Clinical Management of Biomechanical Foot/Ankle Problems BIOMECHANICS REVIEW Edmund M. Kosmahl, PT, EdD © 2001 Edmund M. Kosmahl

Supination and Pronation Plantarflexion Adduction inversion Pronation Dorsiflexion Abduction Eversion Graphic © 1989 Edmund M. Kosmahl.

JOINTS AND FUNCTIONAL UNITS

Ankle Graphic © 1989 Edmund M. Kosmahl.

Ankle Minimum range required for gait = 10o with knee extended and subtalar joint neutral Graphic © 1977 Clinical Biomechanics Corp.

Subtalar Average range of motion 30o (calcaneal inversion/eversion) 2/3 calcaneal inversion, 1/3 calcaneal eversion Minimum 8o – 12o required for gait Graphic © 1989 Edmund M. Kosmahl.

Midtarsal Longitudinal and oblique axes Available range depends on the position of the subtalar joint Graphic © 1977 Clinical Biomechanics Corp.

Midtarsal Axes Longitudinal Oblique Mostly inversion/eversion Range about 4o – 6o Oblique Mostly plantarflexion-adduction / dorsiflexion-abduction Range unknown Graphic © 1977 Clinical Biomechanics Corp.

First Ray Average dorsiflexion 5 mm Ranges of plantarflexion and dorsiflexion should be equal Graphic © 1989 Edmund M. Kosmahl.

Fifth Ray Graphic © 1989 Edmund M. Kosmahl.

First Metatarsophalangeal Joint Minimum 65o dorsiflexion required for gait Dorsiflexion range requires plantarflexion of 1st ray Graphic © 1977 Clinical Biomechanics Corp.

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 1st ray during terminal stance to allow dorsiflexion of 1st MTP Graphic © 1977 Clinical Biomechanics Corp.

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 stance as long as 1st ray is plantarflexed Graphic © 1977 Clinical Biomechanics Corp.

Adductor Hallucis Transverse Head Prevents forefoot splay during terminal stance as long as 1st ray is plantarflexed (Subtalar supinated, peroneus longus) Graphic © 1977 Clinical Biomechanics Corp.

Ideal Alignment “Criteria for Normalcy” Rarely seen clinically Graphic © 1984 American Physical Rehabilitation Network

Ideal Alignment (non-weight bearing) Malleolar Torsion 13o to 18o external Graphic © 1989 Edmund M. Kosmahl.

Ideal Alignment (non-weight bearing) Ankle dorsiflexion minimum 10o with knee extended and subtalar joint neutral Ankle plantarflexion minimum 20o Graphic © 1990 FA Davis Co.

Ideal Alignment (non-weight bearing) Subtalar range 8o to 12o 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 5mm) above and below plane of 2nd 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 each other Graphic © 1984 American Physical Rehabilitation Network

REARFOOT AND LEG PATHOMECHANICS

Muscle Dysfunction Pronators Supinators 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 Alignment Graphic © 1984 American Physical Rehabilitation Network

Abnormal Osseous Structure Calcaneus / Leg Relationships (open chain)

Subtalar Varus Bisection of calcaneus inverted with respect to leg when subtalar joint is neutral Graphic © 1984 American Physical Rehabilitation Network

Subtalar Valgus Bisection of calcaneus everted with respect to leg when subtalar joint is neutral Graphic © 1988 Williams & Wilkens

Abnormal Osseous Structure Calcaneus / Floor Relationships (closed chain)

Rearfoot Varus or Valgus Bisection of calcaneus inverted (varus) or everted (valgus) with respect to floor Rearfoot Varus Graphic © 1988 Williams & Wilkens

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) 1o to 2o 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

Plantarflexed First Ray More plantarflexion ROM than dorsiflexion ROM Graphic © 1984 American Physical Rehabilitation Network

Metatarsus Primus Elevatus (dorsiflexed 1st ray) More dorsiflexion ROM than plantarflexion ROM Graphic © 1989 Edmund M. Kosmahl.