Anterior-Based Muscle-Sparing Approach in the Lateral Position
Nathan B. Haile, MD
Ryland Kagan, MD
Mike B. Anderson, MSc
Christopher L. Peters, MD
Dr. Anderson or an immediate family member serves as a paid consultant to or is an employee of Ortho Development Corporation and Orthogrid Systems, Inc. and has stock or stock options held in Orthogrid Systems, Inc. Dr. Peters or an immediate family member has received royalties from Biomet; is a member of a speakers’ bureau or has made paid presentations on behalf of Biomet; serves as a paid consultant to or is an employee of Biomet; has stock or stock options held in CoNextions Medical and Muve Health; has received research or institutional support from Biomet; and serves as a board member, owner, officer, or committee member of the American Association of Hip and Knee Surgeons and Knee Society. Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter: Dr. Haile and Dr. Kagan.
PATIENT SELECTION
Minimally invasive (MIS) approaches to total hip arthroplasty (THA) are becoming more popular as surgeons strive to reduce the recovery period following this successful and functionally restorative procedure. As such, there has been a surge of published research regarding the outcomes of these approaches with much of the focus on anterior-based approaches, with an unarguable predominance toward the direct anterior approach (DAA).1,2 The increasing popularity of the DAA has been accelerated with significant marketing. For example, a recent study showed that 20% of surgeons in the American Association of Hip and Knee Surgeons advertise their use of the DAA on their website.3 Despite the proposed, and even marketed, benefits of the DAA, controversy still exists surrounding the outcomes of this technique. The benefits of DAA THA have been reported to include decreased hospital length of stay (LOS), higher rates of discharge to home, and improved early functional recovery.4 However, others have reported a greater prevalence of wound complications,5 increased rate of intraoperative fractures, and increased risk for early femoral failure.6 Additionally, the DAA has been associated with a steep learning curve.7 There is concern with many established surgeons whether the increase in these complications during the learning curve is worth the transition to DAA THA as a routine part of their surgical practice. As a result, other anterior-based approaches continue to be evaluated. The anterior-based muscle-sparing (ABMS) approach, originally described in 2004 by Bertin and Rottinger,8 has been reported as a new “innovative” approach to THA. This is a modification of the Watson-Jones approach described in 1938, which had modified the original description of the interval by Sayre in 1894. This approach utilizes the interval between the tensor fascia latae (TFL) and the abductor muscles and maintains the posterior capsule (Figure 1). A key difference in this approach compared with the DAA is that it is performed with the patient in the lateral decubitus position with the operated leg free. As such, it may provide an easier transition for surgeons who are accustomed to the lateral decubitus position. Additionally, this allows the ability to intraoperatively assess hip range of motion and stability and for the inclusion of patients with a variety of body habitus. To be considered for THA via the ABMS approach, patients should have daily hip pain derived from osteoarthritis, inflammatory arthritis, or dysplasia with associated degenerative disease. We recommend that patients exhaust all conservative treatment options prior to proceeding with surgical intervention. Patient selection also includes evaluation of modifiable and non-modifiable risk factors. In our practice, absolute contraindications to THA include smoking and other nicotine use, hemoglobin A1c (HbA1c) > 7.5%, open wounds on the surgical extremity, and active infection. Relative contraindications include BMI >40, lower extremity lymphedema, and untreated mental and/or medical comorbidities.
PREOPERATIVE IMAGING
The standard preoperative imaging examination includes a standing AP pelvis and a cross-table lateral radiograph of the surgical hip. For patients with hip dysplasia further radiographs may include Dunn lateral or false profile views. In cases with minimal radiographic evidence of degenerative disease, advanced studies including MRI or CT may be included.
