1. Comparison of Extraosseous Talotarsal Stabilization Implants in a Stage II Adult- Acquired Flatfoot Model: A Finite Element Analysis 
Jian Xu, PhD, MD, Xin Ma, PhD, MD, Daping Wang, PhD, MD, Wei Lu, PhD, MD, Weimin Zhu, PhD, MD, Kan Ouyang, MM, Haifeng Liu, MM, Hao Li, MM, Luoyong Jiang, MM 
The Journal of Foot and Ankle Surgery 
Volume 56, Issue 5, Pages (September 2017)
DOI: /j.jfas
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

2. Fig. 1
Appearance of the foot of the enrolled patient with stage II adult-acquired flatfoot deformity. (A) Anteroposterior view of the foot. (B) Lateral view with weightbearing showing the collapsed medial arch. (C) Posterior view showing the valgus hindfoot.
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

3. Fig. 2
A finite element model of 16 bones, 56 ligaments, and soft tissues was established. (A) The soft tissues were contained in this finite element model. (B) The bones and ligaments can be seen after soft tissue removal.
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

4. Fig. 3
(A and B) Type IB and type II sinus tarsi implant models were built and simplified by removal of the screw threads (arrow).
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

5. Fig. 4
The sinus tarsi implant placement models were chosen according to the actual size of the sinus tarsi by carefully matching all the models to the sinus tarsi. (A) Lateral view and (B) bottom view of the type IB sinus tarsi implant model chosen. (C) Lateral view and (D) bottom view showing the type II sinus tarsi implant model chosen.
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

6. Fig. 5
The implantation process (arrow) for (A) type IB and (B) type II was simulated, resulting in mechanical feedback for the whole foot.
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

7. Fig. 6
The plantar stress distribution showed the peak stress was kPA under the first metatarsal head by simulation of the mid-stance phase in the model.
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

8. Fig. 7
The measurement from the deformed model showed the (A) talonavicular coverage angle and (B) talo-first metatarsal angle and calcaneus pitch angle was 11.78°, 8.3°, and 14.41°, respectively. (C and D) The corresponding angles measured on the radiographs were 10.17°, 8.2°, and 14.96°.
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions

9. Fig. 8
After the sinus tarsi implant placement process was simulated, the plantar stress distribution were all lowered under weightbearing conditions with a peak stress of (B) kPa for type IB and (C) kPa for type II, compared with preoperative weightbearing KPa (A), under the first metatarsal head.
The Journal of Foot and Ankle Surgery  , DOI: ( /j.jfas )
Copyright © 2017 American College of Foot and Ankle Surgeons Terms and Conditions