Intramedullary nailing for open fractures of the femoral shaft: evaluation of contributing factors on deep infection and nonunion using multivariate analysis.

The purpose of this study was to use multivariate analysis to evaluate contributing factors affecting deep infection and nonunion of open femoral fractures treated with locked intramedullary nailing (IMN). We examined 89 open femoral fractures (88 patients) treated with immediate or delayed locked IMN in static fashion at the Kitasato University Hospital from 1988 to 2001. Multiple regression models were derived to determine predictors of deep infection and nonunion. The following predictive variables of deep infection were selected for analysis: age, sex, Gustilo type (I+II or III), fracture grade by AO type (A or B+C), fracture site (proximal site+distal site or middle site), timing or method of IMN, reamed or unreamed nailing (R versus UR), debridement time (< or =6 h or >6 h), existence of polytrauma (ISS<18 or ISS> or =18), and existence of floating knee injury (+ or -). The predictive variables of nonunion selected for analysis were the same as those for deep infection, with the addition of deep infection (+ or -). Five fractures (5.6%) developed deep infections: one Gustilo type II and four type III. Multivariate analysis revealed that only Gustilo type significantly correlated with occurrence of deep infection (p<0.05). Nonunion occurred in 12 fractures (14.1%). Multivariate analysis revealed that only fracture grade by AO type significantly correlated with occurrence of nonunion (p<0.02).

Evaluation of functional outcome of the floating knee injury using multivariate analysis.

INTRODUCTION: The objective of this study is to evaluate significant contributing factors affecting the functional prognosis of floating knee injuries using multivariate analysis. PATIENTS AND METHODS: A total of 68 floating knee injuries (67 patients) were treated at Kitasato University Hospital from 1986 to 1999. Both the femoral fractures and the tibial fractures were managed surgically by various methods. The functional results of these injuries were evaluated using the grading system of Karlström and Olerud. Follow-up periods ranged from 2 to 19 years (mean 50.2 months) after the original injury. We defined satisfactory (S) outcomes as those cases with excellent or good results and unsatisfactory (US) outcomes as those cases with acceptable or poor results. Logistic regression analysis was used as a multivariate analysis, and the dependent variables were defined as a satisfactory outcome or as an unsatisfactory outcome. The explanatory variables were predicting factors influencing the functional outcome such as age at trauma, gender, severity of soft-tissue injury in the femur and the tibia, AO fracture grade in the femur and the tibia, Fraser type (type I or type II), Injury Severity Score (ISS), and fixation time after injury (less than 1 week or more than 1 week) in the femur and the tibia. RESULTS: The final functional results were as follows: 25 cases had excellent results, 15 cases good results, 16 cases acceptable results, and 12 cases poor results. The predictive logistic regression equation was as follows: Log 1-p/p = 3.12-1.52 x Fraser type - 1.65 x severity of soft-tissue injury in the tibia - 1.31 x fixation time after injury in the tibia - 0.821 x AO fracture grade in the tibia + 1.025 x fixation time after injury in the femur - 0.687 x AO fracture grade in the femur ( p=0.01). Among the variables, Fraser type and the severity of soft-tissue injury in the tibia were significantly related to the final result. CONCLUSION: The multivariate analysis showed that both the involvement of the knee joint and the severity grade of soft-tissue injury in the tibia represented significant risk factors of poor outcome in floating knee injuries in this study.