Paper 19: Efficacy of venous thromboembolic prophylaxis agents after hip arthroscopy

Objectives: Hip arthroscopy (HA) has been increasingly utilized for the treatment of hip pathologies such as labral tears, femoroacetabular impingement, chondral lesions, loose bodies, and synovial disease. As with any surgical procedure, HA carries a small, but dangerous risk of venous thromboembolism (VTE), with an incidence of 2%. Current recommendations from the 2022 International Consensus Meeting on Venous Thromboembolism (ICM-VTE) state that routine prophylaxis is not required but may be beneficial for certain high-risk patients. Still, practices for prescribing VTE chemoprophylaxis are not standardized and can vary significantly among orthopedic providers, especially in the setting of differing postoperative weightbearing protocols. Prior studies have examined incidence of VTE in patients undergoing HA, but no studies have utilized large-scale data from national databases to compare efficacy of different VTE regimens. This study aims to evaluate the effectiveness of various prophylactic agents in preventing deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing elective HA while also assessing adverse outcomes from chemoprophylaxis, such as hematoma development and wound dehiscence.
Methods: This retrospective cohort study utilizes the TriNetX database, which includes electronic medical records (EMR) from over 100 healthcare organizations (HCO). Patients 18 years of age and older were included if they underwent any hip arthroscopy procedure, including removal of loose or foreign bodies, chondroplasty, resection of labrum, synovectomy, femoroplasty, acetabuloplasty, or labral repair. Patients with a prior history of malignancy or DVT were excluded. All patients had a minimum 3 months of follow up. Patients who met the inclusion criteria were divided into three cohorts based on their prescribed chemoprophylaxis agent within one day of surgery: 1) a control group that did not receive any chemoprophylaxis; 2) an experimental arm that received only aspirin; 3) an experimental arm that received low molecular weight heparin (enoxaparin). There were not enough patients taking unfractionated heparin to conduct statistical analyses. Outcomes including DVT, PE, and other wound complications were assessed at 90-days postoperatively. A subgroup analysis of moderate-risk patients prescribed aspirin was conducted and included any patients with oral contraceptive or hormone use within three months, nicotine dependence, obesity, or diabetes mellitus.
Results: A total of 26,822 patients were analyzed; 18,374 patients received no prophylaxis, 7,477 patients received aspirin only, and 544 patients received enoxaparin. The mean age ranged from 32.5 to 37 years, and the mean BMI ranged from 26.6 to 27.6 kg/m2. Patients were predominantly female (>60% in each cohort). Incidence of DVT was 0.28% in those who did not receive prophylaxis and 0.32% in patients who received aspirin. On univariate analysis, aspirin did not lower the incidence of DVT [OR 1.14 (0.70 - 1.84), p = 0.609]. Wound dehiscence was increased in patients who received aspirin (0.40%) or enoxaparin (2.21%) compared to those not receiving prophylaxis (0.19%). On univariate analysis, this was statistically significant (aspirin: p = 0.0022; enoxaparin: p < 0.0001). Superficial wound infection was also analyzed. In the cohort that did not receive prophylaxis (control), there were <=10 patients who developed superficial infection (exact count hidden to protect confidentiality). Assuming that all 10 patients had wound complications, their incidence (0.05%) would still be lower than patients who received aspirin (0.21%, p = 0.0002). Subgroup analysis demonstrated that the incidence of DVT in moderate-risk patients who received aspirin (0.46%) was not decreased compared to those who received no prophylaxis (0.36%, p = 0.3815).
Conclusions: Trends over the past 10 years demonstrate increasing use of chemoprophylactic VTE agents after HA with no corresponding decrease in VTE rates. Data from this study show that aspirin and enoxaparin did not decrease the incidence of thromboembolic events after hip arthroscopy and were instead associated with a small, but statistically significant, increased risk of wound dehiscence and superficial surgical site infections. The low incidence of these complications could be subject to statistical fragility. However, in the context of improved surgical techniques and shorter surgical traction times potentially contributing to lower overall incidence of VTE, the increased risk of anticoagulant-related wound complications is noteworthy. The results of this study reinforce current guidelines recommending against routine VTE prophylaxis after HA except in the setting of high-risk patients, and highlight the often overlooked wound complications associated with commonly prescribed chemoprophylactic agents such as aspirin and enoxaparin.