longer working. This is most commonly the result

Figure 1: The typical location of incisions on the inner side of the foot and ankle.
  of a nerve injury, stroke, or nerve disease (neuropathy). If a person is unable to pull their foot up when they walk, the foot or toes can drag on the ground making walking difficult. Most of the time, a brace can help manage the position of the foot when walking.

What is the goal of foot drop surgery?

The goal of a foot drop procedure is to improve a patient’s ability to pull the foot and ankle up in situations where this function is weak or lost completely.

What signs indicate surgery may be needed?

When the muscles pulling the foot up are not working, but other muscles around the foot and ankle still function, there is a surgery that can be helpful. Wearing a brace is also a reasonable solution for this problem. However, some patients cannot tolerate a brace or would like to walk without the help of a brace. A tendon transfer procedure for a foot drop is reasonable to perform in these patients.

When should I avoid surgery?

If there is no muscle function at the ankle, this procedure cannot be performed. A patient must have some working muscles for a foot drop procedure to be a success.

General Details of the Procedure

The surgical procedure for a foot drop is called a tendon transfer. In general, a tendon transfer is a procedure in which a

Figure 2: Tendon pulled to the front of the leg before transferring down onto the foot.

tendon (and attached muscle) that is still working is taken from one part of the foot and moved to another part of the foot to try to replace the muscle function that is missing. The most common tendon transferred is the posterior tibial tendon.

Specific Technique

The posterior tibial transfer procedure can either involve transfer of the posterior tibial tendon alone or transfer with attachment to two other tendons, the peroneus longus and the anterior tibialis. When all three tendons are used it is called a Bridle procedure because the three tendons are attached in a bridle configuration.
Multiple incisions are needed to move the tendon from one position to another. The posterior tibial tendon is taken off its insertion on the navicular bone on the inner side of the foot. This is the first incision. A second incision is made above the ankle and the tendon and muscle are identified. The location of these incisions is shown in Figure 1. The tendon is pulled into this second incision and then transferred in between the tibia and fibula bones to the front of the ankle.
Another incision is made on the top of the foot at the bone to which the tendon is going to be transferred. The tendon is routed under the skin to this bone and fixed into a tunnel in the bone. Figure 2 shows the tendon after it is transferred around

Figure 3: The typical location of incisions for tendon retrieval on the outer side of the foot and ankle.

  the tibia but before it is routed to the top of the foot. The typical incision on the top of the foot is also shown.
If a Bridle procedure is performed, a second tendon, the peroneus longus, is cut above the level of the ankle on the outer side of the leg. The location of these incisions and preparation of the tendon is shown in Figure 3. This tendon is then routed to the front of the ankle and the free end is attached to the posterior tibial tendon and the anterior tibial tendon in a bridle configuration. With this construct the posterior tibial muscle pulls on all three tendons to pull the foot up. The posterior tibial tendon is routed to the top of the foot as described above. Figure 4 is a diagram of what the tendons look like after the transfer is complete. 
Occasionally, the ankle can be very stiff from long-standing weakness. If it is not possible to pull the ankle up for attachment of the tendon transfer, the Achilles tendon is lengthened to help bring the foot and ankle up. This is done either through an incision on the calf or an incision right over the Achilles tendon. The location of the incision is based on the tightness of the ankle.

What happens after surgery?

A splint is placed on the ankle in the operating room to hold the position of the foot and ankle and protect the newly transferred tendon(s). Strict elevation and non-weightbearing are enforced over the first 10 to 14 days. Stitches are removed at approximately 14 days. A cast is placed after suture removal and continued until six weeks after surgery. The patient is usually non-weightbearing during this time.   
The cast is removed six weeks after surgery and a removable walker boot is placed. The patient is allowed to start walking in the boot. Physical therapy to retrain the tendon in its new position continues for eight to 12 weeks. A night splint is worn until three months post-operative to prevent premature stretching out of the transfer. 
As swelling improves a custom-molded brace can be worn in an athletic shoe and the walker boot is discontinued. Once the patient’s strength and motion are improved with physical therapy, the brace may be discontinued. Ideally, the patient will then walk in a shoe without a brace.

Potential Complications

There are complications that relate to surgery in general. These include the risks associated with anesthesia, the risk of infection, the risk of damage to nerves and blood vessels, and the risk of bleeding or blood clots.
Potential complications of this treatment can include wound infection, deep infection that can compromise the tendon transfer, and failure of the tendon or tearing of the repair.

Frequently Asked Questions

Will I have “normal” ankle movement after this procedure?
A foot drop procedure changes the function of the ankle and allows a patient to walk without a brace. However, it is not possible to restore normal strength and full range of motion with this procedure.
Will I be able to pull up my toes?
Often a nerve injury that causes a foot drop also limits the ability to pull up the toes. The tendon transfer will not restore this function. If this is a concern, make sure that you mention it to your doctor.
Will I be able to walk without a brace?
The purpose of the procedure is to try to improve function of the ankle so that a patient can walk without a brace. However, with severe nerve injury it is not always possible to guarantee that a patient will be brace-free all the time.
Can foot drop surgery be performed if I have no working muscles at all?
The foot drop tendon transfer surgery only works if some of the muscles around the ankle are still working.
Is there a “best time” to have the procedure after a foot drop occurs? Is sooner better than later?
Nerve injuries can improve very slowly over time. At the initial time of injury, it is possible that over months to a year, the foot drop will actually improve and strength will return. By about one year, if no function has returned, a foot drop procedure is reasonable to consider. 
For a long-standing foot drop (that is, the injury happened many years ago) a foot drop procedure can still work if the other muscles around the ankle are still working. So no matter how long ago it happened, it is reasonable to seek the opinion of an orthopaedic foot and ankle surgeon to see if you are a candidate for this procedure.
Will I need physical therapy?
It is helpful to have formal physical therapy to help retrain the muscle for its new function. Therapy continues until progress is made in both strength and motion and you are able to transition out of the boot or brace.
The American Orthopaedic Foot & Ankle Society (AOFAS) offers information on this site as an educational service. The content of FootCareMD, including text, images and graphics, is for informational purposes only. The content is not intended to substitute for professional medical advice, diagnoses or treatments. If you need medical advice, use the "Find an Orthopaedic Foot & Ankle Surgeon" tool at the top of this page or contact your primary doctor.