Abstract
PURPOSE: The aim of our study was to compare the hidden blood loss (HBL) between patients treated with unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) and to identify predictors of HBL in this cohort. METHODS: We conducted a retrospective study including 91 patients who had knee osteoarthritis, of which 31 cases (male/female: 12/19) received HTO and 60 cases (male/female: 24/36) received UKA, from January 2021 to January 2023. Demographics, clinical information and laboratory values were collected and compared. Recording preoperative and postoperative hematocrit and estimating intraoperative blood loss by surgeon to calculate HBL according to Nadler, Gross and Sehat formula. Effect sizes were determined using Cohen's d and Glass rank biserial correlation coefficient to assess clinical difference in the data. The Spearman correlation analysis was used to investigate an association between patient's characteristics and HBL. Multiple linear regression analysis was used to confirm independent risk factors of HBL. RESULTS: The HBL and TBL of the HTO group (534.49 ± 336.05 ml, 639.65 ± 337.81 ml, respectively) are significantly higher than that in the UKA group (359.42 ± 263.51 ml, 408.76 ± 283.50 ml, respectively; P = 0.008, P = 0.001). Effect size analysis indicated moderate clinical significance (Cohen's d [95% CI] = 0.604 [0.160, 1.045] for HBL, 0.762 [0.312, 1.208] for TBL). The multiple linear regression analysis suggested post-operative hemoglobin values and hemoglobin loss were independent risk factors for HBL in the UKA and HTO groups. CONCLUSION: This study provides new insights into the comparative blood loss between HTO and UKA procedures, highlighting that HBL and TBL are significantly higher in HTO than in UKA. The moderate clinical significance of this difference emphasize the need for careful management of post-operative anemia, particularly in patients undergoing HTO, where blood loss may be more pronounced. Its risk factors should be paid more attention during the perioperative period. CLINICAL TRIAL NUMBER: Not applicable.