Ankle and Foot Biomechanics

Tibial Torsion

Distal end rotated 20-35 degrees laterally

Proximal tibfib joint

Synovial Joint

Distal tibfib joint

Fibrous synarthrodial joint

High Ankle Sprains

Syndesmosis tears- high velocity, rotational injuries

Anterior Talofibular Ligament

Commonly injured

TC Joint is Oblique

Primary PF/DF have ADD/ABD and Inv/Evr with it

Talus and Tibia

Biggest weight bearing bone 90-95% of body weight

Talus

Convex

Tibia artho

Concave

Navicular, Cuneiforms, Cuboid

Midfoot

MT and Phalanges

Forefoot

Talocrural joint

Trochlea of talus, distal tibia and med/lat malleolus

Oblique Joint axis

Medial to lateral malleolus

Pronation

Ev+Abd+DF (Shock Absorption)

Supination

Inv+Add+PF (Pushoff)

Open Chain DF

Talus rolls anteriorly, Slides posteriorly (Dorsiglide Dorsiflexion)

Open Chain PF

Talus rolls posteriorly, slides anteriorly

Closed chain ankle movement

Tibia moving same direction

Last few degrees of DF

Tibia and fibula splay (move apart)

During DF the talus moves

Posteriorly

Subtalar Joint

Oblique axis, Inv/Evr

Subtalar Open Chain Inversion

Calcaneus rolls medially slides laterally

Subtalar Open chain eversion

Calcaneus rolls laterally slides medially

Talus

Concave

Calcaneus

Convex

Transverse Tarsal Joint

Follows Subtalar joint

Inv/Evr Landmarks

Stationary: Tib Tub

Axis: Between malleolus

Moving: 2nd MT

Intermetatarsal Joints

Synovial, prone to bursitis

Morton’s Neuroma

Entrapped nerves

MTP artho

Roll and slide in same direction

MTP Flexion ROM

30-45 degrees

MTP extension ROM

90 degrees

IP joints

Hinge (flex/ext only)

Bunion

Hallux Valgus

Medial longitudinal arch

Main shock-absorbing structure of foot (talonavicular=keystone)

Lateral Longitudinal Arch

Rigid, spread force

Transverse Arch

Allows pronation and supination, Keystone-middle cuneiform

Longer leg

Low arch, Pronation

Shorter leg

Higher arch, Supination

Pes Cavus

High medial longitudinal arch, calcaneal inversion

Pes Planus

Loss of medial longitudinal arch, calcaneal eversion

Foot Drop

Bad DF from Ant Tib

Plantarflexion

Gastroc (Knee ext), Soleus, Post Tib, FDL, FHL, Peroneus

Plantarfasciitis

Related to too much pronation or supination

Dorsiflexion ROM Walking

0-15

DF ROM Running

0-20

DF ROM Upstairs

11-27

DF ROM down stairs

21-36

PF ROM walking

0-30

PF ROM Running

0-30

PF ROM up stairs

23-30

PF ROM down stairs

24-40

Gait mechanics normal limiting factor

Dorsiflexion

Increased pronation

Increased genu valgum

Increased supination

Increased genu varum