Laboratory and anatomical factors associated with in-hospital complications in orthopedic polytrauma

Polytrauma with orthopedic injuries poses a significant clinical challenge due to the interaction between anatomical trauma, physiological instability, and metabolic disturbances. In this retrospective cohort study, we evaluated whether admission blood gas parameters are associated with a predefined composite in-hospital complication outcome including mortality and morbidity, in polytrauma patients with orthopedic injuries. A total of 227 polytrauma patients admitted to a Level I trauma center between January 2020 and December 2022 were included. Demographics, trauma mechanism, Injury Severity Score (ISS), stabilization status, admission laboratory parameters (pH, lactate, base deficit, hemoglobin), surgical approach, and in-hospital outcomes were recorded. Discriminative performance was assessed using receiver operating characteristic (ROC) analysis with Youden index cutoffs, and multivariable logistic regression was used to estimate adjusted associations with the composite complication outcome using ROC-derived dichotomized laboratory variables. The mean age was 44.5 ± 16.5 years, and 83.7% of patients were male. Complications occurred in 61 patients (26.9%), and mortality accounted for 49.2% of complications. Traffic accidents constituted 58.6% of mechanisms, with pedestrian accidents accounting for 29.1% of all cases. Femur fractures were associated with higher complication rates in univariable analysis (P = .001), and extremely unstable admission status was strongly associated with complications (P < .001). ROC analysis showed modest discrimination (area under the curve: pH 0.698, base deficit 0.663, lactate 0.647, hemoglobin 0.591), with cutoffs of pH < 7.33, base deficit < -2.6, lactate > 3.4 mmol/L, and hemoglobin < 12.6 g/dL. In multivariable analysis, ISS (P = .001) and hemoglobin (P = .037) remained associated with complications, while pH showed a borderline association (P = .071). Admission blood gas parameters, particularly pH, show modest discriminative ability and may support early risk assessment alongside injury severity and clinical stability. Femoral fractures, higher ISS, and lower hemoglobin identify patients at increased in-hospital complication risk, whereas blood gas markers should be interpreted as supportive rather than definitive predictors.