What is the pathophysiology of plantar heel pain?

Updated: Oct 01, 2018
  • Author: Vinod K Panchbhavi, MD, FACS; Chief Editor: Thomas C Dowd, MD  more...
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Answer

The specialized soft tissue at the heel functions as a shock absorber. The subcutaneous structure consists of fibrous lamellae arranged in a complex whorl containing adipose tissues that attach with vertical fibers to the dermis and the plantar aponeurosis. [11]

The heel can absorb 110% of the body's weight during walking and 200% of the body's weight during running. The plantar fascia is a multilayered fibroaponeurotic structure that arises predominantly from the medial calcaneal tuberosity and inserts distally through several slips into the plantar plates of the metatarsophalangeal joints, the flexor tendon sheaths, and the bases of the proximal phalanges of the toes.

Dorsiflexion of the toes applies traction stress at the origin of the plantar fascia. A contracture in the triceps surae, a pes cavus, or a pes planus can increase the traction load at the origin of the plantar fascia during weightbearing activities.

Other anatomic factors that can have similar effects are overpronation, discrepancy in leg length, excessive lateral tibial torsion, and excessive femoral anteversion. However, overuse, not anatomy, is the most common cause of plantar fasciitis in athletes. The pain of plantar fasciitis is caused by collagen degeneration associated with repetitive microtrauma to the plantar fascia.

An inflammatory response and reparative process can double the thickness of the plantar fascia, which is normally approximately 3 mm. Biopsy specimens reveal collagen necrosis, angiofibroblastic hyperplasia, chondroid metaplasia, and calcification.

The heel pain can also have a neurologic basis. The tibial nerve, with nerve roots from L4-5 and S2-4, courses in the medial aspect of the hindfoot, through the tarsal tunnel, under the flexor retinaculum, and over the medial surface of the calcaneus. The calcaneal branch, arising directly from the tibial nerve, carries sensation from the medial and plantar heel dermis.

The tibial nerve divides into lateral and medial plantar nerves, which proceed into the plantar aspect of the foot through a foramen within the origin of the abductor hallucis muscles, which forms the distal tarsal tunnel. The first branch of the lateral plantar nerve changes course from a vertical to a horizontal direction around the medial plantar heel. It passes deep to the abductor hallucis muscle fascia and the plantar fascia and is the nerve supply to the abductor digiti minimi. The tibial nerve and its branches in the hindfoot can be involved with compressive neuropathies. A valgus heel can stretch in the tibial nerve.


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