Introduction and Objectives: Bleeding during lumbar surgery requires the use of blood products for its management. Autotransfusions are an alternative to blood transfusions, since these are not free of risk. Although autotransfusion is a very effective technique, its efficiency is conditioned by its high cost and the fact that a large number of autodonations have to be destroyed when the patients do not require them during the postoperative period. We wanted to discover the factors that determine the use of blood products during the postoperative period so as to obtain blood autodonations from these patients.

Materials and Methods: We carried out a retrospective study of 143 patients that underwent surgery for degenerative conditions of the lumbar spine. We assessed different variables: Age, sex, lumbar level operated on, operation time, pre and postoperative hemoglobin and associated conditions (Charlson comorbidity index and ASA scale).

Results: We found a significant statistic correlation with female sex, age over 60, ASA 3, preoperative hemoglobin < 136 gr/l. Using logistic regression we found that the combination woman, ASA 3 was the most important prognostic factor with a specificity above 90%. We also found that the possibility of requiring a transfusion in a woman/ASA 3, was 61% and at the other end of the spectrum 1.1% in a man/ASA< 3,

Discussion and Conclusions: If we plan an autotransfusion in a woman with ASA 3, there is a probability of 61% that she will require a transfusion with specificity greater than 90%.

Introduction and Objectives: Cryopreservation as a meniscus conservation method affects cellularity to a lesser degree than simple freezing. Recent studies have shown that freezing alters meniscus ultrastructure. The effects of cryopreservatioin on the meniscus collagen net has not been so extensively studied. The aim of this study was to determine if cryopreservation alters meniscus ultrastructure and cellularity.

Materials and Methods: We obtained 10 external menisci for the purpose of studying their cellularity and collagen structure before and after cryoprservation at −180°C. We analyzed the architecture of the meniscus collagen using transmission electronic microscopy and assessed the degree to which this was altered according to a previously determined scale. We measured collagen fibers in transverse and longitudinal sections, and also calculated the percentage of cells that survived cryopreservation.

Results: Cryopreserved menisci averaged 4.8 points and the control menisci 4.1 (p< 0.17). In the cryopreserved menisci the collagen fibers in longitudinal section had a mean length of 12.61 nm and in the control menisci 13.38 nm (p=0.34), whereas in transverse sections the average was 15.48 nm and 16.7 nm respectively (p=0.41). The percentage of cells that survived cryopreservation went from 3.99 to 53.57%.

Discussion and Conclusions: Cryopreservation does not alter meniscus ultrastructure. Cell survival is highly variable. Results suggest that cryopreservation would be a more appropriate method than freezing at −80°C for the preservation of meniscal allografts.