Plantar fasciitis is the most common cause of heel pain, characterized by degenerative thickening and inflammation of the plantar fascia at its calcaneal medial tuberosity insertion, affecting 10% of the adult population during their lifetime. Histopathologically, chronic degenerative process (plantar fasciosis) dominates rather than acute inflammation — collagen type I degeneration, fibroblast proliferation, mucoid degeneration, and neovascularization are seen, with no significant inflammatory cell infiltration. Common in adults aged 40-60, runners (especially distance runners), obese individuals (BMI >30), those standing for prolonged periods, and individuals with flat feet or excessive pronation. The characteristic clinical finding is stabbing heel pain with first steps in the morning — the fascia remains in a contracted position overnight and stretching on the first step produces pain. On MRI, plantar fascia thickening (>4mm, normal 2-4mm), T2/STIR signal increase at the calcaneal insertion, and calcaneal bone marrow edema are diagnostic findings. Treatment is generally conservative with 80-90% of patients recovering within 12 months.
Age Range
30-60
Peak Age
45
Gender
Equal
Prevalence
Very Common
The plantar fascia is a thick fibrous structure (plantar aponeurosis) extending from the calcaneal medial tuberosity to the metatarsal heads, supporting the foot arch — providing dynamic stabilization through the 'windlass mechanism' during walking and running. Repetitive mechanical stress (running, prolonged standing, obesity → increased body weight) creates microtrauma at the calcaneal insertion (enthesis) of the plantar fascia — particularly affecting Sharpey fibers at the fascia-bone junction. The acute inflammatory response transforms over time into a chronic degenerative process: collagen type I fibers become disorganized and fragment, mucoid degeneration begins (proteoglycan and glycosaminoglycan accumulation), fibroblast proliferation develops (immature, mechanically weak type III collagen production), neovascularization forms (disorganized vascular structures carrying pain nerve fibers) — this composite process is described as 'angiofibroblastic hyperplasia' and histopathologically inflammatory cells are not prominent ('fasciitis' is misleading, 'fasciosis' is more accurate). MRI findings directly reflect this pathophysiology: fascial thickening (>4mm) = collagen degeneration + fibroblast proliferation increasing tissue volume, T2/STIR signal increase = mucoid degeneration + interstitial edema (increased free water protons → long T2), calcaneal bone marrow edema = enthesopathy — chronic traction stress at fascia-bone junction causing trabecular microfractures and vascular congestion. Calcaneal bone spur is a bony reactive response to chronic traction force (Wolff's law — new bone formation along mechanical stress direction) — but not everyone with a spur is symptomatic, and patients without spurs can also be diagnosed with plantar fasciitis.
Plantar fascia thickening >4mm and T2 hyperintense signal increase at calcaneal insertion on sagittal MRI is the most characteristic and reliable MRI finding for plantar fasciitis. Diagnostic confidence increases when calcaneal bone marrow edema and perifascial edema accompany.
On sagittal T2 fat-sat or STIR images, plantar fascia thickening >4mm and T2 signal increase are seen at the calcaneal insertion. Normal plantar fascia appears as a 2-4mm homogeneous low signal band — tight packing of collagen fibers produces ultra-short T2. Thickening and signal increase diminish from insertion distally — the proximal portion (enthesis) is the most affected area. Intrafascial signal increase may be focal (small tear or focal degeneration) or diffuse (widespread degeneration). Axial images evaluate fascial width and lateral extent. Fusiform (spindle-shaped) thickening is typical — reflecting focal concentration of the degenerative process.
Report Sentence
Plantar fascia thickening >4mm and T2 signal increase are noted at the calcaneal insertion, consistent with plantar fasciitis.
On STIR or T2 fat-sat images, hyperintense signal increase in the calcaneal medial tuberosity bone marrow is seen — reflecting chronic traction stress at the fascia-bone junction (enthesis) causing trabecular microfractures and vascular congestion. This indicates enthesopathy and shows strong correlation with pain — patients with bone marrow edema have more severe symptoms. Bone marrow edema concentrates in the subchondral region (insertion point) and does not show diffuse spread — this feature allows differentiation from calcaneal stress fracture (diffuse edema + fracture line). On T1, bone marrow edema shows low signal — loss of bright signal of normal fatty marrow.
Report Sentence
Hyperintense bone marrow edema is noted at the calcaneal medial tuberosity on STIR, consistent with active enthesopathy.
On longitudinal B-mode US, thickening (>4mm, normal 2-4mm) and loss of normal fibrillar echo with hypoechoic appearance are seen at the calcaneal insertion of the plantar fascia. Normal plantar fascia appears as a thin, hyperechoic band with smooth fibrillar pattern — parallel collagen fibers produce strong echoes. In degeneration, fibrillar pattern is disrupted, fascia thickens, and hypoechoic areas develop. Intrafascial calcification (hyperechoic foci) may be seen in chronic cases. Perifascial fluid or edema may appear as surrounding hypoechoic halo. Contralateral comparison reveals asymmetry — bilateral measurement is the standard approach. US is used for primary assessment and treatment response monitoring due to its accessibility and low cost.
