Customized Three-Dimensional-Printed Orthopedic Close Contact Casts for the Treatment of Stable Ankle Fractures: Finite Element Analysis and a Pilot Study

Abstract Ankle fracture is one of the most common traumatic fractures among the elderly population. The majority of ankle fractures are stable types with the typically conservative strategy of close contact casting treatment. The continuous use of unventilated standard cast immobilization severely affects patient’s satisfaction and compliance and markedly increases the rates of various complications. Three-dimensional (3D) printing for casts has advantages of lightweight, ventilated, proper-fit, and esthetic improvements. In this work, this novel 3D-printed cast has been applied to individuals with stable ankle fractures, and its effectiveness can be successfully validated with finite element analysis and a pilot study. A 30% reduction of the volume was chosen as the optimal result in topology optimization. Both 3D-printed casts and conventional casts showed significant ankle function improvement after immobilization for 6 weeks (p = 0.000). The 3D-printed casts were superior to the traditional casts in Olerud–Molander Ankle Scores (OMAS), with the mean difference of 8.3 ± 8.57 OMAS points (95% CI −10.8 to 27.5; p = 0.354) for 6 weeks, implying that the 3D-printed casts possibly maintain the equal clinical efficacy as the traditional casts. The statistically significant difference between groups from the 3D-printed cast and the traditional one observed in C-QUEST 2.0 was 11.3 ± 1.5 points (95% CI 8.0–14.6; p = 0.000), indicating that the 3D-printed cast possesses outperforming satisfaction and compliance and has great potential in practical applications. There were no severe complications in the 3D-printed casts, but more moderate complications were observed in the traditional casts.