Introduction / Definition

Plantar fasciitis is the most prevalent cause of inferior heel pain in adults, accounting for approximately 10% of running-related injuries and a substantial burden of foot and ankle consultations. Although historically considered an inflammatory condition, histological evaluations consistently reveal non-inflammatory, degenerative changes—specifically angiofibroblastic hyperplasia, microtearing of collagen fibres, chondroid metaplasia, and matrix disorganisation. Consequently, the condition is more accurately classified as a plantar fasciosis or enthesopathy.

Epidemiology

• Demographics: Bimodal distribution, peaking in active athletic populations (runners aged 20–40 years) and sedentary individuals aged 40–60 years.
• Sex: Slight female predominance in the non-athletic cohort; equal distribution among runners.
• Risk Factors: Elevated Body Mass Index (BMI > 30 kg/m² confers a significant odds ratio), sudden increase in weight-bearing activity, prolonged occupational standing, reduced ankle dorsiflexion (tight gastrocnemius-soleus complex), and abnormal foot biomechanics (both pes planus and rigid pes cavus).

Relevant Anatomy

• Structure: The plantar fascia (aponeurosis) consists of medial, central, and lateral bands. The central band is the thickest and clinically most significant.
• Origin & Insertion: Arises proximally from the medial process of the calcaneal tuberosity, spans the sole, and divides into five digital slips inserting into the plantar plates, fibrous flexor sheaths, and bases of the proximal phalanges via the superficial transverse metatarsal ligament.
• Windlass Mechanism (Hicks, 1954): During the terminal stance and toe-off phases of the gait cycle, passive extension (dorsiflexion) of the metatarsophalangeal (MTP) joints draws the plantar aponeurosis over the metatarsal heads. This winds the fascia around the head, shortening the distance between the calcaneus and metatarsals, elevating the medial longitudinal arch, and converting the flexible foot into a rigid lever for forward propulsion.
• Neurovascular Relations:
  • First branch of the lateral plantar nerve (Baxter’s nerve): Courses between the abductor hallucis and quadratus plantae, then deep to flexor digitorum brevis. It can become entrapped anterior to the medial calcaneal tuberosity, mimicking or coexisting with plantar fasciitis.
  • Medial calcaneal nerve branches: Pierce the deep fascia to provide sensory innervation to the medial heel pad.

Classification

While no single universal surgical classification dictates treatment, clinical practice categorises the condition based on chronology and morphology:

• Acute: Symptoms persisting < 6 weeks.
• Subacute: Symptoms persisting 6–12 weeks.
• Chronic / Recalcitrant: Symptoms persisting > 3 to 6 months despite compliance with structured conservative management.
• Anatomic Subtyping: Proximal (classic medial calcaneal insertion; >90%), Mid-substance (central arch), or Distal (near cord/insertions, less common).

Clinical Presentation & Examination

Symptoms

• Post-static dyskinesia: Intense, sharp heel pain with the initial steps in the morning or after prolonged periods of rest, easing after initial ambulation ('limping warm-up'), and worsening again towards the end of the day or after prolonged standing.
• Pain aggravated by walking barefoot or on hard surfaces.

Clinical Examination

• Inspection: Assessment of resting foot posture (pes cavus vs pes planus, hindfoot alignment), gait pattern, and presence of heel fat pad atrophy.
• Palpation: Maximal focal tenderness directly over the anteromedial calcaneal tubercle. Tenderness extending along the central slip suggests midfoot fascial involvement.
• Provocative Tests:
  • Windlass Test (Jack’s test in weight-bearing): Passive dorsiflexion of the first MTP joint with the ankle stabilised reproduces inferior medial heel pain (high specificity, moderate sensitivity).
  • Silfverskiöld Test: Evaluates isolated gastrocnemius contracture vs gastrocnemius-soleus complex tightness by comparing passive ankle dorsiflexion with the knee fully extended versus 90° flexed.
  • Baxter's Nerve Assessment: Palpation along the course of the first branch of the lateral plantar nerve between abductor hallucis and quadratus plantae; check for sensory alterations over the lateral plantar heel/fifth digit and motor weakness of abductor digiti minimi.
  • Calcaneal Squeeze Test: Bilateral mediolateral compression of the calcaneal body; positive in calcaneal stress fracture.

Investigations

Plantar fasciitis is predominantly a clinical diagnosis. Imaging is reserved for atypical presentations, red flags, or failure of 2–3 months of non-operative care.

