10.3 Foot and Ankle Conditions: Sprains, Achilles Tendinopathy & Plantar Fasciopathy

10.3 Foot and Ankle Conditions: Sprains, Achilles Tendinopathy & Plantar Fasciopathy

[!NOTE] DHA Clinical Competency Focus: Foot and ankle pathologies feature prominently on the DHA Physiotherapist licensing examination. Candidates are required to demonstrate expertise in the triplanar kinematics of the subtalar joint and the plantar fascia windlass mechanism, apply the Ottawa Ankle Rules to eliminate unnecessary radiography, differentiate lateral ligament injuries from syndesmotic high ankle sprains, construct evidence-based eccentric and heavy slow resistance protocols for Achilles tendinopathies, identify complete Achilles tendon ruptures via the Thompson test, and direct conservative management for plantar fasciopathy.

The foot and ankle complex functions as both a mobile, shock-attenuating adapter during early stance (initial contact to loading response) and a rigid, stable propulsive lever during terminal stance and pre-swing. Pathomechanics at this distal interface reverberate proximally throughout the lower extremity kinetic chain.

---

1. Foot & Ankle Biomechanics, Triplanar Motion & the Windlass Mechanism

Articular Kinematics: Talocrural vs. Subtalar Joints

• Talocrural (Mortise) Joint:
  • Formed by the distal tibia, medial malleolus, lateral malleolus of the fibula, and the trochlea of the talus.
  • It is a uniaxial modified hinge joint with an oblique axis passing through both malleoli (tilted ~8° from the frontal plane and ~20°–30° from the transverse plane).
  • Arthrokinematics: The convex talus articulates within the concave mortise. During dorsiflexion, the talus rolls anteriorly and glides posteriorly while wedging its wider anterior dome into the mortise (close-packed position). During plantarflexion, the talus rolls posteriorly and glides anteriorly.

+-----------------------------------------------------------------------------------+
|                         Subtalar Joint Triplanar Motion                           |
+-----------------------------------------------------------------------------------+
| Open-Kinetic Chain (OKC - Foot Free):                                             |
|   - PRONATION: Calcaneal Eversion + Abduction + Dorsiflexion                      |
|   - SUPINATION: Calcaneal Inversion + Adduction + Plantarflexion                  |
+-----------------------------------------------------------------------------------+
| Closed-Kinetic Chain (CKC - Foot Planted):                                        |
|   - PRONATION: Calcaneal Eversion + Talar Adduction + Talar Plantarflexion        |
|                (Facilitates tibial internal rotation, knee flexion/valgus)        |
|   - SUPINATION: Calcaneal Inversion + Talar Abduction + Talar Dorsiflexion        |
|                (Facilitates tibial external rotation, knee extension/varus)       |
+-----------------------------------------------------------------------------------+

The Windlass Mechanism of the Plantar Fascia (Hicks, 1954)

The plantar aponeurosis originates from the medial process of the calcaneal tuberosity and extends distally into five slips inserting into the plantar plates and proximal phalanges of the toes.

• Mechanical Action: During terminal stance and push-off, the heel rises while the metatarsophalangeal (MTP) joints undergo passive dorsiflexion (hyperextension) up to 60°. This passive extension winds the thick plantar fascia around the rounded heads of the metatarsals (acting as a mechanical windlass drum or pulley).
• Biomechanical Result:
  1. Tensions the plantar aponeurosis and draws the calcaneus toward the metatarsal heads.
  2. Elevates and tightens the medial longitudinal arch.
  3. Drives the subtalar joint into inversion (supination), locking the midtarsal (transverse tarsal) joints.
  4. Converts the flexible, shock-absorbing foot into a rigid, unyielding lever for explosive forward propulsion.

