Total hip arthroplasty (THA) is one of the most successful surgeries performed by orthopedic surgeons. However, technical complications remain, including instability, leg length discrepancy, and abductor dysfunction or gait disturbances. The DAA has been proposed to address component alignment, instability, and early functional recovery.¹ The DAA has become popular during the last decade with the pursuit of minimally invasive surgery.^2,3 Proponents of the DAA believe there is less muscle damage and a lower risk of dislocation,^4,5,6,7 leading to fewer postoperative restrictions and necessary equipment,⁸ quicker recovery,⁹ less pain and narcotic use,¹⁰ and a shorter length of stay with higher rates of discharge to home compared with lateral or posterior approaches.^4,11,12 In a recent clinical practice survey of members of the American Association of Hip and Knee Surgeons, 56.2% currently perform the DAA.¹³

There have been limited outcomes reported in the orthopedic literature comparing the DAA with lateral and posterior approaches, including retrospective reviews and two randomized trials from a single center that are underpowered to show any differences.^14,15,16 Hart et al¹⁷ reported no significant difference in major or minor perioperative complications (within 30 days postoperatively) between the posterior, lateral, and DAA approaches. Long-term outcome studies have not shown any difference beyond 6 months, although one study suggested improved gait mechanics may persist for the DAA.^18,19,20,21 Angerame et al²² reported a similar revision rate for the DAA and posterior approach, but they indicated that the mode of failure may be different. The DAA had a higher early revision rate for femoral component loosening, whereas the posterior approach had a higher incidence of revision for instability.²²

Opponents of the DAA have cited complications reported in association with DAA THA, such as ankle fractures,¹ meralgia paresthetica,²³ and a steep learning curve requiring greater than 100 cases to be safe.^12,24 In a recent study, the procedure time for the DAA only became statistically equivalent to the posterior approach after the 400th DAA case in a group of mature posterior approach surgeons who switched to the DAA.²⁵ Masonis et al²⁶ previously described a stepwise approach that leads to a safe reproducible learning curve. Further study will need to explore whether any such learning curve will still exist for surgeons who learn DAA THA during residency and fellowship training before starting practice. Understanding a specific set of indications and contraindications, as well as identifying the more complex cases that will challenge a surgeon, will hopefully aid in this learning experience.

The indications for the use of the DAA are similar to all indications for primary THA. As for any primary THA, the indications for DAA include pain, functional limitation, stiffness, and radiographic changes consistent with arthritis or deformity that have been recalcitrant to nonoperative measures. Certain prior surgeries may actually be relative indications for DAA THA. For example, previous anterior incisions from a periacetabular osteotomy may be able to be used effectively for DAA THA.

Contraindications to the DAA for total hip replacement may also be similar to that of primary THA via any other approach. However, there may be some additional considerations that could add further complexity and, in some surgeons’ hands, may be relative contraindications to proceed with DAA. As with any approach, arthroplasty may not be indicated in the setting of poor prognostic indications, such as severe medical disease wherein the risk of surgery outweighs the expected benefit, patient noncompliance, or local or systemic infections.

Obesity, in particular morbid obesity (body mass index [BMI] > 40 kg/m²), may be considered a relative contraindication to THA given significantly higher rates of complications (eg, the infection risk increases from 1.8% to 9.1% in the morbidly obese).²⁷ Antoniadis et al²⁸ reported an increased risk of reoperation (relative risk = 4.0) due to wound infection and dehiscence in obese patients compared with nonobese patients. The DAA may be potentially advantageous in the obese patient because the adipose layer in the anterior aspect of the hip tends to be thinner than that found laterally (Figure 5.1).¹ However, higher rates of wound complications have also been reported, which may be the result of the thinner dermis along with the flexion crease, which can be a source of moisture retention, motion, and irritation to the incision (Figure 5.2).²⁹ Furthermore, in the obese patient, the presence of an abdominal pannus can exacerbate this skin irritation and maintain a moist environment, harbor fungal infections, and contribute further to wound healing concerns. Statz et al³⁰ reported survivorship rates of 98.6% at 1, 2, and 5 years postoperatively in 18 patients who underwent superficial incision and drainage for superficial wound dehiscence after DAA THA. They noted higher hazard ratios for patients with BMI > 30 kg/m².³⁰ Surgeons have developed various strategies to deal with these conditions. For example, nystatin powder can be given preoperatively to the patient with flexion crease irritation if noted preoperatively. However, if it is present at the time of surgery, we would strongly consider alternative approaches to avoid placing a surgical incision near such a site of potential contamination.

In addition to causing wound healing issues, an abdominal pannus can create a mechanical challenge to the surgeon, obstructing the necessary placement of instruments, particularly during femoral preparation. The most challenging abdominal deformity is a tense, distended abdomen, which is frequently observed in male patients with metabolic syndrome. The Challenging Cases: Tips and Tricks section in this chapter describes options to overcome these potential contraindications.

Other comorbid conditions may also pose relative contraindications. Hip and knee flexion contractures can make the approach, positioning, and manipulation of the extremity challenging. Conditions such as spinal fusions and other spine pathologies such as ankylosing spondylitis can pose additional risks, including spinal fractures due to the extension moment placed on the spine during femoral exposure.³¹