Consensus on Indications for Isolated Subtalar Joint Fusion and Naviculocuneiform Fusions for Progressive Collapsing Foot Deformity

Abstract

Recommendation: Peritalar subluxation represents an important hindfoot component of progressive collapsing foot deformity, which can be associated with a breakdown of the medial longitudinal arch. It results in a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and pronation. Loss of peritalar stability allows the talus to rotate and translate on the calcaneal and navicular bone surfaces, typically moving medially and anteriorly, which may result in sinus tarsi and subfibular impingement. The onset of degenerative disease can manifest with stiffening of the subtalar (ST) joint and subsequent fixed and possibly arthritic deformity. While ST joint fusion may permit repositioning and stabilization of the talus on top of the calcaneus, it may not fully correct forefoot abduction and it does not correct forefoot varus. Such varus may be addressed by a talonavicular (TN) fusion or a plantar flexion osteotomy of the first ray, but, if too pronounced, it may be more effectively corrected with a naviculocuneiform (NC) fusion. The NC joint has a curvature in the sagittal plane. Thus, preserving the shape of the joint is the key to permitting plantarflexion correction by rotating the midfoot along the debrided surfaces and to fix it. Intraoperatively, care must be also taken to not overcorrect the talocalcaneal angle in the horizontal plane during the ST fusion (eg, to exceed the external rotation of the talus and inadvertently put the midfoot in a supinated position). Such overcorrection can lead to lateral column overload with persistent lateral midfoot pain and discomfort. A contraindication for an isolated ST fusion may be a rupture of posterior tibial tendon because of the resultant loss of the internal rotation force at the TN joint. In these cases, a flexor digitorum longus tendon transfer is added to the procedure. Level of Evidence: Level V, consensus, expert opinion.

Association Between Middle Facet Subluxation and Foot and Ankle Offset in Progressive Collapsing Foot Deformity

“…In other words, an FAO higher than 6.33% might suggest a higher degree of peritalar subluxation. 7,8 Interestingly, in patients with an FAO greater than 6.33%, a BMI higher than 43.12 was found to be a predictor of higher MF subluxation and PTS. This observation augments the idea that obesity may play a role in further aggravation of the disease.…”

“…In other words, an FAO higher than 6.33% might suggest a higher degree of peritalar subluxation. 7,8…”

Intra- and Interobserver Reliability of the New Classification System of Progressive Collapsing Foot Deformity

“…The new PCFD classification indicates significant subtalar subluxation as consistent to clinical and radiographic (subfibular impingement) findings, but peritalar subluxation is acomplex 3D deformity that can be difficult to assess with conventional weightbearing radiography given its limitation to evaluate coronal plane hindfoot deformity. 16,23 Weightbearing multiplanar imaging can enhance interobserver agreement compared to indirect signs of impingement on conventional radiographs, such as sclerosis and subcortical cyst in the sinus tarsi and subfibular region. 14,28,38 The least common (22.5%), but the most agreed (Fleiss kappa = 0.955), class was E (medial ankle instability).…”

Radiographic Cutoff Values for Predicting Lateral Bony Impingement in Progressive Collapsing Foot Deformity

“…Given the high likelihood of talocalcaneal interosseous ligament insufficiency in patients with calcaneofibular impingement in a previous magnetic resonance imaging study, 7 repositional subtalar arthrodesis may be considered if the alignment correction cannot be achieved through calcaneal osteotomies, especially when there is strong evidence of ligament insufficiency. 10 Our WBCT measurement for talocalcaneal and calcaneofibular distances showed excellent interrater reliability. Previous studies have measured talocalcaneal distance in a sagittal plane and failed to reflect the true relationship between lateral process of the talus and the calcaneus because of the rotational deformity that occurs in the PCFD.…”

“…Given the high likelihood of talocalcaneal interosseous ligament insufficiency in patients with calcaneofibular impingement in a previous magnetic resonance imaging study, 7 repositional subtalar arthrodesis may be considered if the alignment correction cannot be achieved through calcaneal osteotomies, especially when there is strong evidence of ligament insufficiency. 10…”