IPSILATERAL FEMORAL AND TIBIAL FRACTURES

Purpose of the study Simultaneous ipsilateral femoral and tibial fract ures cause a floating knee. Treatment of such patients is complicated by fat-embolism syndrom (12 per cent), local soft tissue damage, ipsil ateral knee ligament tear (5 to 39 per cent) and delayed shortening or torsionnal deformity. Our study aimed to determine the frequency of c omplaints about the knee and to study the causes of malunion.Material and methods Twenty-four patients with floating knee were treated betwe en 1987 and 1992. Comminution was assessed according to Winquist et al . Associated soft tissue damage was assessed according to Gustilo at a l. The grade III open fractures were always treated by external fixati on. Intra-medullary nailing was always performed after reaming. Result s One patient died and eighteen were reviewed. Fat-embolism syndrom oc curred in three cases, one superficial infection occurred in femoral p lating, nine deep infection occurred in tibia[ fracture : 7 for grade II and III open fracture treated by external fixation and one after na iling of a grade I open fracture. Malunion occurred in five patients : 2 shortening, 2 external rotational femoral deformity of 15 and 35 de grees, one shortening associated with external rotational femoral defo rmity of 30 degrees. Error in comminution evaluation was the leading c ause of these malunions. Non-union occurred in 2 femoral and one tibia l fracture. These complications were treated by decortication and osse ous grafting. Four patients had a late diagnosis of ipsilateral ligame ntous injury : antero and posterior in three and lateral isolated in o ne. Eighteen patients were reviewed. Results were excellent in 4, good in 7 and poor in 7. The seven poor results were : 1 amputation, four patients with ligamentous injury and 2 of the 5 malunions. Discussion Clinical evidence of fat embolism has been reported after reaming of f ractured long bones. Reaming led to an increase in pulmonary artery pr essure and in pulmonary free fatty acids. Reaming in the same time fem oral and tibial diaphysis increased this kind of complication. We perf ormed femoral and tibia[ fixation during the same operating time : fir st the femur and after the tibia. Tibial open grade III fractures were fixed first by external fixation. Ipsilateral femoral and tibial nail ing increase malunion : shortening and rotational malunion. This probl em can be reduced but not eliminated by using rocking nails : the erro r was established during the operation. Distal femoral traction gives better torsionnal control. Fractures in the distal segment of the femu r are particularly prone to the development of axial malignement. In t his series, malunion occurred in three cases. Knee effusion in patient with ipsilateral femoral and tibial fracture should not be ignored. I t may indicate meniscal or articular pathology, or ligament disruption . If there is suspicion of ligament injury, a supracondylar femoral tr action is recommended for nailing. After femoral and tibial fixation, the knee must be examined clinically. Early surgical repair of periphe ral tears is advocated. Repair of an anterior or posterior ligament wi thout proximal or distal avulsion may not be warranted. Conclusion Sim ultaneous ipsilateral femoral and tibial fracture, or so called floati ng knee, occurs in patients who are involved in a high-velocity injury . Knee instability is however the major cause of poor results.