Thromboembolic Complications

Thromboembolic complications can be life threatening. Their frequencies, the type of diagnostics, and the therapeutic and prophylactic regime are still under discussion.

Deep vein thrombosis (DVT) and/or pulmonic embolisms (PE) are major risk factors for secondary mortality after trauma.¹

Data focusing on incidence,²^,³^,⁴^,⁵^,⁶^,⁷^,⁸^,⁹ risk factors,⁴^,¹⁰^,¹¹^,¹²^,¹³ and optimal prophylaxis¹^,²^,⁶^,⁷^,⁹^,¹¹^,¹²^,¹³^,¹⁴^,¹⁶ remain unclear for trauma patients.

There is also a discussion about overestimating thromboembolic complications. A retrospective study reported an incidence of approximately 2% in patients suffering from multiple trauma. The type of prophylaxis was not reported in detail.¹⁷ Even the necessity of routine screening is under discussion.¹⁸

21.2 Incidence

The incidence of thromboembolic complications after acetabular fractures is unknown and is primarily influenced by the extent of concomitant injuries, the presence of risk factors, and the type of thrombosis prophylaxis. Currently, it is not clear which trauma patients benefit from prophylaxis and which type of prophylaxis is useful.¹⁹

In the present literature, the risk of thrombosis after pelvic injuries is reported to be up to 61%.⁴^,⁸^,¹⁰^,¹⁶^,²⁰^,²¹^,²² Due to different inclusion criteria, it is not possible to specify this rate. It is well known that studies that use only clinical diagnostics underestimate the thrombosis rate.³^,⁴^,⁸^,¹⁰^,¹⁶^,²¹^,²²^,²³

Recently, Knudson et al reported an incidence of 0.36% in 450,375 trauma patients analyzing the American College of Surgeons database.²⁴ A significant relation between fracture patterns and thrombosis formation could not be detected.²⁵ The incidence is reported to be approximately 12–13%, independent of the prophylaxis regime.¹³^,²⁶^,²⁷^,²⁸^,²⁹ The rate of preoperative existing, asymptomatic thrombosis is speculative.³⁰

Clinical Relevance

The exact rate of posttraumatic thrombosis after acetabular fractures is unknown.

21.3 Diagnostics

Different diagnostic methods exist to detect DVT. The current gold standard is still the phlebography,²⁹^,³¹^,³² but potential disadvantages (e.g., procedure is invasive, complication risk due to contrast medium, and inter- and intra-observational variety in evaluation the results) have to be considered.³³

Additionally, the clinical relevance of small, distal DVTs is unknown. The rate of overlooked or incompletely diagnosed DVTs is reported to be 20–40%.³³^,³⁴ As a main disadvantage is that the evaluation of pelvic veins is limited, which are often a potential source of thromboembolic complications.⁶^,⁷^,⁹^,³⁵

Duplex sonography represents a good alternative in analyzing DVTs, but its positive predictive value is lower in the follow-up evaluation of proximal DVTs,³⁶ although its sensitivity and specificity are up to 97%.³⁷

During the last years, magnetic resonance venography (MRV) and computed tomography venography (CTV) have become more important.¹⁰^,³²^,³⁵^,³⁸^,³⁹ Niikura et al recommended CTV or lower extremity sonography without former risk evaluation by D-dimer testing for routine screening, hence higher DVT rates could be achieved.³⁹

Montgomery et al prospectively compared MRV and phlebography for proximal and pelvic DVTs in 45 patients with acetabular fractures.³⁹The general incidence of DVTs detected with MRV was 33%. In 15 patients, 24 DVTs were detected. Regarding localization, the superficial femoral vein was affected in four cases, the femoral vein in nine cases, the external iliac vein in one case, the intern iliac vein in seven cases, and the common iliac vein in three cases. A total of 58% of these DVTs were not detected using phlebography. The DVT localization was either in the pelvis or in the contralateral extremity, whereas 90% of the DVTs in the thigh could be detected using phlebography.³⁸

Stover et al compared MRV with CTV in diagnosing pelvic DVTs after pelvic and acetabular fractures in 30 patients.³²

Thrombosis prophylaxis was performed using compression therapy and additional administration of low-molecular-weight heparin (LMWH) in 23 patients; other forms of prophylaxis were used in five patients; and two patients had no prophylaxis.

