Abstracts: 11th World Congress, Osaka, Japan S79 with 42 femoral and 11 tibial fractures were treated with either reamed intramedullary nailing (Group R, n = 28) or with unreamed nailing (Group NR, n = 20) within three days of their injuries. The mean value for age was 27.4 years (range, 16 to 63 years). In Group R, 28 femoral and four tibial fractures, reaming was performed up to 12.5 mm, and a 9-11 mm nail was inserted. In Group NR, 14 femur and 7 tibial fractures, a 9-10 mm nail was inserted without reaming. BAL was performed within 24 hours postoperatively with the standard procedure, in which sterile normal solution is instilled in 20 mL aliquots for a total of 100 ml, and immediately aspirated manually with a syringe. The cells contained in the lavage fluid were counted on uncentrifuged specimens by using a hemocytometer. The fluid then was centrifuged (1,500 rpm, 5 minutes), and differential cell counts were performed on a preparation that was stained with Wright-Giemsa stain. The percentage of lavage cells containing red or brown-red fat droplets (lipidladen cells) was calculated after examination of at least 200 cells on the slides stained with Sudan III, and the findings for two groups were compared. Results: The average age, ISS, and fracture index (Fl) were 28.1 ±12.4 years, 15.2 ±9.3, and 5.4 ±2.4 in Group R; and 26.3 ±11.7 years, 14.5 ±6.4, and 4.7±3.2 in Group NR, respectively. There were no significant differences between two groups. The mean percentage of lipid-laden cells in BAL fluid was 33.6 ±25.8% (range, 2 -89%) for Group R and 36.6 ±21.3 % (range, 2-70%) in Group NR. This difference also was not significant statistically. In this study, no typical features of fat embolism syndrome were identified in any of the patients.