Purpose: To better establish the incidence of deep venous thrombosis (DVT) after knee arthroscopy without prophylaxis.
Type of study: Meta-analysis.
Methods: A MEDLINE search was performed to find published English-language studies of DVT following knee arthroscopy. Strict inclusion criteria required any investigation included for analysis to (1) be prospective, (2) include a population not given any antithrombotic prophylaxis, (3) perform universal screening of the lower extremity venous system using either ultrasound or venography, and (4) include a discrete population limited to unilateral arthroscopic knee surgery, exclusive of ligament surgery or open procedures. The results of the venographic studies were given additional weight mathematically to account for the increased sensitivity of this imaging modality compared with ultrasound in detecting DVT in asymptomatic lower extremities.
Results: The unprophylaxed patient populations in the 6 studies that met inclusion criteria ranged from 64 to 184 patients, and totaled 684. The total incidence rate of DVT in each study ranged from 3.1% to 17.9%, whereas the incidence rate of proximal DVT ranged from none detected to 4.9%. The total DVT rate was not related to the method of DVT detection, whereas proximal DVT was only noted in the 2 studies using contrast venography. Combining the 6 studies yields a total DVT incidence of 9.9% (95% confidence interval, 8.1%-11.7%), and a proximal DVT incidence of 2.1% (95% confidence interval, 1.2%-3.0%).
Conclusions: DVT following knee arthroscopy is a consistent finding in studies of unprophylaxed patients when routine screening using ultrasound or contrast venography is used. Current data suggest an overall DVT rate of 9.9% and a proximal DVT rate of 2.1% after knee arthroscopy without antithrombosis prophylaxis.
Level of evidence: Level II, Systematic Review of Levels I and II Diagnostic Studies.