CLINICS 2008;64:509-14 Acetabular reconstruction with human and bovine freeze- dried bone grafts and a reinforcement device Rosito R et al. groups to test the effect of these grafts upon outcome. For assessment of possible simultaneous effects of the several factors of the clinical outcomes, bivariate analyses and Cox logistic regression were used.11 In order to compare the radiographic results and clinical outcomes, the two groups were compared by obtaining an estimate of the standardized effect-size (SES). Statistical significance was set at a 5% level (p<0.05) and a confidence interval of 95%. RESULTS No severe complications occurred in the early post- operative period. Only two deaths (one in each group, two and three years after the procedure) were recorded and both were unrelated to RTHA. No patients were lost to follow-up. Overall, no minor events were observed clinically. However, in Group 1 a case of traumatic displacement three years after RTHA required surgical intervention, since attempts for clinical reduction failed. In this case, a histological analysis of the grafted region indicated there was an area of new bone formation and residual spicules from the graft material (Figure 1). In Group 2, a case of superficial infection (cellulitis) occurred six months after the procedure and was successfully treated with antibiotics. The clinical and radiographic outcomes are shown in Tables 2 and 3, respectively. Figure 1 - Histology sample from a three-year follow-up human graft showing areas of new bone formation and residual spicules from the grafted material Table 2 - Clinical outcomes Human Graft (n= 26) n (%) Bovine Graft (n=25) n (%) P value Clinic Evaluation Merle d’Aubigné and Postel Very good and good 12 11 10 Total Medium, fair and poor 9 8 7 or < 7 Total 8 (30.8) 11 (42.3) 5 (19.2) 24 (92.3) 1 (3.8) 1 (3.8) 0 (0) 2 (7.7) 9 (36) 10 (40) 1 (4) 20 (80) 4 (16) 1 (4) 0 (0) 5 (20) 0.384 Figure 2 - Anteroposterior radiography of an acetabular loosening, type IV deficiency by D’Antonio et al. Table 3 - Radiographic results Radiographic Features (SD) Radiolucency Density Trabeculation Migration Radiograph evaluation Scores (%) Very good and good 24 – 22 21 – 19 Total Medium, fair and poor 18 – 16 15 – 13 < 13 Total Human Graft Bovine Graft (n = 26) (n = 25) 5.46 (0.84) 5.40 (0.81) 5.52 (0.69) 4.74 (2.04) 4.92 (1.38) 4.32 (2.16) 5.92 (0.39) 5.84 (0.8) 19 (73.1) 4 (15.4) 23 (88.5) 2 (7.7) 1 (3.8) 0 (0) 3 (11.5) 16 (64) 3 (12) 19 (76) 1 (4) 2 (8) 3(12) 6 (24) P value 0.794 0.085 0.246 0.638 0.424 511