APMLE Part I key terms

A fibro-osseous passage at the medial ankle formed by the flexor retinaculum and the medial malleolus, containing the tibial nerve, posterior tibial artery, and flexor tendons. Compression produces burning pain and numbness in the sole.

A branch of the sciatic nerve that descends through the popliteal fossa and posterior leg, then divides in the foot into medial calcaneal and medial and lateral plantar nerves. It supplies most intrinsic foot muscles and sole sensation.

A thick band of fibrous tissue arising from the medial calcaneal tuberosity and inserting into the metatarsal heads and proximal phalanges, supporting the medial longitudinal arch and storing elastic energy during gait.

The common tendon of the gastrocnemius and soleus muscles, inserting on the posterior calcaneus. It is the strongest tendon in the body and plantarflexes the ankle during push-off.

The tarsometatarsal articulations, stabilized by the Lisfranc ligament between the medial cuneiform and the second metatarsal base. Disruption causes midfoot instability and widening of the first to second metatarsal interval.

The cytosolic pathway that converts one glucose molecule into two pyruvate molecules, generating two ATP and two NADH. Under anaerobic conditions pyruvate is reduced to lactate to regenerate NAD+.

A copper-dependent enzyme that oxidatively deaminates lysine and hydroxylysine residues in collagen and elastin, creating covalent cross-links that give connective tissue its tensile strength.

A cytosolic alternative to glycolysis that produces NADPH for reductive biosynthesis and ribose-5-phosphate for nucleotide synthesis. It is especially active in liver, adipose tissue, and red blood cells.

The hepatic sequence of reactions that converts toxic ammonia into water-soluble urea for excretion. It requires five enzymes, including carbamoyl phosphate synthetase I, and links to the TCA cycle through fumarate.

Acetoacetate, beta-hydroxybutyrate, and acetone, produced in liver mitochondria from acetyl-CoA during prolonged fasting or uncontrolled diabetes and used by extrahepatic tissues as fuel.

Tensioning of the plantar fascia during toe extension, especially at the first metatarsophalangeal joint, which shortens the calcaneus-to-metatarsal distance, raises the medial arch, and inverts the rearfoot in late stance.

The congruent position of the subtalar joint in which the forefoot is maximally pronated against the rearfoot with no residual pronation or supination. It is the reference point for assessing forefoot and rearfoot deformity.

A frontal-plane deformity in which the forefoot is inverted relative to the rearfoot when the subtalar joint is neutral. It forces compensatory rearfoot pronation during weight bearing and predisposes to overuse injury.

Limited ankle dorsiflexion beyond neutral with the knee extended, usually from a tight gastrocnemius-soleus complex. It raises forefoot pressure and contributes to plantar fasciitis, Achilles tendinopathy, and ulceration.

A structured community of microorganisms attached to a surface and embedded in a self-produced extracellular matrix. Biofilms increase antibiotic resistance and are common on diabetic foot wounds and indwelling devices.

Staphylococcus aureus strains resistant to methicillin and most beta-lactams because of the mecA gene product PBP2a. Infections range from skin abscess to osteomyelitis and require agents such as vancomycin.

Coating of a microbe with antibodies or complement fragments such as C3b so that phagocytes bearing Fc or complement receptors can bind and engulf it more efficiently.

A group of plasma proteins activated in cascade by antibody, microbial surfaces, or lectins, producing membrane attack complexes and opsonins that lyse or tag pathogens and drive inflammation.

A focal collection of activated macrophages (epithelioid cells), often with multinucleated giant cells and a rim of lymphocytes, formed in response to persistent intracellular organisms or foreign material.

Reversible replacement of one mature cell type by another, such as columnar by squamous epithelium under chronic irritation. It is an adaptation rather than malignancy but may predispose to cancer.

Infection of bone and marrow, usually bacterial, producing inflammation, edema, and bone necrosis. In the diabetic foot it typically spreads from an overlying ulcer and requires prolonged antibiotics or surgical resection.

Programmed cell death marked by cell shrinkage, chromatin condensation, and membrane blebbing without inflammation. It is executed by caspases and is essential for normal development and tissue turnover.

Blockade of the COX-1 and COX-2 enzymes that convert arachidonic acid into prostaglandins and thromboxanes. It reduces pain and inflammation but can cause gastric ulceration and renal impairment.

Bactericidal antibiotics such as gentamicin and tobramycin that bind the bacterial 30S ribosomal subunit and cause misreading of mRNA. They are nephrotoxic and ototoxic, so levels require monitoring.

An oral anticoagulant that inhibits vitamin K epoxide reductase, lowering synthesis of functional factors II, VII, IX, and X. Its effect is monitored by INR and reversed with vitamin K or factor concentrates.

Weak bases that reversibly block voltage-gated sodium channels from the cytoplasmic side, preventing depolarization and impulse conduction. They work poorly in acidic infected tissue because less drug remains uncharged.

The volume of plasma filtered by the kidneys per unit time, normally about 125 mL per minute. It depends on renal plasma flow, filtration pressure, and the permeability and surface area of the glomerular membrane.

A mineralocorticoid from the adrenal zona glomerulosa that increases sodium reabsorption and potassium secretion in the distal nephron, expanding extracellular fluid volume. Release is driven by angiotensin II and hyperkalemia.

The sigmoidal relationship between oxygen partial pressure and hemoglobin saturation. A rightward shift from higher CO2, hydrogen ion, temperature, or 2,3-BPG lowers affinity and enhances oxygen unloading to tissues.

Lateral deviation of the great toe with medial angulation of the first metatarsal, often accompanied by bunion formation, first-ray hypermobility, and altered weight bearing through the lesser metatarsals.

Progressive destructive joint disease of the foot and ankle in patients with peripheral neuropathy, presenting as a warm swollen foot and leading to midfoot arch collapse with rocker-bottom deformity if not treated.

A break in the skin of the foot in a person with diabetes, usually from combined neuropathy, ischemia, and pressure. It is a leading cause of lower-extremity amputation and requires debridement and offloading.

Perineural fibrosis of an interdigital plantar nerve, most often between the third and fourth metatarsals, causing sharp forefoot pain and numbness that worsens in narrow shoes and with weight bearing.

A fibrous, cartilaginous, or bony bridge between two tarsal bones, most commonly the calcaneus and talus or navicular. It restricts subtalar motion and causes a rigid flatfoot in adolescence.

A behavioral framework describing readiness to change as precontemplation, contemplation, preparation, action, and maintenance, with relapse possible at any stage. Interventions are matched to the patient's current stage.

A framework predicting health behavior from perceived susceptibility, severity, benefits, and barriers, plus cues to action and self-efficacy. It is often used to explain adherence to diabetic foot care.

The ethical and legal requirement to disclose a proposed treatment's nature, risks, benefits, and alternatives, confirm the patient's decision-making capacity, and obtain voluntary agreement before proceeding.