---

2. Lateral Ankle Sprains, Ligamentous Vulnerability & The Ottawa Ankle Rules

Mechanism & Ligamentous Sequence of Injury

Over 85% of all ankle sprains occur secondary to an inversion and plantarflexion mechanism, tearing the lateral collateral ligamentous complex in an established hierarchical sequence:

[ Inversion + Plantarflexion Stress ]
                 │
                 ▼
  ┌────────────────────────────────────────────────────────┐
  │ 1. Anterior Talofibular Ligament (ATFL)                │ ◄── WEAKEST; tears first (~85%)
  │    - Taut in plantarflexion; tested via Anterior Drawer│
  ├────────────────────────────────────────────────────────┤
  │ 2. Calcaneofibular Ligament (CFL)                      │ ◄── STRONGER; tears second (~20-40%)
  │    - Taut in neutral/dorsiflexion; tested via Tilt Test│
  ├────────────────────────────────────────────────────────┤
  │ 3. Posterior Talofibular Ligament (PTFL)               │ ◄── STRONGEST; tears rarely (~<5%)
  │    - Taut in extreme dorsiflexion; severe dislocations │
  └────────────────────────────────────────────────────────┘

Physical Examination & Instability Testing

• Anterior Drawer Test:
  • Target: Evaluates the integrity of the Anterior Talofibular Ligament (ATFL).
  • Technique: Patient supine or sitting, knee flexed to 90° (relaxes gastrocnemius), ankle positioned in 10° to 20° of plantarflexion. Examiner stabilizes distal anterior tibia with one hand while grasping the calcaneus with the other, translating the foot anteriorly.
  • Positive Sign: Increased anterior excursion (>3–5 mm compared to contralateral side) or a visible "dimple" / suction sign over the ATFL fossa.
• Talar Tilt Test (Inversion Stress Test):
  • Target: Evaluates the Calcaneofibular Ligament (CFL).
  • Technique: Ankle positioned in 0° neutral dorsiflexion (which slacks ATFL and tensions CFL). Examiner inverts the calcaneus.
  • Positive Sign: Excessive tilt (>5°–10° difference from uninjured side) with a soft or absent endpoint.

The Ottawa Ankle & Foot Rules for Radiography

The Ottawa Ankle Rules (OAR) possess a sensitivity approaching 100% for identifying acute malleolar and midfoot fractures, safely reducing unnecessary negative radiographs by >30%.

---

3. Syndesmotic (High Ankle) Sprains & Chronic Ankle Instability (CAI)

Syndesmotic (High) Ankle Sprain

• Anatomy: The distal tibiofibular syndesmosis comprises the Anterior Inferior Tibiofibular Ligament (AITFL), Posterior Inferior Tibiofibular Ligament (PITFL), transverse tibiofibular ligament, and interosseous membrane/ligament.
• Injury Mechanism: Violent external rotation of the foot on the tibia, accompanied by hyper-dorsiflexion. As the talus externally rotates, its wide anterior trochlear dome forcibly wedges into the mortise, spreading the distal fibula away from the tibia.
• Special Diagnostic Tests:
  1. Squeeze Test (Hopkins Test): Examiner compresses the fibula against the tibia at the mid-calf level. Positive: Reproduction of sharp pain at the distal syndesmosis (AITFL region).
  2. External Rotation Test (Kleiger Test): Patient seated with knee at 90°; examiner holds ankle in neutral/slight dorsiflexion and passively externally rotates the foot. Positive: Sharp anterolateral pain at the distal syndesmosis.
• Prognostic Rule: Syndesmotic sprains take 2 to 3 times longer to rehabilitate than standard lateral ankle sprains (typically 6 to 12 weeks versus 2 to 4 weeks). Premature return to sport risks heterotopic ossification, chronic syndesmotic widening, and rapid post-traumatic talocrural osteoarthritis.

Chronic Ankle Instability (CAI): Mechanical vs. Functional

• Mechanical Instability: Anatomical laxity (positive drawer/tilt), synovial impingement, osteochondral lesions of the talus, or joint hypomobility (specifically restriction of the posterior talar glide following repetitive anterior subluxations).
• Functional Instability: Subjective feeling of the ankle "giving way" despite normal or near-normal ligamentous laxity. Driven by sensorimotor impairments, mechanoreceptor denervation, delayed reflex contraction of the peroneus (fibularis) longus and brevis, and impaired postural stability.
• Evidence-Based Rehabilitation for CAI:
  1. Manual Therapy: Maitland Grade III–IV posterior talar glides (restores dorsiflexion ROM and normalizes arthrokinematics).
  2. Sensorimotor & Balance Retraining: Balance Error Scoring System (BESS) drills, wobble board, star excursion balance training, and unpredictable perturbation platforms.
  3. Reactive Neuromuscular Training: Agility ladder, sudden direction change drills, and eccentric peroneal strengthening.

