Static finite element analysis of the stability of osteotomy after hallux valgus surgery based on wrapped curtain method with external fixation / 中国组织工程研究

ABSTRACT

BACKGROUND:Integrated Traditional Chinese and Western Medicine minimaly invasive treatment for halux valgus based on wrapped curtain method with “8”-shaped bandage and sub toe pad external fixation has been used for a long time in the clinic. This method abandons the internal implant fixationandexternal plaster fixation. After surgery, patients could take care of themselves. However, theactivity of the broken end may cause fracture nonunion, which once aroused scholars’ question. Recently, with the continuous improvement of foot biomechanics research, foot finite element model and applications become a reality. OBJECTIVE:To evaluate thestability of osteotomy after the operation of wrapped curtain method with“8”-shaped bandage and sub toe pad external fixation on the basis of static finite element method. METHODS:A young female volunteer with halux valgus was selected, whose body weight was 58 kg, and right foot halux abductor valgus angle was 24°; intermetatarsal angle was 13°; proximal articulator set angle was 7°; distal articulator set angle was 7°. CT was used to scan the right foot. ABAQUS software was applied to establish a finite element model of right foot halux valgus bone, and model of the first metatarsal neck minimaly invasive osteotomy was simulated based on wrapped curtain method with external fixation. Von Mises stress and displacement at the osteotomy endwere calculated. RESULTS AND CONCLUSION:(1) The maximum stress was 0.067 MPa without external fixation, and the maximum stress was 1.258 MPa with the external fixation. Stress was mainly distributed in the outer edge of the osteotomy. (2) The maximum absolute displacement was 0.363 mm without external fixation, and the maximum absolute displacement was 0.716 mm with external fixation. The two largest displacements were both in the Z-axis direction. Statistical analysis confirmed that the four nodes absolute displacement and stress were significantly different (P 0.05). The four nodes relative displacements were statisticaly significant in Z-axis (P< 0.05). (5) These findings suggest that the external fixation based on wrapped curtain method after halux valgus surgery could effectively reduce osteotomy displacement. The moderate stress and elastic fixation are conducive to fracture healing.