• Weight-Bearing Plain Radiographs (AP, Lateral, Axial Calcaneum):
  • Lateral views may reveal an enthesophytic plantar calcaneal spur (present in up to 50% of symptomatic patients, but also in 15–25% of asymptomatic controls; spurs arise within the flexor digitorum brevis origin rather than strictly inside the fascia).
  • Excludes calcaneal stress fractures, osteolytic lesions, bone cysts, or Paget's disease.
• Diagnostic Ultrasound:
  • First-line dynamic imaging. Positive findings include fascia thickness > 4.0 mm at the calcaneal insertion (normal: 2–3 mm), hypoechogenicity, loss of normal fibrillar architecture, and perifascial fluid.
• Magnetic Resonance Imaging (MRI):
  • Indicated for diagnostic uncertainty or surgical workup.
  • Demonstrates fusiform fascial thickening (> 4 mm), increased T2/STIR signal hyperintensity within the proximal fascia, and adjacent calcaneal bone marrow oedema. Rules out avascular necrosis, undisplaced calcaneal fractures, and soft tissue tumours.
• Electromyography / Nerve Conduction Studies (EMG/NCS): Indicated if tarsal tunnel syndrome or Baxter nerve entrapment is strongly suspected.
• Inflammatory Markers / Serology (HLA-B27, RF, ESR, CRP): Indicated in bilateral presentation, younger males, or concomitant axial back pain to rule out seronegative spondyloarthropathies.

Management

Non-Operative Management

Non-operative management resolves symptoms in > 90% of patients within 10–12 months.

1. First-Line Conservative Measures (0–3 months):
   • Activity Modification & Analgesia: Relative rest, ice rolling, non-steroidal anti-inflammatory drugs (NSAIDs) for acute pain control.
   • Plantar Fascia-Specific Stretching: DiGiovanni et al. demonstrated that tissue-specific stretching of the plantar fascia (dorsiflexing the toes with the hand) produces superior outcomes compared to non-specific Achilles stretching.
   • Gastrocnemius-Soleus Complex Stretching: Essential when equinus contracture is present.
   • Orthotics & Footwear: Silicon heel cups, prefabricated arch supports, and supportive, stiff-soled shoes with a slight heel raise.
2. Second-Line Interventions (3–6 months):
   • Night Splints: Maintain the ankle in neutral/slight dorsiflexion to prevent nocturnal fascial contracture.
   • Extracorporeal Shock Wave Therapy (ESWT): Induces microtrauma, neovascularisation, and down-regulation of substance P. Strong randomised controlled trial (RCT) evidence supports radial/focused ESWT in chronic recalcitrant plantar fasciitis.
   • Corticosteroid Injections: Provide effective short-term symptom relief (4–8 weeks), but carry risks of plantar fascia rupture (reported in up to 10%) and permanent heel fat pad atrophy. Best performed under ultrasound guidance.
   • Platelet-Rich Plasma (PRP) / Autologous Blood Injections: Emerging biological adjuncts with emerging clinical trial evidence demonstrating efficacy comparable or superior to steroids at 6–12 months without tissue necrosis.

Operative Management

Reserved exclusively for patients with recalcitrant symptoms lasting at least 6–12 months despite exhaustive compliance with multimodality conservative therapy (comprising < 5% of cases).

1. Partial Plantar Fascia Release (Fasciotomy):
   • Open Partial Release: Performed via an oblique medial or direct plantar incision. Crucial rule: Release only the medial 30% to 50% of the central band. Complete release must be strictly avoided to prevent destabilisation of the medial longitudinal arch, lateral column strain, and cuboid syndrome (midfoot subluxation).
   • Endoscopic Plantar Fasciotomy (EPF): Single or dual-portal technique. Offers quicker recovery and lower wound complication rates, though carries a risk of inadvertent over-release or nerve injury (Baxter's nerve or lateral plantar nerve branches).
2. Proximal Medial Gastrocnemius Recession (Strayer Procedure):
   • Indicated in patients with isolated gastrocnemius tightness confirmed on Silfverskiöld testing.
   • Releases the tight posterior tether, alleviating excessive tensile forces transmitted to the plantar aponeurosis via the calcaneus without compromising intrinsic arch stability.
3. Baxter’s Nerve Neurolysis:
   • Often performed concurrently with partial fasciotomy if preoperative examination reveals clinical signs of first branch lateral plantar nerve entrapment.

Complications

• Surgical Complications:
  • Arch Collapse & Lateral Column Overload: Consequence of releasing > 50% of the fascia; manifests as persistent dorsolateral midfoot and cuboid pain.
  • Nerve Injury / Neuroma: Iatrogenic transection of the medial calcaneal nerve or lateral plantar nerve.
  • Recurrence of Symptoms: Often due to inadequate partial release, persistent equinus, or unrecognized Baxter's entrapment.
  • Calcaneal Stress Fracture: Resulting from altered biomechanical weight transfer post-release.
• Non-Operative Complications:
  • Heel fat pad atrophy and spontaneous plantar fascia rupture following repeated corticosteroid injections.

Exam Pearls (Viva & Written)

• Calcaneal spurs are present in flexor digitorum brevis, not the plantar fascia, and excision of the spur is not necessary for clinical resolution.
• Releasing greater than 50% of the plantar fascia drastically diminishes the Windlass mechanism, leading to transverse tarsal collapse and lateral column overload (cuboid syndrome).
• The DiGiovanni stretching protocol specifically tensions the plantar fascia across the metatarsal heads rather than stretching the Achilles tendon alone, showing superior short- and long-term functional recovery.
• The first branch of the lateral plantar nerve (Baxter’s nerve) runs between abductor hallucis and quadratus plantae; nerve entrapment must be differentiated from recalcitrant plantar fasciitis.