Practical Pointers for Ultrasound-Guided Injections

An ultrasound-guided injection is a long-standing intervention used in orthopedics and sports medicine. As musculoskeletal ultrasound imaging availability becomes more common, utilization is also increasing in podiatric practice. In many cases, the injections given can serve both diagnostic and therapeutic purposes.

What Does the Evidence Reveal on Ultrasound-Guided Injections?

Morton’s neuroma is a common non-joint foot injection pathology for which podiatrists may want to consider ultrasound guidance. Multiple studies exist on this intervention to date. In 2016, a randomized controlled trial published in the Bone and Joint Journal compared the difference in efficacy of injectable corticosteroids with and without ultrasound guidance.¹ After study exclusions or participant declination of assessment, researchers studied a total of 36 patients and 45 feet. Group A consisted of 23 feet that did receive ultrasound-guided corticosteroid injections, while Group B comprised 22 feet that received the same corticosteroid without ultrasound guidance. After 3 months, although Group A had better satisfaction, there was no statistical significance between the groups for this metric. Despite this, there was a 55% and 46% reduction in pain symptoms in Groups A and B, respectively. The authors did admit that the relatively small study size was a limitation in result interpretation. They also state that this advanced imaging ultrasound can still be very useful in the assessment and treatment of “patients where the diagnosis is not clear, when there has been a failure to respond to a previous corticosteroid injection, and where other pathologies may be present.”¹

More recently, an article in the Journal of Ultrasonography reviewed ultrasound-guided injections of Morton’s neuroma.² In this analysis, clinicians placed the ultrasound probe dorsally, while researchers in the Bone and Joint Journal took a plantar ultrasound approach.¹ In both cases, injection placement into the foot was dorsal. In the 2021 review, the authors acknowledged that injection therapy results for Morton’s neuroma are not always favorable when looking at long-term relief.² However, the authors also point out that these less favorable studies did not include the use of ultrasound guidance. Finally, they asserted that incorporating ultrasound may allow the user to not only provide more accurate diagnosis, but also immediate pain relief, as the clinician aims to infiltrate local anesthesia into the affected area along with the corticosteroid. This illustrates the idea of an ultrasound-guided injection working as both a diagnostic and therapeutic modality.  

In a sports medicine–focused investigational journal review performed at Penn State Hershey Medical Center and published in the Orthopedic Journal of Sports Medicine, the authors found the accuracy of landmark-guided (non-ultrasound) injections ranged from 58 to 85%.³ The studies measured accuracy in various ways, from outcome to immediate patient perception. With ultrasound guidance introduced, specifically in the foot and ankle, accuracy increased to 100 percent. Additionally, the same authors found that relief over time was remarkable. A majority of patients receiving an ultrasound-guided midfoot corticosteroid injection still had relief 3 months later. The overall result of these studies mobilized the American Medical Society for Sports Medicine (AMSSM) to create a position statement in support of the use of ultrasound guidance in lower extremity joint injections.⁴

Practical Points on Ultrasound Implementation

Ultrasound is, of course, used diagnostically in the lower extremity. However, in my experience, there is also significant positive impact on therapeutic outcomes. I can typically clearly visualize neuromas, which allows accurate targeting of the bulk of the neuroma with the injection, while avoiding surrounding tissue or nearby joints. When planning an intra-articular injection, visualization of the small joints of the foot is also possible via ultrasound. This guidance, in my observation, can be very effective in allowing one to visualize the best access point, especially in a severely arthritic joint. Although plantar fascial injections and large joint injections can typically take place via landmark placement in-office, the ultrasound could still be an effective way to ensure appropriate placement with the least amount of patient discomfort.  

Overall, our practice notes that ultrasound-guided injections of the foot and ankle can be extremely effective medically, but also may lead to better patient outcomes. In my practice, I see almost a “placebo effect” in some patients. The foot and ankle department, consisting of myself, 2 foot and ankle orthopedic physicians, a physician assistant, and another podiatrist, sends their ultrasound-guided injections to me. I have a total of 4 sessions each month with up to 20 people scheduled for each, sometimes more, depending on several factors. As I get situated and visualize the area via ultrasound, I speak with the patients. Many are very interested in the idea of the ultrasound guidance. Some have had injections without ultrasound in the past. I explain the process, discuss why we are doing it this way versus the more typical office injections (which I also do plenty of), and what they can expect.  

If they can see the screen without affecting my view or their positioning, I will also explain the imaging. I find it especially helpful to spend time explaining the “why” of ultrasound guidance particularly to patients who have had unsuccessful injections in the past. These patients can, understandably, start the appointment with some anxiety, especially if it was a painful prior experience. For many, they are comforted by the additional imaging and guidance. They understand that I can clearly identify their pathology and what hurts them. In some cases, they can physically see the medicine going right to where they feel the pain. I find that, overall, it seems as though there is high patient confidence in ultrasound-guided injections.

In my office, an assistant works with me during an ultrasound-guided injection session. We send our saved pictures directly to our imaging system. My assistant will room the patient, hand them a copy of the aftercare instructions, then verify the intended injection laterality. At this point, I enter the room and introduce myself. I explain what I am going to do and discuss any questions the patient may have. I will then find the best visualization of the anatomy to be injected. Next, as I nod or sometimes say “picture,” my assistant saves the image on the machine. As I talk the patient through the steps of the injection, the assistant will hand what I need to my right hand while my left hand keeps the transducer in position.

