Chinese Journal of Tissue Engineering Research ›› 2020, Vol. 24 ›› Issue (18): 2811-2816.doi: 10.3969/j.issn.2095-4344.2666

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Minimally invasive treatment of hallux valgus with bandage for external fixation: finite element analysis of stability of the osteotomy end 

Bai Zixing1, Cao Xuhan1, Sun Chengyi2, Chen Si1, Hu Haiwei1, Wen Jianmin1, Li Yanle1, Lin Xinxiao1, Sun Weidong1   

  1. 1Second Department of Orthopedics, Wangjing Hospital of China Academy of Chinese Medical Sciences, Beijing 100102, China; 2Beijing University of Chinese Medicine, Beijing 100029, China
  • Received:2019-11-04 Revised:2019-11-13 Accepted:2019-12-13 Online:2020-06-28 Published:2020-04-02
  • Contact: Sun Weidong, Chief physician, Second Department of Orthopedics, Wangjing Hospital of China Academy of Chinese Medical Sciences, Beijing 100102, China
  • About author:Bai Zixing, Master candidate, Second Department of Orthopedics, Wangjing Hospital of China Academy of Chinese Medical Sciences, Beijing 100102, China
  • Supported by:
    the National Natural Science Foundation of China, No. 81373802; the Natural Science Foundation of Beijing, No. 7172244; the Science and Technology Project of Beijing, No. Z191100006619024

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Abstract:

BACKGROUND: The clinical effect of minimally invasive treatment of hallux valgus is significant. The osteotomy end is stabilized only by external fixation of the bandage. There is currently no research on the stability of the osteotomy end.

OBJECTIVE: To study the effect of minimally invasive treatment of the “8” bandage external fixation on the stress and displacement of the osteotomy end in the balanced standing condition after hallux valgus.

METHODS: In the minimally invasive treatment of the “8” bandage external fixation finite element model after the hallux valgus operation, three vertical axes (X-axis, Y-axis, Z-axis) were established with the first tibial osteotomy as the center. The X-axis and Y-axis were parallel to the horizontal plane of the foot, pointing to the medial and anterior sides of the foot respectively. The Y axis was perpendicular to the horizontal plane of the foot, pointing upwards. The four nodes defining the distal osteotomy surface were A1 on the upper side, B1 on the outer side, and C1 on the outer side, and D1 on the inner lower side. The proximal end osteotomy surface corresponded to four nodes as A2, B2, C2 and D2. The displacement was positive when it coincided with the direction of the coordinate axis, and negative when it was opposite. Through the finite element analysis, the direction and magnitude of the stress and displacement of the distal and proximal nodes of the osteotomy surface in the balanced standing condition were obtained.

RESULTS AND CONCLUSION: (1) The finite element model of the “8” bandage after minimally invasive treatment of hallux valgus was used in a balanced standing condition. The maximum stress at the osteotomy end was at the dorsal side of the osteotomy surface (B2), which was 0.632 MPa. (2) The first principal stress at the osteotomy surface was at Z-axis. The direction was opposite to the Z-axis, and was the same as the total stress, which was a compressive stress. The shear force was the largest on the XY plane, and the maximum stress was at the dorsal inner side (A2) of the proximal osteotomy surface, which was 0.058 MPa. (3) The major displacements of the distal and proximal ends of the first patella osteotomy were on the X-axis, and the displacements were on the medial condyle (D1) of the osteotomy surface, i.e., -1.002 mm and medial condyle (A2), and 0.621 mm, respectively. (4) The results confirm that the external fixation of “8” bandage can maintain the stability of the osteotomy end after minimally invasive treatment of hallux valgus, and is conducive to the healing of the osteotomy end.

Key words: hallux valgus, minimally invasive, osteotomy, bandage, external fixation, finite element, displacement, stability

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