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Talonavicular (TN) fusion is a common treatment for TN arthritis or deformity correction. There is incongruous evidence regarding remaining motion at the talocalcaneal and calcaneocuboid joints after TN fusion. Additionally, the effects of a malaligned TN fusion are not well understood and alignment of the fusion may be important for overall foot integrity. This project assessed the kinematic and kinetic effects of neutral and malaligned TN fusions. Ten cadaveric feet were tested on a gait simulator in four conditions: unfused, fused in neutral, fused in varus, and fused in valgus. The fusions were simulated with external fixation hardware. An eight‐camera motion analysis system and a 10‐segment foot model generated kinematic data, and a pressure mat captured pressure data. Simulated TN fusion was achieved in eight feet. From unfused to fused‐neutral, range of motion (ROM) was not eliminated in the adjacent joints, but the positions of the joints changed significantly throughout stance phase. Furthermore, the ROM increased at the tibiotalar joint. Plantar pressure and center of pressure shifted laterally with neutral fusion. The malalignments marginally affected the ROM but changed joint positions throughout stance phase. Pressure patterns were shifted laterally in varus malalignment and medially in valgus malalignment. The residual motion and the altered kinematics at the joints in the triple joint complex after TN fusion may subsequently increase the incidence of arthritis. Clinical significance: This study quantifies the effects of talonavicular fusion and malalignment on the other joints of the triple joint complex. [ABSTRACT FROM AUTHOR]

Tibiotalar arthrodesis is a common surgical treatment for end‐stage ankle arthritis. Proper ankle alignment is important as malalignment can lead to complications that may require revision surgery. This study aimed to determine how anteroposterior (AP) translational malalignment of ankle arthrodesis affects distal foot joint kinematics and plantar pressure. Ankle arthrodesis was performed on 10 cadaveric foot specimens using a custom fixture that could fuse the ankle neutrally and induce discrete malalignments (3, 6, and 9 mm) anteriorly and posteriorly. Gait was simulated under each alignment with a robotic gait simulator, and foot bone motion and plantar pressure were quantified. AP translational malalignment did not substantially affect plantar pressure or joint range of motion, but there were several significant differences in joint position throughout stance phase. Differences were seen in five joints (talocalcaneal, talonavicular, calcaneocuboid, fifth tarsometatarsal, and first metatarsophalangeal) and in the position of the first metatarsal relative to the talus. The most extreme effects occurred when the talus was displaced 6 mm or more posteriorly. In vivo, this may lead to aberrant joint loading, which could negatively impact patient outcomes. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:450‐458, 2020 [ABSTRACT FROM AUTHOR]

Standard treatments of adult acquired flatfoot deformity (AAFD) fail to correct associated dysfunction of the posterior tibial tendon (PTT). This study aimed to determine if a novel passive engineering mechanism (PEM) enhanced flexor digitorum longus (FDL) tendon transfer procedure would better restore physiologic PTT function to improve AAFD gait parameters compared to standard treatment. We evaluated the kinetic, pedobarographic, and kinematic effects of a pulley‐based PEM‐enhancement system utilizing a cadaveric flatfoot model and robotic gait simulator. FDL tendon force, FDL tendon excursion, regional peak plantar pressures, center of pressure, and foot bone/joint motions were quantified. Throughout the stance phase of gait, PEM‐enhancement significantly increased FDL tendon forces, resulting in gait cycle medial column unloading, lateral column loading, forefoot adduction, hindfoot inversion, and increased plantar flexion (p < 0.05). This proof‐of‐concept study demonstrated that an innovative PEM‐enhanced FDL tendon transfer procedure better restored physiologic PTT function, resulting in improved correction of the distinctive AAFD gait characteristics—medial column collapse, hindfoot eversion, and forefoot abduction. Clinical significance: Novel PEM‐enhancement of a FDL tendon transfer procedure holds promise as a method for improved treatment of AAFD. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3033–3042, 2018. Standard treatments of adult acquired flatfoot deformity (AAFD) fail to correct dysfunction of the posterior tibial tendon (PTT). We aimed to determine if a novel passive engineering mechanism (PEM) enhanced flexor digitorum longus (FDL) tendon transfer procedure would better restore physiologic PTT function. This study demonstrated that an innovative PEM‐enhanced FDL tendon transfer procedure better restored physiologic PTT function, resulting in improved correction of the distinctive AAFD gait characteristics—medial column collapse, hindfoot eversion, and forefoot abduction. [ABSTRACT FROM AUTHOR]

ABSTRACT Symptom relief of recalcitrant metatarsalgia can be achieved through surgical shortening of the affected metatarsal, thus decreasing plantar pressure. Theoretically an oblique metatarsal osteotomy can be oriented distal to proximal (DP) or proximal to distal (PD). We characterized the relationship between the amount of second metatarsal shortening, osteotomy plane, and plantar pressure. We hypothesized that the PD osteotomy is more effective in reducing metatarsal peak pressure and pressure time integral. We performed eight DP and eight PD second metatarsal osteotomies on eight pairs of cadaveric feet. A custom designed robotic gait simulator (RGS) generated dynamic in vitro simulations of gait. Second metatarsals were incrementally shortened, with three trials for each length. We calculated regression lines for peak pressure and pressure time integral vs. metatarsal shortening. Shortening the second metatarsal using either osteotomy significantly affected the metatarsal peak pressure and pressure time integral (first and third metatarsal increased, p < 0.01 and <0.05; second metatarsal decreased, p < 0.01). Changes in peak pressure ( p = 0.0019) and pressure time integral ( p = 0.0046) were more sensitive to second metatarsal shortening with the PD osteotomy than the DP osteotomy. The PD osteotomy plane reduces plantar pressure more effectively than the DP osteotomy plane. Published 2013 by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 32:385-393, 2014. [ABSTRACT FROM AUTHOR]