Background:Reverse intertrochanteric fractures are usually initially treated with closed reduction.However,sometimes these fractures are not amenable to closed reduction and require open reduction.To date,few studies have been conducted on predictors of and reduction techniques for irreducible reverse intertrochanteric fractures.Therefore,this study aimed to summarize the displacement patts of irreducible reverse intertrochanteric fractures and corresponding reduction techniques,and explore predictors of irreducibility.Methods:We reviewed 1174 cases of trochanteric fractures treated in our hospital from January 2006 to October 2018,113 of which were reverse intertrochanteric fractures.An irreducible fracture was determined according to intra-operative fluoroscopy imaging after closed manipulation.Fractures were assessed for displacement patts,radiographic features of irreducibility,and reduction techniques.Logistic regression analysis was performed on potential predictors for irreducibility,including gender,age,body mass index,AO Foundation/Orthopaedic Trauma Association (AO/OTA) classification,and radiographic features.Results:Seventy-six irreducible fractures were identified,accounting for 67％ of reverse intertrochanteric fractures.Six patts of fracture displacement after closed manipulation were identified;the most common patt was medial displacement and posterior sagging of the femoral shaft relative to the head-neck fragment.Multivariate logistic regression analysis identified three predictors of irreducibility:a medially displaced femoral shaft relative to the head-neck fragment on the anteroposterior (AP) view (odds ratio [OR],8.00;95％ confidence interval [CI],3.04-21.04;P ＜ 0.001),a displaced lesser trochanter (OR,3.61;95％ CI,1.35-9.61;P =0.010),and a displaced lateral femoral wall (OR,2.92;95％ CI,1.02-8.34;P =0.046).Conclusions:A high proportion of reverse intertrochanteric fractures are not amenable to closed reduction.Six patts of fracture displacement after closed manipulation were identified.Different reduction techniques are required for different displacement patts.Predictors of irreducibility include a medially displaced femoral shaft relative to the head-neck fragment on the AP view,a displaced lesser trochanter,and a displaced lateral femoral wall.These patients warrant special consideration in terms of recognition and management.