Adult Acquired Flatfoot

Introduction

• Low arched foot is variable in population• Flatfoot – abnormal loss of arch with pain

Causes• Posterior Tibial Tendon Dysfunction (PTT)• Achilles/Gastroc contracture – 2º PTT dysfunction• Inflammatory arthritis• 1º midfoot arthritis of fracture non-union• Calcaneus or Cuboid fracture malunion• Peroneal Muscle spasm• Neuropathic deformity• Coronal plane angulation

Deformity• Flatfoot is the end point of an medial collapsed arch.• Hindfoot → Valgus• Forefoot → Supinates• Sagittal Plane → longitudinal arch collapses• Axial Plane → Forefoot abducts• Lateral column is shortened• 3D – dorsolateral peritalar subluxation

Deformity

Arches of the foot

• Medial Longitudinal Arch• Lesser Longitudinal Arch• Transverse Arch

Arch Supports

• Static– Spring ligament– Superficial deltoid– Plantar fascia

• Dynamic– PTT– Ext/In toe flexors– Achilles

PTT during Gait

• Heel contact – shock absorber• Midstance – initiates inversion of the hindfoot• Propulsive phase – Vector of Achilles shifts

medially secures hindfoot

Clinically

• Foot Pain (medial, lateral), Knee, Hip• Swelling – medial along PTT• Standing, walking aggravate• Abnormal gait (push off)• Progressive flat foot

Physical Examination • Visualise legs from knee down - Arch height

compared with other side, too many toes sign• Look at heel alignment• Palpate along PTT• Single heel raise• Test Inversion/Eversion • Gastroc-soleus – Contractures• Subtalar joint for mobilty• Fixed vs Rigid

RADIOGRAPHS

Lateral Xray

Lateral talar-1st MT (Meary angle),>4º Flatfoot

17-32° is normal

Talo navicular coverage angle

> 7 degrees indicates lateral subluxation

AP

Look for talar aligment

Other Imaging

• USS – stage 1 of PTT dysfunction correlates well with surgical findings

• MRI – More detailed

PTT - Anatomy

• Posterior Tibia → 1º Navicular Tub, 2º 2-4 MT, Cuniforms, Cuboid

• Also attaches to deep fasica, peroneal tendons and long and short flexors

• Avascular zone in tendon behind medial malleolus

Staging

Treatment

• Aim – pain free and normal biomechanics• Depend on underlying condition • Stage of disease

TREATMENT• Non-operative: Tibialis posterior eccentric

strengthening exercises, NSAIDs, orthotics

• Operative: depending on stage of disease

• Early stages with no fixed deformity = orthotics & tendon transfer and heel osteotomy

• Later stages with fixed deformity = triple fusion or pantalar fusion

Non-operative

• Anti-inflammatory to control pain• Rest in a short leg cast• Bracing and orthotics

– Flexible, Medial supports, AFO, UCBL– Rigid, accommodative devices, custom moulded

AFO

Surgical Principles

• If PTT is source of pain should be addressed with repair and augmentation

• Pain from osseous impingement, arch alignment must be improved to decompress painful area

• Arthritis pain – joint fusion• Consider TA lengthening

Stage 1 PTT dysfunction

• Repair and augment tendon • Consider calcaneal sliding osteotomy• Medial Approach • Diseased tendon maybe excised• FHL/FDL/PB is as an augment

Collapsed Arch, no degeneration

• Aim is to realign the hind foot without sacrificing the hind foot joints

• Augment PTT • Medial Calcaneal osteotomy• Medial column stabilisation• Lateral column lengthening

EARLY STAGES

Medial column stabilisation

• Medial Collapse at met-cun, NC joint• Collapse can be seen on lateral films• Realignment can result in good correction of

the arch• Often combined with calcaneal osteotomy

Lateral column lengthening

• Hindfoot valgus drive the calcaneus posteriorly

• Lengthening drives the foot around the talus through the TNJ

• Osteotomy of ant process of calcaneus or through the cal-cub joint

Lateral column lengthening

• Improves talar head coverage, reduces forefoot abduction, diminishes hindfoot valgus

• Peroneal lever arm is lengthened, planter fascia is lengthened, TA shifts medially

Forefoot Supination

• Collapse of hindfoot leads to compensatory forefoot supination

• Elevated first ray after hindfoot correction• First metatarsocuneiform planter flexion

arthrodesis

Advanced Flatfoot (Stage 3)

• Triple arthrodesis is gold standard for rigid flatfoot (Subtalar, TN, CC)

• Performed with realignment• Address the forefoot supination

Ankle Valgus (Stage 4)

• Pantalar fusion • 2 stage procedure

– Triple fusion– Ankle replacement