Plantar fasciitis is the most common cause of heel pain and one of the few conditions where a single anatomical fact changes what you should tell the patient to do.
That fact, from Dr. Glenn Barnes: you cannot exercise the plantar fascia.
Three cords, and only two that matter
The plantar fascia is not a single sheet. Barnes describes it as “a group of ligaments in the bottom of the foot”, subdivided into cords — and the involvement pattern is remarkably consistent:
- Central cord — the most commonly involved, and the usual site of pain
- Medial cord — never involved, in his teaching
- Lateral cord — sometimes involved
That is unusually useful for a differential. Pain clearly localised to the medial side of the plantar surface is pointing somewhere other than the fascia — toward the posterior tibial tendon, tarsal tunnel, or a calcaneal stress reaction.
Why you cannot strengthen it, and what to do instead
Here is the reasoning that changes the advice. These are ligaments, and Barnes's point follows directly: “since these are ligaments and they have no muscle attached to them, you cannot exercise your plantar fascia.”
Ligaments do not contract. There is no exercise that strengthens the plantar fascia, because there is nothing in it to train.
But the useful half of the statement is what follows: “There are, however, several layers of muscle within the foot that you can exercise in order to offload the plantar fascia.”
So the rehabilitation target is the intrinsic foot musculature. Strengthening those layers transfers load away from the fascia, which is a mechanical solution to a mechanical problem. The fascia is not made stronger; it is made to carry less.
That reframes the whole conversation. A patient told to “strengthen the plantar fascia” has been given an instruction that cannot be followed. A patient told to strengthen the intrinsic foot muscles to unload it has been given one that can.
What ultrasound shows
Ultrasound is well suited to this diagnosis because the fascia is superficial, accessible and easy to compare against the other foot.
Tissue is described by echogenicity — how much sound it reflects. Degenerate tissue appears hypoechoic, darker than healthy tissue, which is exactly how a thickened, degenerate fascia presents. Barnes uses tendinosis as his teaching example of a hypoechoic finding, and the same appearance applies here.
Because this is a superficial structure, the probe is a high-frequency linear one, and for a small target area a smaller footprint helps the probe sit flat against the contour of the heel.
Scanning both feet is worth the extra minute. The asymptomatic side gives you that patient's normal.
Sterile requirements: foot injections are the strict category
This is where the foot differs from most other targets, and the reason is consequence rather than probability.
Barnes recommends a complete sterile setup for all injections of the hand and foot: antiseptic preparation of the foot — he prefers small chlorhexidine surgical scrubs — plus sterile probe cover, sterile gel, sterile gloves and a sterile draped procedure tray.
His stated reason is “the serious nature of iatrogenic foot infections.”
Elsewhere his rule is proportionate: if the needle does not pass through gel or enter beside the probe, sterile skin preparation alone is enough. The foot is the deliberate exception, because the population presenting with heel pain contains a great many patients with diabetes or peripheral vascular disease, in whom a foot infection is a serious event.
Guidance technique
In-plane, as the default throughout guided injection: the entire needle including the bevel remains visible, which Barnes says “maximises safety and accurate placement.”
Out-of-plane carries the trap he describes clearly — the needle appears only as a bright white dot, and the first appearance of that dot is your best estimate of the tip. Advance beyond it and the tip travels unseen. In a superficial structure sitting directly on the calcaneus, that is an unnecessary risk.
Two fingers of the probe hand anchored on the patient, as always. The heel is a curved, awkward surface and the probe will slide.
The steroid question
Corticosteroid remains widely used here and deserves a caveat rather than an endorsement.
Chronic plantar fasciitis is degenerative rather than inflammatory — fasciosis more than fasciitis — which makes an anti-inflammatory a partial answer at best. Repeated steroid injection into the plantar fascia also carries a recognised concern about rupture and fat pad atrophy, and the fat pad is the structure you least want thinned in a heel.
This is the same logic set out for tendon in corticosteroid injections, and it is why the regenerative options are a reasonable conversation in chronic cases — the published evidence in tendon being the strongest part of that category, as set out in regenerative pain medicine.
What the injection is for
The honest framing is that the injection buys a window in which the thing that actually works can happen.
What actually works for most patients is load management, calf and intrinsic foot muscle work, footwear, and time. The injection reduces pain enough for that programme to be tolerable.
A patient who receives an injection and no rehabilitation has had the window and not used it — which is the most common reason heel pain returns.
Learn blocks with your hands, not from a page
Empire’s Pain Management Training (THE Pain Show) is accredited for 25.25 AMA PRA Category 1 Credits™, jointly provided by AKH, Inc, and Empire Medical Training. For narrower peripheral work, Joint, Extremity and Non-Spinal Injection Training carries 6.75 credits for the complete in-person hybrid program, and Advanced Musculoskeletal Ultrasound Guided Injections builds the guidance skills above.
Claim Your Prize!