Plantar fasciitis is a prevalent condition characterised by inflammation or, more accurately, degeneration of the plantar fascia—a thick band of tissue that runs across the bottom of your foot, connecting your heel bone to your toes. This vital structure supports the arch of your foot and acts as a shock absorber. The condition typically arises from repetitive traction forces and overuse, leading to micro-tears and degenerative changes in the fascia at its attachment to the heel bone [1, 5].

Common risk factors include prolonged standing, excessive walking or weight-bearing activities, wearing poorly supportive footwear, and certain foot mechanics such as pes planus (flat feet) or pes cavus (high arches). A high body mass index (BMI) is also a significant contributor [9]. The hallmark symptom is often a sharp, stabbing pain in the heel, particularly with the first steps in the morning or after periods of inactivity. This is known as classic first-step pain [2, 5].

Key Entities and Associated Attributes

• Plantar Fasciitis: This condition is primarily identified by classic first-step pain and tenderness along the bottom of the heel. On ultrasound, a key diagnostic indicator is a fascia thickness greater than 4mm at its insertion into the calcaneus [1, 6]. The pain is often worse after rest and improves slightly with activity, though prolonged activity can exacerbate it.

• Calacaneal Spur (Heel Spur): Often found in conjunction with plantar fasciitis, a calcaneal spur is a bony protrusion that develops on the underside of the heel bone. While frequently associated with heel pain, it is important to note that these spurs are often asymptomatic and are not always the direct cause of pain. They are considered a modest calcification of the plantar fascia and are brittle and thin, not typically a significant mechanical problem on their own [5]. Many individuals with heel spurs experience no pain, highlighting that the pain is usually due to the plantar fascia itself rather than the spur [5].

Differential Diagnoses

When evaluating heel pain, it is essential to consider other conditions that can mimic plantar fasciitis. Accurate differentiation ensures appropriate treatment.

• Fat-pad atrophy: The heel fat pad provides crucial cushioning and shock absorption. With age or repetitive stress, this fat pad can thin or shift, leading to reduced cushioning and increased pressure on the heel bone, causing pain. Unlike plantar fasciitis, the pain from fat-pad atrophy is often described as a deep bruise and tends to worsen with prolonged standing or walking, rather than being most severe with the first steps.

• Baxter\'s nerve entrapment: Also known as first branch of the lateral plantar nerve entrapment, this condition involves the compression of a nerve in the heel. Symptoms can include burning, tingling, or numbness, often radiating towards the arch or outer side of the foot. The pain can be similar to plantar fasciitis but may not have the classic morning stiffness and often presents with neurological symptoms that are absent in typical plantar fasciitis.