Hip Arthroscopy for Femoroacetabular Impingement

Abstract

Background:

Femoroacetabular impingement (FAI) is pain due to shape mismatch at the hip joint commonly affecting young athletes, and there are 2 main types depending on which bone has the underlying deformity: cam (femoral) and pincer (acetabular). Hip arthroscopy is an invaluable technique in the sports surgeon repertoire, and there is a need for a comprehensive tutorial that elucidates the best practices and nuances.

Indications:

Pain with evidence of FAI and labral tear on imaging, and failing conservative treatment, warrants arthroscopy.

Technique Description:

FAI surgery requires anatomical labral repair, thorough osteoplasty to correct the underlying deformity and prevent labral retearing, and careful treatment of soft tissues and capsular closure.

Results:

Reduced pain and improved hip function are the goals of treatment, with approximately 90% of patients returning to sport at 6 to 8 months postoperatively.

Discussion/Conclusion:

Hip arthroscopy is a safe and effective treatment for patients with FAI who failed conservative therapy.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

Hip arthroscopy has been one of the upcoming modalities for treating femoroacetabular impingement (FAI) in the last 20 years. In this tutorial, we show the basics of FAI diagnosis and arthroscopic treatment.

Here are our disclosures.

This is an overview of the topics that we will discuss in this tutorial.

Femoroacetabular impingement is pain from shape mismatch between the femoral head and the acetabulum. There are 2 main types of impingement: cam and pincer.

Pain in FAI usually arises after bony contact eventually shears the labrum. Many people have asymptomatic FAI morphology or labral tear, so pain is essential for indicating surgery.^1,2

Our patient is a 15-year-old high school kicker who presented before his sophomore season and endorsed pain after an extended practice. He initially failed conservative treatment, and his pain progressed over the course of the season.

His physical examination showed anterior groin pain and a positive impingement test. The hallmarks of FAI on imaging are listed here.^5,8

Here is the imaging for our patient.

The alpha angle was >55° bilaterally, a sign of cam impingement. Although pain on the right side predominated, we had the intention to follow-up on the left side at a later date if it became symptomatic. Magnetic resonance imaging showed a tear of the right anterosuperior labrum.

Management options for FAI are listed here, and our patient failed 5 months of conservative therapy, indicating a right arthroscopic labral repair with femoroplasty.

A postless table is used with a friction pad with the patient placed in slight Trendelenburg position. Postless tables have been shown to reduce the incidence of perineal soft tissue trauma and pudendal neurapraxia.

Four preoperative x-rays are taken at varying degrees of flexion. Gentle preoperative gross traction is applied.

Draw a vertical line from the anterior superior iliac spine to the patella. Draw a “C” around the greater trochanter. Connect the vertical line to the tip of the “C” with another line. All possible portal placements are shown. We prefer to use the 3 portals in red with the distal anterolateral accessory (DALA) portal for anchors and accessing the peripheral compartment for femoroplasty. The outlined portals form the arthroscopic safe zone, bounded by the femoral neurovasculature and lateral femoral cutaneous nerve anteriorly and the sciatic nerve and gluteal neurovasculature posteriorly. Due to its central position in the safe zone, we will access the anterolateral portal first using a spinal needle.

After placing traction on the hip, aim the needle parallel to the floor and slightly cephalad while keeping the needle at the inferior margin of the fluoroscopic clear space as shown here. Trajectory through the upper portion of the clear space may perforate the labrum, which will have increased resistance compared to the capsule. The bevel should be facing down toward the femoral head. As soon as you feel puncture through the joint capsule, stop advancing the needle to avoid scuffing the femoral head. Remove the stylus, relieving the vacuum seal of the hip joint and forming an air arthrogram. This may outline the lateral edge of the labrum helping you further adjust your trajectory if needed. Normal saline may also be injected within the joint to help further distend the labrum away.

Once satisfied with the final position, insert a guidewire and withdraw the needle. Use a “nick and spread” technique to open any skin bridges. Advance the cannula over the guidewire and remove the obturator. Insert the arthroscope through the portal. For the majority of the operation, the arthroscope will remain in the anterolateral portal. We will now establish the other portals using the same method. Direct arthroscopic visualization will help us avoid the labrum and femoral head.

