A Comprehensive Etiological and Differential Analysis of Heel Pain
Etiological Analysis of Prevalent Heel Pain: Plantar and Posterior Pathologies
Heel pain is one of the most common complaints presenting to musculoskeletal, orthopedic, and primary care clinics. Its etiology is extensive, but the differential diagnosis is heavily guided by the specific anatomic location of the pain. The two most prevalent categories of mechanical heel pain are plantar fasciitis, affecting the bottom (plantar) aspect of the heel, and Achilles tendinopathy, affecting the back (posterior) aspect.
Plantar Fasciitis (Plantar Fasciopathy)
Plantar fasciitis is one of the most frequently diagnosed causes of pain on the bottom, or plantar-medial, aspect of the heel (Alshami & Babri, 2024; American Academy of Family Physicians, 2018a). The condition is prevalent, with millions of individuals treated for it annually (Thomas & Christensen, 2024).
Pathophysiology The plantar fascia is a robust band of tissue that supports the arch of the foot and absorbs shock. The condition develops when high stresses, overuse, or excessive tension damage or create micro-tears in the fascial tissue (Thomas & Christensen, 2024). In many chronic cases, the underlying pathology is more accurately described as a degenerative process ("fasciosis") rather than a purely inflammatory one. Imaging studies often reveal changes consistent with chronic degeneration and dysfunctional vasculature, suggesting a non-inflammatory state of failed tissue healing (Thomas & Christensen, 2024).
Clinical Presentation and Risk Factors The clinical presentation of plantar fasciitis is classic. Patients typically report a sharp, localized pain at the plantar-medial aspect of the heel (Thomas & Christensen, 2024). The hallmark symptom is "first-step pain," also known as post-static dyskinesia: the pain is most intense with the first few steps after awakening or after a prolonged period of rest (Thirunavukkarasu et al., 2023).
The cause is multifactorial, arising from factors that increase stress on the fascia (Thomas & Christensen, 2024):
Activity: A new or sudden increase in activity level or repetitive high-impact activities (e.g., running) (Thomas & Christensen, 2024).
Occupational Factors: Jobs that require prolonged standing on hard surfaces (Thomas & Christensen, 2024).
Biomechanical Factors: Foot mechanics play a crucial role. Both flat feet (pes planus) and high arches (pes cavus) can put added stress on the plantar fascia (Agrawal & Jeyaprakash, 2022; Li et al., 2024).
Intrinsic Factors: Obesity is a major contributor, as excess weight places significant stress on the fascia (Thomas & Christensen, 2024). Age is also a factor (Thomas & Christensen, 2024).
Achilles Tendinopathy
Achilles tendinopathy is a common cause of pain in the posterior aspect of the heel (American Academy of Family Physicians, 2018a). It is an overuse injury affecting the Achilles tendon, which connects the calf muscles to the calcaneus. The term "tendinopathy" is a broad descriptor that often involves degeneration ("tendinosis") (Mach-Lutsen et al., 2024).
Pathophysiology The condition is caused by repeated or intense strain on the tendon, frequently seen in athletes who suddenly increase the intensity or duration of their exercise (Mach-Lutsen et al., 2024). The pathology can manifest in two locations: non-insertional (affecting the middle portion of the tendon) or insertional (occurring where the tendon attaches to the heel bone) (Mach-Lutsen et al., 2024).
Clinical Presentation and Risk Factors The primary symptom is pain localized to the insertion site of the tendon on the posterior heel (American Academy of Family Physicians, 2018a). Risk factors include age, biomechanical issues like a flat or high arch, and excessive exercise (Mach-Lutsen et al., 2024).
Structural and Osseous Conditions of the Calcaneus
Pain can also originate from the calcaneus (heel bone) itself. These conditions range from overuse injuries, such as stress fractures, to incidental radiographic findings, such as heel spurs, that are often misattributed as the source of pain.
Calcaneal Stress Fractures
A calcaneal stress fracture is an overuse injury, representing a small crack in the heel bone caused by repetitive, submaximal stress (American Academy of Family Physicians, 1999). It is a critical differential diagnosis for plantar heel pain (Alshami & Babri, 2024; American Academy of Family Physicians, 1999). These fractures are often precipitated by an abrupt increase in activity or a change in training (e.g., running on a harder surface) (American Academy of Family Physicians, 2018a).
