An Emphasis on the Role of Peroneus Brevis to Peroneus Longus Transfer in Progressive Collapsing Flatfoot Deformity

The role of the peroneal tendons in progressive collapsing flatfoot deformity (PCFD), also traditionally known as posterior tibial tendon dysfunction, is likely overlooked and almost certainly understudied. We explored the impact of peroneus brevis (PB) to peroneus longus (PL) transfer in the adult population with flexible PCFD deformities class A1 (flexible hindfoot valgus), B1 (flexible midfoot abduction), and C1 (flexible forefoot varus) as an augmentative measure combined with various bony procedures with proper assessment functionally, clinically, and radiologically. PB to PL tendon transfer poses a simple procedure dealing with muscle imbalance between the medial and lateral columns of the foot. It deals with the new understanding of the PCFD complex as a three-dimensional deformity. It works mainly on the axial plane to limit midfoot abduction and strongly augments the PL acting on the sagittal plane to address the forefoot varus. Finally, to a lesser extent, it deals with the coronal plane of hindfoot valgus, eliminating the primary evertor of the foot (PB) while simultaneously strengthening the PL, which contributes to the medial longitudinal and transverse arches of the foot, therefore decreasing the possibility of lateral column overload commonly caused by the Evans osteotomy through reducing pressure across the calcaneocuboid joint. This procedure is preferably indicated for flexible PCFD deformities class (A1, B1, and C1), yet is contraindicated in neuromuscular deformities with peroneal nerve palsy.Level of Evidence: Level IV.