The Foot & Ankle

ankle ankle eversion ankle inversion ankle ligaments calcaneocuboid joint calcaneus eversion foot inversion inversion and eversion metatarsals midtarsal joint midtarsal joint ligaments phalanges subtalar joint talocalcaneonavicular joint talocrural joint talocrural ligaments tarsal bones

The Foot and Ankle Physiotherapy Solihull Simon Evans

The Skeleton of the Foot

  • Comprises of up to 26 bones
    • 7 Tarsal bones 
    • 5 Metatarsals
    • 14 Phalanges
    • Plus a variable number of  sesamoid bones
  • Provides a strong but mobile base of support structured to meet its functions:
    • Stability - base of support and rigid lever for propulsion
    • Mobility - adaptor to terrain, shock absorption

The Ankle (Talocrural) Joint

  • Mortise and tenon arrangement between the tibia/fibula and talus - inherently stable
  • Classified as a synovial hinge joint - uniaxial / strong set of collateral ligaments
  • Articular Surfaces - 3 areas to describe - continuous with each other and all covered with hyaline cartilage
  • Lateral triangular facet on body of the talus articulates with corresponding facet on fibula (lateral malleolus) 
  • Medial comma shaped facet on body of the talus articulates with corresponding facet on medial malleolus
  • Trochlea (pulley shaped) surface on body of talus articulates with inferior aspect of lower end of tibia
  • Articular surfaces provide ankle with inherent stability
  • Motion permitted into dorsiflexion / plantarflexion
  • Capsule :
    • attached to articular margins of tibia, fibula and talus except anteriorly
    • to neck of talus anteriorly (weakest part of capsule to allow plantarflexion)
  • Synovial membrane attached to all articular margins, lines capsule and covers neck of talus

The Ankle (Talocrural) Joint - Ligaments

  • 2 sets of strong collateral ligaments
  • Medially (continuous and collectively known as the Deltoid ligament) arise from the medial malleolus
    • Anterior tibiotalar (green)
    • Tibionavicular (brown)
    • Tibiocalcaneal (blue)
    • Posterior tibiotalar (red)
      (Each named according to its attachments)
  • Lateral collateral ligaments - 3 distinct structures arising from the lateral malleolus – weaker than the medial collateral
    • Anterior talofibular (blue)
    • Calcaneofibular (green)
    • Posterior talofibular (red)
      Each named according to its attachments
  • In addition to the collateral ligaments there are thickenings in the anterior and posterior capsule - anterior and posterior ligaments
  • Role of the ligaments is to limit:
    • Plantarflexion - anterior ligaments
    • Calcaneal adduction/abduction (component of inversion/eversion) - calcaneal ligaments
    • Dorsiflexion - posterior and calcaneal ligaments
  • Close packed position of the ankle is dorsiflexion
  • Loose packed position is plantarflexion (least stable)

The Calcaneus

  • Lies immediately below talus
  • Largest bone in foot
  • Role is to provide attachments for calf muscle and act as a short lever for propulsion
  • Points to note:
    • Sustentaculum tali
    • Peroneal tubercle
    • Medial and lateral tubercles (plantar aspect)
  • Articular facets 
    • Superior - for talus
    • Anterior - for midtarsal joint

    Subtalar Joint

    • Synovial modified multiaxial joint
    • Between posterior facet on superior aspect of calcaneus (convex)
    • and concave facet on inferior aspect of body of talus
    • Has a loose capsule attaching to articular margins
    • Ligaments :
      • Interosseous ligament - Found in sinus tarsi (from sulcus tali above to sulcus calcanei below
      • Reinforced medially by:
        • Medial talocalcaneal ligament - medial talar tubercle to posterior border of sustentaculum tali
        • Limits abduction of the calcaneum
      • Reinforced laterally by:
        • Cervical ligament - from lateral aspect of neck of talus to anterior part of sinus tarsi
        • Lateral talocalcaneal ligament - from lateral talar tubercle to lateral aspect of posterior calcaneum
        • Both limit adduction of calcaneum

    Midtarsal Joint

    • Complex joint made up of the calcaneum and talus posteriorly and cuboid and navicular anteriorly
    • Anatomically divided into
      • Talocalcaneonavicular joint (medially)
      • Calcaneocuboid joint (laterally)

    Talocalcaneonavicular Joint

    • Synovial modified ball and socket joint
    • Head of talus (ball) articulates with
    • posterior facet on navicular, superior facets on calcaneum and superior surface on ‘Spring’  (plantar calcaneo-navicular) ligament (socket)
    • All covered in hyaline cartilage except Spring ligament - simple capsule lined with synovial membrane 

    Calcaneocuboid Joint

    • Forms lateral part of midtarsal joint
    • Synovial saddle joint
    • Between posterior cuboid and anterior calcaneum
    • Both articular surfaces covered in hyaline cartilage
    • Capsule extends just beyond articular surfaces and lined with synovial membrane 

    Ligaments of the Midtarsal Joint

    • 5 to consider
    • Dorsal:
      • Dorsal talonavicular ligament
      • Bifurcate ligament
    • Plantar:
      • Spring (plantar calcaneonavicular) ligament - from sust. Tali to navicular
    • Short plantar (Plantar calcaneocuboid) ligament - anterior tubercle to cuboid
    • Long plantar ligament – medial and lateral tubercles to bases of 4 lateral metatarsals

      Inversion & Eversion

      • Complex movements made up of the combined accessory movements occurring at the subtalar and midtarsal joints
      • Inversion - adduction at the subtalar joint and supination at the midtarsal joint
      • Eversion - abduction at the subtalar joint and pronation at the midtarsal joint 

      Surface Anatomy

      • Surface markings of the ankle joint area line passing from a point 2cm above the tip of the medial malleolus to a point 3cm above the lateral malleolus
      • Surface markings of the ligaments are done by identifying the relevant bony points
      • Midtarsal joint - a line concave proximally passing from a point just proximal to the navicular tuberosity to a point 1cm proximal to the tip of the styloid process of the base of the 5th metatarsal

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