Clinical Presentation The presentation of a stress fracture is distinct from plantar fasciitis. The pain typically worsens progressively with activity and is relieved by rest (American Academy of Family Physicians, 2018a). A highly specific clinical sign is a positive "squeeze test," where medial and lateral compression of the calcaneus reproduces the patient's pain (Alshami & Babri, 2024).
Heel Spurs (Calcaneal Spurs)
A calcaneal spur is a bony projection, or exostosis, that forms on the calcaneus (Agrawal & Jeyaprakash, 2022).
The Role of Heel Spurs in Pain: A Diagnostic Clarification One of the most significant clinical clarifications in the differential diagnosis of heel pain is the role of the heel spur. A spur is often identified on an X-ray in a patient with plantar heel pain, leading to the assumption that the spur is the cause of the pain.
The available evidence refutes this assumption.
First, many individuals who have heel spurs on X-ray do not have any heel pain.
Second, the pain associated with a heel spur is not caused by the spur itself, but rather by the underlying plantar fasciitis (Thomas & Christensen, 2024).
The heel spur is a result of chronic mechanical stress, not the cause of the pain. It represents a calcification of the plantar fascia insertion, which the body forms over a long period in response to the chronic tension and pulling from the inflamed or degenerated fascia (Agrawal & Jeyaprakash, 2022; Thomas & Christensen, 2024). Therefore, the spur is a radiographic sign of long-standing plantar fasciitis, not the primary pain generator. This is a critical concept, as it dictates that treatment must be directed at the plantar fasciitis (Thomas & Christensen, 2024).
Inflammatory Etiologies: Localized Bursitis and Systemic Arthritic Disease
Heel pain can also be driven by primary inflammatory processes. These are broadly divided into localized mechanical inflammation, such as bursitis, and systemic autoimmune or metabolic diseases that manifest in the heel.
Localized Inflammation: Bursitis and Haglund's Deformity
Retrocalcaneal Bursitis This condition involves the inflammation of the retrocalcaneal bursa, a small, fluid-filled sac located between the Achilles tendon and the posterior-superior aspect of the calcaneus (National Library of Medicine, 2024). This bursa functions to reduce friction between the tendon and the bone. It can be difficult to distinguish from, or may co-exist with, insertional Achilles tendinopathy (National Library of Medicine, 2024).
Haglund's Deformity This is a structural condition, not an inflammatory one, though it directly causes inflammation. It is characterized by a bony enlargement or prominence on the posterosuperior aspect of the calcaneus (American Academy of Family Physicians, 2018a). This bony prominence itself is not the primary source of pain. Instead, it creates a mechanical impingement, rubbing against the overlying Achilles tendon and retrocalcaneal bursa. This chronic friction is a direct cause of retrocalcaneal bursitis (American Academy of Family Physicians, 2018a).
Systemic Inflammatory Disease
In some cases, heel pain is not a localized mechanical issue but a peripheral manifestation of a systemic inflammatory disease.
Spondyloarthropathies (e.g., Ankylosing Spondylitis) Ankylosing Spondylitis (AS) is a chronic, inflammatory, autoimmune disease that primarily affects the axial skeleton (Cuesta-Vargas & Roldán-Jiménez, 2024). Heel pain is a common peripheral manifestation of AS (Cuesta-Vargas & Roldán-Jiménez, 2024).
The mechanism is enthesitis, which is inflammation at the enthesis—the site where tendons and ligaments attach to bone. In the heel, AS-related inflammation specifically targets the two major entheses: the Achilles tendon insertion (causing Achilles enthesitis) and the plantar fascia insertion (causing plantar fasciitis) (Cuesta-Vargas & Roldán-Jiménez, 2024).
The presence of enthesitis, particularly involving both the Achilles and plantar fascia, should raise a clinician's suspicion for a systemic condition. If this heel pain is accompanied by other "red flag" symptoms—such as inflammatory back pain, a family history of spondyloarthritis, or eye inflammation (uveitis)—the patient should be evaluated for a spondyloarthropathy (Frontiers in Medicine, 2021).
Gout (Metabolic Arthritis) Gout is an intensely painful form of inflammatory arthritis caused by the deposition of monosodium urate (MSU) crystals in and around joints, resulting from sustained hyperuricemia (Dalbeth et al., 2021; Singh & T, 2024).