PROCEDURE
Patient Positioning
The patient is positioned on a standard operating table in the lateral decubitus position, with the surgical hip facing up. A simple inexpensive peg board attachment is placed over the table, which is used to stabilize the patient; the standard configuration for a right THA is shown in Figure 2. Posteriorly a short peg is placed in the most
caudal peg hole to brace the sacrum. The second posterior peg is placed two to three holes more cephalad to support the torso. Two pegs are placed on the anterior side of the patient. The caudal peg is placed at the level of the pubis to support the pelvis, and the second is placed two to three holes more cephalad to support the torso. A gel pad is placed over the peg board prior to patient positioning and egg crate pads are used to protect the patient. This configuration will accommodate a spectrum of patients with varying body habitus. After the patient is secured in the peg board with padding of all bony prominences, the hip is taken through full range of motion to ensure that all surgical positions and intraoperative stability testing can be achieved. Ideally the surgical hip should be able to achieve 100° of flexion, 15° of extension and 25° to 30° of internal and external rotation without impingement of the peg board (Figure 3). After the patient is sterilely prepped and draped, the foot of the bed is dropped to allow easy extension and external rotation of the surgical extremity (Figure 4). A vascular roll or sterile blankets can be used to abduct the surgical extremity. This will relieve tension on the TFL and the gluteus medius during the initial exposure (Figure 5).
caudal peg hole to brace the sacrum. The second posterior peg is placed two to three holes more cephalad to support the torso. Two pegs are placed on the anterior side of the patient. The caudal peg is placed at the level of the pubis to support the pelvis, and the second is placed two to three holes more cephalad to support the torso. A gel pad is placed over the peg board prior to patient positioning and egg crate pads are used to protect the patient. This configuration will accommodate a spectrum of patients with varying body habitus. After the patient is secured in the peg board with padding of all bony prominences, the hip is taken through full range of motion to ensure that all surgical positions and intraoperative stability testing can be achieved. Ideally the surgical hip should be able to achieve 100° of flexion, 15° of extension and 25° to 30° of internal and external rotation without impingement of the peg board (Figure 3). After the patient is sterilely prepped and draped, the foot of the bed is dropped to allow easy extension and external rotation of the surgical extremity (Figure 4). A vascular roll or sterile blankets can be used to abduct the surgical extremity. This will relieve tension on the TFL and the gluteus medius during the initial exposure (Figure 5).
 FIGURE 1 Intraoperative photograph shows Watson-Jones interval between the gluteus medius muscle posteriorly and the tensor fascia lata muscle anteriorly. |
 FIGURE 2 Photograph shows an example of table setup with the peg board attachment for right total hip replacement. Peg board extension supports the nonsurgical leg, while cut-out allows for anterior dislocation of surgical leg. Notice that the foot of the operating table must be lowered to facilitate use of the peg board. |
VIDEO 59.1 Total hip arthroplasty through the anterior-based muscle-sparing approach. Nathan B. Haile, MD; Ryland Kagan, MD; Mike B. Anderson, MSc; Christopher L. Peters, MD (13 min)Video 59.1
Special Equipment
The peg board modification to a regular operating room table is the only other equipment required.
