The medial longitudinal arch is maintained by the plantar fascia, intrinsic foot muscles, and the spring (calcaneonavicular) ligament. In adult-acquired flatfoot deformity (AAFD) stage II, the primary tendon insufficiency driving progressive valgus hindfoot and forefoot abduction is:
- A Tibialis anterior tendon
- B Tibialis posterior tendon (TPT) ✓
- C Peroneus longus tendon
- D Flexor hallucis longus tendon
Correct answer: B. Tibialis posterior tendon (TPT)
Explanation
Tibialis posterior tendon dysfunction (TPTD) is the dominant pathology in adult-acquired flatfoot deformity. The TPT is the primary dynamic invertor and supinator of the foot, and its insufficiency allows progressive valgus hindfoot deformity, spring ligament attenuation, and forefoot abduction ('too many toes' sign). Johnson and Strom staging: Stage I — tenosynovitis, no deformity; Stage II — tendon elongated or ruptured, flexible flatfoot; Stage III — rigid flatfoot; Stage IV — ankle valgus. Peroneus longus (C) actually assists the arch by plantarflexing the first ray.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.