Given the ongoing epidemic of obesity, femoral fracture management in the population affected by this condition is likely to become more frequent. Fracture treatment in obese patients poses a special challenge given greater difficulty in establishing an accurate diagnosis and confirming associated injuries. Adequate intraoperative positioning and obtaining accurate reduction and stable fixation may require special considerations. Obese patients have a high predisposition for complications such as compartment syndrome, nerve injuries, and pressure ulcers, and are at increased risk for medical complications given the high prevalence of comorbidities. A thorough understanding of the risks associated with obesity and the diagnostic and therapeutic challenges involved with femoral shaft fractures in this setting is paramount to achieve adequate results.
Given the ongoing epidemic of obesity, femoral fracture management in the population affected by this condition is likely to become more frequent. Obesity in the United States has been steadily increasing over the last few decades, rising from 13.3% in 1960 to 31% in 2002. Similarly, the prevalence of obesity has dramatically increased among children from 10 to 17 years from 6% in 2003 to 16% in 2007. Also, obesity increased by up to 33% among Hispanic children and children from single-parent households, with rates reported as high as 40%. Extreme obesity (body mass index [BMI] >40 kg/m 2 ) has further increased from 2.9% from 1988 to 1994 to 4.7% from 1999 to 2000, and was reported to be 5.7% from 2007 to 2008 with an especially high prevalence in non-Hispanic black women (14.2%).
Fracture treatment in obese patients poses a special challenge, given the greater difficulty in establishing an accurate diagnosis and confirming associated injuries. Adequate intraoperative positioning and obtaining accurate reduction and stable fixation may require special considerations. Obese patients have a high predisposition for complications such as compartment syndrome, nerve injuries, and pressure ulcers, and are at increased risk for medical complications given the high prevalence of comorbidities. A thorough understanding of the risks associated with obesity and the diagnostic and therapeutic challenges involved with femoral shaft fractures in this setting is paramount to achieve adequate results.
The obese patient
Obese patients have lower self-reported health-related quality of life as well as an increased risk of having coronary artery disease, type 2 diabetes mellitus, and endometrial, breast, colon cancer, hypertension, dyslipidemia, stroke, gallbladder disease, osteoarthritis, sleep apnea, and respiratory problems. As a consequence, obese patients carry an increased risk for systemic complications including infection, deep venous thrombosis, myocardial infarction, and pneumonia. Maheshwari and colleagues studied the effect of obesity on the morbidity of patients who suffered femur or tibia fractures during a motor vehicle collision. In a cohort of 665 patients, obese subjects had a higher prevalence of reported baseline cardiac disease and diabetes compared with nonobese patients. Furthermore, obese patients had more severe fracture patterns involving the distal femur (90% vs 61%, P <.01). No differences were found in postoperative complications, but obese patients had an almost 2-fold mortality risk that approached statistical significance (9.5% vs 5.6%, P = .07). Other studies on critically injured blunt trauma patients have confirmed obesity as an independent risk factor for mortality, increased hospital and intensive care unit length of stay, and prolonged use of mechanical ventilation in survivors. Regarding nosocomial infections, Choban and colleagues compared a cohort of 849 patients undergoing general, urologic, vascular, thoracic, or gynecologic surgical procedures and found an increased incidence in patients with higher BMI. Although infections occurred in 0.5% of patients with BMI of less than 27 kg/m 2 , frequencies increased to 2.8% in patients with BMI of 27 to 31 kg/m 2 and 4.3% in patients with BMI greater than 31 kg/m 2 . Wound healing problems have additionally been found to be more frequent in obese patients undergoing acetabular and femoral fracture fixation, with diabetes and the presence of extensive panniculus contributing to the occurrence of this complication.
