Mechatronic 5-DOF Parallel External Fixator With Correction-Assisted Software for Correcting Foot–Ankle Deformities

Gradual correction with parallel external fixators (PEFs) is a common treatment strategy for foot–ankle deformities. Designing appropriate PEFs and developing correction-assisted software (CAS) with comprehensive functions are clinically important to assure a successful treatment and the proper recovery of the patient. However, existing PEFs are inadequately targeted for specific deformity types of foot–ankle, and CAS is not available for detecting multiple interference phenomena, thus, the safety and accuracy of the corrective process cannot be guaranteed. In this article, an electromechanical drive PEF prototype with good deformity-targeting property is proposed for a common type of foot–ankle deformity with five corrective degree-of-freedom. The system is supported with the CAS that involves digital reconstruction technology, trajectory planning technology, and safety inspection technology. In safety inspection technology, collision inspection is carried out based on the oriented bounding box method, and inspection of the distraction rod overstroke and of the singularity are realized based on the kinematic model. In this way, an interference-free correction scheme can be generated and executed using the proposed PEF system. Case simulation demonstrates the feasibility of correction-assisted technologies, the applicability of the prototype, and the postural synergy between the virtual model and substantiation.