title: Risk factors for lower limb swelling after primary total knee arthroplasty.
abstract: BACKGROUND
  Total knee arthroplasty (TKA) is a successful surgical technique for patients with advanced knee osteoarthritis; however, some peri-operative complications can not be predicted or avoided completely. This study aimed to investigate the factors affecting limb swelling after primary total knee arthroplasty, to guide and improve patient rehabilitation.
  
  
  METHODS
  Using a hospital database, we retroactively analyzed the mean changes in limb circumferences of 286 consecutive patients who underwent primary unilateral total knee arthroplasty between October 2007 and August 2009. The lower limb circumference change was calculated and analyzed statistically. The influence of age, gender, body mass index, the presence of deep vein thrombosis, methods of anti-coagulation, operation time, hidden blood loss, and type of prosthesis on post-operative lower limb swelling was studied.
  
  
  RESULTS
  Swelling was most pronounced from the third to the fifth post-operative day and usually occurred in both lower limbs. Swelling was significantly more pronounced in the operated limb than in the non-operated limb. The swelling above the knee was also significantly greater than that below the knee. The change in limb circumference at 10 cm above the knee was significantly different between the patients with body mass index ≤ 25 kg/m(2) and those with body mass index > 25 kg/m(2). However, the change in limb circumference at 10 cm below the knee was not significantly different between the two groups. There was no statistically significant difference in limb swelling between different age groups (P > 0.05). Similarly, gender, methods of anti-coagulation, the presence of deep vein thrombosis, the type of prosthesis, and operation time did not significantly affect post-operative limb swelling. Multivariate linear regression showed that the factors affecting post-operative limb swelling were body mass index and hidden blood loss.
  
  
  CONCLUSIONS
  Lower limb swelling after total knee arthroplasty is related to early post-operative hidden blood loss. The patient's hemoglobin level should be monitored. The degree of limb swelling is correlated with the patient's body mass index and the amount of hidden blood loss. Early intramuscular deep vein thrombosis formation has little effect on limb swelling.
authors.affiliation: Department of Orthopaedics, Peking University Third Hospital, Beijing 100191, China.
authors.forename: Fu-Qiang
authors.initials: FQ
authors.lastname: Gao
authors.forename: Zi-Jian
authors.initials: ZJ
authors.lastname: Li
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.forename: David
authors.initials: D
authors.lastname: Huang
authors.forename: Zhong-Jun
authors.initials: ZJ
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D004487:Edema / Q000209:etiology*; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult