In the last years there is an increase in the interest in the study of growth factors that take part in the process of consolidation of the fracture to be used as treatment. The different types of fixations modify the natural process of the fracture healing and the production of growth factors could also be affected. There is not evidence in the literature of the effect that the intramedullary reaming has on the osteogenesis. We did a study to analyse the effect of intramedullary reaming on the production of growth factors during the process of fracture healing in the femur of rats. We did a pospective study in San Carlos Clinical Hospital from Madrid in which was made a fracture on the femur of 64 adults rats type Sprague-Dawley. The rats were divided in two main groups; each group received one different treatment: 30 rats with intramedullary nail and 34 rats did not receive any treatment. The rats of each group were sacrificed in 4 different moments: at the 24th hour, 4th, 7th and 15th days after the fracture was done, and we measured the amount of growth factors that appeared in the callus fracture, by anatomopathology study. The group in which was done the intramedullar nailing recovered normal walk after surgery. In this group were found more production of BMP and PDGF compared to the control group but did not reveal any significant difference between the groups (p> 0,05). Differences about other growth factors as TGF were not found. We conclude that in the results we have taken, the increase on BMP and PDGF could be produced by the intramedullary reaming by the surgery technique but we would need more studies.

Introduction and purpose: To assess the validity of determining polymorphonuclear leukocytes in frozen intraoperative samples for diagnosing infections in hip and knee prosthetic revision surgery.

Materials and methods: We reviewed the 146 revisions (83 hips and 63 knees) carried out between 1996 and 2002. We analysed the polymorphonuclear leukocytes per high-magnification field in frozen intraoperative sections (diagnostic test) and periprosthetic tissue culture (gold standard). We evaluated sensitivity (S), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), Youden index, positive likelihood ratio (PLR) and negative likelihood ratio (NLR). We compared the intraoperative results with the analysis of the same samples embedded in paraffin in the knee group.

Results: In the knee group we found S=66.7% (CI 95%); Sp=89.7% (CI 95%); PPV=81% (CI 95%); NPV=81.4% (CI 95%); Youden index=0.56; PLR=6,5 (CI 95%); and NLR=0.4 (CI 95%). In the analysis of the same samples in paraffin (postoperative) we found S=91% (CI 95%); Sp=87% (CI 95%); PPV=81% (CI 95%); NPV=94% (CI 95%); PLR=7 (CI 95%); NLR=8.7 (CI 95%) (significant differences between the two analyses with p< 0.05). In the hip group we found S=50%; Sp=100% (CI 95%); PPV=100%% (CI 95%); NPV=94.9% (CI 95%); Youden index=0.5; and NLR=0.5 (CI 95%).

Conclusions: The analysis of the validity of the test showed that the presence of polymorphonuclear leukocytes is related to infection, but negative results of the test do not rule out infection. It is a quick, low-cost test that we recommend for inclusion in the diagnostic protocol for hip revision surgery.