Case Report

A 33-year-old woman initially presented with right groin pain secondary to a nondisplaced acetabular labral tear. The patient had no prior history of DVT or malignancy, was a nonsmoker, and routinely used either oral contraceptives or a NuvaRing (Merck, Whitehouse Station, New Jersey). Her body mass index was 26.8.

Intraoperatively, the patient was placed in the supine position on a HANA hip distraction table (Mizuho OSI, Union City, California). A well-padded hip arthroscopy perineal post, measuring approximately 9 inches in diameter, was positioned centrally (Figure 1). Under general anesthesia, gentle axial traction was placed across bilateral lower extremities to stabilize the pelvis about the perineal post. Additional fine traction was placed across the operative hip to allow for distraction of the hip joint, which was confirmed fluoroscopically. The patient underwent hip arthroscopy (including peripheral compartment examination) and labral debridement. The total traction time was 55 minutes, and the patient was transferred to the recovery room in stable condition. The patient was discharged from the hospital on the same day, bearing weight as tolerated with crutches. Discharge medications were narcotic pain medicine only.

Figure 1: The patient was placed in the supine position on a HANA hip distraction table. Traction forces are generated distally and applied through the feet. Note the large traction post placed securely in the groin.

On postoperative day 13, the patient reported increased swelling and tenderness of the contralateral thigh, with specific tenderness localized to the left groin. Ultrasonography revealed acute DVTs in the left common femoral, superficial femoral, and popliteal veins. The patient was hospitalized and therapeutic anticoagulation was initiated. A thrombophilic workup revealed normal prothrombin, anti-thrombin III, and activated protein C levels. The patient never developed signs or symptoms consistent with a pulmonary embolus, and pulmonary workup was therefore never initiated.

Discussion

Deep vein thrombosis is a rare but known complication of lower-extremity arthroscopic surgery. In our case, a proximal, contralateral DVT developed in an otherwise healthy 33-year-old woman 13 days following a routine hip arthroscopy. The patient had no known history of a clotting disorder, and the only known risk factor for developing a thrombus was her use of oral contraceptives. According to criteria set forth by Deitelzweig et al, ⁹ hip arthroscopy places a patient at moderate risk for a venous thromboembolism. Based on these factors, we opted not to place this patient on postoperative pharmacologic prophylaxis. Moreover, as the patient was ambulating immediately after the procedure, venous stasis was immediately reduced. According to Virchow’s Triad of venous stasis, hypercoaguability, and endothelial injury, immediate ambulation should have eliminated 1 of the main factors in the development of a thrombus.

Venous thromboembolism may present in various ways. Patients may be asymptomatic and may be diagnosed as an incidental finding. Symptomatic disease, however, may present locally or at a location far from the initial insult. Deep venous thromboses may present locally with pain, soft tissue swelling, a palpable cord, or even a persistent low-grade fever. These clots may dislodge and embolize to distant sites, most notably the lung, and cause patients to present with tachycardia, dyspnea, tachypnea, hypoxia, or chest pain. As the presentation for symptomatic venous thromboembolism can be variable, it is critical that physicians are able to recognize the signs and symptoms and provide a rapid, accurate diagnosis.

Thromboembolic events following knee arthroscopy have been well documented. A recent meta-analysis assessing 6 studies yielded a total DVT incidence of 9.9% in patients without pharmacologic prophylaxis, with a proximal DVT incidence of 2.1%. ⁷ Reports of venous thromboembolism following hip arthroscopy, however, are scarce. Clarke et al, ¹ in their prospective study of 1054 consecutive hip arthroscopies, reported no cases of DVT or pulmonary embolism. Philippon et al ¹⁰ reported no cases of venous thromboembolism after 2 years of follow-up in 112 hip arthroscopies. McCarthy and Lee ¹¹ reported 1 case of DVT in the setting of factor V-Leiden deficiency. A recent report in the literature reports a fatal pulmonary embolism associated with hip arthroscopy after a traumatic injury. ¹²

Salvo et al ⁸ recently reported a symptomatic DVT rate of 3.7% in 81 hip arthroscopy patients, with all confirmed cases of DVT occurring in the operative leg, all of which demonstrated calf pain on the first postoperative follow-up of 8 days (2 cases of DVT in the deep popliteal vein and 1 in the midcalf, extending to the peroneal vein). One patient was taking oral contraceptives; the other patients had no risk factors. Two of the 3 patients were nonweight bearing. Operative traction time was <2 hours for each patient. However, this study was retrospective, and ultrasonography was only initiated for patients with clinical concern for a DVT. Although this provides initial insight into the incidence of a thromboembolic event following hip arthroscopy, more research is warranted to fully understand the risk of DVT after hip arthroscopy.

Due to the paucity of literature regarding venous thromboembolism and hip arthroscopy, there has been no direct assessment regarding increased risk in the setting of oral contraceptive use. One of the 3 patients in the study by Salvo et al ⁸ used oral contraceptives, as did our patient. It is postulated that these drugs cause an increase in prothrombotic factors and a decrease in antithrombotic factors and have equivocal effects on fibrinolysis. ¹³ These changes in the coagulation pathway may explain why women using oral contraceptives have an increased risk of developing venous thromboembolism.

We hypothesize that the cause for DVT in our patient is multifactorial. The patient’s use of oral contraceptives placed her at an elevated risk for a perioperative thromboembolic event. Traction of the lower extremities against the post could have theoretically placed stress along the vasculature and produced endothelial injury. This type of traction has been thought to be the cause of pudendal and, less frequently, sciatic nerve injuries, with some authors advocating performing the procedure without the post. ^14,15 Moreover, we believe that there are asymmetric forces that are placed across the bilateral lower extremities during the procedure. Greater traction forces are placed across the operative hip, causing the pelvis to partially rotate around the post. This could theoretically create a greater pressure concentration at the contralateral groin and cause compression in the region of the pelvic veins (Figure 2). Although Eriksson et al ¹⁶ reported a force variation of 300 to 500 N required in anesthetized patients for sufficient distraction of the hip, the majority of hip arthroscopies can be performed with <100 lb of traction. Insufficient evidence exists in the literature to correlate these forces with vascular traction injury or endothelial damage.

Figure 2: Illustration depicting traction forces during hip arthroscopy. Longitudinal traction is being placed on the right leg. We hypothesize that asymmetric forces are placed across the bilateral lower extremities during the procedure. Greater traction forces are placed across the operative hip (solid black arrow), causing the pelvis to partially rotate around the post. This could theoretically create a greater pressure concentration at the contralateral groin (dotted arrow) and cause compression in the region of the pelvic veins.

The risk of DVT secondary to hip arthroscopy is generally thought to be low; however, we report a case of multiple DVTs in the contralateral limb manifesting almost 2 weeks after the surgical procedure. We believe that mechanical compression of the contralateral femoral vein created a prothrombotic situation that reached a clinical threshold 13 days postoperatively. We believe that the rate of DVT is underestimated in this population, and only symptomatic cases have been reported in the literature.

We do not routinely provide pharmacological prophylaxis despite our experience with this case, as the reported rates of DVT are low and we are not aware of any other documented cases at our institution of thrombotic disease after hip arthroscopy. However, we attempt to minimize the amount and duration of traction placed on the lower extremities during these procedures and attempt, if clinically warranted, to encourage weight bearing bilaterally. Further study is required to establish the effect of traction on the development of a thrombus, the true incidence of DVT following hip arthroscopy, and possible recommendations regarding pharmacologic prophylaxis.

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