Surgical Technique
The surgeon stands on the anterior side of the patient, while the assistant stands on the posterior side. Surgical landmarks including the femoral shaft, greater trochanter, and anterior superior iliac spine (ASIS) are drawn. The incision is approximately 2 cm anterior and parallel with the greater trochanter. It is approximately an 8 cm incision with one-third of the length above the tip of the greater trochanter and two-thirds of the length below the tip of the greater trochanter. To confirm correct placement of the incision, the ASIS is referenced. A line connecting the ASIS and the greater trochanter should pass through the middle of the incision (Figure 6). The skin is incised sharply, and electrocautery is used to obtain hemostasis and dissect the subcutaneous fat away from the iliotibial band (ITB). Self-retaining retractors are used as needed to facilitate exposure. The
anterior border of the greater trochanter is palpated to confirm correct positioning, and the ITB is incised longitudinally on the anterior aspect of the greater trochanter in line with the skin incision. Care is taken to avoid injury to the gluteus medius muscle, which is just deep to the ITB at the superior aspect of the incision. Next the “gateway vessels” are identified (Figure 7). These are a fascial bridge between the TFL and the gluteus musculature and can be ligated or cauterized to aid in exposure. With the assistant abducting the hip, a cobra retractor is placed over the superior aspect of the femoral neck, between the capsule and the gluteus medius. A second cobra retractor is placed under the inferior aspect of the femoral neck. The direct head of the rectus femoris is preserved, but the indirect head can be released from the hip capsule if necessary to aid in exposure. Next, an L-shaped capsulotomy is carried out (Figure 8). The
initial limb is horizontal along the superior neck from the acetabular rim to the saddle region. The vertical limb then travels inferiorly, parallel to the intertrochanteric ridge, to the inferior neck. The corner of the capsule is then tagged using heavy, nonabsorbable suture to be used later in the capsular repair. Next the capsule is further mobilized off the inferior neck using electrocautery. After the capsule is released, the inferior cobra retractor is replaced, inside the capsule and over the anterior rim of the acetabulum. The superior cobra retractor is removed and replaced by a modified Hohmann retractor on the superior femoral neck. With the hip reduced, the initial femoral neck cut is made using a reciprocating saw in the subcapital femoral neck. This cut is made from inferior to superior, with the surgeon’s hand angled toward the patient’s head to facilitate femoral mobilization (Figure 9). The femur is then mobilized by a combination of extension and external rotation of the hip. An osteotome is placed in the osteotomy site to aid in femoral mobilization. After the femur has been mobilized, the final femoral neck cut is made perpendicular to the axis of the femoral neck, using the saddle and the lesser trochanter as reference points. This cut is also made with
a reciprocating saw from inferior to superior (Figure 10). Next, the acetabulum is exposed. A modified Hohmann retractor is placed over the posterior acetabular wall, between the labrum and the capsule, at the 9-o’clock position for a right hip (3-o’clock for a left hip). The femoral head can then be removed with a corkscrew. The labrum is removed and the pulvinar is débrided from the cotyloid fossa, revealing the true floor of the acetabulum and the tear drop. A Schanz pin can be placed superior to the acetabulum to aid in visualization and to protect the gluteus medius during reaming (Figure 11). Reaming is carried out per surgeon preference. After reaming the final acetabular implant is impacted into place. Attention is then turned back to the femur. The posterior modified Hohmann retractor is removed from its position and placed over the greater trochanter. The capsule over the superior neck is then released from the saddle to the posterior facet of the greater trochanter. During this release the assistant brings the leg into the reverse figure-of-4 position, with the hip extended and externally rotated and the extremity adducted (Figure 12). This capsular release is extended medially to take down the obturator externus, if necessary. The other short external rotators are left in place. A two-pronged femoral retractor is then placed along to inferior neck to facilitate femoral exposure. Any femoral stem design can be used with this approach, and the femoral preparation is carried out according to surgeon preference. After femoral preparation trialing can be performed, the hip is reduced by a combination of in-line traction and internal rotation by the assistant. The surgeon can assist in the reduction by applying traction to the anterior capsule and with the use of a head pusher. Length, alignment, stability, ROM, combined anteversion, and shuck may be tested. To dislocate the hip, the surgeon will place a bone hook along the trial neck. The assistant will then bring the hip to neutral abduction, and a combination of in-line traction and external rotation is used to dislocate the hip. Intraoperative fluoroscopy or flat plate radiographs may be used based on surgeon preference to confirm alignment, as well as length and offset. Closure is performed in a layered fashion per surgeon preference, and perioperative joint injection may be used for additional anesthetic and postoperative pain control. As needed, this approach may be easily carried proximally or distally for an extensile approach, allowing the surgeon to gain access to the entire femur. With internal rotation the intramuscular septum can be identified and vastus lateralis may be exposed and lifted anteriorly as required, for periprosthetic fractures or revision arthroplasty.
