Heel fat pad syndrome: not all heel pain is plantar fasciitis
Not all heel pain is plantar fasciitis. A frequent cause that gets mistaken for it is heel fat pad syndrome, also called fat pad syndrome: damage to the plantar fat pad that cushions the impact of the calcaneus at every step. When that cushion loses thickness, elasticity or structure, the calcaneus "strikes" the ground and hurts. The difference from fasciitis changes the treatment, and ultrasound makes it possible to tell them apart in clinic.
How it differs from fasciitis
The heel fat pad is a structure organised into microchambers and macrochambers of adipose tissue separated by fibroelastic septa. When it is damaged, the pain appears in the centre of the heel, deep, described as a "bruise" or "walking on a pebble", worse with prolonged walking or on hard surfaces. Plantar fasciitis, by contrast, hurts on the medial aspect of the calcaneus and is worse with the first steps of the morning, easing after walking for a while. Confusing the two conditions is common, and it leads to treatments that get nowhere.
A condition in its own right, distinct from fasciitis
Probably the second most common cause of plantar heel pain
Scoping review gathering the available evidence on heel fat pad syndrome: it may be the second most frequent cause of plantar heel pain after fasciitis, and diagnostic confusion between the two is common even in the scientific literature.
The authors summarise the most reported causes: acute trauma (a high-impact landing), chronic overuse (running, jumping or a lot of walking on hard surfaces) and progressive atrophy associated with age, excess weight, diabetes or rheumatological disease. The review makes clear that the literature is still sparse and that controlled trials are lacking for the usually recommended conservative measures (viscoelastic heel cushions, taping), but distinguishing the syndrome from fasciitis is decisive in order not to treat the wrong condition.
Chang AH, Rasmussen SZ, Jensen AE, Sørensen T, Rathleff MS. What do we actually know about a common cause of plantar heel pain? A scoping review of heel fat pad syndrome. J Foot Ankle Res. 2022;15(1):60. doi:10.1186/s13047-022-00568-x
Diagnosis: ultrasound makes the difference
The key sign: hypoechoic areas that collapse under the probe
Sonographic review of heel pain in adults: heel fat pad syndrome is recognised as focal hypoechoic areas within the plantar fat pad adjacent to the calcaneus, which collapse under minimal probe compression. That compressibility sign distinguishes fat pad damage from fibrous pathology.
To separate it from plantar fasciitis, the thickness of the fascia is examined: in fasciitis there is focal thickening of >4 mm with hypoechogenicity, and the fascia does not collapse under pressure. If the fascia is of normal thickness and the fat pad is thinned and gives way under the probe, the diagnosis changes. Ultrasound can separate the two conditions in clinic and direct treatment in under ten minutes.
Kim YH, Chai JW, Kim DH, Kim HJ, Seo J. A problem-based approach in musculoskeletal ultrasonography: heel pain in adults. Ultrasonography. 2022;41(1):34-52. doi:10.14366/usg.21069
First step: selective offloading of the calcaneus
The silicone heel cup: robust classic evidence
Multicentre RCT with 236 patients across 15 centres: the silicone heel cushion achieved 95 % symptomatic improvement at 8 weeks, with positive results for prefabricated inserts in general. The evidence supports the silicone heel cup as the first step in plantar heel pain.
The first step in heel fat pad syndrome combines selective offloading with a viscoelastic heel cushion or silicone heel cup, custom orthoses with targeted cushioning under the impact zone of the calcaneus, offloading functional taping in the acute phase (low-dye taping has support in recent meta-analyses for plantar heel pain) and footwear modification (shock-absorbing soles, avoiding long spells on hard surfaces). To this we add capacitive-resistive radiofrequency diathermy (INDIBA) as a tool to support the trophism of the adipose tissue and the reorganisation of the fibres of the plantar fat pad.
Pfeffer G, Bacchetti P, Deland J, Lewis A, Anderson R, Davis W, et al. Comparison of custom and prefabricated orthoses in the initial treatment of proximal plantar fasciitis. Foot Ankle Int. 1999;20(4):214-21. doi:10.1177/107110079902000402
When conservative care is not enough: ultrasound-guided intervention
Cross-linked hyaluronic acid: pain improvement at 24 weeks
Prospective series with 28 patients (30 feet) treated with cross-linked hyaluronic acid injection: VAS from 6.86 ± 1.67 to 3.50 ± 2.67 at 24 weeks (p < 0.001), improvement in EQ-5D-3L, FAOS and FFI, and an increase in fat pad thickness of 1.45 ± 1.59 mm at the heel.
Six adverse events (local pain, swelling, filler migration) resolved with conservative measures. It is the best evidence available to date to support hyaluronic acid injection in fat pad atrophy, with the limitation of being a series without a control group and with short follow-up (24 weeks). Longer-term durability remains to be studied, but the change in pain and function is clinically relevant.
Ko SH, Kim B. Short-term clinical outcomes of cross-linked hyaluronic acid filler injection in the treatment of plantar fat-pad atrophy syndrome. J Foot Ankle Surg. 2026;65(1):7.e1-7.e6. doi:10.1053/j.jfas.2025.07.004
Take-home
- If heel pain is central, deep and worse with prolonged walking or hard floors, think heel fat pad syndrome, not automatically fasciitis.
- Ultrasound distinguishes the two conditions by fascia thickness (thickened >4 mm in fasciitis), fat pad thickness and the compressibility sign under pressure.
- Treatment starts with the non-invasive options: silicone heel cup or cushion, orthoses with selective cushioning under the calcaneus, offloading taping, footwear modification and capacitive-resistive radiofrequency diathermy (INDIBA). This settles a substantial proportion of cases.
- Only when conservative care is not enough is ultrasound-guided intervention considered: cross-linked hyaluronic acid injection showed significant pain improvement at 24 weeks in a prospective series of 28 patients.
At Avanza Salud we can help
We assess heel pain with musculoskeletal ultrasound in clinic to determine whether the source of the pain is the fascia, the fat pad or both. If the diagnosis is heel fat pad syndrome, the plan starts with the non-invasive options: silicone heel cup or cushion, Podonexus custom orthoses with selective offloading and heel cushioning, functional taping, footwear advice and INDIBA diathermy to support tissue trophism and the reorganisation of the fat pad. Only if this approach does not settle the pain do we consider an ultrasound-guided hyaluronic acid injection. If you have spent weeks being treated for fasciitis without improvement, a second opinion with ultrasound is worthwhile: many persistent cases of heel pain come down to an initial diagnosis that was not correct.