title: [Impact factors for hidden blood loss after primary total knee arthroplasty].
abstract: 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.
authors: Department of Orthopaedics, Peking University Third Hospital, Beijing 100191, China.
authors: Fu-qiang
authors: FQ
authors: Gao
authors: Zi-jian
authors: ZJ
authors: Li
authors: Ke
authors: K
authors: Zhang
authors: Yan-qing
authors: YQ
authors: Liu
authors: Hua
authors: H
authors: Tian
authors: Yan
authors: Y
authors: Liu
authors: Zhong-jun
authors: ZJ
authors: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D019106:Postoperative Hemorrhage; D012044:Regression Analysis; D012189:Retrospective Studies; D055815:Young Adult