Tibialis Posterior Dysfunction (TPD)
Posterior tibial tendon dysfunction is the most common cause of adult acquired flatfoot. Patients will complain of medial foot pain, weakness, and a slowly progressive foot deformity. A “too many toes” sign may be present and patients will be unable to perform a single heel raise test. The optimal treatment may change based on the progression of deformity and stage of disease. Early identification and prompt initiation of treatment can halt progression of the disease and help avoid surgery.
The tibias posterior muscle originates in the deep legs and its tendon runs behind the ankle and inserts onto the midfoot. It stabilises and raises the arch of the foot and is essential in preparing the foot for forward progression. Damage to the tendon is usually due to repetitive microtrauma. With poor blood supply to the area, the trauma results in progressive degeneration leading to a rigid flatfoot deformity.
Risk Factors for TPD:
- Diabetes – Hypertension
- Obesity – Cortisone use/ local steroid injection
- Previous Surgery – Foot and ankle trauma
- Arthritic conditions
Stages of TPD:
Stage 1: Tendon intact with inflammation but no deformity
Stage 2: Tendon is ruptured or nonfunctional with flatfoot that is passively correctable
Stage 3: non correctable and arthritis evident of the rear foot
Stage 4: Stage 3 with ankle degeneration and gross malalignment
Management of posterior tibial tendon dysfunction relies upon accurate staging of the disease, as both nonoperative and operative treatment options change with each disease stage. Aims of treatment are to relieve pain, improve function, restore alignment by correction of any deformity, and to halt or slow progression of the disease.
A CAM boot can be used to immobilise the foot. If this brings relief, the patient can have shoe inserts or modifications, orthotics or an ankle-foot orthosis (AFO) fitted. Orthotics aims to provide arch support and correct the flexible component of the deformity. Physiotherapy for achilles tendon stretching and tibialis posterior strengthening can also help. In cases that do not respond to conservative therapy or cannot be managed with bracing, surgery may be considered. Surgery involves complex procedures with very long recovery periods.