Clinical Presentation: While it most commonly affects the great toe (a condition known as podagra), gout can attack any joint, including the talar, subtalar, and ankle joints (Singh & T, 2024). A gout flare is unmistakable: it is characterized by the sudden and intense onset of severe pain, often waking the patient at night (Singh & T, 2024). The attack typically reaches maximum intensity within 12 to 24 hours (Dalbeth et al., 2021; Singh & T, 2024). The affected heel or ankle becomes extremely swollen, red, warm, and exquisitely tender to even the slightest touch, such as the weight of a bedsheet (Singh & T, 2024). This presentation can closely mimic a bacterial infection (septic arthritis) (Singh & T, 2024).
Other systemic arthritic conditions, including Psoriatic Arthritis and Reactive Arthritis, are also seronegative spondyloarthropathies that can cause inflammatory heel pain and enthesitis (Alshami & Babri, 2024).
Neurological Causes: Nerve Entrapment and Compression Syndromes
A critical, and often misdiagnosed, category of heel pain is neuropathic. In these cases, the pain originates not from the fascia, tendon, or bone, but from a compressed or entrapped nerve. These conditions are "mimics" of mechanical heel pain and require a completely different treatment approach.
Tarsal Tunnel Syndrome (TTS)
Tarsal Tunnel Syndrome is an entrapment neuropathy of the posterior tibial nerve (National Library of Medicine, 2022). This nerve runs through a fibro-osseous passage on the medial (inner) side of the ankle known as the tarsal tunnel (American Academy of Family Physicians, 2018a). Compression or damage to this nerve causes the syndrome (American Academy of Family Physicians, 2018a).
Clinical Presentation The symptoms of TTS are distinctly neuropathic, not mechanical.
Pain Character: The pain is described as burning, tingling, or "pins and needles" (American Academy of Family Physicians, 2018a). Numbness may also be present.
Location and Radiation: The pain is typically located on the inner side of the ankle and radiates down to the heel, sole of the foot, and sometimes into the toes (American Academy of Family Physicians, 2018a; National Library of Medicine, 2022).
Aggravating Factors: Symptoms usually worsen with prolonged standing or walking (American Academy of Family Physicians, 2018a).
Baxter's Nerve Entrapment (Inferior Calcaneal Nerve Entrapment)
Baxter's nerve entrapment is an underrecognized and frequently misdiagnosed cause of chronic heel pain (Fondazione Società Italiana di Neurologia, 2025). It involves the compression of the inferior calcaneal nerve (also known as the first branch of the lateral plantar nerve, or "Baxter's nerve") (Alshami & Babri, 2024; American Academy of Family Physicians, 1999).
The "Great Mimic" of Chronic Plantar Fasciitis The clinical significance of Baxter's nerve entrapment (BNE) is profound: it is estimated to be the true cause in up to 20% of cases of chronic plantar heel pain that have been misdiagnosed as plantar fasciitis (Fondazione Società Italiana di Neurologia, 2025).
The reason for the misdiagnosis is that the pain is located in the exact same area as plantar fasciitis: the plantar-medial aspect of the heel (Alshami & Babri, 2024; Fondazione Società Italiana di Neurologia, 2025). However, a careful history and physical examination can reveal critical differences:
Pain Character: Plantar fasciitis pain is typically described as "stabbing." BNE pain, being neuropathic, is more often described as burning, tingling, or shooting (American Academy of Family Physicians, 1999; Fondazione Società Italiana di Neurologia, 2025).
Response to Activity: Plantar fasciitis pain may temporarily improve with mild activity. BNE pain typically gets progressively worse with prolonged activity, such as standing or walking, and may even persist at rest (American Academy of Family Physicians, 1999).
Therefore, any patient presenting with "recalcitrant" or "chronic" plantar fasciitis that is not responding to standard conservative care must be re-evaluated for Baxter's nerve entrapment.
Pediatric and Adolescent Heel Pain
Heel pain in children and adolescents presents a distinct set of diagnostic challenges. While they can experience conditions like plantar fasciitis, the most common cause is unique to their skeletally immature status: an injury to the growth plate.
Calcaneal Apophysitis (Sever's Disease)
Sever's disease, also known as calcaneal apophysitis, is the most common cause of heel pain in growing, physically active children (Sha, 2023; T, 2025). It typically affects children between the ages of 8 and 15 (Fares et al., 2021; James, 2024; T, 2025).
