In this video, I demonstrate a cortisone injection into the sinus tarsi of a patient with chronic sinus tarsi syndrome from a work-related inversion ankle sprain. The patient has chronic sinus tarsi pain and has benefitted in the past from my previous cortisone injections, allowing her to continue to work in her weightbearing occupation. Most patients only need 1-2 of these injections total in their lifetime, to rid their foot of sinus tarsi pain, others require more.
The patients that tend to most need sinus tarsi injections have post-traumatic sinus tarsi syndrome, nearly always due to inversion ankle sprains. In these cases, there is painful scar tissue within the sinus tarsi causing the sinus tarsi pain. Sinus tarsi injections, in these specific cases, works very well, probably by reducing the bulk of the painful scar tissue. Contrary to what clinicians who have never done this technique may think, judicious use of sinus tarsi cortisone injections cause a minimum of side effects, and greatly decrease the pain with weightbearing activities. Degenerative changes in the subtalar joint have not been noted long term with judicious use of sinus tarsi cortisone injections.
Sinus tarsi injections can be given reliably without fluoroscopic or ultrasound guidance by precisely following the injection technique described here since the sinus tarsi has a relatively consistent morphology from one individual to the next. Correct hypodermic needle-stick placement and correct three-dimensional hypodermic needle angle relative to foot and ankle landmarks are the keys to a relatively pain-free and effective sinus tarsi injection. In this case, a 5 cc syringe is being used with a 25g 1.5″ hypodermic needle. In this example, the syringe contains 0.5 cc (10 mg) of Depo Medrol cortisone solution mixed with 2 cc of 0.5% Marcaine plain local anesthetic, for a total of a 2.5 cc injection.
First of all, the patient should be positioned on the examining table so that they are laying on the side that is contralateral to the foot being injected (e.g. have the patient lay on their right side for a left foot sinus tarsi injection). Then, the patient’s foot is allowed to hang off the table, with the foot being passively supinated by gravity. This positioning, with the foot hanging off the table, also allows the foot to be manually supinated even further by the clinician during the sinus tarsi injection in order to increase the volume of the sinus tarsi cavity which allows a smooth introduction of the needle into the sinus tarsi without hitting bony prominences as the needle is advanced.
Next, before the patient has been prepped, palpate for the superior edge of the floor of the sinus tarsi of the calcaneus and mark it on the foot with an ink pen. This line serves as a guide to where the needle-stick should occur. The needle-stick should be about 2 mm superior to the floor of the sinus tarsi of the calcaneus. Then, after prepping, a 5-10 second ethyl chloride spray is used to anesthetize the skin to decrease the pain of the needle-stick. Note, that once the skin “frosts over” with the ethyl chloride spray, the needle-stick should be able to occur with a minimum of pain to the patient.
It is very important now that the angle of the hypodermic needle is pointed directly toward the posterior aspect of the medial malleolus, in a lateral-posterior-superior direction. This will allow the hypodermic needle to pass smoothly into the sinus tarsi cavity, with a minimum of trauma. The hypodermic needle is then gradually advanced deep into the sinus tarsi, to the hub of the hypodermic needle. The clinician can then distribute the full amount of the cortisone-local anesthetic mixture into the sinus tarsi region of the subtalar joint with relative ease and in a relatively short period of injection time.
In selected cases, sinus tarsi cortisone injections can very helpful and therapeutic for patients with chronic sinus tarsi pain. These injections may allow patients to return to work and activities sooner and with a minimal chance of adverse side effects. In this patient’s case, where she walks at a hospital 5-6 miles per day on concrete floors for her work, these cortisone injections (along with foot orthoses, boots and physical therapy) have allowed her to continue working where she, otherwise, would have likely needed to retire due to her chronic ankle pain or needed to have an arthrodesis of her subtalar joint. Sinus tarsi cortisone injections are not done frequently in my office, but for the right patient, they can provide a dramatic amount of pain relief and allow a return to pain-free walking activities, when combined with foot orthoses, correct shoe gear and physical therapy.
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