Hallux valgus is the most common deformity of forefoot and the patients would suffer pain and disable of walking and wearing normal shoes. Chevron osteotomy of the first metatarsal is widely used for the treatment of mild or medium hallux valgus. It is a "V" sharp osteotomy that can decrease the intermetatarsal degree of first-second metatarsal by pushing the distal side of osteotomy laterally.A 2.5mm or 3.0mm steel cannulated screw is usually used for the fixation of the osteotomy side to provide stability.However,there are some shortcomings of steel screws such as rejection of internal fixation or the financial cost of the second surgery of fixation taken-out. To obviate these shortcomings of steel screws, bioabsorbable screw fixation may be an alternative method for chevron osteotomy.

This trial is a randomized, prospective, controlled, parallel experimental design, to compare the clinical and radiographic outcomes of bioabsorbable screw versus steel screw for the treatment of hallux valgus with chevron osteotomy. The patients will be randomized to two groups, one treated with bioabsorbable screws while the other treated with steel screws.Data collection for the outcomes measures will occur pre-op,immediate post-op and then 6 weeks, 12 weeks, and at 1 years post operation.

The clinical outcomes measure are the VAS (visual analogue scale) score and AOFAS (American orthopedic foot and ankle society) forefoot score.The radiographic outcomes measures are the IMA (intermetatarsal angle) and the HVA (hallux valgus angle)

Inclusion Criteria:

1. hallux valgus treated with distal chevron osteotomy
2. age between 18-70

Exclusion Criteria:

1. hallux valgus treated with other procedure (scarf,ludloff,lapidus,etc)
2. age <18 or age >70
3. rheumatoid
4. osteoporosis -