---

4. Achilles Tendinopathy & Acute Achilles Tendon Rupture

Achilles Tendinopathy: Midportion vs. Insertional

Achilles tendinopathy is a non-inflammatory degenerative tendinosis characterized by failed tendon healing, tenocyte proliferation, hypervascular neovascularization, and disorganized collagen bundles.

+-----------------------------------------------------------------------------------+
|                Achilles Tendinopathy: Midportion vs Insertional                   |
+-----------------------------------------------------------------------------------+
| 1. Midportion Tendinopathy:                                                       |
|    - Location: 2 to 6 cm proximal to calcaneus in the hypovascular watershed zone |
|    - Royal London Hospital Test: Tendon tenderness decreases when dorsiflexed     |
|    - Painful Arc Test: Palpable nodule moves with plantar/dorsiflexion            |
|    - Exercise: Alfredson Eccentric Heel Drops OFF THE EDGE OF A STEP              |
+-----------------------------------------------------------------------------------+
| 2. Insertional Tendinopathy:                                                      |
|    - Location: At the bone-tendon junction / superior calcaneal tuberosity        |
|    - Association: Retrocalcaneal bursitis, Haglund's deformity                    |
|    - Critical Rule: Heel drops must be performed on FLAT GROUND; avoiding         |
|      dorsiflexion beyond neutral prevents compressive impingement against calcaneus|
+-----------------------------------------------------------------------------------+

• Evidence-Based Loading Protocols:
  • Alfredson Eccentric Protocol: 3 sets of 15 repetitions, twice daily for 12 weeks, performed with the knee straight (isolates gastrocnemius) and knee bent (isolates soleus). Patient raises up using unaffected limb, then lowers down eccentrically using only the injured tendon.
  • Heavy Slow Resistance (HSR) Training: 3 sessions per week; 3–4 sets of 6–8 repetition maximum (RM) with a 3-second concentric and 3-second eccentric tempo using leg press, calf raises, and seated soleus raises. Equal clinical efficacy to Alfredson with superior long-term tissue compliance.

Acute Achilles Tendon Rupture: The Diagnostic Triad

Acute rupture typically occurs in male "weekend warrior" athletes aged 30–50 during sudden explosive plantarflexion push-off or violent forced dorsiflexion. The classic triad includes:

1. Thompson (Simmonds) Calf Squeeze Test: Patient lies prone with feet extending off the table. The examiner firmly squeezes the middle third of the calf belly. Positive Sign: Complete absence of passive plantarflexion. (Normal response is reflexive passive plantarflexion).
2. Palpable Tendon Defect: A visible and palpable gap / divot 2 to 6 cm proximal to the calcaneus.
3. Positive Matles Test: Patient lies prone with both knees actively flexed to 90°. On the uninjured side, the foot rests in natural slight plantarflexion (~20°–30°). On the ruptured side, the foot falls into neutral or passive dorsiflexion due to loss of resting Achilles tension.

---

5. Plantar Fasciopathy: Pathomechanics & Rehabilitation

Clinical Presentation & Diagnostic Windlass Test

• Pathomechanics: Repetitive tensile microtrauma at the origin of the plantar aponeurosis on the medial process of the calcaneal tubercle, leading to myxoid degeneration, collagen fragmentation, and calcification (heel spurs may coexist but are asymptomatic incidental findings in ~50% of the population).
• Hallmark Symptom: Excruciating, sharp, stabbing heel pain during the very first steps in the morning or when standing up after prolonged sitting (post-static dyskinesia). Pain eases somewhat after walking for several minutes as the tissue warms up, but intensifies by the end of the day with prolonged weight-bearing.
• The Windlass Test:
  • Patient non-weight-bearing (sitting) or weight-bearing (standing on a step with toes extending over edge).
  • Examiner stabilizes the calcaneus and forcibly dorsiflexes (hyperextends) the first metatarsophalangeal (MTP) joint while palpating the medial calcaneal tubercle.
  • Positive Sign: Reproduction of familiar plantar heel pain at the medial tubercle.

