Benjamin J. Shore, Samir Sabharwal, Sabharwal.

Response/Recommendation: The overall risk of venous thromboembolism (VTE) in pediatric patients undergoing orthopaedic surgery is low. Pediatric orthopaedic patients undergoing surgery for the management of certain severe musculoskeletal infections (Methicillin-resistant Staphylococcus aureus [MRSA] with Panton-Valentine Leukocidin [PVL] +) are an increased risk of VTE. Additionally, hip, spine, and sports surgery have been identified as risk factors of VTE. Furthermore, the risk of VTE after pediatric orthopaedic surgery appears to be greatest in adolescents. Moreover, coagulation disorders (such as familial thrombophilia), as well as the presence of indwelling central venous catheters (CVC), were found to increase VTE risk substantially more than any specific orthopaedic surgical procedure. In conclusion, adolescents with identifiable confounding VTE risk factors in this setting would benefit greatly from the utilization of perioperative VTE screening tools and risk stratification models.

Strength of Recommendation: Moderate.

Rationale: VTE, a disease process that encompasses both deep venous thrombosis (DVT) and pulmonary embolism (PE), is a rare occurrence in pediatric patients. Estimates have placed the occurrence of VTE in pediatric patients to be between 0.07 to 0.49 per 10,000. However, it is the second most common cause of hospital-acquired morbidity for pediatric patients in the United States, with a reported incidence of 5.3 per 10,000 pediatric hospital admissions^1-5. Previous literature has demonstrated that the incidence of VTE in pediatric patients has a bimodal distribution, with the highest proportions reported in infants aged 1 to 23 months and in adolescent females^5,6. In hospitalized pediatric patients, the risk factors for VTE development include venous catheterization/central line, malignancy, infection/sepsis, congenital heart disease, trauma/surgery, and inherited thrombophilia. From the aforementioned list, the presence of a central venous catheter/center line demonstrated the greatest risk of VTE development^7-9. Despite this, there is a paucity of pediatric-specific literature aimed at determining the risk of VTE risk after orthopaedic surgery.

Recent studies have demonstrated that the incidence of VTE in pediatric patients has been rising over the last two decades^1,10-12. It is hypothesized that this rise may be attributed to a combination of factors. These include: increasing awareness of pediatric VTE, increasing medical complexity of pediatric patients, and increased frequency of application of central venous access¹³. In adults, certain orthopaedic procedures are associated with an increased risk of VTE. Despite this, the same association has not been demonstrated in pediatric patients. Conversely, in pediatric patients, individual patient attributes are more predictive of VTE risk than the procedure being performed. Georgopoulous et al.¹⁴, first reported on the incidence of pediatric VTE after elective orthopaedic surgery. In a study evaluating the Pediatric Health Information System (PHIS) database, the authors found that the incidence of pediatric VTE after elective orthopaedic surgery was 0.0515%. Increased age, a diagnosis of a metabolic condition (such as fluid-electrolyte imbalance), obesity, and complications associated with implanted devices and/or surgical procedures were independently identified as significant risk factors for VTE development.

Central catheter-related thrombosis has been reported to have the greatest risk for VTE development in pediatric patients¹⁵. In a retrospective study of 78 patients, Sandoval et al.¹, found that in patients with a CVC, 45% experienced a DVT episode, 50% of which occurred in the femoral vein. To summarize, recognition of increased VTE risk in pediatric patients undergoing orthopaedic surgery with a CVC in place is critical. Furthermore, immediate removal of the catheter as soon as it is no longer needed is paramount.

Infection is a known risk factor for the development of VTE as inflammatory mediators contribute to the activated blood coagulation cascade¹⁶. This risk is compounded in patients with immobility associated with musculoskeletal infections such as osteomyelitis or septic arthritis of the lower extremity¹⁷. In particular, children suffering from disseminated musculoskeletal infection with Staphylococcus aureus appear to be at the greatest risk of VTE development¹⁷. Specifically, infection with MRSA possessing the PVL gene has been implicated¹⁸. In one study, Crary et al.¹⁷, retrospectively reviewed 35 patients with confirmed osteomyelitis. They found that 29% of patients with an active MRSA infection developed DVT during the acute infection phase, of which eight occurred adjacent to an infection, and two secondary to CVC use. Additionally, Hollmig et al.¹⁹, found that patients > 8 years old presenting with MRSA and a C-reactive protein > 6 mg/dL are at an increased risk for the development of VTE. Clinicians must be wary of the increased risk of VTE associated with pediatric patients undergoing orthopaedic surgery for the management of disseminated musculoskeletal infection. Moreover, chemical VTE prophylaxis in this population must be considered.

