Current Concepts Review

The authors present an overview of currently available data relating to acquired dysfunction of the tibialis posterior tendon (TPT).This condition has only gained wide recognition over the past twenty years, although isolated cases had been reported much earlier. They describe the anatomy of the tendon and its complex distal insertions, together with particular features of the vascularisation and histology of the retromalleolar portion of the tendon. They analyse the biomechanical role of the TPT under normal conditions and the mechanism of the foot deformities that occur secondary to acquired dysfunction of the tendon. A number of theories have been suggested to explain the occurrence of acquired TPT dysfunction, such as degenerative tendinosis, chronic inflammation, retromalleolar impingement, hypovascularity. Most cases are not linked to any specific aetiological factor and are therefore termed “idiopathic”. Several classification schemes have been proposed, based on MRI findings or clinical presentation. In the latter classification, stage I is characterised by medial pain without any clinical or radiological deformities; in stage II, with elongation of the TPT, pain is present medially and/or laterally, with a pes planovalgus deformity that remains flexible; the deformity becomes fixed and irreducible in stage III and stage IV is the end stage, with osteoarthritis of the ankle. The diagnosis is essentially clinical, with the “too many toes” sign, a positive single-heel rise test together with medial pain and swelling and weakness of ankle inversion. Plain radiographs are useful to rule out any concomitant abnormalities; various methods have been proposed to quantify the flatfoot deformities on weight-bearing radiographs. Ultrasound and MRI may be useful to assess tendon pathology. Conservative treatment (rest, orthoses, shoe modifications, NSAIDs) may alleviate symptoms in patients with minimal deformity but is not effective in cases with advanced pathological changes. Surgical treatment is therefore often necessary but controversy persists with regard to which technique or combination of techniques is preferable. Stage I is an indication for synovectomy, possibly combined with repair of the deltoid ligament and augmentation of the TPT with soft tissue transfer from the flexor digitorum longus, the flexor hallucis longus or the anterior tibialis tendon. Treatment of stage II is controversial; the current trend is to combine tendon transfer with a joint-sparing bony operation such as a lateral column lengthening procedure or a medial translational osteotomy of the calcaneus. Subtalar, double or triple arthrodesis are the procedures of choice for stage III TPT dysfunction whereas tibiocalcaneal arthrodesis or pantalar fusion is the only remaining option in stage IV.