Heel Pain: Heel Fat Pad Syndrome, Lateral Plantar Nerve Entrapment

By admin Last updated Sep 24, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Reno Ravindran

Richard E. Rodenberg

Thomas L. Pommering

Basics

Description

Heel fat pad syndrome:
- The heel pad is composed of columns of adipose tissue separated by fibrous septae. It is located directly below the calcaneus and acts as a hydraulic shock-absorbing layer (1).
- The encapsulated fat acts in a hydraulic fashion to absorb shock by resisting compressive loads.
- Degeneration or trauma may cause local loss of the heel pad or rupture of the fibrous tissue septa, which may result in loss of the heel pad compressibility.
- Cause is often multifactorial
- The syndrome may result from a direct blow to the bottom of the heel, resulting in a bruise and loss of heel pad elasticity.
- Displacement, loss, or atrophy of fat pads causes pain from excessive pressure.
Lateral plantar nerve entrapment:
- Lateral plantar nerve (LPN) and the 1st branch of the LPN are branches of the tibial nerve, which supplies autonomic, sensory, and motor fibers to the plantar foot. The LPN is the most common cause of plantar heel pain of neural origin (2).
Synonym(s): Calcaneodynia; Heel pain syndrome; Calcaneal neuritis; Policeman's heel; Runner's heel; Tennis heel; Stone bruise; Tuber calcanei pain; Subcalcaneobursitis

Epidemiology

1 in 10 people develop heel pain in their lifetime.
Peak age 40–60 yrs (3)
15% of all adults with foot problems are thought to be related to heel pain.
More common with increasing age, obesity, and diabetes
Relationship with athletic overuse injuries (stress-related pathogenesis)
More common with occupations requiring prolonged standing or walking on hard surfaces (4)

Risk Factors

Elderly, advancing age
Obesity, body mass index >30
Occupations requiring prolonged standing or walking
Repetitive trauma, such as in distance runners, hurdlers, long jumpers, triple jumpers, gymnasts, or dancers
Overuse in recreational or professional athletic activities (4)

Etiology

LPN entrapment can occur at different sites:

Where the nerve passes at the sharp edge of the deep fascia of the abductor hallucis
Distal to the medial edge of the calcaneus
Between the abductor hallucis and the medial head of quadratus plantae muscle (2)

Diagnosis

History

Gradual onset of plantar heel pain, which may be unilateral or bilateral
May have a history of local trauma
Pain may radiate into the arch or proximally to the medial heel area.
If pain is severe enough, a patient may walk on the ball or lateral aspect of the foot.
Heel fat pad syndrome:
- Pain primarily with weight-bearing and relieved with rest
- Pain is usually nonspecific and occurs diffusely over the heel pad.
- Pain does not tend to radiate or increase with dorsiflexion (1).
LPN entrapment:
- Burning, sharp, shooting, shocklike pain; localized to the medial inferior aspect of the heel and proximally into the medial ankle region. Pain may radiate across the plantar aspect of the heel to the lateral aspect of the foot.
- Pain worse during or after weight-bearing activities and improves with rest, but can also occur at rest and in non-weight-bearing positions
- Pain at night may be due to nerve compression as a result of venostasis and venous engorgement.
- Post-static dyskinesia: Plantar heel pain when patient 1st stands after periods of rest. Can be typical in patients with heel pain of neural origin, but this can also occur in plantar fasciitis.
- Sensory deficit may not be common, but occasionally can cause tingling and/or numbness in the heel or foot (2).

Physical Exam

Heel fat pad syndrome:
- Thorough examination of the lower extremity, including neurovascular exam, is recommended.
- Exam is facilitated by having the patient lie prone
- Tenderness directly over the weight-bearing part of the calcaneus rather than on the distal tuberosity
- May have palpable absence or diminution of a compressible pad
- In prolonged cases, the underlying bone can be felt underneath the skin due to significant fat pad atrophy.
LPN entrapment:
- Palpation over 1st branch of the LPN deep to the abductor hallucis muscle or medial calcaneal tuberosity with reproduction of pain/symptoms proximally and distally. Should have minimal tenderness over the plantar fascia origin.
- Dorsiflexion with eversion of the ankle can reproduce symptoms. Although not specific, can help with diagnosis.
- Plantar flexion-inversion may reproduce symptoms, although not specific
- Negative Tinel's test (2)

Diagnostic Tests & Interpretation

Imaging

Anteroposterior, lateral, and oblique plain radiographs. Radiographs may reveal calcaneal spurs or calcifications, fractures, tumors, arthrosis, or other unusual causes of heel pain.
High-resolution US or MRI to look for benign tumors or neuromas entrapping a nerve
Lumbar spine radiographs and MRI to rule out causes of lumbar radiculopathy
Consider bone scan or MRI to rule out suspected stress fracture.

P.293

Diagnostic Procedures/Surgery

LPN:

Electromyography and nerve conduction studies can reveal abnormalities in LPN.
Quantitative sensory testing, also known as the pressure-specified sensory device, determines pain mechanisms by assessing function of large and small sensory nerve fibers.
If nerve entrapment is suggested by history and exam, a diagnostic injection with local anesthetic providing complete pain relief can help with diagnosis (2,5).

