Clinical Management of Biomechanical FootAnkle Problems BIOMECHANICS REVIEW

Supination and Pronation • Supination – Plantarflexion – Adduction – inversion • Pronation –

JOINTS AND FUNCTIONAL UNITS

Ankle • Minimum range required for gait = 10 o with knee extended and

Subtalar • Average range of motion 30 o (calcaneal inversion/eversion) • 2/3 calcaneal inversion,

Midtarsal • Longitudinal and oblique axes • Available range depends on the position of

Midtarsal Axes • Longitudinal – Mostly inversion/eversion – Range about 4 o – 6 o • Oblique – Mostly plantarflexionadduction / dorsiflexionabduction – Range unknown Graphic © 1977 Clinical Biomechanics Corp.

First Ray • Average dorsiflexion 5 mm • Ranges of plantarflexion and dorsiflexion should

Fifth Ray Graphic © 1989 Edmund M. Kosmahl.

First Metatarsophalangeal Joint • Minimum 65 o dorsiflexion required for gait • Dorsiflexion range

MUSCLE FUNCTION

Muscle Function • Gastrocnemius, Soleus, Tibialis posterior, Flexor Digitorum Longus, Flexor Hallucis Longus • Supinators, or pronation controllers

Muscle Function • Peroneus Longus and Brevis – Evertors of foot or supination controllers – Peroneus longus has special function. . .

Peroneus Longus • Plantarflexes 1 st ray during terminal stance to allow dorsiflexion of

Muscle Function • Tibialis Anterior, Extensor Hallucis Longus, Extensor Digitorum Longus, Peroneus Tertius – Dorsiflexors of ankle or plantarflexion controllers – TA and EHL balance EDL and PT to neutralize inversion and eversion

Adductor Hallucis Transverse Head • AKA Transverse Pedis • Prevents forefoot splay during terminal

Adductor Hallucis Transverse Head • Prevents forefoot splay during terminal stance as long as

Ideal Alignment • “Criteria for Normalcy” • Rarely seen clinically Graphic © 1984 American

Ideal Alignment (non-weight bearing) • Malleolar Torsion 13 o to 18 o external Graphic

Ideal Alignment (non-weight bearing) • Ankle dorsiflexion minimum 10 o with knee extended and

Ideal Alignment (non-weight bearing) • Subtalar range 8 o to 12 o minimum • Subtalar neutral position – calcaneal bisection and distal 1/3 leg bisection parallel Graphic © 1984 American Physical Rehabilitation Network

Ideal Alignment (non-weight bearing) • Midtarsal joint – plantar plane of forefoot parallel to plantar plane of rearfoot (and perpendicular to calcaneal bisection) when subtalar is neutral and midtarsal pronated maximally Graphic © 1984 American Physical Rehabilitation Network

Ideal Alignment (non-weight bearing) • First Ray – equal range (about 5 mm) above and below plane of 2 nd met when subtalar is neutral and midtarsal pronated maximally Graphic © 1977 Clinical Biomechanics Corp.

Ideal Alignment (non-weight bearing) • Fifth Ray – equal range above and below plane of middle three meets when subtalar is neutral and midtarsal pronated maximally Graphic © 1977 Clinical Biomechanics Corp.

Ideal Alignment (weight bearing) • Distal 1/3 leg bisection vertical • Knee, ankle, subtalar in transverse plane parallel to floor • Subtalar neutral • Calcaneus bisection verticlal • Midtarsal axes locked in maximally pronated position • Forefoot and rearfoot parallel to floor and Graphic © 1984 American Physical Rehabilitation Network

REARFOOT AND LEG PATHOMECHANICS

Muscle Dysfunction Pronators • Peroneus longus and brevis, extensor digitorum longus, peroneus tertius • Charcot-Marie-Tooth disease (peroneal atrophy) • Weakness leads to supinated rearfoot (cavus foot) Supinators • Gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, flexor hallucis longus, tibialis anterior • Weakness leads to pronated rearfoot (flatfoot)

Abnormal Osseous Structure • Most common causes of foot/ankle pathomechanics • Deviations from Ideal

Abnormal Osseous Structure Calcaneus / Leg Relationships (open chain)

Subtalar Varus • Bisection of calcaneus inverted with respect to leg when subtalar joint

Subtalar Valgus • Bisection of calcaneus everted with respect to leg when subtalar joint

Abnormal Osseous Structure Calcaneus / Floor Relationships (closed chain)

Rearfoot Varus or Valgus • Bisection of calcaneus inverted (varus) or everted (valgus) with

Tarsal Coalition • Abnormal union between two or more tarsals – Syndesmosis – fibrous – Synchondrosis – cartilage – Synostosis – bony (usually no motion or irritation) • Compensation = persistent pronation Graphic © 1988 Williams & Wilkens

Tibial Varum or Valgum • Distal 1/3 of tibia bowed toward midline (varum) or away from midline (valgum) • 1 o to 2 o is common • Varum calcaneal inversion rearfoot varus Graphic © 1988 Williams & Wilkens

Abnormal Osseous Structure Forefoot / Rearfoot Relationships

Forefoot Varus • Plantar plane of forefoot inverted with respect to plantar plane of rearfoot • ROM of midtarsal joint is normal (position is incorrect) Graphic © 1984 American Physical Rehabilitation Network

Forefoot Valgus • Plantar plane of forefoot everted with respect to plantar plane of rearfoot • ROM of midtarsal joint is normal (position is incorrect) Graphic © 1984 American Physical Rehabilitation Network

Forefoot Supinatus • Fixed varus position caused by soft tissue adaptation • ROM of midtarsal joint is limited • Result of ambulating on everted calcaneus Graphic © 1984 American Physical Rehabilitation Network

Abnormal Osseous Structure Forefoot Relationships