Evidence-Based Rehabilitation Interventions

+-----------------------------------------------------------------------------------+
|                    Evidence-Based Interventions for Plantar Fasciopathy           |
+-----------------------------------------------------------------------------------+
| 1. Plantar Fascia-Specific Tissue Stretching (DiGiovanni Technique):             |
|    - Patient sits, crosses affected foot over opposite knee. Pulls all toes back  |
|      into maximal extension with one hand, palpating taut plantar fascia with     |
|      the other. Perform 10s holds x 10 reps, 3x/day (CRITICAL BEFORE FIRST MORNING|
|      STEPS to prevent acute micro-tearing).                                       |
+-----------------------------------------------------------------------------------+
| 2. High-Load Tensile Strength Training (Rathleff Protocol):                       |
|    - Unilateral heel raises performed with a rolled towel under the toes to       |
|      engage the windlass mechanism.                                               |
|    - 3-second concentric, 2-second isometric pause at top, 3-second eccentric.    |
|    - 3 sets of 12RM, progressing to 8RM every other day for 12 weeks.             |
+-----------------------------------------------------------------------------------+
| 3. Night Splints:                                                                 |
|    - Holds ankle in 5° dorsiflexion and toes in extension overnight to prevent    |
|      fascial contracture in shortened plantarflexion, reducing morning agony.     |
+-----------------------------------------------------------------------------------+
| 4. Orthoses & Taping:                                                             |
|    - Low-Dye arch taping provides immediate short-term pain relief.               |
|    - Prefabricated or custom medial longitudinal arch supports redistribute loads.|
+-----------------------------------------------------------------------------------+

---

6. Clinical Scenario & DHA Exam Traps

Clinical Scenario: High Ankle Sprain vs. Inversion Sprain

Scenario: A 26-year-old rugby player is tackled with his right foot pinned to the turf while his torso rotates vigorously outward. He presents to the clinic with severe anterior lower leg pain, marked swelling above the ankle joint, and an inability to bear full weight. On examination:

• Anterior drawer test of the ankle is negative; talar tilt test is unremarkable.
• Tenderness is absent along the distal tip of both malleoli (Ottawa Ankle Rules negative for fracture).
• The Squeeze test at mid-calf reproduces intense, sharp pain at the distal anterior syndesmosis.
• The External Rotation (Kleiger) test reproduces exquisite pain over the anterior inferior tibiofibular ligament (AITFL) and proximal interosseous membrane.

Clinical Decision-Making: The patient has sustained an acute syndesmotic (high ankle) sprain, NOT a standard lateral ankle sprain. The physical therapist must educate the patient that recovery will take significantly longer than an ordinary sprain (6–10 weeks). Initial management requires a period of non-weight-bearing immobilization in a walking boot, strict avoidance of early aggressive dorsiflexion and external rotation, and progressive functional retraining only once syndesmotic separation has fully healed.

DHA Exam Traps to Avoid

[!WARNING]

• Trap 1: Insertional vs. Midportion Achilles Exercise Technique: In insertional Achilles tendinopathy, do NOT prescribe heel drops off the edge of a step. Dropping below neutral into deep dorsiflexion produces severe compressive impingement of the insertion against the calcaneus. Insertional tendinopathy must be trained on flat ground only.
• Trap 2: Ottawa Ankle Rules Timing & Weight-Bearing: DHA questions often test the weight-bearing criterion of the Ottawa rules. A patient must be unable to bear weight both immediately after the injury AND for 4 steps during clinical evaluation. If a patient was carried off the field but can walk 4 steps in the clinic, the weight-bearing criterion is NOT positive.
• Trap 3: Interpreting the Thompson Test: In an Achilles tendon rupture, squeezing the calf produces NO movement (absent plantarflexion). Do not select "hyperactive plantarflexion" or "excessive dorsiflexion"—the absence of movement confirms the complete loss of tendon continuity.