Summary

The determination of hemoglobin level in the immediate post-operative course after TKA did not provide a significant indication of the possible need for allogenic blood transfusion.

Abstract

Introduction

Postoperative hemoglobin determination after total knee arthroplasty (TKA) is considered essential to detect and possibly treat significant anemia. However, the usefulness of this systematic procedure has never been validated. The hypothesis of this study was that this determination performed the day after surgery did not provide clinically useful information when modern blood saving procedures are used.

Methods

All patients undergoing TKA between October 2016 and October 2017 were eligible for a prospective observational study. Patients operated for unilateral primary TKA were selected. All patients received a preoperative injection of tranexamic acid (2 g IV). Surgery was performed under general anesthesia by one of two surgeons experienced in knee prosthetic surgery with a standardized operative technique. All procedures were performed under navigation control without violation of the femoral and tibial medullary canal. All procedures were performed under inflated tourniquet before the incision at 300 mm Hg and deflated after dressing preparation. No blood recovery system was used. No drainage was left.
The usual demographic criteria, the preoperative hemoglobin level and the hemoglobin level at the day following surgery were collected. The possible existence of clinical signs of anemia (tachycardia, asthenia, malaise ...) after the intervention was recorded. The need for allogenic transfusions during or after the procedure was noted. The transfusion indications were previously arbitrarily established: hemoglobin determination below 9g/dl and/or presence of clinical signs of anemia.

Results

108 patients were included: 42 men and 66 women, with an average age of 70 ± 10 years, with an average body mass index of 30 ± 6 kg/m². The preoperative hemoglobin level was 13.8 ± 1.2 g/dl, and all patients had a rate greater than 11 g/dl. 7 patients (6%) received allogenic transfusion during the procedure (2 pockets). The hemoglobin level at the first post-operative day was 11.6 ± 1.3 g/dl, and all but one patient had a hemoglobin level greater than 9 g/dl. 12 patients (11%) had clinical signs of anemia the day after the procedure; 2 had a hemoglobin level of less than 10 g/dl. 5 patients (5%) received allogenic transfusion during the early postoperative phase: the 2 previous patients (2 pockets), one patient with functional renal failure, and two patients for no obvious reason.

Discussion

The determination of hemoglobin level in the immediate post-operative course after TKA did not provide a significant indication of the possible need for allogenic blood transfusion when modern blood saving procedures are used and there are no clinical signs of anemia. The cost of this procedure is certainly low, but not negligible in a period of constrained financing. It therefore seems logical to eliminate this routine dosage in the absence of clinical signs of anemia.