[Biomechanical study on repair and reconstruction of talar lesion by three-dimensional printed talar components].

Objective: To explore the feasibility of the repair and reconstruction of large talar lesions with three-dimensional (3D) printed talar components by biomechanical test.

Methods: Six cadaveric ankle specimens were used in this study and taken CT scan and reconstruction. Then, 3D printed talar component and osteotomy guide plate were designed and made. After the specimen was fixed on an Instron mechanical testing machine, a vertical pressure of 1 500 N was applied to the ankle when it was in different positions (neutral, 10° of dorsiflexion, and 14° of plantar flexion). The pressure-bearing area and pressure were measured and calculated. Then osteotomy on specimen was performed and 3D printed talar components were implanted. And the biomechanical test was performed again to compare the changes in pressure-bearing area and pressure.

Results: Before the talar component implantation, the pressure-bearing area of the talus varied with the ankle position in the following order: 10° of dorsiflexion > neutral position > 14° of plantar flexion, showing significant differences between positions ( P <0.05). The pressure exerted on the talus varied in the following order: 10° of dorsiflexion < neutral position < 14° of plantar flexion, showing significant differences between positions ( P <0.05). The pressure-bearing area and pressure were not significantly different between before and after talar component implantations in the same position ( P >0.05). The pressure on the 3D printed talar component was not significantly different from the overall pressure on the talus ( P >0.05).

Conclusion: Application of the 3D printed talar component can achieve precise repair and reconstruction of the large talar lesion. The pressure on the repaired site don't change after operation, indicating the clinical feasibility of this approach.