ABSTRACT
BACKGROUND: Deep vein thrombosis (DVT) remains a leading cause of postoperative morbidity and mortality in patients who undergo total knee arthroplasty (TKA). Although patients with previous thrombotic episodes are inherently at a higher risk for subsequent episodes of DVT, it remains difficult to predict such an occurrence and to make a diagnosis in early stages. One potentially useful assay that can be used in the determination of changes of coagulation among patients who undergo arthroplasty is platelet activation. The goal of this study was to establish a predictive value for DVT with measurement of P-selectin levels that could help in planning appropriate perioperative management strategies for patients at high risk for DVT. METHODS: A total of 52 patients who underwent TKA with general anesthesia underwent contrast venography on the 5th postoperative day. Platelet activation before and after operation was measured with platelet surface expression of P-selectin with flow cytometry in these two groups of patients for TKA. None of the patients underwent any anticoagulation therapy. RESULTS: Nineteen of the 52 patients for TKA showed radiologic evidence of DVT, whereas 33 patients for TKA had no radiologic signs of DVT. There was no difference in platelet activation at baseline, which was 1 hour before induction of anesthesia, between the two groups (P >.05) as measured with P-selectin assays. Differences were noted between the two groups on the 5th day after operation, wherein P-selectin was expressed in only 2.72% +/- 0.9% (mean +/- standard deviation) of platelets in patients for TKA with healthy venogram results. This differed significantly from platelets in patients for TKA with DVT, who had P-selectin expression of 6.56% +/- 3.1% (mean +/- standard deviation; P <.01). Sensitivity for the diagnosis of DVT with P-selectin assay was calculated to be 74%, and specificity was found to be 94%. CONCLUSION: The findings showed that radiologically confirmed DVT in patients for TKA surgery with general anesthesia is associated with an elevated number of activated platelets. Perioperative assessment of P-selectin may predict the early onset of DVT in patients who undergo high risk surgical procedures like TKA. This laboratory assay may help prevent the occurrence of the fatal events caused by DVT with use of early therapeutic intervention, such as heparinization.