Incidence and mechanism of injury
Despite femoral shaft fractures having been a subject of extensive research, only limited literature has focused on the management of these fractures in the obese population. According to Tucker and colleagues, 20% of patients with femur fractures are obese (BMI ≥30 kg/m 2 ), with an obesity rate among women of 32% compared with 15% in men. Motor vehicle accidents account for about 50% of femoral shaft fractures. This proportion is similar between obese and nonobese individuals. Sports and motorcycle accidents account for a substantial proportion of fractures in nonobese patients but not in obese patients, presumably because the latter are less frequently engaged in these activities. Falls, however, account for 31% of femur fractures in obese patients compared with only 14% in nonobese individuals. Furthermore, it is not infrequent in obese individuals for fractures to occur unrelated to or after only a minimal traumatic event. Although the absence of significant trauma may lead to the perception of the fracture having been caused by low energy, the opposite is, however, most likely the case. Contrary to nonobese patients in whom low-velocity fractures are likely to be related to decreased bone mineral density, in obese individuals they occur in the presence of increased bone mineral density and bone cross-section area. Owing to a large body mass, even at low trauma velocities, significant energy can be generated leading to significant fracture comminution and soft-tissue damage.
Incidence and mechanism of injury
Despite femoral shaft fractures having been a subject of extensive research, only limited literature has focused on the management of these fractures in the obese population. According to Tucker and colleagues, 20% of patients with femur fractures are obese (BMI ≥30 kg/m 2 ), with an obesity rate among women of 32% compared with 15% in men. Motor vehicle accidents account for about 50% of femoral shaft fractures. This proportion is similar between obese and nonobese individuals. Sports and motorcycle accidents account for a substantial proportion of fractures in nonobese patients but not in obese patients, presumably because the latter are less frequently engaged in these activities. Falls, however, account for 31% of femur fractures in obese patients compared with only 14% in nonobese individuals. Furthermore, it is not infrequent in obese individuals for fractures to occur unrelated to or after only a minimal traumatic event. Although the absence of significant trauma may lead to the perception of the fracture having been caused by low energy, the opposite is, however, most likely the case. Contrary to nonobese patients in whom low-velocity fractures are likely to be related to decreased bone mineral density, in obese individuals they occur in the presence of increased bone mineral density and bone cross-section area. Owing to a large body mass, even at low trauma velocities, significant energy can be generated leading to significant fracture comminution and soft-tissue damage.
Diagnosis
Heightened suspicion for a femoral fracture should be present in the obese patient with marked thigh pain after even minor trauma. Given the large body habitus, fractures of the femur may not be readily apparent in the patient population. Concomitant injuries to ipsilateral and contralateral acetabulum, pelvis, hip, and knee should be actively ruled out during the secondary survey, as the probability of these going unnoticed is increased in the patient population. Dedicated views for the hip and knee as well as trauma series for pelvis and acetabulum should be taken. In the general population up to 9% of femoral shaft fractures have an associated femoral neck fracture, of which up to 50% are missed at initial assessment ( Fig. 1 ). Although no specific data have been published for obese patients, this population is at increased risk for missed diagnosis owing to poor visualization of the femoral neck given the presence of large amounts of adipose tissue. Although active screening for these fractures on femur radiographs as well as specific internal rotation hip views should be performed, computed tomography scans of the proximal femur may be indicated in this patient population. In a cohort of 152 femoral shaft fractures, Yang and colleagues found 12 femoral neck fractures at the moment of admission. Of these, a total of 6 nondisplaced fractures were not detectable using conventional radiography but could be observed on computed tomography (CT) scans. Tornetta and colleagues showed that fine-cut (2 mm) CT scanning of the proximal femur was able to detect 12 of 13 (92%) femoral neck fractures associated with fractures of the ipsilateral femoral shaft, as opposed to only 8 (62%) fractures using only hip radiographs. Furthermore, with CT scanning the incidence of delayed diagnosis could be reduced from 57% to 6%, allowing for earlier femoral neck fracture recognition and management. CT scanning is of additional use for the postoperative assessment of the acetabulum and femoral neck after closed reduction of associated ipsilateral hip dislocations ( Fig. 2 ).