In time, the transducer positioning will change as you begin to improve your own skills and take into account the physical properties of your patient. As previously mentioned, although joints and neuromas typically exhibit easy identification, in my observation, they may require continued exploration to find the best access point. For tendon sheath injections, the transducer must remain perpendicular to tendons to avoid misinterpretation.¹ The fluid within the tendon sheath can best be visualized this way to allow for discrimination between the tendon sheath and the tendon itself. This can improve the precision of injecting in the tendon sheath rather than intratendinous disruption. Injecting directly into the tendon increases the risk of collagen breakdown and/or rupture of the tendon.¹ Decreasing this risk is one appealing feature of ultrasound-guided injections for tendinopathies. In some cases, based on the anatomy or the degree of inflammation, this separation of the sheath and tendon cannot be clearly visualized. If this is the case, local anesthetic infiltrated prior to the corticosteroid may distend the sheath enough to allow for a safer injection.    

One Podiatrist’s Experience and Details to Consider

Working in an orthopedic practice, my tables are wide and flat. Although some have the ability to lift the back into a seated position, I refrain from doing so when possible. I find that most patients are more comfortable and less likely to flinch or shift in a supine position, causing the potential need for the probe to be repositioned. Of course, if the patient has a physical inability to, or difficulty with, lying flat, the table back can be raised to their comfort. Because the imaging loads immediately into our PACS system, my room set up is crucial, as well. My ultrasound is on a wheeled cart, but requires a cable port, so a cord must be placed out of the patient’s path. I prefer angling the exam table so the foot or ankle is not against the wall. As comfortable as you want to make the patient, I feel it is important to account for your own positioning and comfort as well. Patients tend to be very accommodating with moving to a more lateral position, bending their knee and resting their foot flat, or “whatever works best for you, Doc!”  

Getting to the injection itself, after the patient is in the best position and you have determined your access point, it is still helpful to talk the patient through the injection process. If you have the ability to take pictures while you go through the process and review them back, patients tend to enjoy seeing those images. Seeing the joint open and spread while the medication infiltrates can further positively influence patient confidence and trust. The first metatarsophalangeal joint is a particularly satisfying visual example, I have found, for patients. They can see the decreased joint space and usual exostoses prior to the injection, then through the images (or watching live if they are able), they can see the medicine spread down into the joint and widen the space. Although a tendon sheath injection can also share a similar very clear impact in the images captured, most patients can also track the course of the medication clinically. Depending on the medication mixture, patient morphology, and tendon size, this can be very clearly visible to them immediately.

In my practice, we have a handout with what to expect after the injection. Also, as I give these injections for multiple providers, I give further verbal advice based on the provider and the condition. Immediately after the injection, the course we recommend is the same as for any injection. I advise at minimum rest, elevation, and icing for any discomfort. In patients receiving these injections for tendinopathy, I find there can be more to consider.

In many cases, these patients are more active or potentially even athletes. In experiencing pain relief, these patients may inadvertently return to activity too quickly. They are at an increased risk of overuse and reinjury. If possible, it may be useful to place the patient into a walking/controlled ankle motion boot for immobilization at least until a follow up or other intervention, such as physical therapy, begins. Depending on the patient and the circumstances of their tendinopathy, it can also be very useful to complete a full biomechanical evaluation to prevent recurrence of the injury or strain. 

In Conclusion

Incorporating ultrasound-guided injections into your practice can be somewhat intimidating. There is investment necessary of equipment, supplies, and time. Not only does it take time to turn on and ready the machine, there is time spent with the patient, as well as with cleanup. One may lessen the time spent by actually scheduling a longer session of time with more injections to minimize the before and after tasks. The time a staff person may spend assisting you pulls him or her away from other duties and care. Finally, this requires education. The necessary education can come in the form of formalized training or courses, practice, or literature review, pending the individual needs of the provider.  

If ultrasound-guided injections can be incorporated in a way that makes sense to your practice, you may notice financial rewards, improvement in patient outcomes, and potential for practice growth. As mentioned earlier, in my practice, I notice these injections do seem to inspire patient confidence, which can alter their overall treatment and outcome. If you have not already incorporated ultrasound-guided injections into your practice, I hope that this article sheds some light on potential advantages.

Dr. Hook is a Trustee of the New York State Podiatric Medical Association (NYSPMA) and Chair of the NYSPMA Population and Public Health Committee. She is a Director of the American Board of Podiatric Medicine and is the ABPM Marketing/Communications Chair. Dr. Hook is in private practice at Syracuse Orthopedic Specialists in Syracuse, NY.

References

1.    Mahadevan D, Attwal M, Bhatt R, Bhatia M. Corticosteroid injection for Morton’s neuroma with or without ultrasound guidance: a randomised controlled trial. Bone Joint J. 2016;98-B(4):498-503. doi: 10.1302/0301-620X.98B4.36880.
2.    Klontzas ME, Koltsakis E, Kakkos GA, Karantanas AH. Ultrasound-guided treatment of Morton’s neuroma. J Ultrason. 2021 Jun 7;21(85):e134-e138. doi: 10.15557/JoU.2021.0022.
3.    Daniels EW, Cole D, Jacobs B, Phillips SF. Existing evidence on ultrasound-guided injections in sports medicine. Orthop J Sports Med. 2018 Feb 22;6(2):2325967118756576. doi: 10.1177/2325967118756576.
4.    Finnoff JT, Hall MM, Adams E, Berkoff D, Concoff AL, Dexter W, Smith J. American Medical Society for Sports Medicine (AMSSM) position statement: interventional musculoskeletal ultrasound in sports medicine. PM R. 2015 Feb;7(2):151-68.e12. doi: 10.1016/j.pmrj.2015.01.003.