Over the past 20 years, the direct anterior approach (DAA) has been popularized for total hip arthroplasty (THA) in a minimally invasive fashion. For a long time, it was assumed that the DAA can only be used for primary THAs. A better understanding of the periarticular anterior hip anatomy has led to the development of extensile approaches that allow surgical access to both the proximal and distal sides of the hip in order to perform complex revision procedures.

There are multiple explanations why distal extension of the approach was deemed difficult, if not impossible. First, the DAA was propagated with the label of “minimal invasiveness” with a strong focus on small skin incisions. Therefore, revisions seemed to be out of the scope of minimally invasive surgeries in general. Yet, surgeons who had vast experience with primary DAA procedures gradually expanded the indications and ran into some cases in which small revisions of the cup or the head had to be performed.^1,2 With growing experience and concurrent development of specialized curved and offset instruments, it became clear that these surgeries could be performed quite easily.

The next level of THA revision surgery would be an endofemoral revision of the stem.³ Retrieving a loose stem and reimplanting a larger revision stem or a cemented stem with or without bone impaction grafting does not require a significantly longer skin incision. In some cases, it might be necessary to release the iliac insertion site of the tensor fascia lata (TFL). This can facilitate a straight access into the femoral cavity. Such a release is performed by incising two-thirds of the TFL about 1 cm distal to its origin from the iliac crest. This keeps the muscle in place and allows for easy refixation at the end of the procedure. Transosseous suturing can be used but is not required when using Kessler sutures.

Figure 23.1 illustrates how a proximal TFL release at the lateral tendon origin can be performed. A TFL release improves the femoral access by pushing the muscle structures underneath the femoral elevator more posteriorly.

Femoral component revision procedures are prone to further damaging the proximal femur. Perforating the bone, or even splitting it, is a realistic complication that may occur during the retrieval of the old implant or during the reimplantation of the new revision stem. The removal of cement endofemorally is especially difficult, even with the use of ultrasound devices. In these cases, an extended femoral osteotomy can be very helpful. In cases of revision procedures of a well-fixed cementless component, an osteotomy of the proximal femur is part of the surgical plan. In cases in which an extended femoral osteotomy is required, distal extension of the approach to reach the femoral diaphysis is mandatory.

Figure 23.2 shows the anterior periarticular muscular anatomy relevant to the distal extension of the DAA. DAA THA is performed underneath the rectus interspace between the intertrochanteric line, which is the distal border of the femoral neck and the acetabulum. The long head of the rectus femoris muscle originates from the anterior inferior iliac spine and the reflected head at the acetabular rim and the capsule. This is the only part of the quadriceps muscle that originates from the pelvis. The other three parts originate from the femur distal to the intertrochanteric line. The proximal origin of the vastus lateralis reaches from the intertrochanteric line and marks the distal end of the femoral neck. It serves as a surgical landmark, and, together with the more anterior vastus intermedius, it defines the distal border of the femoral insertion of the joint capsule.

The intermedius muscle inserts more distally. A distal extension of the DAA using the interval between the vastus intermedius and lateralis could jeopardize the nerve supply.^4,5,6 The quadriceps is supplied by the femoral nerve, which leaves the pelvis underneath the medial inguinal band and splits into several branches. Those branches cross the DAA interval underneath the rectus femoris and cross anteriorly to supply the vastus intermedius muscle and then transit more laterally to supply the vastus lateralis muscle. These bundles are typically observed distal to the lesser trochanter. Thus, noncareful dissection of the space between the vastus intermedius and the vastus lateralis can jeopardize the nerve supply of the vastus lateralis.

Figure 23.3A shows the nerve branches of the femoral nerve reaching across the intermedius muscle into the vastus lateralis. For all anterior and lateral approaches to the femur, the typical access route to the diaphysis is from the lateral direction, going underneath the vastus lateralis. This muscle reaches relatively far dorsally to the posterior aspect of the femur. Yet, muscle fibers can safely be separated from the bone surface and the femoral diaphysis can be reached at its dorsal border. With this standard access route to the femur, the nerve supply of the vastus lateralis is not in danger. The downside of this approach is that the bone is denuded from muscular tissue. Figure 23.4 demonstrates the access to the femoral diaphysis posterior to the vastus lateralis.