Hindfoot: Anatomy, Location, and Function

The hindfoot, sometimes also referred to as the rearfoot, is the posterior region of the human foot as differentiated from the midfoot and the forefoot. The hindfoot area includes the talus and calcaneus bones; the subtalar and talocrural (ankle) joints; and the muscles, tendons, and ligaments in the heel area. Differences in the way the hindfoot strikes the ground, such as overpronation and supination, can contribute to pain in the feet, knees, legs, hips, or back. Irregularities in the fascia, or connective tissue, of the hindfoot contribute to the condition known as plantar fasciitis. Additionally, inflammation or degeneration in the Achilles tendon can cause pain in the heel area.

The hindfoot contains only two bones, which together make up the largest bony structures of the foot: the talus, or the ankle bone, and the calcaneus, or heel bone.

The ankle joint, also known as the talocrural joint, is located between the talus and the two bones of the lower leg: the tibia (shin bone) and fibula (small bone supporting the tibia). It operates as a hinge joint, allowing the foot to tilt upward (dorsiflexion), and downward (plantarflexion).

The subtalar joint is located between the calcaneus and the talus bones and allows the foot to roll from side to side, thereby turning the sole inward (inversion) or outward (eversion). This action is particularly necessary when navigating rough terrain.

The foot contains numerous intrinsic muscles (muscles that originate in the foot), that are responsible for toe movements, arch support, and maintaining upright posture.

Of these, the abductor hallucis, abductor digiti minimi, and the flexor digitorum brevis are found in part in the hindfoot area. Ligaments and tendons in the hindfoot connect the rear parts of the foot to other parts of the foot or leg (as is the case with the Achilles tendon), aid movement, and contribute to balance and stability.

Because of their location in the heel area, the various components of the hindfoot affect—and are affected by—the rest of the foot and the lower leg. Misalignments in the way the hindfoot strikes the ground can contribute to pain further up the leg, as well as in the hips and back.

Numerous anatomical variations, such as the presence of accessory ossicles (small bones) or muscles, extra sesamoid bones, and irregular bone configurations can be seen in the rearfoot on a radiograph. Such variations typically are asymptomatic, though it's also possible for them to contribute to pathology or pain.

The rearfoot's structure is essential to the functionality of the entire foot. Additionally, the health and biomechanics of the rearfoot help determine gait and can contribute to pain in the feet and many of the joints above.

For many people, the rearfoot strikes the ground first when walking or running, though there is disagreement about whether rearfoot strikes—as opposed to forefoot and midfoot strikes—are the optimal pattern of movement.

Regardless of your strike pattern, the rearfoot area works along with the rest of the foot to allow movement, balance, and stability for a variety of everyday actions.

Overpronation refers to an inward roll of the foot often associated with flat feet, and supination (or underpronation) refers to the opposite—an outward roll of the foot. Both overpronation and supination can exert stress on the bones, joints, tendons, and ligaments in the rearfoot itself as well as in other parts of the foot and the leg.

Overpronation and supination are common congenital abnormalities that become apparent in childhodd and can often be detected by a person's gait. These differences cause the foot to invert or evert—or "tilt" inward or outward at the ankle—when the hindfoot is weight-bearing. While rarely serious, overpronation and supination can cause pain in the feet, legs, knees, hips or back. 

In addition to the hereditary factor, overpronation and flat feet can also can be caused by pregnancy, obesity, and repetitive activities such as running.

Plantar fasciitis is a common condition involving the fascia, or connective tissue, that spans the sole of the foot from the hindfoot to the forefoot. Its most common symptom is a burning sensation in the heel area when walking, particularly first thing in the morning or after prolonged sitting. While it was previously thought that plantar fasciitis resulted from inflammation, it's now regarded as a degenerative process.

Chronic plantar fasciitis is a common cause of heel spurs—small, bony growths on the heel.

The Achilles tendon runs down the back of the leg and attaches the calf muscle to the calcaneus. When the Achilles is inflamed due to repetitive stresses such as running, pain and tenderness can occur anywhere along the tendon—which spans the distance from just above the heel bone to the bottom of the calf muscle.

Inflammation of the Achilles can progress to degeneration, known as tendonosis, in which microscopic tears may be visible in an X-ray. Tendonosis is typically more painful than tendonitis, as the tendon itself may enlarge and develop bumps or nodules.

In addition to problems stemming from overpronation, supination, plantar fasciitis, and inflammation of the Achilles tendon, other conditions affecting the hindfoot may include fractures, bruises, bursitis, arthritis, and entrapped nerves.

In some cases, pain in the hindfoot area can be treated or prevented by wearing good quality shoes that provide cushion and stability. Simple stretching and strengthening exercises for the foot, ankle, and calf also can help alleviate pain or discomfort.

For relief from plantar fasciitis, a combination of rest, stretching, strengthening, icing, sports taping, and orthotics can be helpful. If home care doesn't help with the pain, consult with your doctor about the next steps, which could include physical therapy, ultrasound treatment, or surgery.

When overpronation leads to flat feet, it may be possible to correct flat feet with stretching, orthotics, or surgery. Depending on the severity, Achilles tendonitis and tendonosis may respond to immobilizing the foot and lower leg, icing, anti-inflammatory medications, orthotics, or physical therapy.