Plantar fasciitis is a common condition causing pain and stiffness in the heel and arch of the foot. It involves the plantar fascia, a thick band of tissue on the bottom of the foot connecting the heel bone to the toes. This tissue acts as a shock absorber and supports the foot’s arch during weight-bearing activities. When irritated or degenerated, this tissue causes heel pain.
Anatomical Links Between Foot and Ankle
The plantar fascia forms a direct anatomical link to the ankle through its attachment to the calcaneus, or heel bone. This heel bone is a component of the ankle joint complex. The plantar fascia originates from the calcaneus, supporting the arch and stabilizing the foot during movement.
Surrounding muscles and tendons, such as the Achilles tendon and calf muscles, also attach to the calcaneus. The Achilles tendon connects the calf muscles to the back of the heel bone. These muscles and tendons influence both foot mechanics and ankle stability, creating a biomechanical chain. Tension or dysfunction in one area, such as the plantar fascia, can transmit stress along these shared attachments and influence the mechanics of the ankle.
How Gait Changes Affect the Ankle
Pain from plantar fasciitis often causes individuals to alter their walking patterns, also known as gait. To avoid discomfort in the heel or arch, a person might subconsciously shift their weight, walk on the outer edge of their foot, or shorten their stride. These compensatory movements can lead to uneven pressure distribution across the foot.
Such altered biomechanics place abnormal stress and rotational forces on the ankle joint and its supporting ligaments and tendons. For example, changes in foot pronation or supination can increase tension on the plantar fascia and, consequently, affect ankle stability. This unnatural loading can result in ankle pain, instability, or secondary injuries like ankle sprains over time.
Understanding Referred Pain and Other Causes
Ankle pain alongside plantar fasciitis can sometimes be referred pain. This occurs when pain from the plantar fascia is perceived in a nearby area, such as the ankle, even if the ankle itself is not directly injured. The brain interprets pain signals from one location as originating from another, closely related area.
Ankle pain can also stem from a separate, co-occurring condition. Common examples include Achilles tendonitis, which involves inflammation of the Achilles tendon at the back of the heel. Other possibilities include an ankle sprain, a stress fracture, or nerve entrapment, such as tarsal tunnel syndrome, where the tibial nerve near the ankle is compressed.