Joint replacement surgery increases blood clot formation risk in certain patients

A study published in the Journal of Bone and Joint Surgery reports that despite treatment with blood thinners prior to and immediately after joint replacement surgery, the risk of clot formation is still relatively high in certain patients.

“The rate of knee replacement has increased substantially worldwide, and continued increases are anticipated in the future,” Alma Pederson, MD, PhD, stated in an American Academy of Orthopaedic Surgeons press release. “The formation of clots, including pulmonary emboli, is a serious complication in patients undergoing knee arthroplasty.”

Pedersen’s team used medical databases to identify primary knee arthroplasty patients who also received pharmacological thromboprophylaxis in Denmark between 1997 and 2007. Hospitalization with symptomatic venous thromboembolism (VTE) within 90 days postoperatively was used as an outcome, with Cox regression analyses being used to analyze potential patient- and surgery-related predictors for VTE.

Four hundred and forty-one (1.2%) of the 37,223 primary knee arthroplasty patients identified in the study were hospitalized for VTE within 90 days of surgery. Deep venous thrombosis patients accounted for 323 of these hospitalizations, with 127 being hospitalized for pulmonary embolism. Nine patients were hospitalized for both.

VTE rates increased over the study period, and the authors noted that the patients who received a high score on the Charlson comorbidity index were at an increased relative risk for VTE when compared with patients who demonstrated a low score. Those patients who were reported to have a history of cardiovascular disease or previous VTE were noted in the study as being at increased risk for postoperative VTE when compared to patients who did not have similar conditions. Age greater than 80 years and increased number of accompanying medical conditions were also found to be risk factors.

“Despite the use of blood thinners, patients undergoing knee arthroplasty continue to remain susceptible for blot formation for several weeks following surgery,” Pedersen stated in the release. “Future studies should focus on the improvement of prophylaxis following hospital discharge, particularly among elderly patients and those with a history of cardiovascular diseases or previous clot formation.”

Reference:

Pedersen AB, Mehnert F, Johnsen SP, et al. Venous thromboembolism in patients having knee replacement and receiving thromboprophylaxis: A Danish population-based follow-up study. J Bone Joint Surg Am. 2011. doi:10.2106/JBJS.J.00676

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