Managing Obesity in the Direct Anterior Approach

Andrew Poole

Mazin Ibrahim

Jason Thompson

Brent A. Lanting

Key Learning Points

Understand the importance of optimizing high-body mass index (BMI) patients preoperatively, especially optimizing hemoglobin and skin health.
To know about the surgical approach, positioning, and closure of the wound in this cohort of patients using the direct anterior approach (DAA) to the hip.
Understand the postoperative implications of performing surgery in this high-BMI population including financial implications.
To anticipate complications associated with this surgical approach related to the obese patients and their frequency.

Introduction

Globally, obesity has quickly grown to epidemic proportions and now rivals other leading public health concerns with regard to prevalence and incidence. Clinicians most commonly quantify obesity, or the lack thereof, by using BMI, which is calculated by dividing one’s weight in kilograms by their height in meters squared (kg/m²). Normally, individuals have a BMI between 18.5 and 24.9, whereas overweight adults have a BMI in the 25 to 29.9 range according to the World Health Organization (WHO).¹ Obese individuals are people whose BMI is equal to or greater than 30; this category of individuals is then further subcategorized into three classes defined by WHO based on a person’s degree of obesity. However, these classes are less commonly used in the surgical literature and practice; instead, the classification terms morbidly obese and super obese are customarily used to indicate a BMI between 40 and 49.9 and a BMI equal to or greater than 50, respectively. Although the health risks associated with an elevated BMI are well recognized, the impact of a person’s weight distribution on their health may be overlooked because central obesity not only negatively impacts one’s overall health but also has the potential of affecting surgical options and outcomes.

The need for joint arthroplasty is projected to rise at a near exponential rate in developed countries due in part to the aging population and also to increased access to health care. Likewise, the obesity epidemic in many of these same countries is growing at a comparable rate. The relative risk of requiring a joint replacement increases as the WHO obesity class increases; it peaks at 8.5 times for total hip arthroplasty (THA) in class III obese patients compared with normal-weight individuals.² Before performing THA, surgeons must consider the risks, benefits, and alternatives of their recommendations and subsequent decisions for each patient’s care pathway; these considerations are heightened in the obese population.

Surgeons must familiarize themselves with all possible complications when performing surgery, specifically with the DAA in obese and/or morbidly obese patients. As orthopedic surgeons strive to provide value-based care, developing strategies to manage this growing subset of patients will prove to be pivotal in the future. Despite the high success rate of all aspects achieved by THA since its invention, the clinical outcomes and early revision rates are poorer for obese patients.³ This chapter reviews the surgical challenges, complications, and outcomes from the DAA to the hip in obese patients. This chapter is divided based on preoperative, intraoperative, and postoperative considerations.

Preoperative Assessment

Minimizing complications in patients who are obese starts from the preoperative period. Surgeons should evaluate patients on a case-by-case basis. These patients should undergo full nutritional and diabetic evaluation from their respective primary care providers before surgery should be considered. Abnormalities in electrolytes, albumin, and blood glucose should be corrected preoperatively and closely monitored in the immediate postoperative period. It is important to make sure that the hemoglobin level is optimized preoperatively due to increased expected blood loss during the operation in this cohort of patients.⁴ In their study, Antoniadis et al⁴ demonstrated that this cohort had statistically significant more blood loss compared with a control group of nonobese patients. Logistically, this group of patients requires more time in the operating room (OR) because of their increased body habitus. Tracking the time the patient enters the OR to the time the wound is closed and the patient exits the room, Antoniadis et al demonstrated that obese patients had a longer total time in the OR as well as longer operative times. Russo et al⁵ confirmed this fact in their study with longer OR times in obese patients compared with nonobese patients.

Additionally, surgeons should evaluate patients on a case-by-case basis and educate themselves on the complications and technical challenges associated specifically with the DAA in the obese and morbidly obese. Although
wound complications are known to be higher in obese patients regardless of the surgeon’s approach, they are of particular concern in obese patients who undergo DAA THA. The skin overlying the surgical field of a DAA experiences different stresses and moisture levels and has a higher incidence of fungal colonization, particularly in the obese population.⁶^,⁷^,⁸

Obese patients who have a large abdominal panniculus often have intertrigo in their inguinal area. Intertrigo (intertriginous dermatitis) is characterized by excessive moisture in skin folds resulting in skin breakdown and an inflammatory condition. Surgeons should evaluate the inguinal area in patients who are obese or who have excess skin, and if there are signs of intertrigo such as redness, blisters, or maceration, then a referral for management of the inflammation before considering surgery might be prudent. Topical skin protectants, antibiotics, and antifungals are effective at improving the inflammation and eradicating concurrent bacterial or fungal infections.⁶ Watts et al⁷ showed that obese patients who underwent the DAA had higher wound complications, particularly in the proximal part of the incision near the waist crease.⁷

