Musculoskeletal trauma in obese pediatric patients

Pediatric patients most commonly seek orthopaedic care for musculoskeletal trauma, and most fractures in childhood are treated with closed methods. Maintaining correct alignment and positioning using splints or casts relies on the principles of 3-point contact and proper molding. The large soft-tissue envelope of obese children can make safe and secure casting difficult, potentially leading to skin complications, to loss of fracture reduction, and to a decision to treat injuries operatively rather than with casting. When surgery is planned, the greater loads across the fracture in obese patients may require more rigid fixation than is typically used in pediatric patients.

In the adult population, obesity has been found to be an independent risk factor of trauma-related morbidity, although there is a decreased risk of fractures. However, a chart review and questionnaire study performed by Taylor and colleagues noted that overweight children had a higher incidence of fractures. They also found a higher incidence of musculoskeletal pain, specifically knee pain. Skaggs and colleagues found that girls who sustained forearm fractures from a low-energy mechanism were more likely to be obese, with a radius that had a decreased cross-sectional area when compared with matched controls without forearm fractures. It was proposed that the smaller cross-sectional diameter combined with increased body mass and minor trauma created a predisposition to fracture in these patients.

Others studies have questioned the reasons for increased numbers of fractures in the obese adolescent population. Leonard and colleagues and Taylor and colleagues found increased bone mineral density in obese adolescents, although the relationship of bone mass to obesity is controversial and often conflicting. These findings have led some to propose that the increased risk of fracture is due to the inactivity that contributes to obesity. Inactivity may lead to decreased proprioception and poor balance, leading to an increased risk of falling.

When fractures do occur in the obese, complications are increased. Rana and colleagues examined the effect of obesity on numerous outcome measures at their level 1 trauma center. They found that obese children had an increased incidence of extremity fractures, fractures necessitating operative intervention, decubitus ulcers, and deep venous thrombosis (DVT). The findings of increased DVT were confirmed in a study by Vu and colleagues examining the risk factors of DVT in hospitalized children, which found that obesity was a risk factor with a prevalence ratio of 2.1. Literature on adults suggests that obesity may be a risk factor of venous thromboembolic disease (VTED). VTED is fortunately rare in children who do not have coagulopathies, and this rarity leads to controversy about the appropriateness of chemoprophylaxis in pediatric patients, especially in adolescents approaching skeletal maturity/adulthood. Not enough data is available to make recommendations about the value or efficacy of VTED prophylaxis in obese adolescents.

Leet and colleagues found that obese children (BMI >95th percentile) and extremely heavy children (BMI between the 90th and 94th percentile) with operatively treated femur fractures had a significantly increased incidence of complications. The complications included: refracture, pin-site infection requiring debridement, loss of alignment in frame, wound infection, malunion, osteomyelitis, wound dehiscence, compartment syndrome, broken rod, and broken pin. Fracture stabilization must be augmented in the obese patient, because of the known limitations and increased incidence of implant failure. Recent studies of titanium elastic nails used for pediatric femur fractures has found an increased incidence of malunion in children weighing more than 45 kg. Several studies have found that weight was an independent risk factor of malunion. Some have suggested that patients weighing more than 45.36 kg should undergo intramedullary nail fixation using small diameter nails with interlocking screws. The key with any of these devices is to enter the femur though the trochanter, not the piriformis fossa, and not to cross the distal femoral epiphysis with the implant. Another fixation option that is more rigid than elastic nailing is plate fixation, with open or submuscular approaches.

If operative treatment is chosen, obesity can alter physiologic responses to surgical procedures. Studies indicate that obese adults undergoing surgical procedures have an increased risk of complications, and the actual procedures are technically more challenging because of their body mass. The senior author’s experience is that musculoskeletal procedures to stabilize fractures or perform osteotomies in obese pediatric patients are technically more difficult, involving positioning challenges, difficulties obtaining adequate intraoperative imaging, larger incisions, longer operative times, and more complications.

Few studies are available to evaluate the impact of childhood obesity on surgical procedures. A retrospective review of pediatric surgical patients over a 4-year period found increased preoperative diagnoses of medical comorbidities and prolonged recovery room stays in obese children compared with normal-weight children. Davies and Yanchar found that obese children undergoing appendectomies had problems before, during, and after surgery that were similar to those experienced by obese adults. An increased use of sophisticated scanning suggested that appendicitis is difficult to diagnose in obese children. Additionally, they found that childhood obesity led to increased surgical times, increased risk of wound infections, and increased time to ambulation.

The difficulties noted earlier also translate to orthopaedic practice. Obese children presenting for orthopaedic evaluation may prove more difficult to manage, because physical examinations to identify joint effusions, joint laxity, and soft tissue masses are more difficult when the extremities have a thick layer of subcutaneous fat. Operative procedures on the lower extremities in obese children can substantially impair mobility, because the children often do not have sufficient upper extremity strength to ambulate safely with crutches or a walker. Postoperative respiratory difficulties may be exacerbated by poor mobilization.

Similar to adults, obstructive sleep apnea (OSA) is a comorbidity that warrants consideration in children, because it can increase the risks of anesthesia during a surgical procedure. OSA can lead to nocturnal snoring, hypoxia, and hypercarbia and has a prevalence of 2% in children. OSA has been associated with increased perioperative anesthetic complications, including difficulty with intubation and acute respiratory failure during the induction of anesthesia. Additionally, postoperative complications have been reported, including hypoxia, airway edema, obstruction of the upper airway, pulmonary edema, and respiratory failure. Gordon and colleagues reported that 11 of 18 patients with Blount disease who were older than 9 years had been diagnosed with sleep apnea and required noninvasive positive-pressure ventilation. The orthopaedic surgeon should ask obese adolescents about snoring as a risk factor of OSA and take appropriate supportive measures before, during, and after surgery.