Hip Preservation: Surgical Techniques via the Hueter Anterior Approach

Kenneth Milligan

Paul Beaule

Frederick Laude

Introduction

In the field of hip preservation, anterior-based approaches have become a very valuable tool. This is due to the strength of the HAA for providing minimally invasive and muscle-sparing access to the hip joint. Most notably, the HAA has become popular when performing a periacetabular osteotomy (PAO). The PAO is increasingly being used for treating developmental dysplasia in the skeletally mature patient.¹ The typical dysplastic patient presents with a shallow acetabular socket, acetabular or femoral head anteversion, and a lateralized acetabular socket resulting in deficient anterolateral femoral head coverage.²^,³ This leads to abnormal femoral acetabular loading mechanics, causing pain, gait abnormalities, and premature osteoarthritis.²^,⁴^,⁵ Surgical reorientation of the acetabular socket can improve these loading mechanics and has proven to have good patient-reported outcomes and survivorship.⁶^,⁷^,⁸

The ideal candidate for PAO is a relatively young patient with minimal arthritis and a congruent femoral head who has symptomatic acetabular dysplasia.¹^,⁹^,¹⁰ This procedure also can be used to address patients presenting with femoral acetabular impingement as a result of acetabular retroversion.¹¹ The recent literature suggests that treating the retroverted acetabulum with an anteverting PAO may offer improved outcomes compared with arthroscopic rim trimming.¹² One particularly strong feature of performing a PAO through the HAA is that it allows additional hip preservation procedures to be performed concurrently. This includes proximal femoral osteotomies, labral repair or debridement, and femoral head chondroplasty or “mosaicplasty,” which can all be performed through the same incision (Figure 37.1).

FIGURE 37.1 A, A patient who underwent right periacetabular osteotomy and proximal femoral osteotomy through the same anterior-based incision. B, The healed incision from the procedure performed.

Surgical Technique

Patients can be placed in a supine position on a radiolucent flat-top table. A small or medium-sized triangle can be used to hold the leg flexed when needed. The fluoroscopic imager should be positioned to come in from the contralateral side. Obtaining 50° false profile, posteroanterior pelvis, and posteroanterior outlet views with the fluoroscopy machine before prepping and draping is recommended.¹³ Neuromonitoring can also be considered when performing PAO to monitor for sciatic nerve injuries. The operative extremity should be draped free to allow the leg to be manipulated in various positions throughout the case.

The anterior superior iliac spine (ASIS) and iliac crest are important landmarks. A curvilinear incision is made starting 2 cm lateral and 1 cm distal to the ASIS and extends distally parallel to a line connecting the ASIS and the ipsilateral fibular head; proximally, the incision follows along the iliac crest. Alternatively, one can use a bikini incision, which is centered over the inguinal crease.¹⁴ The bikini incision possibly provides an improved cosmetic appearance, but additional care has to be taken to prevent lateral femoral cutaneous nerve injury, and exposure can be difficult in heavier patients.

After skin incision, the interval between the tensor fascia lata (TFL) and sartorius is developed by first incising the fascia over the TFL muscle belly and bluntly dissecting between the TFL and sartorius to protect the lateral femoral cutaneous nerve.¹⁵ After the interval is developed, the sartorius and inguinal ligament are sharply dissected off of their attachment on the ASIS. Alternatively, an osteotomy of the ASIS can be performed depending on the surgeon’s preference. Next, the anterior portion of the external obliques is dissected off the iliac crest. The dissection is then carried down the inner table of the pelvis, releasing the iliacus subperiosteally to limit bleeding. Bone wax can be used to achieve hemostasis if bleeding is encountered from the nutrient vessel of the ilium.

The superior pubic ramus is then exposed from lateral to medial. The direct head of the rectus is identified at its origin attachment to the anterior inferior iliac spine. It is possible to perform a “rectus-sparing” PAO by not releasing the rectus during the PAO, which allows for easier recovery. Just medial to the rectus is where the iliopsoas muscle exits the pelvis. The fascial overlying the iliopsoas is incised to expose the interval between the psoas and rectus. Further subperiosteal dissection is performed using a Cobb elevator toward the pubic eminence. A sharp Hohmann retractor can be used to retract the psoas tendon medially to allow for proper exposure of the pubis.

Next, the hip is flexed and adducted, allowing for the psoas to be mobilized medially. The rectus is then retracted laterally to expose the iliocapsularis fibers. The iliocapsularis fibers can be identified because these fibers run from the anterior inferior iliac spine along with the rectus fibers but they attach on the hip capsule. These fibers are released off of the capsule. A set of large, curved Mayo scissors can then be introduced between the capsule and psoas medially to identify the infracotyloid groove of the ischium. Care should be taken to make sure your dissection remains proximal to the transversely oriented fibers of the obturator externus. The medial circumflex vessels run along the inferior border of the obturator externus. At this step, the first osteotomy can be performed.

