Contact Mapping Using a Low-Cost Velostat Sensor Array in a Synthetic Ankle Model

Estimating joint pressure distribution is crucial for understanding how pathologies disrupt natural biomechanics and for optimizing rehabilitation outcomes. While numerous computational, cadaveric, and “in vivo” studies have investigated joint mechanics, most have focused on the hip and knee, leaving the ankle underrepresented. Flexible matrix sensors offer a compelling solution for intra-articular pressure mapping due to their thin profile and sensing networks. This study presents a single experimental synthetic model of the human ankle joint—characterized by high-curvature joint surfaces—incorporating ligamentous constraints, a custom Velostat™ piezoresistive 6 × 4 sensor array, and low-cost microcontroller electronics. Joint kinematics was evaluated in the sagittal plane across the range of motion from dorsiflexion to plantarflexion in five angular positions under four clinical conditions: intact joint, unreduced posterior malleolar fracture, and fracture fixation using two distinct syndesmotic stabilization techniques. Motion was passively induced without external axial loading to isolate the mechanical contribution of the ligaments. Qualitative intra-articular contact maps revealed distinct differences among surgical approaches. These preliminary results demonstrate the viability of flexible, low-cost piezoresistive sensing systems as a proof of concept for intra-articular contact monitoring in complex anatomical joints.