Foot Health Glossary
Understand the medical terminology behind your foot health. Search our comprehensive guide to foot conditions, symptoms, and podiatry terminology.
Dr. William Naughton
Board Certified Podiatrist
A
Achilles Tendonitis
Inflammation of the large tendon connecting the calf muscles to the heel bone. Often caused by overuse, tight calves, or unsupportive footwear.
Signs & Symptoms:
- Pain/stiffness along the back of the heel.
- Tenderness when squeezing the tendon.
- Swelling that worsens with activity.
- Pain is often worse in the morning.
Abduction
Movement of the foot away from the midline of the body.
Adduction
Movement of the foot toward the midline of the body.
Arch Support
A device or contoured insole designed to support the arch of the foot, reducing strain on the plantar fascia.
Arthritis (Foot & Ankle)
Inflammation of one or more joints. Osteoarthritis (wear and tear) and Rheumatoid Arthritis (autoimmune) commonly affect the foot joints.
Symptoms:
- Joint pain and stiffness.
- Swelling around the joint.
- Reduced range of motion.
Arch Strain
A burning sensation or pain in the arch of the foot, often caused by inflammation of the plantar fascia or overuse.
B
Biomechanics
The study of the mechanical laws relating to the movement or structure of living organisms, specifically the foot.
Bunions (Hallux Valgus)
A bony bump that forms on the joint at the base of the big toe. It occurs when the big toe pushes against the next toe, forcing the joint to stick out.
Signs & Symptoms:
- Bulging bump on the outside of the big toe.
- Swelling/redness around the big toe joint.
- Persistent or intermittent pain.
- Restricted movement of the big toe.
Bursitis
Inflammation of the fluid-filled sacs (bursae) that cushion bones and muscles near joints. In feet, it often affects the heel or big toe.
Bone Spur (Osteophyte)
Bony projections that develop along bone edges. In the foot, they commonly form on the heel (Heel Spur) or top of the foot.
C
Calcaneus
The heel bone; the largest bone in the foot.
Custom Orthotics
Medical devices custom-molded to an individual's foot.
Calluses
Thickened, hard layers of skin caused by friction and pressure. Usually found on the soles.
Charcot Foot
A serious condition affecting people with neuropathy (often diabetic). It causes weakening of the bones in the foot that can occur in people who have significant nerve damage.
Warning Signs:
- Warmth/redness in the foot (compared to other).
- Swelling without pain (due to numbness).
- Deformity (rocker-bottom appearance).
Consumable
Components of an orthotic, such as the top cover padding, that naturally wear down over time and require periodic replacement.
Corns
Distinct, hard, center-focused bumps of skin that usually develop on the tops and sides of toes due to shoe friction.
Cushioning
The layer of material in an orthotic that absorbs impact and provides comfort, typically made of EVA foam or similar materials.
D
Deep Heel Cup
An orthotic feature where the heel seat is deeper than average to provide maximum stability and motion control.
Diabetic Neuropathy
Nerve damage that can occur if you have diabetes. It most often damages nerves in your legs and feet.
Symptoms:
- Numbness or reduced ability to feel pain.
- Tingling or burning sensation.
- Sharp pains or cramps.
Dorsiflexion
The biomechanical action of raising the foot upwards towards the shin. Limited dorsiflexion can cause Achilles tendonitis and plantar fasciitis.
E
EVA (Ethylene Vinyl Acetate)
A dense, medical-grade foam material used in orthotics for shock absorption and durability.
Eversion
A movement where the sole of the foot turns outwards, away from the body's midline.
F
Flat Feet (Pes Planus)
A condition where the arches of the foot collapse, with the entire sole touching the ground. This often leads to overpronation and strain on the ankles and knees.
Signs & Symptoms:
- Feet tire easily (foot fatigue).
- Pain in the arch or heel area.
- Bottom of feet become fully flat when standing.
- Inward rolling of the ankles.
Forefoot
The front part of the foot, containing the five metatarsal bones and the phalanges (toes).
