Abstract
Introduction: The chevron osteotomy is an accepted method for the correction of mild and moderate hallux valgus and generally advocated for patients younger than the age of sixty years. In the current work the finite element analysis applied to calculate the stress (force per unit area) on different cuts in the metatarsal bone model of the first ray in the human foot.
Material and Methods: The cuts have the form of a simple angle with 90 degrees ‘modified chevron osteotomy’, 60 ‘typical chevron osteotomy’ 70, 50 and 30, openings correspondingly, and share a common corner C, which is at the centre of a circle that fits the head of the metatarsal. In order to calculate the maximum stresses on the cuts, the bone is assumed to be with a 150 angle to the floor, which is the angle that it takes during the push-off phase.
Results: The calculations show a considerable difference on the stress distribution on the differnt cuts. In particular in the ‘90 degrees cut’ the normal (to the cut) stress is much larger than the shear stress. The opposite is true for the 60 cut. Since shear stresses are the ones that cause material failure, it is predicted that the 90 cut will heal much faster than the 60 cut. The nodes along the cuts where the normal and the shear stress were calculated in different osteotomies.
Conclusion: The FEM analysis confirm our clinical results of this modified chevron osteotomy of 90 degrees. The osteotomy site is firmly secured, avoiding early displacement of the lateral fragment and give earlier fusion.
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