Abstract: Objective  To investigate the application of operation plan based on injury stress sequence in the treatment of degree Ⅲ and Ⅳ ankle fractures with Lange-Hansen classification of pronation and external rotation.Methods From May 2019 to May 2022,80 eligible patients of degree Ⅲ and Ⅳ ankle fractures with Lange-Hansen classification were selected prospectively and randomely divided into 2 groups:40 patients in the study group were treated with surgical reduction according to the sequence of injury stress,and the other 40 patients in the control group were treated with traditional reduction sequence.The operative time, intraoperative blood loss, fracture healing time, full weight-bearing time, Ankle dorsoextension Angle, plantar flexion Angle, and American Orthopaedic Foot and Ankle Association were compared between the two groups Society,AOFAS) Ankle and posterior foot function scores and complications.Results The surgical time [(44.80±5.12) min vs.(47.61±6.42) min] and surgical bleeding volume [(43.81±9.02) ml vs.(51.50±12.01) ml] between the study group and the control group were statistically significant(all P＜0.05).Before surgery,there had no significant differences in ankle joint dorsiflexion angle,plantar flexion angle,AOFAS ankle and hind foot function score in 2 groups(all P＞0.05).The ankle dorsiflexion angle at 3 months after surgery [(16.84±1.77) ° vs.(15.50±1.65) °],plantar flexion angle at 3 months after surgery [(45.64±4.10) ° vs.(42.58±3.86) °] and at 6 months after surgery [ (52.38±3.03) °vs.(50.64±3.74) °],the maximum walking distance score [(3.50±0.64) vs.(3.16±0.60)],ground walking score [(2.06±0.56) vs.(1.72±0.48)] and ankle joint anteroposterior activity score at 3 months after surgery [(4.96±1.38) vs.(4.16±1.07)] of the study group were all higher than those in the control group(all P＜0.05).There was no statistically significant difference in terms of fracture healing time,complete weight-bearing time,postoperative pain score,ankle joint function autonomous activity support score,abnormal gait score,maximum walking distance score at 6 months after surgery,ground walking score,ankle joint anterior and posterior activity score and surgical complications between 2 group(all P＞0.05).Conclusion According to the sequence of injury stress,surgical reduction for the treatment of grade Ⅲ and Ⅳ ankle fractures of Lange-Hansen classification of middle pronation and external rotation can shorten the operation time and promote the early recovery of joint function.

Key words: damage stress sequence, open reduction and internal fixation, Lange-Hansen classification, pronation external rotation, broken ankle joint