Obese patients are at higher risk of having comminuted fractures. According to Tucker and colleagues, whereas nonobese patients had comminuted (Orthopedic Trauma Association type C) fractures in 18% of cases, obese patients had comminution in 25% of cases. Open fractures occurred with equal frequency in obese and nonobese patients in 17% and 16% of cases, respectively. However, no type III open fractures were found in obese patients, whereas they accounted for 35% of open fractures in nonobese patients. This finding may suggest that femur fractures in obese patients rarely lead to inadequate soft-tissue coverage; however, open fractures in this patient population should suggest an even higher level of energy, as expected for this type of fracture in nonobese subjects. Furthermore, a high level of suspicion should be present regarding vascular injury, given the clinical difficulty for assessing such an injury. The ankle brachial index (ABI) is considered the test of choice for the initial assessment of vascular injury in the lower extremity. To perform this test in obese patients, however, a special cuff may be necessary that fits the increased circumference of the calf. An ABI of less than 0.9 should prompt additional vascular investigations.
Skeletal traction using either smooth Kirschner wires with bow tensioner or threaded Steinman pins inserted from medial to lateral at the level of the superior pole of the patella may be required for initial fracture stabilization and pain management. Although traction with 15 lb (6.8 kg) is usually sufficient for nonobese patients, significantly higher weights may be required in morbidly obese patients and should be calculated at approximately 10% to 15% of body weight.
Perioperative considerations
Because of increased body habitus, special surgical equipment is frequently required. Special surgical equipment includes larger and stronger tables, special supports, as well as specially designed instruments. In a group of obese patients with a BMI ranging from 33.2 to 57.1 kg/m 2 undergoing nonunion surgery, Jupiter and colleagues reported on the occurrence of several complications including peroneal compartment syndrome, gluteal compartment syndrome with sciatic nerve palsy, bilateral brachial plexus stretch injuries, anterior interosseous nerve palsy, and postoperative development of a patch of scalp alopecia. These complications were thought to be related in every case with poorly protective positioning and prolonged ischemic pressure under the patient’s body weight during the surgical procedure. Therefore, adequate padding of bony prominences as well as continuous intraoperative monitoring of compartment tension of the contralateral leg and buttock should be performed.
To achieve adequate fracture visualization, image intensifiers with good imaging quality are required. Owing to the high prevalence of femoral neck fractures in the presence of femoral shaft fractures, imaging quality is of special relevance in this setting, because the large amount of soft tissue may obscure adequate visualization. Intra-articular injection of contrast medium has been proposed to enhance visualization of the femoral head in massively obese patients, to facilitate adequate screw placement when cephalomedullary devices are required and to rule out iatrogenic fractures of the femoral neck after intramedullary nailing.
Treatment
Assessment and management of obese patients should be addressed in a similar fashion to nonobese patients, and should follow the guidelines of the advanced trauma life support. An important consideration in the initial physiologic stabilization of these patients is that despite the large body mass, total blood volume in obese individuals is similar to that of normal-sized individuals because excess body mass is mainly composed of adipose tissue. As a consequence, the percentage of blood loss caused by femoral fracture should be calculated in relation to lean body mass rather than total patient weight.
Fracture stabilization should adjust to the patient’s physiologic reserve, with early definitive fracture fixation in the stable patient and temporary stabilization after damage-control guidelines in unstable individuals with additional major injuries ( Fig. 3 ). Given the increased rate of complications and the prolonged metabolic acidosis of obese patients, even after adequate resuscitation, a lower threshold for a damage-control approach should exist. Similar to nonobese patients, the presence of concomitant head and/or chest trauma may indicate initial external fixation in order to reduce the risk of acute respiratory distress syndrome and multiorgan failure.
External fixation is considered the method of choice for temporary fixation in unstable patients, and can be safely followed by staged intramedullary nailing. In morbidly obese patients, however, fixation may be challenging to achieve, given the long distance between the skin surface and the femoral cortex ( Figs. 4 and 5 ). Tactile feedback as well as visual orientation using an image intensifier should lead to adequate pin placement. Given the large loads the construct supports, additional pins may be required as well as the use of double bars for fracture bridging. Nonreamed retrograde nailing with or without locking has been recently proposed as an alternative to temporary external fixation.
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