Pathophysiology The pathology of Sever's disease is entirely different from adult tendinopathies. It is an inflammatory overuse injury of the calcaneal apophysis—the cartilage growth plate at the back of the heel bone (Fares et al., 2021; Sha, 2023). In a growing child, this growth plate is made of cartilage, which is softer and more vulnerable to injury than mature bone (Fares et al., 2021).
The condition is caused by repetitive microtrauma from two main sources:
Impact: Repetitive pounding from running and jumping on hard surfaces (Fares et al., 2021).
Traction: The Achilles tendon attaches directly to this growth plate. During a growth spurt, the tight Achilles tendon can exert a repetitive pulling force on the vulnerable growth plate, causing inflammation and pain (Fares et al., 2021; Sha, 2023).
Clinical Presentation The primary symptom is pain and tenderness at the back of the heel (Fares et al., 2021). Unlike adult plantar fasciitis, the pain of Sever's disease is brought on by physical activity (running, jumping) and is relieved by rest (Fares et al., 2021; S, 2024). The diagnosis is clinical and can be supported by a positive "Sever sign" (or squeeze test), where medial and lateral compression of the posterior calcaneus reproduces the pain (James, 2024; Smith & Varacallo, 2024).
Other Pediatric Considerations
While Sever's disease is the most common cause, it is not the only one. One study of pediatric visits for heel pain found that plantar fasciitis was responsible for 40% of cases (Thirunavukkarasu et al., 2023).
Atypical Musculoskeletal and Other Etiologies
This category includes less common degenerative conditions as well as "red flag" pathologies, such as tumors and infections, which are critical to identify.
Heel Fat Pad Atrophy/Syndrome
The plantar heel pad is a specialized structure of fat and fibrous tissue designed to act as a natural shock absorber. With age or repetitive microtrauma, this fat pad can thin, degenerate, and lose its elasticity (Vicente-Sempere et al., 2022). This condition is known as heel fat pad atrophy or syndrome (Alshami & Babri, 2024).
Clinical Presentation Heel fat pad syndrome is another key mimic of plantar fasciitis, but with distinct differentiating features:
Location: The pain is typically a deep, "bruise-like" pain located in the center of the heel (American Academy of Family Physicians, 2018a). This is in contrast to the more common plantar-medial, insertional pain of plantar fasciitis.
Aggravating Factors: The pain is specifically and significantly aggravated by walking barefoot on hard surfaces (e.g., hardwood floors, concrete, ceramic tile) and by prolonged standing (Alshami & Babri, 2024).
Neoplastic Causes (Tumors and Cysts)
Though rare, tumors and cysts within the calcaneus or surrounding soft tissues can present as heel pain (Alshami & Babri, 2024; Apreiss et al., 2023). These include benign entities like intraosseous lipomas (Asfina et al., 2022), ganglion cysts (Apreiss et al., 2023), and unicameral or aneurysmal bone cysts, as well as malignant lesions like sarcomas (Apreiss et al., 2023).
Identifying "Red Flag" Symptoms When a patient's pain presentation does not fit a typical mechanical pattern, clinicians must screen for "red flag" symptoms. For a calcaneal tumor, these symptoms include:
Persistent or severe pain that is not relieved by rest (Li et al., 2018).
Night pain that awakens the patient.
Localized swelling of the ankle or heel (Li et al., 2018).
The absence of trauma or a clear overuse mechanism (Li et al., 2018).
The presence of these symptoms warrants immediate radiological investigation (X-ray, MRI) to rule out a neoplastic process (Li et al., 2018).
Infectious Causes (Calcaneal Osteomyelitis)
Calcaneal osteomyelitis is a serious bacterial (or, rarely, mycobacterial) infection of the heel bone (Lee & Kim, 2018).
Etiology This condition is not an overuse injury and is almost always linked to a specific inciting event:
Trauma: A puncture wound to the foot or an open fracture (Kumar & Pruthi, 2019).
Ulceration: Most commonly, it arises from heel ulceration in patients with severe comorbidities, such as diabetic neuropathy (Kumar & Pruthi, 2019).
Post-Operative: Infection following surgical fixation of a calcaneal fracture (Kumar & Pruthi, 2019).
Iatrogenic: In very rare cases, it has been documented after multiple local steroid injections for plantar fasciitis, though infection post-injection is generally extremely rare when performed properly (Chae et al., 2019; Lee & Kim, 2018).
