Predictors of mechanical complications after intramedullary nailing of unstable trochanteric fractures in elderly patients

Introduction. The use of cephalomedullary nails in the treatment of "unstable" acetabular fractures is recognized as a gold standard. The most common mechanical complication of its use is cut-out which is a varus fracture collapse with neck implant penetration of the femoral head. The role of various variables in predicting the risk of this complication is not fully understood and the data are inconsistent. The aim of this study was to investigate possible predictors of cut-out during intramedullary osteosynthesis of unstable trochanteric fractures in patients over 75 years of age.Materials and Methods. A retrospective study involved 183 patients operated on between August 2017 and December 2019. We analyzed the incidence of cut-out depending on several variables: gender, the severity of osteoporosis, the type of neck implant, the quality of reduction and some radiologicalparameters of the location of the neck implant in the femoral head (tip-apex distance (TAD), position in the Cleveland system zones (modified by Caruso) and Parker's ratio index (PRI).Results. The incidence of mechanical complications was 6.01%. Significant variables were TAD (p=0.017), the quality of fracture reduction (p=0.02) and male gender (p=0.027). The factors not showing statistical significance were the age (p=0.44), PRI value (p=0.29), screw position in the modified Cleveland system (p=0.772), the degree of osteoporosis (p=0.812) and the type of neck fixator (p=0.608). Conclusion. As a result of the study, we obtained three significant predictors of cut-out: TAD, reduction quality and male gender. Therefore, in order to minimize mechanical complications, proper attention should be paid to achieving reduction and correct positioning of the cervical implant.