A novel approach to characterize the correction path features for the tibia deformity correction.

Preoperative correction path planning is an important preparation for obtaining the desired correction. However, a convenient and effective model has not been proposed to characterize the correction path features, especially how to visualize the growth process of the bone cross-section has not been investigated. In this paper, a new characterization approach of the correction path features and corresponding evaluation indexes are proposed for the tibia deformity correction. We represent the growth process of new bone cross-section by a series of continuous and discrete circles. Based on the definition and assumptions of the bone cross-section, three evaluation indexes are proposed to assist the clinician in critically comparing and analyzing the feasibility of preoperatively correction approaches. A motor-driven parallel external fixator (MD-PEF) is developed to verify the proposed characterization approach. Finally, the features of the generated correction paths are compared and analyzed based on three correction methods. The results show that the proposed method can well present the growth process of bone cross-section and can detect the overlap phenomenon between bone cross-sections. And the approach of joint adjustment for equal bone distraction can generate a smooth correction path, uniform distraction rate and effectively avoid the overlap of bone cross-sections. This study is an important addition to facilitating the development of deformity correction techniques.