Report Sentence
Plantar fascia thickening >4mm, hypoechoic degeneration, and fibrillar pattern disruption are noted at the calcaneal insertion on US, consistent with plantar fasciitis.
On T2 fat-sat images, soft tissue edema (perifascial edema) around the plantar fascia is seen as hyperintense signal increase. Perifascial edema reflects acute exacerbation and correlates with pain — an important parameter for treatment response monitoring. Edema is most prominent at fascial insertion and decreases distally. Edema is prominent at the boundary between the plantar fat pad (heel fat pad) and fascia. Patients with clinically active symptoms have perifascial edema, while it is generally absent in chronic asymptomatic degeneration.
Report Sentence
Perifascial soft tissue edema is noted surrounding the plantar fascia, consistent with active plantar fasciitis.
Increased vascularity (neovascularization) at the calcaneal insertion of the plantar fascia is seen on power Doppler — indicating active degenerative process. Normal plantar fascia is avascular with no Doppler signal — any intrafascial Doppler signal is considered pathological. Neovascularization identifies pain-generating regions — newly formed vessels carry pain nerve fibers (free nerve endings carrying substance P, CGRP). Doppler signal decrease in treatment monitoring correlates with clinical improvement.
Report Sentence
Neovascularization is noted at the plantar fascia insertion on power Doppler, consistent with active degenerative process.
On lateral radiograph and CT, a traction osteophyte (bone spur) may be seen on the plantar surface of calcaneus — a bony reactive response to chronic traction force of the plantar fascia (Wolff's law). Spur size varies from millimeters to centimeters. Diagnostic value is limited — calcaneal spurs are also found in 10-27% of asymptomatic individuals, while 40-60% of plantar fasciitis patients have spurs. Large spurs (>10mm) with surrounding soft tissue edema support symptomatic disease. CT thin-section evaluation provides detailed assessment of spur morphology, fascia-spur relationship, and accompanying pathologies.
Report Sentence
A traction osteophyte (bone spur) is seen on the plantar surface of the calcaneus.
Criteria
<6 weeks symptom duration. Fascial and perifascial edema prominent on MRI, enhancement on contrast sequences.
Distinct Features
Calcaneal BME commonly accompanies. Usually responds well to conservative treatment — stretching, ice, NSAIDs. Pain worst with first morning steps.
Criteria
>6 months symptoms. Histopathologically degeneration predominates, no inflammatory cell infiltration.
Distinct Features
Fascial thickening prominent but less or absent perifascial edema. T2 signal increase may be focal and heterogeneous. Calcaneal spur common. Lower response to conservative treatment — PRP, ESWT, or surgery may be considered.
Criteria
Partial or complete loss of fascial continuity. Usually after corticosteroid injection or acute trauma.
Distinct Features
MRI shows fascial discontinuity + fluid-filled gap (T2 hyperintense gap). Perifascial hemorrhage and edema prominent. History of acute pain increase — 'pop' sensation. Rupture risk 2-3% after corticosteroid injection — risk increases with number of injections.
Distinguishing Feature
Calcaneal stress fracture shows linear low-signal fracture line on T1 and diffuse bone marrow edema, while plantar fasciitis shows prominent fascial thickening with marrow edema limited to insertion (focal). Fascia is normal thickness in stress fracture.
Distinguishing Feature
Achilles tendinopathy shows tendon pathology (thickening, signal increase) at posterior calcaneus level, while plantar fasciitis shows fascial pathology on plantar (inferior) surface — anatomic localization differs. Both pathologies may coexist.
Distinguishing Feature
Retrocalcaneal bursitis shows distended fluid-filled bursa anterior to Achilles tendon, while plantar fasciitis shows fascial thickening at insertion — different anatomic structure and location.
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
3-monthPlantar fasciitis treatment follows a stepwise conservative approach with 80-90% recovery in 6-12 months. First step (first 6 weeks): stretching exercises (plantar fascia and gastrosoleus — most effective conservative method), NSAIDs (ibuprofen 2-4 weeks), ice massage (3-4 times daily, 15-20 minutes), activity modification (shock-absorbing shoes, avoid running), night splint (dorsiflexion position — reduces morning pain). Second step (6 weeks-3 months): orthotic insoles (medial arch support — corrects pronation), US-guided corticosteroid injection (around fascia — effective short-term but 2-3% rupture risk — maximum 3 injections recommended), physiotherapy (eccentric exercises, deep friction massage). Third step (3-12 months non-responsive — 10-20%): ESWT (60-80% success), PRP injection (more effective long-term than corticosteroid — evidence level increasing), US-guided tenotomy (tendon fenestration — targets neovascularization). Fourth step (12+ months refractory — 5-10%): surgical plantar fascia release (partial or complete — medial 1/3 cut), endoscopic plantar fasciotomy. Complications: pes planus progression (arch loss with excessive release), lateral column pain, nerve damage.
Plantar fasciitis resolves with conservative treatment in 6-12 months in 90% of cases. Treatment options include stretching exercises, orthotics, NSAIDs, corticosteroid injection, and extracorporeal shock wave therapy. Partial plantar fascia release may be performed in resistant cases. Chronic corticosteroid injections increase fascia tear risk.