Clinical Presentation The signs are those of an active infection: unilateral localized swelling, erythema, localized pain, increased limb temperature, and potentially a sinus tract or ulcer draining purulence from the heel (Kumar & Pruthi, 2019).
Analysis of Biomechanical and External Contributing Factors
Mechanical overuse injuries often do not occur in isolation. They are frequently the result of underlying intrinsic biomechanical flaws or extrinsic lifestyle factors that place pathological stress on the heel.
Gait Abnormalities (Intrinsic Factors)
The structure of a person's foot is a primary determinant of their risk for mechanical heel pain. A "normal" foot has a balance of mobility (pronation) to absorb shock and rigidity (supination) to propel the body forward. Deviations to either extreme increase risk (Bar-David & M, 2005).
Overpronation (Pes Planus / Flat Feet): This is a primary driver. Overpronation is the excessive inward rolling of the foot during gait. A collapsed or diminished medial arch (flat foot) causes this excessive motion, which in turn significantly increases tension and strain on the plantar fascia (Agrawal & Jeyaprakash, 2022; Bar-David & M, 2005; Li et al., 2024).
Underpronation (Pes Cavus / High Arches): The opposite end of the structural spectrum is also a significant risk factor (Agrawal & Jeyaprakash, 2022). A rigid, high-arched (cavus) foot is too stable and lacks the necessary mobility and pronation to effectively dissipate ground-reaction forces (Bar-David & M, 2005). This "decreased shock absorption" means that impact forces are transmitted directly to the heel bone and plantar fascia, leading to increased tension and injury (Bar-David & M, 2005).
Extrinsic Risk Factors
Inadequate Footwear: This is one of the most significant and modifiable contributors. Footwear lacking adequate arch support, possessing poor shock absorption, or having worn-out soles places excessive stress on the plantar fascia and heel (Naeem et al., 2022). A 2022 study noted that 83.2% of people diagnosed with plantar fasciitis wear "inappropriate shoes" (e.g., minimal heel height, thin sole, hard insole), and that this correlates directly with the severity of their pain (Naeem et al., 2022). People with plantar heel pain frequently report difficulty with footwear comfort, fit, and choice (Risk & Buldt, 2015).
Abrupt Changes in Activity: An abrupt increase in activity, such as starting a new training program or changing to a harder running surface, is a primary trigger for mechanical overuse injuries, particularly calcaneal stress fractures (American Academy of Family Physicians, 2018a).
Synthesis and Differential Diagnosis Framework for Heel Pain
The extensive range of etiologies for heel pain necessitates a structured diagnostic approach. A clinician can effectively "triage" a patient's presentation by first categorizing the likely source of the pain into one of three primary buckets: (1) Mechanical/Overuse, (2) Neuropathic, or (3) Systemic/Sinister.
Category 1: Mechanical/Overuse: This is the most common category. It includes Plantar Fasciitis (Thomas & Christensen, 2024), Achilles Tendinopathy (American Academy of Family Physicians, 2018a), Sever's Disease (in children) (Sha, 2023), Calcaneal Stress Fractures, and Heel Fat Pad Syndrome (Alshami & Babri, 2024). The unifying feature of this group is that the pain has a clear and logical relationship to mechanical load and activity cycles.
Category 2: Neuropathic (The "Mimics"): This is the most commonly misdiagnosed category, including Tarsal Tunnel Syndrome (National Library of Medicine, 2022) and Baxter's Nerve Entrapment (Fondazione Società Italiana di Neurologia, 2025). The key feature is not the timing of the pain, but its character. The pain is described as "burning, tingling, numbness, or shooting" (American Academy of Family Physicians, 1999, 2018a).
Category 3: Systemic/Sinister (The "Red Flags"): This is the most dangerous category, as it may signal a more serious underlying disease. This group includes Gout (Singh & T, 2024), Ankylosing Spondylitis (Cuesta-Vargas & Roldán-Jiménez, 2024), Calcaneal Tumors (Li et al., 2018), and Osteomyelitis (Kumar & Pruthi, 2019). The key features are non-mechanical. The presentation is one of acute inflammation (a hot, red, swollen, and exquisitely tender joint) (Kumar & Pruthi, 2019; Singh & T, 2024) or neoplastic/infectious "red flags" (e.g., night pain, pain at rest, fever, or pain in the absence of any trauma or overuse) (Li et al., 2018).