Functional Orthotics
Orthotics designed to correct abnormal foot function and biomechanics, as opposed to accommodative orthotics which simply cushion.
Fungal Nail (Onychomycosis)
An infection of the nail unit by fungi. It accounts for up to 50% of all nail problems.
G
Green (Active)
Bilt Labs designation for high-rebound, responsive foam orthotics designed for sports and high-impact activities.
Gait Analysis
A systematic study of human walking motion (walking), used to identify biomechanical abnormalities.
Gout
A form of arthritis characterized by severe pain, redness, and tenderness in joints. It most often affects the joint at the base of the big toe.
Gait Cycle
The sequence of motions that occur from one initial contact of the heel to the next consecutive initial contact of the same heel.
H
Hallux
The medical term for the big toe.
Heel Spurs
A calcium deposit causing a bony protrusion on the underside of the heel bone. Frequently associated with Plantar Fasciitis.
Signs & Symptoms:
- Intermittent or chronic pain at the heel base.
- Pain that feels like a pin sticking into the heel.
- Pain usually subsides after walking.
Heel Cup
The curved, depression area in the heel of an orthotic designed to hold the heel in a neutral position and use the body's natural fatty pad for cushioning.
High Arches (Pes Cavus)
A foot condition where the arch is raised more than normal, often causing instability and poor shock absorption.
Hammertoe
A deformity where a toe bends downward at the middle joint (PIP), causing it to curl like a hammer. Usually affects the second, third, or fourth toe.
Hallux Rigidus
Stiffness of the big toe. It is a form of degenerative arthritis affecting the MTP joint at the base of the big toe.
I
Inversion
A movement where the sole of the foot turns inwards, towards the body's midline.
Ingrown Toenail
A common condition in which the corner or side of a toenail grows into the soft flesh. The result is pain, redness, swelling and, sometimes, an infection.
J
Joint (MTP)
The Metatarsophalangeal joint connecting the toe bones to the foot bones, common site for bunions.
K
Kit (Impression)
A bio-foam casting system used to capture a 3D mold of the foot for custom orthotic manufacturing.
Kinetic Chain
The interconnected relationship between the foot, ankle, knee, hip, and back.
L
Lisfranc Injury
An injury to the midfoot where one or more of the metatarsal bones are displaced from the tarsus.
Symptoms:
- Swelling of the top of the foot.
- Bruising on the bottom of the foot.
- Pain that worsens when standing.
Lateral Arch
The arch running along the outer edge of the foot.
M
Memory Foam
Viscoelastic foam used in top covers to mold to the foot's contours for personalized cushioning.
Met Pad
A small cushion placed behind the ball of the foot to relieve pressure on the metatarsal heads.
Metatarsals
The five long bones of the forefoot connecting the tarsal bones to the toes.
Medial Arch
The main arch on the inside of the foot.
Metatarsalgia
A condition in which the ball of your foot becomes painful and inflamed. Often caused by high impact activities or ill-fitting footwear.
Signs & Symptoms:
- Sharp, aching or burning pain in the ball of the foot.
- Pain worsens when standing, running or walking.
- Numbness or tingling in your toes.
Morton's Neuroma
A thickening of the tissue around one of the nerves leading to your toes, causing sharp, burning pain in the ball of the foot.
Signs & Symptoms:
- Feeling like you are standing on a pebble.
- Burning pain in the ball of the foot.
- Numbness or tingling in the toes.
N
Neutral Foot
A foot structure where the ankle remains straight and aligned with the leg during walking, providing ideal shock absorption.
Navicular
A boat-shaped bone in the midfoot that is crucial for maintaining the medial arch.
O
Overpronation
When the foot rolls inward excessively while walking or running. This misalignment puts strain on the arch and can cause knee and hip pain.
Signs & Symptoms:
- Wear on the inner side of shoe soles.
- Knee pain that turns inward.
- Flattening of the arches.
