Plantar Fascia Injection
William O. Roberts, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 27 - NO. 9 - SEPTEMBER 1999
Plantar fasciitis is a major cause of heel pain in athletes and active people. The pain can usually be controlled with conservative measures, such as stretching, the use of arch supports, night splinting, and short-term activity modification, which allow the injured tissue to heal. However, persistent cases sometimes require an injection of a corticosteroid and local anesthetic into the calcaneal origin of the plantar fascia to relieve pain and promote healing.
Plantar Fasciitis Mechanics
The plantar fascia originates from the calcaneus and stretches along the bottom of the foot to attach on the base of the proximal phalanx of each toe (figure 1). The plantar fascia helps support the medial longitudinal arch by tensing like a bowstring on the plantar surface when the foot bears weight. The greatest force is transmitted to the medial side of the plantar fascia. Tension on the plantar fascia increases when the foot and toes are dorsiflexed in the push-off phase of walking or running.
If the plantar fascia is subjected to excessive stress in running or other activities, inflammation develops and causes pain, usually at the medial calcaneal attachment. In some cases, the inflammatory response will cause calcification at the origin of the plantar fascia and result in spur formation along the lines of traction.
Conservative treatment usually resolves patients' plantar fasciitis symptoms within 2 to 12 weeks. When such measures fail, steroid injection should be considered.
Site location. During this procedure, the patient can be prone, supine, or seated, so long as the foot is comfortably supported and can be securely held by the physician's free hand to avoid accidental withdrawal of the foot during the injection.
The injection point is at the medial aspect of the plantar fascia origin. The site can be located by dorsiflexing the foot and great toe, which stretches the plantar fascia so that the approximate site of the origin can be seen. Palpating the tender area with the thumb can also help to locate the fascia origin more precisely (figure 2).
The safest, least painful approach to the origin of the plantar fascia is from the medial side of the foot but near the plantar surface. An approach through the plantar surface should be avoided because it is more painful than the medial approach and might allow corticosteroid to leak into the fat pad.
Injection solution. Combine 10 mg (0.05 mL of a 20-mg/mL solution) of triamcinolone hexacetonide with 1 mL of 1% lidocaine and 1 mL of 0.5% marcaine for a total of 2.5 mL of injection solution. A 1.5-in. 25-gauge needle is small enough to enter the area without using a local anesthetic, and it is rigid enough to allow a "hunt and peck" infiltration technique. (This technique involves moving the needle tip around the area of pain by partially withdrawing, redirecting, and reinserting the needle, without removing it from the original entry site.)
Injection. Clean the skin with betadine or alcohol. Place the needle about 0.5 to 2.0 cm distal to the estimated location of the origin at an angle of up to 45° to the coronal plane of the foot, and aim toward the plantar fascia origin (figure 3); this initial position will facilitate the distribution of the medication. Quickly insert the needle through the skin and, using the patient's pain as a guide, carefully advance it until it touches the bone or enters the painful area. If the calcaneus is touched, the needle tip can be marched along the bone in a series of hunt-and-peck maneuvers until the plantar fascia origin and painful area are located.
Each time the tip of the needle enters a painful area, inject a small amount (0.1 to 0.2 mL) of the solution. The aim is to blanket the painful area by injecting small aliquots of the medication solution around the fascial origin until the pain is relieved. The space around the plantar fascia origin will not comfortably tolerate a large volume of solution, so the minimum required to relieve the pain should be injected. Local massage after the injection may help distribute the medication more uniformly.
Cover the entry site with bacitracin ointment and a dressing. Patients may walk but should avoid impact loading activities, such as running and jumping. They should gently stretch the plantar fascia and continue to use night splints and orthoses. Analgesics and ice packs may help relieve any postinjection pain. Patients should see a physician at any sign of infection.
The major risk of injecting the origin of the plantar fascia is rupture of the tissue. This is most common in athletes who have multiple injections and do not restrict impact loading activities for 7 to 14 days after the injection. Patients who avoid impact loading activities, use an arch support, and follow a gentle stretching program for 10 to 14 days rarely have postinjection ruptures. In the absence of definite rules, injections may reasonably be limited to three separated by 8 to 12 weeks.
In addition, the injection could thin the fat pad of the heel or damage the medial calcaneal nerve and artery if the infiltration volume is too great or if the injection site is inaccurate. An injection proximal to the plantar fascia origin could affect the plantar nerve. Proper needle placement and a low-volume injection should prevent these potential complications.
For billing purposes, the injection should be coded with a Current Procedural Terminology evaluation or consultation code, a procedure code (20550), and the medication used in the injection.
Dr Roberts is a family physician at MinnHealth SportsCare in White Bear Lake, Minnesota, and medical director of the Twin Cities Marathon. He is a fellow of the American College of Sports Medicine, a charter member of the American Medical Society for Sports Medicine, and an editorial board member of The Physician and Sportsmedicine.