Differential Diagnosis

Calcaneal spurs
Local inflammatory conditions (plantar fasciitis, subcalcaneal bursitis, periostitis, tenosynovitis, blister)
Systemic inflammatory conditions (ankylosing spondylitis, Reiter's syndrome, psoriatic arthritis, rheumatoid arthritis, sarcoidosis, gout, and pseudogout)
Calcaneal fracture or stress fracture
Entrapment (tarsal tunnel syndrome, medial calcaneal nerve)
Infectious (osteomyelitis, tuberculosis)
Tumors (glomus tumor of heel pad, osteoid osteoma, osteoblastoma, chondromyxoid fibroma, chondrosarcoma, simple and aneurysmal cysts)
Neuropathy (diabetes mellitus, alcoholism, reflex sympathetic dystrophy)
Metabolic (osteomalacia, Paget disease)
Calcaneal apophysitis (4)

Treatment

NSAIDs of choice
Modified weight-bearing activities
Injections of local anesthetics/steroids at site of nerve entrapment for LPN. Caution should be exercised with repeated injections or improper technique, due to the risk of irreversible damage to the heel pad by mechanical disruption of the heel septae and by steroid-induced fat necrosis.
Immobilization rarely necessary, symptom-directed
Treatment of other associated conditions (eg, night splints in plantar fasciitis)
Taping of the heel in fat pad syndrome can provide support and limit movement of the heel's fat pad. This can also help confirm diagnosis (5).

Additional Treatment

Additional Therapies

Various methods for altering the biomechanical forces on the heel have been advocated:

Weight control
A well-fitted heel cup cushions the heel and prevents the heel pad from splaying, thereby improving the intrinsic cushioning of the calcaneus. There is no consensus as to which type of orthosis is best. Regardless of whether over-the-counter heel cups or custom orthoses are used, consistent features should be support of the arch, presence of adequate cushioning material, recess for area of pain beneath the heel, and slight medial elevation.
Shoes with softer midsoles, which provide more cushioning of the fat pad
Raising the heel may thereby transfer the weight-bearing anteriorly with heel strike and in midstance.
Medial heel wedge to relieve the pressure on the medial tuberosity, causing more lateral pressure
Physical therapy may be useful for patients not adequately responding to other conservative modalities. US, extracorporeal shock wave therapy, laser modalities.

Surgery/Other Procedures

Heel fat pad syndrome:
- Surgery reserved for patients when conservative treatment fails to provide adequate pain relief
- Some experts advocate that symptoms be present for more than 1 yr, despite appropriate conservative treatment, before surgery is considered.
- Surgical options are directed towards the cause of heel pain and include spur resection, wide release of plantar fascia, drilling decompression, and neurolysis.
- It is important to have an exact diagnosis of the pain before surgical intervention, due to the multifactorial and often recurrent nature of plantar heel pain (6).
LPN entrapment:
- Considered after failure of conservative treatment for 6–12 mos
- Surgical decompression of the 1st branch of LPN (2)

Ongoing Care

Follow-Up Recommendations

Heel fat pad syndrome responds very well to conservative treatment and is usually self-limited.

References

1. Aldridge T. Diagnosing heel pain in adults. Am Fam Physician. 2004;70:332–338.

2. Alshami AM, Souvlis T, Coppieters MW. A review of plantar heel pain of neural origin: Differential diagnosis and management. Man Ther. 2007.

3. Toomey EP. Plantar heel pain. Foot Ankle Clin. 2009;14:229–245.

4. Alvarez-Nemegyei J, Canoso JJ. Heel pain: diagnosis and treatment, step by step. Cleve Clin J Med. 2006;73:465–471.

5. Franson J, Baravarian B. Tarsal tunnel syndrome: a compression neuropathy involving four distinct tunnels. Clin Podiatr Med Surg. 2006;23:597–609.

6. Bateman JE. Disorders of the foot and ankle, medical and surgical management. Philadelphia: WB Saunders, 1991.

Additional Reading

Bordelon RL. Orthopedic sports medicine, principles and practice. Philadelphia: WB Saunders, 1994.

Cailliet R, ed. Foot and ankle pain. Philadelphia: FA Davis, 1997.

Karr SD. Subcalcaneal heel pain. Orthop Clin North Am. 1994;25:161–175.

Simons SM. Foot injuries of the recreational athlete. Phys Sports Med. 1999;27:57–70.

Turgut A, Gokturk E, Kose N, et al. The relationship of heel pad elasticity and plantar heel pain. Clin Orthop Rel Res. 1999;360:191–196.

Codes

ICD9

355.6 Lesion of plantar nerve

Clinical Pearls

Both soft heel cups and more rigid ones have been used with some success. The hard cups are intended to encompass the heel pad beneath the calcaneus, helping to restore some of its compressibility. The softer cups are designed primarily to cushion the fat pad. Athletes who run a lot in their sport often prefer softer heel cups or orthotics.
To prevent heel fat pad syndrome, training errors should be identified and corrected. The athlete should be certain to wear proper shoes with an energy-absorbing heel cushion, avoiding excessive wear of the shoes. Mileage should be increased gradually, and running on steep hills should be avoided. Training on safe and shock-absorbing surfaces is essential (eg, running on an all-weather track or on a surface softer than concrete or asphalt).