Should we routinely perform a post-operative hemoglobin check following unicompartmental knee arthroplasty?

To study the significance of checking post-operative hemoglobin and hematocrit following unicompartmental knee arthroplasty (UKA).

Single center. Multiple surgeons.

Retrospective case series. Level of evidence IV.

Following institutional approval, a retrospective analysis of all patients undergoing UKA at our level one academic university hospital was conducted. Operative records of all patients undergoing primary UKA were reviewed between March 2016 and March 2019. Patients' pre-operative hemoglobin and hematocrit, BMI, co-morbidities, application of tourniquet, tourniquet time, administration of tranexamic acid, need for post-operative blood transfusion, hospital length of stay, complications, and re-admission were all recorded. Blood loss was estimated using the post-operative hematocrit.

A total number of 155 patients were included. There were 70 females (45%) and 85 males (55%). The mean age was 66 ± 10 years. Median pre-op blood volume was 4700 mLs (interquartile range (IQR); 4200-5100). Median blood loss was 600 mLs (IQR; 400-830). Mean pre-op hemoglobin was 135 ± 14 g/L and mean post-op hemoglobin was 122 ± 13 g/L. No patient had a post-op hemoglobin under 80 g/L (range 93-154). No patients in our study needed transfusion.

The results of our study indicated that post-operative hemoglobin and hematocrit check proved unnecessary in all of our patients and could have been omitted from post-operative routines. We conclude that routine post UKA check of hemoglobin and hematocrit can be avoided and be saved for special circumstances depending on patient's physiology.