The Direct Anterior Approach: A Comprehensive Guide for the Learner and Educator

*Bijan Dehghani, Avi Dravid, Praneeth Thota and Neil P. Sheth*

### **Abstract**

Total hip arthroplasty is one of the most widely performed procedures demonstrating excellent clinical outcomes and implant longevity. Enhanced imaging modalities, advancements in material science, and improvements in surgical technique have contributed to the global success of this procedure. One such technique has gained significant attention over the past decade – the direct anterior approach (DAA). First described by Carl Hueter in 1881, the DAA is now more commonly credited to Smith-Peterson. This technique demonstrates rapid recovery, reduced hospital length of stay, and enhanced stability. Despite these advantages, there is a well reported learning curve for surgeons, particularly for those who trained using an alternative surgical approach. In this chapter we explore a methodological approach to mitigate and decrease the learning curve; allowing for a safe and reproducible guide to teach surgeons how to transition to the DAA.

**Keywords:** total hip arthroplasty, direct anterior approach, learning curve, hip replacement, posterior approach

### **1. Introduction**

Total Hip Arthroplasty (THA) is one of the most commonly performed orthopaedic procedures for the treatment of end-stage hip degeneration. With a robust track record of effectiveness and safety, THA has become a widely accepted method for providing pain relief, restoring function, and reestablishing a patient's quality of life [1]. Sir John Charnley pioneered one of the first low friction arthroplasties in the 1950s, laying the groundwork for future advancement in the field [2]. Since then, advents in technology in the arena of biomaterials, implant design, and surgical technique have contributed to THA's widespread acceptance [1]. An estimated 370,770 hip replacements were performed in 2014, with this number expected to reach 635,000 in 2030; this represents a projected 71% increase [3]. A rapidly aging population, widening surgical indications, as well as an increased prevalence of obesity and associated osteoarthritis have fueled this increase in demand [4].

Total hip arthroplasty can be performed through several surgical exposures, including the posterior, posterolateral, direct lateral, anterolateral, and direct anterior approaches [2]. The direct anterior approach (DAA), in particular, has exhibited a tremendous amount of enthusiasm in recent years. German surgeon Carl Hueter first characterized the anterior approach for accessing the hip joint in 1881, describing an inter-nervous and inter-muscular plane between the tensor fasciae latae and sartorius muscles – known today as the Hueter Interval [5]. However, American surgeon Marius Nygaard Smith-Petersen is credited with popularizing this surgical approach. Although this surgical approach was first adopted as a means of reducing congenital hip dislocations, Smith-Petersen also used it to perform mold arthroplasties in 1949 [2, 5].

There is a growing body of literature substantiating the benefits of the DAA. This surgical approach is considered less invasive, exhibits greater stability compared to other approaches, and results in less overall tissue damage [6, 7]. A randomized clinical study comparing the DAA and the posterior approach demonstrated lower pain scores and better function during the early stages of recovery with the DAA [8]. Additional studies have reported lower pain scores, less blood loss, and increased walking speed compared to the direct lateral approach [9]. In the immediate postoperative period, the DAA patients were discharged from the hospital earlier and with greater mobility [10]. However, other studies have shown that differences in post-operative recovery may not be clinically significant as they equalize by 6 weeks, and maintain in the longer term [6] Regardless of surgical approach, clinical success in THA is predicated on adequate surgical exposure, correct component position, and proper soft-tissue balancing [11].

Patient demand, as well as marketing by industry and orthopaedic practices has contributed to the rise in popularity of the DAA [11]. In an effort to meet demand, surgeons may choose to switch from an alternative surgical approach, but, the steep learning curve has always been a major barrier, especially if the transition occurs once already in practice and dedicated time to pursue formal fellowship training is not practical. The DAA is typically performed with the patient in a supine position, requiring different sets of retractors, and often use of a specialized operative table [12]. Some studies suggest that surgeons should perform at least 100 such operations in order to become adequately proficient in the technique [12].

Adult reconstruction fellowships and orthopaedic residency training programs have taken notice of this enthusiasm for the DAA, and have addressed this demand through formal didactics, surgical videos, hands-on training, cadaveric workshops, and educational simulation platforms [13]. For surgeons that do not have the luxury of formally training, a systematic, dedicated methodology must be employed when transitioning to the DAA in order to minimize complications, achieve favorable clinical outcomes, and recognize the benefits associated with the surgical approach.

### **2. Surgical technique of the direct anterior approach**

The first step in learning the DAA is understanding the anatomy, and more particularly the anterior structures of the hip. The important landmarks include the anterior superior iliac spine (ASIS) and the greater trochanter (GT). Proper equipment and positioning are paramount for successful procedure. A specialized surgical table is often used to allow for controlled manipulation of the extremity; however, many surgeons successfully perform this procedure using a regular table. The Hana table is commonly described for this purpose as it allows the surgeon to apply traction, rotate, and abduct/adduct the extremity as needed. The principal author of this paper utilizes a Medacta table extension which can be readily attached to a regular
