Review Question - QID 219460

Triple arthrodesis is indicated most commonly in patients with stage III posterior tibial tendon insufficiency (PTTI) to address rigid deformities of the forefoot and hindfoot in addition to the primary flatfoot deformity.

PTTI is one of the most common acquired foot conditions in the aging population and affects women more commonly than men. Early tenosynovitis is thought to progress to insufficiency of the posterior tibial tendon which leads to collapse of the medial longitudinal arch and valgus deformity of the hindfoot. Forefoot abduction also develops over time in many patients. Compensatory deformities include a progressive forefoot varus that attempts to maintain a plantigrade foot. One of the primary factors dictating treatment is whether or not these deformities are flexible or rigid. If flexible, osteotomies of the hindfoot in addition to tendon transfers (flexor digitorum longus) are often successful in restoring function and relieving pain (stages I and II). In cases where rigid deformities of the hindfoot and forefoot develop (stage III), triple arthrodesis is often required. Triple arthrodesis includes arthrodesis of the subtalar, talonavicular, and calcaneocuboid joints. Important consideration should be given to the position of the fusion to ensure that the subsequent function is optimized.

Jackson et al. published an updated JAAOS review on adult-acquired flatfoot deformity, noting that PTTI is thought to be the primary etiology of this deformity. They talk about nonoperative strategies such as orthotics and bracing and go on to discuss specific operative strategies based on the severity of the disease process. They also touch on future goals in research, including trying to better understand the natural history of PTTI and what makes certain people symptomatic.

Wapner wrote a JAAOS review article on triple arthrodesis for adults, noting that it is a technically demanding procedure. He mentions that the procedure, if done well, is typically reliable for pain relief but can lead to other complications including secondary arthritis of the ankle and tarsometatarsal joints. He ultimately recommends it as a salvage or end-stage procedure in patients who have exhausted other nonoperative and operative measures.

Incorrect Answers:
Answer 1: Stage I PTTI consists of tenosynovitis with no deformity and the ability to still perform a single-leg heel raise. Surgical intervention is rarely needed, but if necessary, a synovectomy/debridement would be the appropriate procedure.
Answer 2: Stage IIA PTTI consists of a flatfoot deformity with a flexible hindfoot and no forefoot abduction. Surgical intervention normally consists of a flexor digitorum longus (FDL) transfer and a medializing calcaneal osteotomy.
Answer 3: Stage IIB PTTI consists of a flatfoot deformity with a flexible hindfoot and forefoot abduction with talonavicular un-coverage. Surgical intervention normally consists of a flexor digitorum longus (FDL) transfer, medializing calcaneal osteotomy, and a lateral column lengthening.
Answer 5: Stage IV PTTI consists of rigid forefoot abduction, rigid hindfoot valgus, and deltoid ligament compromise which typically requires a tibiotalocalcaneal arthrodesis.