Aspirin response variability after major orthopedic surgery

Thromb Res. 2012 Aug;130(2):216-20. doi: 10.1016/j.thromres.2012.04.006. Epub 2012 May 9.


Introduction: Variability in platelet response to aspirin has been reported in patients undergoing cardiac surgery but has rarely been described in other operative settings and its mechanism remains uncertain. We performed a prospective cohort study to investigate the variability in platelet response to aspirin and to explore its mechanism in patients undergoing major orthopedic surgery.

Materials and methods: Twelve aspirin-treated patients undergoing elective hip or knee replacement were recruited. Once-daily aspirin was continued throughout the perioperative period. We measured platelet function using light transmission aggregation (LTA) in response to arachidonic acid (PL(AA)) and serum thromboxane B(2) (TXB(2)) at baseline (before surgery) as well as on days 1, 2, 3, 4, 5, 6, and 8 after surgery. We defined aspirin low response as a PL(AA)>20%.

Results: Six patients exhibited aspirin low response, which typically started on post-operative days 3 or 4; the remaining 6 patients had normal response to aspirin. Compared to aspirin responders, patients with aspirin low response showed significantly higher serum TXB(2) levels, a more pronounced early decrease in platelet count, and a significantly more rapid recovery of the platelet count after surgery.

Conclusion: Aspirin response variability occurred in patients after major orthopedic surgery, with one-half of the patients in our study exhibiting post-operative aspirin low response. Increased platelet turnover might be a contributor to aspirin response variability after orthopedic surgery.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arachidonic Acid / metabolism
  • Arthroplasty, Replacement, Hip / adverse effects
  • Arthroplasty, Replacement, Knee / adverse effects
  • Aspirin / pharmacology
  • Aspirin / therapeutic use*
  • Blood Platelets / cytology
  • Blood Platelets / drug effects*
  • Cohort Studies
  • Female
  • Humans
  • Male
  • Middle Aged
  • Platelet Aggregation / drug effects*
  • Platelet Aggregation Inhibitors / pharmacology
  • Platelet Aggregation Inhibitors / therapeutic use*
  • Platelet Count
  • Prospective Studies
  • Thromboxane B2 / blood


  • Platelet Aggregation Inhibitors
  • Arachidonic Acid
  • Thromboxane B2
  • Aspirin