Hallux Valgus Introduction
From the biomechanical point of view, the medial column of the foot plays a very important role in the stability of the lower limbs, especially for the forefoot The first metatarsophalangeal joint, the point of maximum weight stress, forefoot activity most adaptable strongest part, so this site is the most common part of congenital malformations and acquired deformities, but also easy to accumulate a variety of diseases site. For normal people, for the biomechanical measurement of hallux valgus, the first 2 metatarsal angle between the normal upper limit is 8 ~ 9 °, the first metatarsophalangeal joint angle normal upper limit is 15 ~ 20 °, this angle Biomechanical analysis and research of hallux valgus is very important, and measurement and understanding of these two aspects are crucial to the setting of surgical methods. A simple thumb valgus, the first metatarsophalangeal joint valgus angle increases, accompanied by metatarsal joint valgus will appear a lot of combined disease. When the thumb valgus angle increases more than 3 0 ~ 35 °, pronation occurs premature pronation deformity, with this congenital malformation, abduction of the hallux valgus to the plantar, thumb and adductor retraction hallux valgus, So that the medial first metatarsophalangeal joint support structure weakened strength, metatarsal head relative to the seminal vesicle shift, on the contrary, also the same relative to the sesamoid bone outside the shift. At the same time, flexor hallucis, flexor hallucis longus, thumb adductor muscle and thumb extensor increased valgus arm, and then increase deformity. For sesamoid bone displacement, especially the tibial sesamoid and the first metatarsal head straddling portion become flattened due to pressure, the fibular sesamoid bone is displaced to the outside and displaced to the first metatarsal region. The patient's body mass shifts from the first metatarsal to the other metatarsal heads, causing metastatic metatarsalgia, painful callus, and stress fractures. So the hallux valgus deformity will be complicated by a lot of forefoot deformity, at the same time in the design of the surgical approach, to consider a lot of deformity related factors to the specific design of the surgical approach. In addition to the above deformities, the second toe hammer toe, toe overlap occurs in patients with severe hallux valgus. The first metatarsophalangeal joint will also be associated with metatarsophalangeal arthritis changes. For such a serious hallux valgus, consider the first metatarsal and second metatarsophalangeal orthopedic. In order to understand the degree of hallux valgus and congenital malformations, detailed preoperative physical examination and imaging assessment were performed on each patient. Specific to the imaging assessment, often need to do more patients with hallux valgus position film. For example, the necessary film is a negative position, dorsal metatarsal position, anterior foot position, the anterior position of the anteroposterior film, the negative position of the lateral films, but also non-weight-bearing external oblique films, and phalanges. Through these four angles of the X-ray examination can help group analysis of the degree of hallux valgus and accompanying with the various forefoot deformed hallux valgus to understand the changes in biomechanics to help design the way of surgery. In clinical practice, there are many observer differences in the actual measurement. Different people to measure, often come to perspective is not exactly the same. In order to standardize this measure internationally, it is prescribed that the medial-lateral ratio of the first metatarsal be demarcated its definite sign on the X-ray. The midpoints of the two metatarsals are determined by the central axis of the first metatarsal. By the same token, the first metatarsal and the second metatarsal axis can be identified, so that the angle of the hallux valgus and the angle between the first and second metatarsals can be measured.
This picture shows that after the first metatarsal and first phalanges and the medial and lateral cortices of the second metatarsus are indexed to the central axis, the central axes are connected and the angle they make is measured to measure the required biomechanical The value of each angle to help select the surgical approach to determine the degree of hallux valgus.