The objective of our research program is to determine the transfusion threshold required to maximize functional recovery after major orthopedic surgery (total hip/knee replacement) in these, most often, elderly patient with serious comorbidities.

Hypothesis: we hypothesize that a threshold hemoglobin concentration exists below which functional recovery becomes difficult, even if the vital prognosis of patients is not impaired.

Anemia is frequent after a surgical procedure. Postoperative anemia is associated with an increased incidence of transfusions and, probably, with an increased incidence of morbidity and mortality. However, the majority of studies evaluating the consequences of postoperative anemia are retrospective and, since anemic patients were transfused, they are unable to distinguish between the effects of anemia per se and those of transfusion. In orthopedic surgery, only two randomized controlled trials (RCT) have attempted to determine the benefits of transfusions in this patient population. The first evaluated the benefits of allogeneic transfusions in patients undergoing surgery for a fractured hip while the second evaluated autologous transfusions in patients undergoing total knee replacement. The small number of patients included in both studies did not allow definitive conclusions on the benefits (or lack thereof) of transfusions in orthopedic surgery.

Traditionally, a transfusion trigger of 100 g/L has been recommended in the postoperative period, especially in older patients and in those with serious comorbidities. In the Transfusion Requirements in Critical Care trial, a much lower transfusion threshold (70 g/L) was adopted in the group of patients in whom transfusions were restricted. This prospective randomized trial that included 838 patients, is, to this day, the most important in the field and generated unexpected results. Serious morbidity (cardiac and respiratory in particular) and mortality were not increased by the adoption of a low transfusion trigger while the number of transfusions was decreased significantly.

On the other hand, it is common to observe fatigue, decreased exercise capacity and muscle strength, and impaired performance of activities of daily life in the presence of anemia, especially when the hemoglobin concentration decreases below 90 - 100 g/L. In orthopedic surgery, a decrease in "postoperative vigor" can prevent patients from undertaking the rehabilitation program required to improve functional recovery after hip fracture repair.

The objective of our research program is to determine the transfusion threshold required to maximize functional recovery after major orthopedic surgery (total hip/knee replacement) in these, most often, elderly patient with serious comorbidities.

Inclusion Criteria:

• Patients undergoing isolated elective total hip or knee arthroplasty (primary or revision surgery for a non-malignant condition), aged 60 years or older and able to walk prior to surgery.

Exclusion Criteria:

• Since this an observational study, all patients conforming to inclusion criteria will be included.

Patients undergoing isolated elective total hip or knee arthroplasty (primary or revision surgery for a non-malignant condition), aged 60 years or older and able to walk prior to surgery.