Intraoperative Considerations

Positioning

The positioning of patients for DAA THA follows the standard positioning for any other patient but with more attention paid to the panniculus. In these patients, the abdominal fat folds over the anterior superior iliac spine (ASIS), which is an important bony landmark for the incision. Patients can be positioned with the use of a specialized traction table (Figure 15.1) or on a standard table (Figure 15.2). For both operative table choices, the patient is placed in a supine position. The senior author (BL) uses a traction table in all cases.⁹ Patient positioning must take into account the need for proper exposure and the placement of assistants and provide access to intraoperative fluoroscopy. Regardless of bed choice, patients are most commonly positioned supine. Although positioning in a lateral position for a DAA has been described, the literature has shown the supine position to have more reliable pelvic positioning, leading to more consistent acetabular component orientation (40° of inclination and 20° of anteversion, +/−. 10°) as found by Grammatopoulos et al¹⁰ when comparing the supine with the lateral decubitus position.

FIGURE 15.1 The specialized table (the Hana fracture table, Mizuho OSI) that we use with the DAA. The table has boots attached to a lever arm to allow intraoperative traction and position adjustment. The perineal post allows countertraction. There is a motorized lift to facilitate femoral exposure.

FIGURE 15.2 A standard table (EZ Slide, Skytron, Grand Rapids, MI, USA) with a patient positioned with ischium at the level of the hinge to allow femoral extension through the table.

When using the Hana table (Mizuho OSI, Union City, CA, USA; see Figure 15.1), we wrap both feet with a special adhesive bandage and place them into the traction boots for added grip, allowing intraoperative maneuvering and traction of the operative leg at the end of the table. The perineum post is secured in the middle to provide countertraction during the procedure, especially when additional traction is necessary (see Figure 15.2).

DAA hip arthroplasty can be performed on patients who are obese using a standard table as well. A 3- to 4-in well-padded bump placed under the sacrum, ending at the level of the ischium, aids with femoral extension and exposure. Similarly, if the surgeons prefer, the patient can be placed with the ischium at a hinge point in the bed, allowing the patient’s legs to be lowered throughout the case to allow femoral extension. Adduction of the operative leg can be improved by placing an arm board next to the contralateral leg (Figure 15.3). Abduction of the contralateral leg will allow increased adduction of the operative leg or allow an easier figure-4 position. Additional upright supports can (and should) be placed along the patient’s contralateral hip and thorax to prevent the obese patient from potentially falling off the bed during reaming or leg positioning (Figure 15.4).

FIGURE 15.3 A standard table with arm board extension on the contralateral side to allow for more abduction of the contralateral leg.

FIGURE 15.4 A support post on the contralateral side for the off-traction table DAA.

A unique challenge to the supine DAA in obese patients is the management of the patient’s panniculus during surgery. An obese patient’s panniculus can provide a surgical challenge throughout the entire case and must be addressed before draping and incision. At our institution, we routinely will tape the panniculus away from the surgical field in our obese patients. Skin sensitive tape that is 6 to 8 in in width will provide adequate strength without causing skin trauma at the end of the case (Figure 15.5). In patients who have a large panniculus, it can be helpful to have the patient undergo an isopropyl alcohol bath before placing the tape to remove any oils or residue from the skin. During final draping, after the surgical field is draped, we routinely use an antimicrobial incise drape to cover the surgical area. Intentionally placing this in a lateral to medial direction can allow the surgeon to pull any remaining excess skin or fat away to provide a taught surgical field just lateral to the ASIS. Additionally, adding a slight rotational tilt to the OR table toward the contralateral side can help induce the panniculus to be positioned away from the surgical site.

FIGURE 15.5 Taping of the panniculus in an obese patient.

(Reprinted with permission from Dr. Gilliland.)

Incision and the Approach

The DAA in obese patients uses the same fundamental internervous plane that is well described in the literature.¹¹^,¹² Using the ASIS as a reference point, our standard incision starts approximately 2 cm distal and lateral to the ASIS and follows the path of the tensor fascia lata (TFL) for approximately 8 to 10 cm. In obese patients, the incision may need to be started more proximal, at the same level of the ASIS, to allow proper exposure to the acetabulum and femur. Care must be taken not to place excess traction on the superior part of the incision because this is where wound breakdown is most likely to occur.⁷^,⁸ Although bikini incisions have been described for obese DAAs and are discussed elsewhere in this textbook, we do not currently recommend it because of the medial aspect of the incision being at greater risk to be enveloped by soft tissue.¹³

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