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Subtalar Joint

Joints

The subtalar (talocalcaneal) joint is a triplanar joint between the talus and calcaneus that produces the clinically essential movements of inversion and eversion — the movements that allow the foot to adapt to uneven terrain. It is the primary site of pronation and supination in the rearfoot and a key link in the kinetic chain between the ankle and the midfoot.

Classification

  • Type: Synovial plane (with three facets creating triplanar motion)
  • Degrees of freedom: 1 (functionally triplanar — the single axis of rotation produces simultaneous inversion/eversion, adduction/abduction, and plantarflexion/dorsiflexion)
  • Region: Rearfoot (between anatomy/joints/talocrural above and anatomy/joints/midtarsal below)

Articular Surfaces

  • Inferior talus: Three facets — posterior (largest, concave), middle (convex), and anterior (convex) — that articulate with corresponding calcaneal facets
  • Superior calcaneus: Three reciprocal facets — posterior (largest, convex), middle (concave), and anterior (concave)
  • Tarsal canal and sinus tarsi: The space between the posterior and middle/anterior facets forms the tarsal canal (medially) and sinus tarsi (laterally). The sinus tarsi is palpable as a depression just anterior and inferior to the lateral malleolus — it is a key clinical landmark for sinus tarsi syndrome and subtalar pathology.

Movements and ROM

Movement Normal ROM Axis Clinical Presentation
Inversion 20–30° Oblique (42° from transverse, 16° from sagittal) Sole turns medially — the foot supinates
Eversion 5–10° Same oblique axis Sole turns laterally — the foot pronates
Pronation and supination are triplanar motions. Pronation = eversion + dorsiflexion + abduction. Supination = inversion + plantarflexion + adduction. These combined motions occur around the subtalar joint's single oblique axis. Overpronation is the most common foot dysfunction and a contributor to numerous lower extremity conditions.

Capsular Pattern

Inversion (varus) limitation Inversion is more limited than eversion in subtalar capsular restriction.

Resting Position

  • Midway between inversion and eversion (subtalar neutral)
  • Subtalar neutral is the reference position for orthotic assessment

Close-Packed Position

  • Full inversion (supination)
  • Maximum surface interlocking, ligaments taut

End-Feels

Movement Normal End-Feel Type
Inversion Capsular (firm) Lateral capsule, CFL, peroneal tendons, extensor retinaculum
Eversion Capsular (firm) Medial capsule, deltoid ligament, tibialis posterior tendon

Ligaments

Interosseous Talocalcaneal Ligament

  • Attachments: Within the tarsal canal — talus to calcaneus
  • Function: The primary intrinsic stabilizer of the subtalar joint. Resists inversion and eversion. Very strong — rarely torn in isolation.

Cervical Ligament

  • Attachments: Within the sinus tarsi — lateral talar neck to superior calcaneus
  • Function: Resists inversion and supination. Often involved in sinus tarsi syndrome.

Calcaneofibular Ligament (CFL)

  • Function at the subtalar joint: The CFL crosses both the talocrural and subtalar joints. It resists subtalar inversion — its injury in ankle sprains affects subtalar stability as well as talocrural stability.

Mobilization Techniques

Hands-on instruction is required. The descriptions below provide clinical reference detail for understanding and supervised practice. They are not a substitute for instructor-led technique training. Correct hand placement, force dosage, and tissue response interpretation require hands-on coaching and feedback.

General Contraindications

  • Absolute: Calcaneal fracture, talar fracture, subtalar dislocation, active infection, acute inflammatory arthritis
  • Relative: Acute ankle sprain with subtalar involvement, significant subtalar OA with bony end-feel, tarsal coalition (congenital bony or fibrous bridging that restricts subtalar motion — mobilization is ineffective)

Medial-Lateral Calcaneal Glide (Talar Tilt)

Purpose: Restores inversion (medial glide of calcaneus) or eversion (lateral glide of calcaneus). The most commonly performed subtalar mobilization. Patient position:
  • Supine or prone with the foot over the edge of the table
  • Ankle in the resting position (10° plantarflexion, subtalar neutral)
Hand placement:
  • Stabilizing hand: Grips the talar neck and distal tibia/fibula, stabilizing the talus within the mortise
  • Mobilizing hand: Cups the calcaneus, gripping it from below and behind. For medial glide (restores inversion): shift the calcaneus medially. For lateral glide (restores eversion): shift the calcaneus laterally.
Technique execution:
  • Apply an oscillatory force directing the calcaneus medially (for inversion) or laterally (for eversion)
  • Grade I–II: Gentle oscillations for pain modulation and assessment
  • Grade III: Oscillations into end-range for capsular stretch
  • Duration: 30 seconds per direction, 2–3 sets
Indications:
  • Decreased subtalar inversion or eversion on accessory motion testing (compare bilaterally)
  • Post-ankle sprain subtalar stiffness (often overlooked — clinicians treat the talocrural joint and forget the subtalar)
  • Subtalar hypomobility contributing to compensatory overpronation or oversupination
Technique notes:
  • Common error: Mobilizing the talocrural joint instead of isolating the subtalar. The stabilizing hand must firmly hold the talus/tibia while the calcaneus is moved. If the talus moves with the calcaneus, subtalar isolation is lost.
  • Reassessment: Re-test calcaneal inversion and eversion. Also recheck weight-bearing foot position (calcaneal valgus/varus angle).

