Tibialis posterior tendon dysfunction: a primary or secondary problem?

Seventeen patients with a mean follow-up of 64.4 months following a tibialis posterior tendon transfer to regain active foot dorsiflexion were clinically examined specifically for signs of tibialis posterior tendon dysfunction. The results show that 8 patients (47%) had Grade 4 or better power of eversion but none had a clinical flatfoot on the Harris-Beath footprints. Only 6% had forefoot abduction; 17% exhibited hindfoot valgus and 82% were able to perform the single-heel rise. Tibialis posterior tendon dysfunction therefore does not appear to be an inevitable sequel of tibialis posterior tendon transfer even in the presence of a functioning peroneal muscle. Other studies have noted that a pre-existent flatfoot was often present in patients with tibialis posterior tendon dysfunction. None of the patients in this study had pre-existent flatfoot. We suggest that a predisposition, in the form of a pre-existent tendency to flatfoot may also be a factor in the pathogenesis of tibialis posterior tendon dysfunction. This may explain the long-term failure of flexor digitorum longus and flexor hallucis longus tendon transfers in the treatment for tibialis posterior tendon dysfunction when the biomechanics of the foot has not been altered.