Ultrasound-guided hyaluronic acid injection: an option for hallux rigidus and ankle osteoarthritis
Hallux rigidus (osteoarthritis of the big toe) and ankle osteoarthritis hurt when you walk, when you push off and when you put your shoes on, and they do not always settle with painkillers, exercise or orthoses. Hyaluronic acid, a natural lubricant of the joint, is a safe and minimally invasive option when first-line treatment is not enough. And guiding the injection with ultrasound makes the difference between injecting and injecting accurately: the product reaches the joint itself, which in the foot is small and easy to miss with a blind injection.
What it is and what it is for
Hyaluronic acid injection ("viscosupplementation") gives the joint a substance that is normally present in its synovial fluid and is lost in osteoarthritis. It does not regenerate cartilage or reverse the osteoarthritis, but it can improve pain and function for a time. It makes sense as a second-line option: when big toe or ankle pain is limiting and has not settled with painkillers, exercise, orthoses or footwear changes. Its main strength, beyond the potential relief, is a very favourable safety profile.
Hallux rigidus: relieving big toe pain
Big toe pain fell by more than half after one injection
Prospective multicentre study of 65 patients with hallux rigidus treated with a single image-guided intra-articular injection of hyaluronic acid: mean pain fell from 6.5 to 2.8 out of 10 at 3 months (change −3.1; p<0.0001), with the greatest benefit in mild to moderate grades.
This study had no placebo group, so its authors call for controlled trials to confirm the finding, and adverse effects were mild and transient (a passing flare of toe pain that settled within a few days). Even so, it reflects what we see in clinic: in early hallux rigidus, many patients get appreciable pain relief and recover their stride.
Galois L, Coillard JY, Porterie J, Melac-Ducamp S, Conrozier T. Open-Label Pilot Study of a Single Intra-Articular Injection of Mannitol-Modified Cross-Linked Hyaluronic Acid (HANOX-M-XL) for the Treatment of the First Metatarsophalangeal Osteoarthritis (Hallux Rigidus): The REPAR Trial. Clin Med Insights Arthritis Musculoskelet Disord. 2022;15:11795441211055882. doi:10.1177/11795441211055882
Why guide it with ultrasound
In the big toe, ultrasound takes the needle into the joint
Anatomical study describing the in-plane ultrasound-guided technique for the first metatarsophalangeal joint: 10 out of 10 injections reached the target joint, while also minimising damage to the neighbouring cartilage.
The big toe joint is small, and hitting the joint space blind is not trivial. Watching the needle advance in real time on the ultrasound screen lets us place the product where it needs to act and steer clear of the structures best left untouched. It is not a cosmetic extra: it is what makes the injection reach its target.
Sahler CS, Spinner DA, Kirschner JS. Ultrasound-guided first metatarsophalangeal joint injections: description of an in-plane, gel standoff technique in a cadaveric study. Foot Ankle Spec. 2013;6(4):303-6. doi:10.1177/1938640013493465
Blind injections miss; ultrasound-guided ones do not
Direct comparison in a small joint of the foot: all 5 ultrasound-guided injections entered the joint, while the 5 performed by palpation alone missed (one even ended up in a different joint), as confirmed by fluoroscopy.
In the small joints of the foot, injecting by feel alone leaves a wide margin of error: the product can end up outside the joint and have no effect. Ultrasound not only confirms that the needle is where it should be, it also shows the state of the tendon or joint along the way. That is why we always inject under ultrasound guidance.
Jha AJ, Viner GC, McKissack H, Anderson M, Prather J, Shah AB, et al. Accuracy of talonavicular injection using ultrasound versus anatomical landmark: a cadaver study. Acta Radiol. 2020;61(10):1359-1364. doi:10.1177/0284185120901507
Safety and tolerability
Better tolerated than placebo itself
In the most recent Cochrane review on osteoarthritis of the big toe joint, there were fewer adverse events with hyaluronic acid than with placebo (27 of 75 versus 43 of 76; RR 0.64; 95% CI 0.44 to 0.91), mostly transient discomfort at the injection site, and no withdrawals due to adverse events.
That same review is cautious about the efficacy of a one-off injection (a modest benefit over placebo), which is why we do not offer it as an isolated jab: we build it into a plan, assessing the response and repeating or adjusting the regimen when needed. What is clear is that this is a clinic-room treatment, safe and well tolerated.
Munteanu SE, Buldt A, Lithgow MJ, Cotchett M, Landorf KB, Menz HB. Non-surgical interventions for treating osteoarthritis of the big toe joint. Cochrane Database Syst Rev. 2024;6(6):CD007809. doi:10.1002/14651858.CD007809.pub3
Ankle and plantar fascia
In the osteoarthritic ankle, sustained improvement at six months
Systematic review pooling three randomised trials (109 patients): hyaluronic acid improved symptoms compared with saline at 6 months, with a mean difference of 12.47 points on the AOS scale (95% CI 1.18 to 23.77; p=0.03).
These are small studies and the benefit is modest, so the decision is individualised. But for many patients with ankle osteoarthritis who do not want surgery, or cannot have it, this is a reasonable second-line option: minimally invasive, repeatable and compatible with the rest of the treatment.
Vannabouathong C, Del Fabbro G, Sales B, Smith C, Li CS, Yardley D, et al. Intra-articular Injections in the Treatment of Symptoms from Ankle Arthritis: A Systematic Review. Foot Ankle Int. 2018;39(10):1141-1150. doi:10.1177/1071100718779375
The heel too: relief in the plantar fascia
Randomised, double-blind, multicentre trial of 168 patients with chronic plantar fasciitis: high-molecular-weight hyaluronic acid relieved pain more than the control (change on the visual analogue scale −3.3 vs −2.4 cm; p=0.029), with no serious adverse events.
It is not all about joints: here the hyaluronic acid is injected into the fascia, and it serves as a complementary route when the heel keeps hurting despite standard treatment. Follow-up in this trial was short term, so we frame it as support within the plan, not a substitute for exercise and progressive loading.
Kumai T, Samoto N, Hasegawa A, Noguchi H, Shiranita A, Shiraishi M, et al. Short-term efficacy and safety of hyaluronic acid injection for plantar fasciopathy. Knee Surg Sports Traumatol Arthrosc. 2018;26(3):903-911. doi:10.1007/s00167-017-4467-0
Take-home
- In hallux rigidus, prospective studies show pain relief with hyaluronic acid, especially in mild to moderate grades.
- Ultrasound guidance makes sure the product reaches the joint: in the small joints of the foot, blind injections miss frequently.
- It is a safe, well-tolerated, clinic-room treatment with few, mild adverse effects.
- In the osteoarthritic ankle the benefit is modest but real. Hyaluronic acid does not regenerate cartilage and does not replace exercise, orthoses or footwear changes: it is a second-line option, individualised and part of a plan.
How we can help at Avanza Salud
We perform ultrasound-guided hyaluronic acid injections in the foot and ankle: hallux rigidus, ankle osteoarthritis and other joints where accuracy matters. We start with a clinical and ultrasound assessment to confirm the indication; the injection is done in clinic, with ultrasound making sure the product reaches the joint, and always within a plan that includes exercise, orthoses and footwear advice. It is not a magic bullet and it does not replace exercise: it is a safe, well-tolerated option for when first-line treatment is not enough. If your big toe or your ankle limits your walking, we can assess whether hyaluronic acid is a good fit for your case.