Subtalar Distraction

Purpose: General pain modulation and capsular stretch. Separates the calcaneus from the talus, decompressing the articular surfaces. Patient position:
  • Supine, ankle off the table edge
Hand placement:
  • Stabilizing hand holds the talus/tibia. Mobilizing hand cups the calcaneus and applies traction inferiorly (pulling the calcaneus away from the talus along the long axis of the hindfoot).
Technique execution:
  • Sustained or oscillatory traction
  • Grade I–II: Pain modulation
  • Grade III: Capsular stretch
  • Duration: 30 seconds, 2–3 sets
Indications:
  • General subtalar stiffness
  • Subtalar OA with weight-bearing pain
  • Adjunct before medial-lateral glides

Muscles Crossing This Joint

Invertors (Supination)

Evertors (Pronation)

Conditions Affecting This Joint

  • Subtalar hypomobility — post-ankle sprain, post-immobilization; limits rearfoot adaptation to uneven surfaces; contributes to recurrent ankle sprains
  • Sinus tarsi syndrome — pain and tenderness in the sinus tarsi (lateral foot, anterior to lateral malleolus); often follows ankle sprains; may involve cervical ligament damage
  • conditions/osteoarthritis — subtalar OA limits inversion/eversion; produces rearfoot stiffness and difficulty on uneven ground
  • Tarsal coalition — congenital bony (synostosis), cartilaginous, or fibrous bridging between the talus and calcaneus (talocalcaneal coalition) or calcaneus and navicular (calcaneonavicular coalition); produces a rigid flatfoot; mobilization is ineffective against bony coalition
  • Subtalar dislocation — the talus dislocates from both the calcaneus and navicular simultaneously; high-energy trauma; medical emergency

Clinical Notes

  • Subtalar stiffness is commonly overlooked after ankle sprains. Clinicians typically focus on the talocrural joint and lateral ligaments. However, the CFL crosses the subtalar joint, and subtalar stiffness after inversion sprains is common. Always assess and treat subtalar mobility alongside talocrural mobilization.
  • Overpronation begins at the subtalar joint. Excessive eversion at the subtalar joint produces the overpronation cascade — tibial internal rotation → knee valgus → hip internal rotation. This kinetic chain effect is the link between foot biomechanics and proximal conditions (patellofemoral syndrome, ITB syndrome, medial tibial stress syndrome).
  • Subtalar neutral is the orthotic reference position. Assessing the calcaneal position in subtalar neutral (the position where the talar head is equally palpable medially and laterally) determines whether the foot is in a pronated or supinated resting posture. This informs orthotic prescription and exercise selection.

Key Takeaways

  • The subtalar joint produces inversion/eversion (not dorsiflexion/plantarflexion — that is the talocrural joint); it is the primary site of rearfoot pronation/supination.
  • Subtalar stiffness is commonly overlooked after ankle sprains — always assess subtalar mobility alongside the talocrural joint.
  • Overpronation cascades from the subtalar joint up the kinetic chain — tibial IR → knee valgus → hip IR → patellofemoral and ITB syndrome.

Related

  • anatomy/joints/talocrural — dorsiflexion/plantarflexion occurs here; works with subtalar for ankle complex function
  • anatomy/joints/midtarsal — the Chopart joint; subtalar position determines midtarsal joint locking/unlocking
  • conditions/lateral-ankle-sprain — CFL injury affects subtalar stability

Sources

  • Berry, D., & Berry, L. (2011). Cram session in joint mobilization techniques: A handbook for students and clinicians. SLACK Incorporated. (Ch. 5: The Ankle and Foot)
  • Edmond, S. L. (2017). Joint mobilization/manipulation: Extremity and spinal techniques (3rd ed.). Elsevier. (Ch. 8: The Ankle and Foot)
  • Kisner, C., & Colby, L. A. (2017). Therapeutic exercise: Foundations and techniques (7th ed.). F.A. Davis.
  • Magee, D. J., & Manske, R. C. (2021). Orthopedic physical assessment (7th ed.). Elsevier. (Ch. 13: Ankle and Foot)
  • Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2023). Clinically oriented anatomy (9th ed.). Wolters Kluwer. (Ch. 5: Lower Limb)
  • Tortora, G. J., & Derrickson, B. H. (2021). Principles of anatomy and physiology (16th ed.). Wiley. (Ch. 9: Joints)
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