There are many causes of heel pain. One of the less familiar sources of injury to the heel is to the calcaneal fat pad. This injury can be mistaken for plantar fasciitis, but is a completely different entity.
What is it?
Fat pad injury refers to damage or disruption of the calcaneal (heel) fat pad. This structure is approximately one inch thick and made up of fatty tissue enclosed by ligamentous baffles or chambers. The purpose of this uniquely designed structure is to absorb shock and cushion the heel bone.
If the fat pad is displaced or thins, then its ability to protect the heel bone from impact is decreased, which can result in heel pain.
What are the symptoms?
Fat pad injuries usually present as centralized heel pain that feels like a deep ache or bruise. You can recreate the symptoms by pressing down in the middle of the heel. Walking barefoot on hard surfaces is generally painful.
Plantar fasciitis differs from this presentation as it is felt more towards the instep and is more forward in position. Plantar fasciitis is usually a sharper pain than fat pad-associated pain.
Other conditions to consider and rule out in heel pain are: tarsal tunnel syndrome (and other peripheral nerve entrapment syndromes), sciatica, stress fracture, tumor, infection and inflammatory arthritic conditions.
Because of this laundry list of other ailments, you should visit to your friendly neighborhood health care provider when you develop heel pain to rule out these nastier conditions.
What are the causes/predisposing factors of this condition?
It appears there are two categories of fat pad injury: degenerative and traumatic.
Degenerative injuries refer to the thinning or atrophy of the fat pad. This loss of cushioning can lead to greater impact loads on the heel and subsequently, heel pain. Risk factors appear to be increased age and obesity.
Traumatic onset can be due to increased activity levels or a single sharp blow to the heel such as stepping on a stone.
Other risk factors include the presence a calcaneal bone spur and a history of corticosteroid injections in the heel.
Corticosteroid injections tend to thin the fat pad making it more susceptible to injury. This is important since some doctors use corticosteroid injections to treat plantar fasciitis.
What can be done to treat or prevent this injury?
When treating this condition, an obvious point is that no corticosteroid injections are used. If the doctor does inject the fat pad, it is with an anesthetic. Surgery is also contraindicated since it usually results in a poor outcome.
Conservative treatment consists of heel taping, using heel cups or a heel pad, icing the area after activity, using well-cushioned shoes, running on softer surfaces, using orthotics (if needed) and anti-inflammatory medication.
Some other treatments to consider would be laser, shockwave and ultrasound modalities.
Activity modification and reducing bodyweight, if overweight, are also indicated.
As with most running injuries, a sensible return to running as symptoms improve is a tried and true approach. Running through this injury is not recommended. I would suggest that water running and cycling would be appropriate cross training exercises since they are non-weight bearing.