Arthroscopic Treatment of Femoroacetabular Impingement

J. W. Thomas Byrd

Understanding and Planning for Treatment of Femoroacetabular Impingement (FAI)

• Distinguishing FAI morphology from FAI pathology

• FAI may be present as an asymptomatic, incidental finding.¹,²

• The etiology of pathologic FAI often is multifactorial (“perfect storm”).

• FAI may explain why damage occurs, but how are some individuals lifelong compensators?

• Numerous factors coming together just wrong lead to joint damage.

• All factors may never be identified, but enough factors should be treated with both surgical and nonsurgical means to achieve symptomatic improvement.

• Pelvic orientation influences over- or undercoverage from the anterior acetabulum.³

▪ This can be significantly influenced by lumbar kyphosis or lordosis.

▪ Coverage can be partly altered with a pelvic stabilization program.

• It is essential to know femoral version.⁴

▪ This can be calculated with the addition of images through the femoral condyles with either MRI or CT (Fig. 32-1).

Figure 32-1 | Superimposed CT images illustrate determination of the femoral version as the angle formed from a line approximating the axis of the femoral neck and a line across the posterior femoral condyles.

▪ Increased femoral version may make modest cam lesions tolerable but may also increase concerns of instability.

▪ Reduced femoral version can make small cam lesions clinically relevant or result in pincertype labral failure, even in the presence of normal acetabular morphology.

• Radiographs are two-dimensional images attempting to interpret complex three-dimensional anatomy.⁵,⁶,⁷

• 3-D CT scans are helpful at precisely discerning bony architecture (Fig. 32-2A-C).

▪ Lower radiation dose protocols are now equivalent to a five-radiograph hip series.

• Software systems are available for dynamic analysis discerning areas of bony collision between the acetabulum and proximal femur.⁸

Figure 32-2 | AP (A) and lateral (B) radiographs illustrate the presence of FAI, especially cam type. 3-D CT scan (C) more clearly delineates the presence of a pincer lesion with accompanying os acetabulum.

Portal Positions (Fig. 32-3A and B)⁹

• The anterolateral portal is the most consistent workhorse portal for viewing.

• This portal is used by most surgeons with just slight variations.

Figure 32-3 | A. The anterior portal roughly coincides with the intersection of a sagittal line drawn distally from the anterosuperior iliac spine and a transverse line across the superior margin of the greater trochanter. Generally, it is directed ˜45 degrees cephalad and 30 degrees toward the mid-line. Depending on the patient’s anatomy, this may be placed slightly more lateral and distal to properly intersect the joint. The anterolateral and posterolateral portals are positioned at the anterior and posterior borders of the trochanteric tip, converging slightly as they enter the joint. B. The relationship of the major neurovascular structures to the three standard portals is demonstrated. The femoral artery and nerve lie well medial to the anterior portal. The sciatic nerve lies posterior to the posterolateral portal. Small branches of the lateral femoral cutaneous nerve lie close to the anterior portal. Injury to these is avoided by using proper technique in portal placement. The anterolateral portal is established first because it lies most centrally in the safe zone for arthroscopy.

• The anterior working portal is the most often modified.

• It often is modified laterally and distally to optimize triangulation within joint.

• Modifications for anchor placement are not necessary because anchors can be placed percutaneously.

• An anterior portal often is useful for placement of far-medial anchors, avoiding perforation of the medial pelvic cortex because of a more anterior-to-posterior direction of placement (Fig. 32-4).

▪ Avoiding perforation of the acetabulum is of paramount importance.

Figure 32-4 | 3-D CT image illustrates an anchor perforating the medial cortex at the psoas groove (arrow).

• A percutaneous distal site equidistant between the anterior and anterolateral portals allows more divergence of anchors from the acetabular surface, providing a broader safe zone for placing anchors close to the acetabular rim (Fig. 32-5).¹⁰

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