Mechanical and suboptimal pharmacologic prophylaxis and delayed mobilization but not morbid obesity are associated with venous thromboembolism after total knee arthroplasty: A case‐control study

Abstract

BACKGROUND:The FDA‐approved dose of low‐molecular‐weight heparin (LMWH) may not provide adequate thromboprophylaxis in morbidly obese patients after total knee arthroplasty (TKA). Suboptimal dosing, delayed initiation, and overreliance on mechanical methods may also limit the effectiveness of thromboprophylaxis.OBJECTIVE:We explored the associations between the type of thromboprophylaxis, obesity, time of mobilization, and undergoing bilateral TKA on development of symptomatic venous thromboembolism (VTE) after TKA.DESIGN/SETTING/PATIENTS:This was a case‐control study of patients undergoing TKA in 15 teaching hospitals between October 2008 and March 2010. Cases were screened using the Agency for Healthcare Research and Quality's Patient Safety Indicator 12 and had objectively documented acute VTE within 9 days of surgery; controls were randomly selected from the same hospital. Multivariable logistic regression was used to analyze risk factors for postoperative VTE, adjusted for age and gender.RESULTS:Among 130 cases with and 463 controls without acute VTE, body mass index (BMI) ranged from 17 to 61 (median = 34). Thromboprophylaxis was LMWH in 284 (48%), warfarin in 189 (32%), both in 55 (10%), and mechanical prophylaxis alone in 120 (20%). Overall, 77% ambulated on day 1 or 2 after surgery. Factors significantly associated with VTE were bilateral simultaneous TKA (odds ratio [OR] = 4.2; 95% confidence interval [CI]: 1.9–9.1), receipt of FDA‐approved pharmacological prophylaxis (OR = 0.5; 95% CI: 0.3–0.8), and ambulation by postoperative day 2 (OR = 0.3; 95% CI: 0.1–0.9). Obesity was neither a significant confounder nor a modifier of these effects.CONCLUSIONS:Severe obesity was not a significant independent predictor for VTE and did not modify the beneficial effect of FDA‐approved pharmacological thromboprophylaxis. Bilateral TKA and failure to ambulate by the second day after surgery were significant risk factors. Journal of Hospital Medicine 2012. © 2012 Society of Hospital Medicine

Thromboprophylaxis following hip and knee arthroplasty

“…84 Early postoperative mobilisation can reduce relative VTE risk by 65%. [85][86][87] Conversely, an increased duration of anaesthesia (3.5+ hours) has been associated with an almost four times increased overall VTE risk in bilateral knee arthroplasty patients (7.5% vs. 30.2%). 83 Notably, bilateral simultaneous knee arthroplasty itself is associated with an increased VTE risk compared to unilateral knee arthroplasty (up to four times increased VTE risk and 80% increased PE risk), irrespective of time to mobilisation.…”

“…83 Notably, bilateral simultaneous knee arthroplasty itself is associated with an increased VTE risk compared to unilateral knee arthroplasty (up to four times increased VTE risk and 80% increased PE risk), irrespective of time to mobilisation. 85,88 Interestingly, the type of anaesthesia may also infuence VTE risk: regional anaesthesia has been reported to carry a lower VTE risk than general anaesthesia; consequently it is often recommended in guidelines and commonly used in practice. 17,51,89,90 A recent study reported that East Asian patients experience very little to no symptomatic VTE following hip and knee arthroplasty, suggesting the value of using routine thromboprophylaxis is debatable in East Asia.…”

Thromboprophylaxis Following Hip And Knee Arthroplasty

“…84 Early postoperative mobilisation can reduce relative VTE risk by 65%. [85][86][87] Conversely, an increased duration of anaesthesia (3.5+ hours) has been associated with an almost four times increased overall VTE risk in bilateral knee arthroplasty patients (7.5% vs. 30.2%). 83 Notably, bilateral simultaneous knee arthroplasty itself is associated with an increased VTE risk compared to unilateral knee arthroplasty (up to four times increased VTE risk and 80% increased PE risk), irrespective of time to mobilisation.…”

“…83 Notably, bilateral simultaneous knee arthroplasty itself is associated with an increased VTE risk compared to unilateral knee arthroplasty (up to four times increased VTE risk and 80% increased PE risk), irrespective of time to mobilisation. 85,88 Interestingly, the type of anaesthesia may also infuence VTE risk: regional anaesthesia has been reported to carry a lower VTE risk than general anaesthesia; consequently it is often recommended in guidelines and commonly used in practice. 17,51,89,90 A recent study reported that East Asian patients experience very little to no symptomatic VTE following hip and knee arthroplasty, suggesting the value of using routine thromboprophylaxis is debatable in East Asia.…”

“…Those that do not require medical intervention are simple measures such as maintaining adequate hydration; early postoperative mobilisation; promoting healthy postoperative food intake; and encouraging healthy preoperative patient weight or BMI. 17,85,86,[94][95][96][97][98][99][100][101] Measures that involve medical intervention are mechanical prophylaxis and pharmacological prophylaxis; together these strategies tackle the sluggish blood flow and increased clotting factor levels that occur with lower limb surgery. …”