Orthopedic surgery is one of the most blood-consuming surgeries. Currently there has been a radical change in transfusion policies, developing a series of therapeutic measures essentially created to minimize the use of allogeneic blood.

On the one hand, the safety of our patients must be even more our main objective. On the other hand, our economic resources are more restricted and therefore we must evaluate our surgical techniques and proceedings in order to be safer and more cost-effective.

The aim of this study is to report our results of the blood lost, the percentage of blood loss, the necessity of transfussions and how many blood pakages are needed.

From a sample of 2400 total knee arthroplasties proceedings, we analyze some surgical proceedings such as lligament balance, patelar traking, artrotomy, ischemia, femoro-tibial axis and type of arthroplasty.

We also examine the total blood lost and the percentage of total blood loss after 4 hours, after 24hours and after 48 hour of the total knee arthoplasty surgery.

We made a statistical analysis with t-test or anova test when it was necesassary.

The outcome of our investigation show that the blood loss when the ischemia is less than 50 minutes is 1470 cc and 1603 cc when is more than 50 minuntes (p<0.05). If we use the medial arthrotomy, the total bleeding is 1563cc, but with subvastus arthrotomy is 1294cc (p<0.05). If we use a primary rotational total knee arthroplasty the bleeding is 953cc, but if we use a PS or PCR the bleeding is 874cc (p<0.05).

As a conclusion we should know that our patients have more blood loss when the ischemia is more than fifty minutes, the bleeding is higher when we make a medial arthrotomy and when we use a rotational knee primary arthroplasty.