Altered Range of Motion and Plantar Pressure in Anterior and Posterior Malaligned Total Ankle Arthroplasty

Abstract

Background: Malaligned ankle arthroplasty components have been associated with increased postoperative pain and reduced ankle range of motion. With this study, we aimed to quantify how anterior and posterior malalignment of the talar component affects foot bone kinematics and plantar pressures in a dynamic, cadaveric gait simulation. Methods: Ten cadaveric foot specimens received a modified ankle prosthesis. Proper alignment was defined as the prosthesis being neutral to a plantigrade foot, where varus/valgus and internal/external rotation were determined using the tibial alignment guide from the prosthesis manufacturer. Axially loaded lateral radiographs were made to measure the tibiotalar ratio (TTR) preoperatively and postoperatively. Specimens were prepared for gait simulation and mounted into the robotic gait simulator. Foot bone kinematics and plantar pressures were measured for each alignment condition. Results: Posterior malalignment of the talar component decreased mean sagittal-plane range of motion (p ≤ 0.0005) in the tibiotalar joint (by up to 3.9°) and in the first metatarsophalangeal joint (by up to 7.7°) and increased sagittal-plane range of motion (p ≤ 0.0005) in the calcaneocuboid joint (by up to 2.0°). Posterior malalignment increased mean transverse-plane range of motion (p ≤ 0.0005 and p = 0.012) in the tibiotalar joint (by up to 2.3°) and in the calcaneocuboid joint (by 2.3°). Posterior malalignment decreased mean peak plantar pressures (p = 0.001 and p = 0.013) under the hallux and the first metatarsal (by up to 82.1 and 110.1 kPa, respectively) and increased (p = 0.012 and p = 0.0006) peak plantar pressures under the third metatarsal and the hindfoot (by 23.0 and 47.8 kPa, respectively). Anterior malalignment decreased (p = 0.0006) mean hindfoot peak plantar pressure (by 127.7 kPa). Anterior and posterior malalignments shifted center of pressure laterally during early and late stance. The TTR weakly to moderately correlated with range-of-motion changes in the tibiotalar, calcaneocuboid, and first metatarsophalangeal joints (r2 ≤ 0.39) and weakly correlated with plantar pressure changes under the hindfoot, the first metatarsal, and the hallux (r2 ≤ 0.15). Conclusions: Anterior and posterior malalignments of the talar component altered foot bone kinematics and plantar pressures. Mild malalignments produced fewer significant differences than moderate and extreme malalignments. A greater number of significant differences were found for posterior malalignments than for anterior. The TTR weakly to moderately correlated with changes in range of motion and plantar pressures. Clinical Relevance: The observed changes in range of motion and plantar pressures may explain why malaligned ankle arthroplasties are associated with unfavorable clinical outcomes and poor prosthesis longevity. Posterior malalignments may produce worse clinical outcomes than anterior malalignments.

Finite element analysis of the initial stability of arthroscopic ankle arthrodesis with three-screw fixation: posteromedial versus posterolateral home-run screw

“…TAA can maintain a normal range of motion of the ankle joint, prevent degeneration of adjacent joints, and help patients restore normal gait and function [ 19 , 20 ]. However, ankle replacement is not as mature as hip and knee replacement due to factors including prosthetic design and anatomical characteristics [ 21 , 22 ]. A recent meta-analysis compared ankle arthrodesis with ankle replacement using third-generation prostheses and suggested that the overall complication rate was higher in the AAA group, but the revision rate was higher in the TAA group [ 19 ].…”

ISB recommendations for skin-marker-based multi-segment foot kinematics

“…1). 3D kinematic analysis of individual bones is valid and reliable only via invasive approaches such as intracortical pins (Arndt et al, 2007;Lundgren et al, 2008;Westblad et al, 2002), actuator-controlled gait simulators in vitro (McKearney et al, 2019;Nester et al, 2007;Okita et al, 2013;Saito et al, 2019), quasi-dynamic radiostereometric analysis (RSA) which involves insertion of intracortical markers (Lundberg, 1989;Lundberg et al, 1989aLundberg et al, , 1989bLundberg et al, , 1989c and bi-planar video fluoroscopy (Komistek et al, 2000;Lenz et al, 2021). Intracortical pins, actuator controlled gait simulators and RSA methods all track bones very precisely by utilizing at least three non-collinear markers inserted surgically into each bone segment of interest.…”

Preoperative Guidance With Weight-Bearing Computed Tomography and Patient-Specific Instrumentation in Foot and Ankle Surgery

“…Due to the novelty of WBCT technology, there are limited data on its usefulness in reducing postoperative complications, and further clinical studies are warranted. While correlations between implant positioning and outcomes have been reported [8,33,42], further investigation is needed to determine the position that yields optimal outcomes. The available evidence shows that using preoperative WBCT for intraoperative procedures can both decrease operative time and increase rates of implant survival [1,41].…”

“…While not yet approved for use in TAA, advanced intraoperative radiologic techniques have already improved surgical methods for multiple procedure types in foot and ankle surgery [33,41]. Unlike traditional fluoroscopy, which produces 2-dimensional (2D) images, intraoperative 3D fluoroscopic imaging uses a mobile isocentric C-arm to obtain CT-like 3D images.…”