Objective: To investigate the relative factors for hidden blood loss (HBL) after primary total knee arthroplasty (TKA).
Methods: A retrospective study of 422 consecutive patients who underwent primary TKA between October 2007 and August 2009 was carried on. There were 60 male and 362 female patients with a mean age of 65.7 years. The HBL was calculated according to Gross formula. The effect of patient gender, age, body mass index (BMI), pre-operative diagnosis, unilateral or simultaneous bilateral TKA, tourniquet time, type of prosthesis, postoperative anticoagulation method and deep vein thrombosis (DVT) on the postoperative HBL were analyzed.
Results: The HBL in patients underwent unilateral TKA was significantly lower than that in those underwent simultaneous bilateral TKA [(1284 ± 207) ml vs. (2248 ± 504) ml, P = 0.000]. Unvaried analysis showed that the HBL were associated with BMI, tourniquet time, prosthesis type and postoperative anticoagulation method. Multivariate linear regression analysis showed that the impact factors of postoperative HBL include BMI, tourniquet time and prosthesis type.
Conclusions: BMI, bilateral simultaneous TKA, tourniquet time and intercondylar open prosthesis impact the HBL after primary TKA. However, the influence of gender, age, diagnosis, postoperative anticoagulation method and DVT on the HBL are not significant.