A tendon is a strong, flexible, cord-like structure that connects a muscle to bone. When the muscle tightens, it pulls on the tendon, which in turn moves the bone. Some of the tendons in the foot include: Achilles tendon, peroneus longus tendon, peroneus brevis tendon, tibialis posterior tendon, and tibialis anterior tendon.
In a tendon injection, your foot and ankle orthopaedic surgeon puts a substance into either your tendon or the area around your tendon with a needle. The goal may be to decrease inflammation, which may be causing pain, or to help kick start healing of the tendon.
Two tendon diseases that can be treated with injection are paratenonitis and tendinosis. Paratenonitis is inflammation around the tendon. This can be caused by irritation to the tissues surrounding the tendon from exercise, changes in playing surface, or bad shoe wear. Tendinosis refers to a "wear and tear" or degeneration of the tendon itself. Oftentimes, the tendon is thickened and swollen.
You should let your foot and ankle orthopaedic surgeon know if you have diabetes since a steroid injection may temporarily increase your blood sugar. Steroid injections for tendons should be done carefully and in limited numbers as they may increase the risk of rupturing the tendon.
A corticosteroid injection, also referred to as cortisone or steroid, is one common type of injection used for its anti-inflammatory effects. Typically, your surgeon will inject a mixture of an anesthetic agent with the steroid. The anesthetic agent numbs the pain fibers surrounding and within the tendon and the steroid decreases inflammation.
Another substance that can be injected is called platelet-rich plasma (PRP). PRP is a concentration of blood clotting factors derived from the patient’s own blood. It may help support or even start the healing process, although there is ongoing research to better understand the best uses of PRP.
The skin over the tendon is thoroughly cleaned with an cleansing solution. A small needle is used to inject the contents of a syringe into the area surrounding the tendon. The patient may feel the needle prick and/or pressure in the injected area. Once the procedure is performed, an adhesive bandage is placed over the area. Some surgeons immobilize the foot and ankle in a walking boot for a short period after the injection.
The numbing anesthetic agent usually works within a couple minutes. Depending on the type of agent used, the pain relief may last for 2-10 hours. The steroid takes anywhere from 3-10 days to start decreasing inflammation. The response to a tendon injection is different for every patient. Some patients experience total relief for many months; others do not have any relief.
The complication rate of steroid injections is low. The most common complication is temporary and short-lived pain. Some may experience a flare reaction, which is a return or worsening of pain between the time the local anesthetic wears off and when the steroid starts to work. Skin or fat degeneration around the injection area can occur. There is a potential risk of infection with any kind of injection, but this is rare. Despite being placed locally, the steroid may cause a temporary increase in blood sugar levels in diabetics. When injecting a diseased tendon, the tendon itself may rupture.
There are no specific rules for how many times a physician can inject a tendon. Many surgeons will not inject more than three times. Depending on the concentration, steroid injections may weaken the tissue. If non-surgical treatment is no longer working, surgery may be the next step.
Original article by Christopher Gross, MD
Contributors/Reviewers: Hyong Nyun Kim, MD; David Lee, MD
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