Age is an important factor when considering the risk of VTE in pediatric patients undergoing orthopaedic surgery. When stratified by age, the incidence ranges from 0.02% for patients < 5 years to 0.13% in those aged 10 – 15 years. A 10-year survey of a single trauma center reported zero cases of VTE in patients < 13 years of age²⁰. Additionally, recent date from the American National Trauma Bank suggests that the incidence of VTE is 0.1% in patients < 12 years, 0.3% in those 13 – 15 years, and 0.8% in patients > 16 years²¹. In conclusion, pediatric patients > 13 years old are at an increased risk for developing VTE after orthopaedic surgery. Furthermore, chemical prophylaxis should be initiated in this patient population if additional risk factors are identified preoperatively.

Although the rates of VTE in patients < 15 years-old are 100-fold less compared to VTE rates in an 80 years-old patient, adolescents are known to have significantly increased risk of VTE after trauma than their younger counterparts^21,22. In a study of the PHIS database, Murphy et al.²³, found the incidence of VTE to be 0.058% after lower extremity trauma. Additionally, Allen et al.²⁴, found that at a single institution, the incidence of VTE after orthopaedic trauma was 1.1%. Interestingly, in this cohort, 86% of children who developed VTE were receiving thromboprophylaxis. Moreover, motor vehicle injuries and orthopaedic surgery were found to be synergistic predictors for the development of VTE after orthopaedic trauma. Careful consideration of the mechanism of injury, age of the patient, and identification of additional comorbid risk is paramount in these patients. Due to the high risk of VTE occurrence, the use of chemoprophylaxis in trauma patients is warranted.

The incidence of anterior cruciate ligament (ACL) reconstruction in patients aged 15 – 18 has nearly doubled in the last 10 years²⁵. Although major complications after knee arthroscopy are rare, pediatric VTE has been reported after elective knee arthroscopy²⁶. In one study, Murphy et al.²⁶, reported a VTE incidence of 0.25% at a single institution. Similarly, in a study of the National Health Service (NHS) database, Nogaro et al.²⁷, found the incidence of VTE in patients undergoing ACL reconstruction to be approximately 0.37%. Additionally, in a more recent study, Ellis et al.²⁸, found that risk factors for VTE development were present in 32.5% of adolescents undergoing elective arthroscopic procedures. In conclusion, the findings of the aforementioned studies suggest that adolescents undergoing knee arthroscopy may benefit from the utilization of a preoperative VTE screening tool.

Adolescent idiopathic scoliosis (AIS) is the most common cause of structural spinal deformity in patients between the ages of 10 and 18²⁹. Although surgical correction provides good outcomes for most patients, it carries significant risk of medical complications, including VTE³⁰. In one study of the National Inpatient Sample (NIS) database, the overall complication rate of AIS surgery was 7.6%, with 0.2% of patients experiencing a VTE event³¹. Jain et al.³², found that using the same database the incidence of VTE in pediatric patients over a 10 year period was low. Additionally, univariate analysis identified increasing age and the presence of congenital or syndromic scoliosis as independent risk factors for the development of VTE. Fatal VTE is a rare occurrence after pediatric spine surgery. However, the risk of bleeding following administration of VTE chemoprophylaxis is well-established. Therefore, expert opinion has recommended against the routine use of chemical prophylaxis in this patient population³³. Despite this, VTE chemoprophylaxis should always be considered in pediatric spine surgery patients immobilized for prolonged periods of time^31,33.

Although recent literature has demonstrated an increase in incidence of pediatric VTE, the overall rate of VTE occurrence in pediatric orthopaedic patients remains quite low. Furthermore, particular risk factors specific to individual patients, rather than type of orthopaedic procedure, are more predictive of the risk of VTE development in this patient population. In conclusion, chemical prophylaxis should be considered in both pediatric patients with disseminated musculoskeletal infection (especially MRSA PVL +) and in adolescents undergoing orthopaedic procedures who have additional risk factors for the development of VTE.

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