Using CTV, two DVTs were detected (common iliac vein, superficial femoral vein), representing an incidence of 6.6%, whereas MRV detected 13.3% of DVTs. In only one case did both methods identified the same DVT. In five cases, suspicious results were additionally analyzed by phlebography. Thus, the negative predictive value for MRV was 100% and for CTV 50%.³³^,³⁴

A recent study concerning different screening methods revealed that ultrasonography was preferred by 82.1% of orthopedic and trauma surgeons. An MRV was conducted in 8.2% and an isolated clinical examination in 27.4%.⁴⁰

Clinical Relevance

Selective pelvic phlebography with additional duplex sonography of the extremity veins seems to be the safest combination to diagnose pelvic and lower extremity DVTs. The value of MRV and CTV is not yet stated.

No clear data are available whether elevated D-dimers levels indicate the presence of DVT in patients with acetabular fractures.

It is known that in patients with a low thrombosis risk and low D-dimers, a DVT is almost excludedHowever, patients with acetabular fractures are considered high risk patients. In these patients, elevated D-dimer values are not safe for DVT diagnosis. An additional clinical examination is recommended,⁴²^,⁴³ as the trauma load itself and surgical treatment lead to an increase of D-dimers.⁴⁴

21.4 Prophylaxis

Presently, no clear data are reported in current literature regarding which kind of prophylaxis is useful.¹⁹ Even meta-analyses were not able to report clear recommendations.⁴⁵

Morgan et al reported a rate of 87.8% prophylaxis measures in trauma patients with pelvic and/or acetabular fractures.⁴⁰ Especially in conservatively treated patients with pelvic and/or acetabular fractures, routine prophylaxis is rarely performed.²² Overall, 50% of surgeons reported to have performed at least one DVT prophylaxis. Compression therapy is most often performed (77.8%), followed LMWH therapy in 44.9%, and selective cava vein filters in 22.2%.⁴⁰

Postoperatively, at least one DVT prophylaxis is performed in 98.9%. Compression therapy is performed in 71.5%, followed by subcutaneous application of LMWH, mobilization, and warfarin therapy with approximately 50%. In nearly 80% of all cases, more than two DVT prophylactic regimes were used.⁴⁰ Pharmacologically, a DVT prophylaxis using unfractionated heparin (> 3400 IU/d) or fondaparinux is recommended for at least 7 days, whereas their application should be linked to the existing cardiovascular risk profile and extent of allowed partial weight bearing.¹⁵

Steele et al reported on the value of an early LMWH application in patients with pelvic and acetabular fractures.⁴⁶ Patients with a combined LMWH and compression therapy that were started within 24 hours had a lower DVT rate compared to patients in whom prophylaxis started after 24 hours (3% vs. 22%).⁴⁶ Additionally, the pulmonary embolism rate was significantly lower (0% vs. 14%). Both groups had comparable injury severity, so that a major risk factor could be excluded.¹⁷

Stannard et al, in a prospective, randomized trial, analyzed high-risk patients with and without pelvic/acetabular fractures, which received either compression or pharmacological prophylaxis.²⁹ The DVT incidence was in both groups (10% vs. 12%). A tendency to a higher rate of pelvic DVTs was found in patients with pelvic trauma.

In another prospective, randomized trial by Stannard et al, the combined prophylaxis with compression therapy and LMWH was compared to isolated LMWH application.³¹ A clear trend to reduced DVT rates was observed using the combined prophylactic regimen (8.7% vs. 13.4%). DVT presence was associated with higher transfusion requirements.

In general, when performing pharmacological prophylaxis, a higher bleeding risk has to be considered. Blanchard et al reported a 1.5% higher bleeding rate after LMWH prophylaxis.⁴⁷ Additionally, in some patients, contraindications against pharmacological prophylaxis can be present.⁴⁸

The optimal DVT prophylaxis is still unclear. Venet et al analyzed 12 prospectively randomized trials with 2374 trauma patients. The DVT incidence was reported between 0.8% and 44% after either LMWH and unfractionated heparin (UFH), whereas after compression therapy a rate between 3.1% and 12% was reported.⁴⁹

In contrast, Velmahos et al reported no difference after compression therapy and heparin application in a meta-analysis.⁵⁰ Roberts et al reported no difference between LMWH and UFH.¹²

Clinical Relevance

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