Overview
Adult acquired flatfoot deformity is most commonly related to posterior tibial tendon dysfunction with progressive failure of the medial supporting structures of the foot.
Clinical features
- medial ankle or hindfoot pain in earlier stages
- collapse of the medial longitudinal arch
- hindfoot valgus
- forefoot abduction
- “too many toes” sign
- inability or difficulty performing a single-leg heel raise
Examination
Assess:
- flexibility of the hindfoot
- single-leg heel rise
- posterior tibial tendon strength and tenderness
- Achilles or gastrocnemius tightness
- forefoot varus or supination after hindfoot correction
- ankle valgus or deltoid insufficiency in advanced disease
Investigations
- weight-bearing AP and lateral foot radiographs
- hindfoot alignment view
- ankle radiographs when ankle valgus is suspected
- MRI or ultrasound selectively for tendon assessment
Treatment
Early and flexible deformity
- activity modification
- orthoses or AFO
- physiotherapy
- Achilles or gastrocnemius stretching
Progressive flexible deformity
Reconstruction may combine tendon procedures with osteotomy and soft-tissue balancing according to the deformity.
Rigid deformity or arthritis
Fusion procedures may be required when deformity is fixed or when substantial hindfoot or midfoot arthritis is present.