Ischial Osteotomy

The ischial cut begins at the infracotyloid groove and is directed posteriorly for 15 to 20 mm, ending approximately midway in the posterior column. The goal is to completely cut the medial cortex while notching the lateral cortex. Initially, the curved Mayo scissors can be used to palpate the medial lateral borders of the ischium. A Ganz osteotome can then be inserted using the curved Mayo scissors as a guide to the ischium. Fluoroscopic posteroanterior or outlet imaging of the pelvis can be used to confirm the starting placement of the osteotome. As the osteotome is advanced, a 55° to 60° false profile image can be used to judge the depth of the cut. It typically takes two to three passes with the osteotome to complete the cut. The medial cortex is first cut with the osteotome directed at the contralateral shoulder. The last pass should only notch the lateral cortex to protect the sciatic nerve. Additionally, the leg should be extended and abducted before performing the osteotomy to protect the nerve.

Pubic Osteotomy

The superior pubic ramus is cut under direct visualization. This cut is made just medial to the pubic eminence and directed at a 45° angle away from the acetabulum to ensure the joint is not violated. The overlying fascia should initially be elevated using a Cobb elevator to ensure the pubic bone can be mobilized once the cut is made. Next, a sharp Hohmann retractor can be used to retract the psoas medially, exposing the surface of the superior ramus and protecting the femoral neurovascular bundle. Creager or curved Hohmann retractors should be placed around the pubic rami to protect the neurovascular structures exiting the obturator foramen. The cut is made with a straight osteotome in a single pass. Gentle levering of the osteotome should gap the osteotomy site to verify the cut is complete.

Iliac Osteotomy

The iliac cut is made in three segments. The first segment is supracetabular and begins at the distal portion of the ASIS directed transversely and stopping 15 mm before the pelvic brim. A blunt Hohmann retractor can be placed along the outer pelvis to protect the abductors. A pencil-tip burr can be used to create a target hole before cutting with an oscillating saw.

The second segment is through the posterior column and is directed at the iliac spine inferiorly along the posterior column and forms a 110° to 115° angle with the prior cut. It is typically made using a straight osteotome. A 50° false profile view on fluoroscopic imaging can be used to guide this cut. Care should be taken to maintain
a distance of 15 mm from the posterior margin of the posterior column and not violate the hip joint. After the segment is made, the first and second segments are connected using a pencil-tip burr for the medial cortex and a straight osteotome for the lateral cortex. This sequence is done to protect against possible fracture propagation into the sciatic notch due to dense sclerotic bone at the pelvic brim.

The third segment connects the posterior column cut with the initial ischial cut. It is typically made with an angled osteotome scoring the medial cortex. To help complete the osteotomy, a Schanz pin can be placed into the acetabular fragment along with a large lamina spreader to hinge open the prior iliac wing cuts to improve the exposure of the quadrilateral plate.

The final step is to complete the osteotomy by controlled fracture through the remaining lateral cortex of the ischial cut. This can be done by rotating the Schanz pin medially while the lamina spreader is used to hinge open the posterior column cut. A lion jaw clamp can be used for additional control of the acetabular fragment. This step sometimes requires additional passes of osteotomes for the fragment to be mobilized. The hip should be extended to prevent neurologic injury when making these additional passes (Figure 37.2).

FIGURE 37.2 Dash line 1 represents the path of the ischial cut, which is typically performed first. Dash 2 represents the pubic symphysis cut, which should be medial to the pubic eminence. Dash 3a-b is the iliac wing and posterior column cuts. The circle denotes the area that a burr can be used to aid in cutting the dense bone of the pelvic brim. The star denotes the starting point for the Schanz pin used for manipulating the acetabular fragment. The arrows denote the starting point and trajectory of the 3.5-mm or 4.5-mm cortical screws used for final fixation.

Deformity Correction

After completion of these individual osteotomies, the Schanz screw should be rotated to verify the acetabular is completely free. The correction can be made in a stepwise fashion and should be assessed using fluoroscopic imaging. An initial fluoroscopic posteroanterior shot of the pelvis should be taken in the uncorrected position to use as a comparison. In typical acetabular cases, the patient will lack anterolateral coverage. This can be corrected by first adducting the hip to address lateral coverage and then adding a small amount of forward tilt to improve anterior coverage. The next step is to address the medialization of the fragment, which will sometimes automatically become corrected when performing the first two steps. The final step is to make minor adjustments to the acetabular version to avoid impingement.

Assessment of the correction is first made by evaluating the Tonnis angle, which should not be less than zero. Second, the medial femoral head should be less than 1 cm from the ilioischial line to ensure sufficient medialization. Third, the acetabular wall index is used to confirm appropriate acetabular version.¹⁶ Once the acetabular fragment orientation is acceptable, it can be secured in place with 2.5-mm Kirschner wires.

Additionally, during PAO surgery, the hip range of motion should be clinically assessed with a dynamic range of motion examination.¹ A goal of 30° of both internal and external rotation should easily be achieved, and femoroacetabular impingement should be assessed. If needed, an anterior capsulotomy can be performed at this point to address cam lesions causing impingement, as discussed in a prior chapter in this section.

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