Abstract: ObjectiveTo observe and compare the application effect and safety of open and closed reduction and internal fixation in posterior malleolus fractures via posterolateral approach. 
MethodsThe clinical data of 87 patients with ankle fracture combined with posterior malleolus fracture were retrospectively analyzed, and they were divided into the open group(n=44) and the closed group(n=43) according to different treatment methods. The open group was treated with open reduction and internal fixation via the posterolateral approach, and the closed group was treated with closed reduction and internal fixation. Operation-related indexes, complications, excellent and good rate of ankle joint function recovery at 12 months after operation, bone metabolism indexes before operation, at 2 weeks and 4 weeks after operation［type Ⅰ collagen carboxy-terminal peptide β special sequence(β-CTX), procollagen type Ⅰ carboxy-terminal peptide(PICP), bone gla protein(BGP)］,and ankle range of motion(ROM)at 6 months and 12 months after surgery were compared. 
ResultsThe duration of operation and fracture healing time of the closed group were shorter than those of the open group, and the intraoperative blood loss was less than that of the open group(P＜0.05).Serum β-CTX levels in the two groups showed a gradually decreasing trend, while PICP and BGP levels gradually increased.The difference of interaction between groups, time points and time points between groups were statistically significant(P＜0.05). The incidence of postoperative complications in the closed group was lower than that in the open group(P＜0.05). There was no significant difference in the ROM of plantar flexion, dorsiflexion, valgus and varus between the two groups at 6 and 12 months after operation(P＞0.05).There was no significant difference in the excellent and good rate of ankle function recovery between two groups at 12 months after operation(P＞0.05). 
ConclusionCompared with open reduction and internal fixation via the posterolateral approach, closed reduction and internal fixation for the treatment of posterior ankle fractures has the advantages of convenient operation, less trauma, fewer complications, improved postoperative bone metabolism indexes, and faster fracture healing. Ankle joint function has recovered well.

Key words: ankle fracture, open reduction and internal fixation, closed reduction and internal fixation