Biomechanical Evaluation of Hemiarthroplasty in First Metatarsal Bone

Abstract

Hallux valgus and hallux rigidus are the most common pathologies of the first metatarsophalangeal joint. Despite advances in the treatment of hallux valgus and hallux rigidus, no one technique can address the various stages of these pathologies. To alleviate these pathologies there are destructive techniques such as cheilectomies, arthrodesis and arthroplasties, and there are non-destructive techniques such as certain osteotomies. Hemiarthroplasty in the first metatarsal bone allows to recover the mobility of the first ray as well as to eliminate the pain caused by hallux valgus and hallux rigidus. However, there are no studies that allow us to know the biomechanical effect that the implant researched in this article produces on the human foot. Finite element analysis is a good technique that allows to understand these biomechanical effects. The objective of this work is to make a biomechanical evaluation of the HemiCAP®Toe DF by Arthrosurface and in that way to know the effects that this type of devices produces in the foot. To do this a finite element model of the foot after having performed a hemiarthroplasty in the first metatarsal bone was developed. It was detected a loss of capacity to support load in the first ray after introducing the implant, as well as an increase of principal stresses in the second and third ray. Effects of the hemiarthroplasty might cause postoperative medical complications. It was found loss of passive windlass mechanism in the model, leading to a loss of effectiveness in walking.