anterior border of the greater trochanter is palpated to confirm correct positioning, and the ITB is incised longitudinally on the anterior aspect of the greater trochanter in line with the skin incision. Care is taken to avoid injury to the gluteus medius muscle, which is just deep to the ITB at the superior aspect of the incision. Next the “gateway vessels” are identified (Figure 7). These are a fascial bridge between the TFL and the gluteus musculature and can be ligated or cauterized to aid in exposure. With the assistant abducting the hip, a cobra retractor is placed over the superior aspect of the femoral neck, between the capsule and the gluteus medius. A second cobra retractor is placed under the inferior aspect of the femoral neck. The direct head of the rectus femoris is preserved, but the indirect head can be released from the hip capsule if necessary to aid in exposure. Next, an L-shaped capsulotomy is carried out (Figure 8). The
initial limb is horizontal along the superior neck from the acetabular rim to the saddle region. The vertical limb then travels inferiorly, parallel to the intertrochanteric ridge, to the inferior neck. The corner of the capsule is then tagged using heavy, nonabsorbable suture to be used later in the capsular repair. Next the capsule is further mobilized off the inferior neck using electrocautery. After the capsule is released, the inferior cobra retractor is replaced, inside the capsule and over the anterior rim of the acetabulum. The superior cobra retractor is removed and replaced by a modified Hohmann retractor on the superior femoral neck. With the hip reduced, the initial femoral neck cut is made using a reciprocating saw in the subcapital femoral neck. This cut is made from inferior to superior, with the surgeon’s hand angled toward the patient’s head to facilitate femoral mobilization (Figure 9). The femur is then mobilized by a combination of extension and external rotation of the hip. An osteotome is placed in the osteotomy site to aid in femoral mobilization. After the femur has been mobilized, the final femoral neck cut is made perpendicular to the axis of the femoral neck, using the saddle and the lesser trochanter as reference points. This cut is also made with
a reciprocating saw from inferior to superior (Figure 10). Next, the acetabulum is exposed. A modified Hohmann retractor is placed over the posterior acetabular wall, between the labrum and the capsule, at the 9-o’clock position for a right hip (3-o’clock for a left hip). The femoral head can then be removed with a corkscrew. The labrum is removed and the pulvinar is débrided from the cotyloid fossa, revealing the true floor of the acetabulum and the tear drop. A Schanz pin can be placed superior to the acetabulum to aid in visualization and to protect the gluteus medius during reaming (Figure 11). Reaming is carried out per surgeon preference. After reaming the final acetabular implant is impacted into place. Attention is then turned back to the femur. The posterior modified Hohmann retractor is removed from its position and placed over the greater trochanter. The capsule over the superior neck is then released from the saddle to the posterior facet of the greater trochanter. During this release the assistant brings the leg into the reverse figure-of-4 position, with the hip extended and externally rotated and the extremity adducted (Figure 12). This capsular release is extended medially to take down the obturator externus, if necessary. The other short external rotators are left in place. A two-pronged femoral retractor is then placed along to inferior neck to facilitate femoral exposure. Any femoral stem design can be used with this approach, and the femoral preparation is carried out according to surgeon preference. After femoral preparation trialing can be performed, the hip is reduced by a combination of in-line traction and internal rotation by the assistant. The surgeon can assist in the reduction by applying traction to the anterior capsule and with the use of a head pusher. Length, alignment, stability, ROM, combined anteversion, and shuck may be tested. To dislocate the hip, the surgeon will place a bone hook along the trial neck. The assistant will then bring the hip to neutral abduction, and a combination of in-line traction and external rotation is used to dislocate the hip. Intraoperative fluoroscopy or flat plate radiographs may be used based on surgeon preference to confirm alignment, as well as length and offset. Closure is performed in a layered fashion per surgeon preference, and perioperative joint injection may be used for additional anesthetic and postoperative pain control. As needed, this approach may be easily carried proximally or distally for an extensile approach, allowing the surgeon to gain access to the entire femur. With internal rotation the intramuscular septum can be identified and vastus lateralis may be exposed and lifted anteriorly as required, for periprosthetic fractures or revision arthroplasty.
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