Heel fat pad syndrome, also known as plantar fat pad syndrome or heel fat pad atrophy is a common but not well-known cause of heel pain in the adult population.
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Epidemiology
Heel fat pad syndrome is common. It is the second most common cause of plantar heel pain after plantar fasciitis. It is thought to account for up to 15% of cases 1.
Risk factors
The following factors have an increased risk of plantar fat pad syndrome 1,2:
aging
corticoid injections
Clinical presentation
Typical complaints are pain and tenderness beneath the posterior weight-bearing portion of the calcaneus aggravated during standing or prolonged weight-bearing and walking on hard surfaces 1-3.
Pathology
Heel fat pad syndrome is thought to arise from rupture of the fibrous tissue septa with attrition of the fat pad and decreased shock absorption capacity 1,5.
Etiology
Plantar fat pad syndrome can be a result of acute trauma or from chronic overuse such as excessive heel strike ref.
Radiographic features
Plain radiograph
Plain radiography might show the absence of a plantar calcaneal spur.
Ultrasound
Ultrasound might show a reduction in thickness of the heel fat tissue with overall normal echogenicity 4. A plantar heel fat pad thickness of <12 mm might suggest fat pad atrophy ref.
CT
CT might visualize fat pad atrophy and thickened fibrous bands ref.
MRI
MRI can depict band-like signal intensity changes of the fat pad reflecting fibrotic and a reduction of the thickness of the plantar fat pad 4,5.
In addition, it allows evaluation of the plantar fascia, the calcaneus, the Achilles tendon and flexor digitorum longus and flexor hallucis longus tendons as well as the tarsal tunnel and the plantar muscles.
Signal characteristics
T1: low signal
T2: high signal
STIR: high signal
Treatment and prognosis
Treatment is conservative with proper footwear, insoles or heel cups and taping, and mobilization and manual therapy. Patient education about the discontinuation of symptom increasing activities such as high impact exercises should also occur. Additionally, the pain might be treated with rest and ice and non-steroidal anti-inflammatory drugs 1,2.
Differential diagnosis
Other clinical conditions mimicking the imaging appearance of heel fat pad syndrome include 1-5:
plantar fasciitis: inflammatory changes of the proximal plantar fascia, plantar calcaneal spur
plantar fibromatosis: nodular thickening of the plantar fascia
plantar fascial xanthoma: fusiform tendinous or aponeurotic enlargement of the plantar fascia
flexor hallucis longus or flexor digitorum longus tenosynovitis
insertional Achilles tendinopathy
retrocalacaneal bursitis