What Is a Tendon Injection?
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. The tendons in the foot include: Achilles tendon, peroneus longus tendon, peroneus brevis tendon, tibialis posterior tendon, and tibialis anterior tendon.
Two of the diseases of tendons 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 slow degeneration of the tendon. Oftentimes, the tendon is thickened and swollen.
Injections are a very useful diagnostic and therapeutic tool. The goals of a tendon injection may be to decrease inflammation, which may be causing pain, or to help kick start healing of the tendon.
You should let your physician know if you have diabetes since a steroid injection may temporarily increase your blood sugar. Steroid injections should be done carefully and in limited numbers as they may increase the risk of rupturing the tendon.
Most frequently, the physician will inject a mixture of an anesthetic agent and a 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.
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 a slight prick and 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 two to ten hours. The steroid takes anywhere from three to 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 obtain any relief.
Risks and Complications
The complication rate of steroid injections is low. The most common complication is temporary and short-lived pain. Some may experience a flare reaction – 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.
Can the physician repeat a tendon injection?
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.
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