Aquired Adult Flatfoot Deformity

Definition

 

Acquired Adult Flatfoot Deformity (AAFD)

- collapse of medial longitudinal arch

- secondary to ligament / tendon / joint or bony pathology

 

Classification

 

1. Congenital

 

Flexible / Physiological

 

Ligamentous Laxity (DIAL HOME)

 

Rigid 

- Congenital Vertical Talus 

- Tarsal Coalition

 

2.  Acquired

 

Tibialis Posterior Dysfunction

 

RA Flat Foot

 

Neurological

- Charcot Foot

- spinal dysraphism

- CP

- polio

 

OA

 

Midfoot OA / Lis Franc injury

 

Midfoot OA Planovalgus

 

Subtalar joint OA (calcaneal fracture)

Ankle OA

 

Ankle OA Valgus Tilt

 

Ligament

- isolated spring ligament rupture (rare)

- iatrogenic / traumatic plantar fascia rupture (rare)

 

Compensory to Rotational & Coronal plane deformities

- tibial torsion

- genu valgum

- ankle equinus 2° tight TA

 

Biomechanics of FlatFoot

 

Normal Gait / 3 phase rocker

 

1.  Heel Strike 

 

Tibia IR 

 

Hindfoot Everts

- unlocks TNJ & CCJ 

- forefoot pronates

 

Allows shock absorption by hind/mid/forefoot

 

2.  Stance 

- WB axis passes through ASIS to patella to middle of foot

 

3.  Toe Off

 

T Posterior "locks" the midfoot (i.e. the transverse tarsal joints)

- T Anterior inverts the hindfoot

- T Achilles plantar flexes the calcaneum

- Tibia externally rotates

 

Flatfoot Gait

 

The above components are exaggerated

- More stress on ligament structures

 

WB axis shifts medially, causing

- increased femoral anteversion

- internal knee rotation

- increased Q angle

 

T Achilles becomes evertor

 

Increased pronation

- may cause Hallux Valgus

 

Specific Conditions

 

Lisfranc Joint OA

 

Acquired Adult Flatfoot

 

Aetiology

 

1.  Post injury

 

Degenerative arthritis develops after fracture dislocation

- Acute injury often missed

- Adequate acute treatment may not prevent occurrence

 

2.  Idiopathic 

- not related to trauma

 

3.  Charcot

 

X-ray

 

Degenerative changes invariably involve second MT/ 2nd Cuneiform joint

- may involve 1st & 3rd joints

- rarely involves 4th & 5th joints

 

Midfoot AP Secondary to Missed Lis Franc

 

Non-operative

 

Moulded arch support / UCBL initially if correctable

Lateral Single Upright caliper with Medial T strap if not

 

Operative

 

Realignment of Lisfranc joint with arthrodesis

 

Rheumatoid Flat Foot

 

50% will get flat foot

- subtalar OA

- spring ligament attenuation

- tibialis post dysfunction

- progressive valgus deformity at hindfoot 

 

OA of Ankle Joint

 

Usually post traumatic

- valgus tilt of Talus leads to pronation of Talus & Calcaneus

 

Flatfoot def corrected when AJ realigned

 

Charcot Flat Foot

 

90% changes in hind and midfoot

- repetitive microtrauma in presence of neuropathy leads to microfracture

- 2° to Sensory & Autonomic Neuropathy

 

Progressive subluxation / collapse

 

Usually associated with Diabetes

- may be marked collapse

- develop bony prominence on medial sole

- may cause ulceration

 

Plantar Fascia Rupture

 

Traumatic or spontaneous

- pain at calcaneal origin

- palpable gap

- often 2° excess HCLA

 

Management

- arch support

- longitudinal arch will slightly flatten, but rupture should heal

 

Spring Ligament Rupture

 

Rare

- ? Repair

- probably in reality treat as for PTTD