Orthotics (Custom)
Prescription medical devices worn inside shoes to correct foot biomechanics. Unlike store-bought inserts, they are molded to your unique foot structure.
P
P-Cell
A durable, closed-cell EVA foam material used for orthotic top covers to provide cushioning and shock absorption.
Posting
An angled wedge added to the orthotic shell to correct the degree of pronation or supination.
Plantar Fasciitis
Inflammation of the plantar fascia ligament, causing sharp heel pain. It is the most common cause of heel pain in adults.
Signs & Symptoms:
- Stabbing pain near the heel.
- Pain is worst with the first steps in the morning.
- Pain triggers after standing for long periods.
- Tightness in the Achilles tendon.
Pronation
The natural side-to-side movement of the foot as you walk or run. Moderate pronation is normal and helps absorb shock.
Plantar Fascia
The thick band of tissue (ligament) that connects your heel bone to your toes and supports the arch of your foot.
Posterior Tibial Tendon Dysfunction (PTTD)
Often called "adult-acquired flatfoot." It occurs when the posterior tibial tendon becomes inflamed or torn, leading to a fallen arch.
Pes Cavus (High Arch)
A condition where the foot has a very high arch. This places excessive weight on the ball and heel of the foot while walking.
Signs & Symptoms:
- Pain in the ball and heel of the foot.
- Instability of the ankle.
- Claw toes or hammertoes.
Q
Questionnaire (Medical)
The intake form used to diagnose foot conditions and lifestyle needs for orthotic design.
R
Raynaud's Disease
A condition causing some areas of the body—such as toes—to feel numb and cool in response to cold temperatures or stress.
Rearfoot
The back part of the foot, consisting of the calcaneus (heel) and talus (ankle) bones.
Rebound
The ability of the orthotic material to return to its original shape after compression, providing energy return.
Recover
The process of removing worn top covers and replacing them with new material to extend orthotic life.
Refurbish
Restoring an existing custom orthotic to like-new condition, typically including new top and bottom covers.
S
Supination
Also known as underpronation. This occurs when the foot rolls outward as you walk, placing stress on the outer edge of the foot.
Signs & Symptoms:
- High arches are often present.
- Wear on the outer edge of shoes.
- Ankle sprains are more common.
Sesamoiditis
Inflammation of the sesamoid bones in the ball of the foot (under the big toe joint). Common in dancers and runners.
Shin Splints
Pain along the shin bone (tibia). Often caused by overpronation or flat feet which puts torque on the lower leg muscles.
Shell
The rigid or semi-rigid base of a custom orthotic that provides structural support and correction.
Shock Absorption
The capacity of an orthotic material to dampen impact forces during walking or running, protecting joints from stress.
T
Tarsal Tunnel Syndrome
A compression neuropathy of the posterior tibial nerve as it travels through the tarsal tunnel (inside of the ankle). Similar to carpal tunnel in the wrist.
Symptoms:
- Burning sensation on sole of foot.
- Shooting pain or tingling.
Turf Toe
A sprain of the main joint of the big toe. It happens when the toe is forcibly bent upward (hyperextension), common in football players.
Talus
The ankle bone that connects the leg to the foot.
Top Cover
The material layer on top of the orthotic shell that contacts the foot, providing cushioning and comfort.
U
Ulcers (Diabetic Foot)
An open sore or wound on the foot, occurring in approximately 15 percent of patients with diabetes.
V
Varicose Veins
Gnarled, enlarged veins, most commonly appearing in the legs and feet, caused by valve failure in the veins.
Valgus
A deformity where the segment distal to a joint is angled outward (away from midline).
Varus
A deformity where the segment distal to a joint is angled inward (toward midline).
W
Weight-Bearing
The act of supporting the body's weight through the feet, crucial for functional orthotic assessment.
X
X-Ray
Imaging used to view bone structure and fractures.
Y
Yellow (Everyday)
Bilt Labs designation for medium-density, memory foam orthotics designed for daily comfort.
Z
Zero Drop
Footwear where the heel and toe are at the same height level.
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