Repeat the process to create the anterior portal. This time, insert the capsulotomy knife instead of the cannula alone. Withdraw the sheath to maneuver the knife freely in the capsule for an interportal capsulotomy and greater freedom within the joint capsule. Interportal capsulotomy begins at the midanterior portal and connects to the anterolateral portal. This is preferred over longer incisions starting from the direct anterior portal. Interportal capsulotomy also requires capsular closure and a protected postoperative range of motion to facilitate healing. Other techniques such as puncture capsulotomy may be used instead; however, these offer less mobility.

Here we see some inflammation along with a Seldes type I labral tear and a chondral wave sign showing labral instability. The Seldes classification system describes the location of labral tears with Type I at the chondrolabral junction, Type II in the labral substance, and Type III a combination of both. To affix the labrum back to anatomical position or perform acetabuloplasty for pincer lesions, we must first access the acetabular rim. However, the labral blood supply located at the capsulolabral junction is at risk of injury. Nwachukwu et al. (2013) describes using a knife rasp to elevate the labrum and staying 3 to 5 mm proximal to the capsulolabral junction to preserve this blood supply. ⁶ Then, acetabuloplasty may be performed through this window. In our case, there is no pincer lesion requiring resection; therefore, you see preparation of the acetabular rim for anchor placement. Avoid excessive acetabuloplasty which can decrease the lunate surface area and increase joint stress and risk of arthritis.

Next, the DALA portal is established for anchor placement. We use a cannulated drill guide to place pilot holes in the acetabular rim. Each pilot hole should be placed about 1 cm apart with the number of anchors based on the size of the labral tear. We use a curved suture passer to pass through the chondrolabral junction first and then back through the labral substance in vertical mattress fashion. Excess suture is pulled through so that it does not slip back through the first bite. We then use a mallet to hammer the anchors into the acetabular rim, securing the suture. A knotless anchor is used so that the labrum can be restored back to anatomical position by pulling on the 2 limbs of suture to the desired level of tension. We prefer knotless anchors due to their ease of insertion and avoiding abrasive knots in the joint space. The tails of the excess suture are cut. We mostly use the arthroscope in the anterolateral portal and place the anchors with the distal anterolateral portal; however, you can move the arthroscope to the midanterior portal to visualize more lateral aspects of the labrum. Here we see the labrum restored back to anatomic position and assess its stability.

We can then release traction and flex the hip to 30° to prepare to access the peripheral compartment. Relaxing traction before tying down the knot or pulling tension on knotless anchors can help maintain the labral seal and prevent an out-of-round labral repair. ¹⁰ After lowering traction, inspect to ensure the labral seal is restored.

We now access the peripheral compartment and view a cam lesion both grossly and under fluoro, using your instruments to mark out the start and end of the lesion. For femoroplasty, the arthroscope is again in the anterolateral portal, while the midanterior will be our main working portal. However, both the scope and the burr may be moved to fully take down the cam lesion. Starting at the equator of the femoral head, we then use our radio frequency device to expose the underlying bony surface and begin our takedown of the cam deformity using a high-speed burr working proximally to distally. Careful debridement of excess debris helps prevent heterotopic ossification. We use a gentle rocking motion for osteoplasty. Avoid over-resection of the femoral head due to disruption of the labral seal and predisposition to femoral neck fracture and arthritis. Using the burr on reverse spin may assist with this. Conversely, under-resection is the main cause of labral retearing and revision arthroscopy. To avoid under-resection, the following hip and C-arm positions from Lall and colleagues provide a systematic framework for working across the peripheral compartment. ³ Keep femoroplasty in the vascular safe zone bounded by the medial and lateral synovial folds which carry the retinacular vessels. Following femoroplasty, lift the capsule to inspect these to prevent avascular necrosis of the femoral head.

Capsular retention stitches can be used to better visualize the peripheral compartment for femoroplasty. We place these through the midanterior portal and hold tension on them with a hemostat against the skin. Take special care in smoothing out the junction between the cartilage and the bone so as to prevent a harsh step-off that would disrupt the sphericity of the femoral head. We can now confirm sphericity of the femoral head and ensure that the labral seal is intact. Here are the final x-rays to confirm perfect head sphericity. Again, we use 4 views in varying degrees of flexion. A good rule-of-thumb is to ensure that both sides of the femoral neck have the same curvature.

Two to 5 sutures are used proximally to distally and tied down with an arthroscopic locking knot to ensure water-tight closure. Taking small capsular bites ensures that the capsule is not over-constrained. Here is the final closure.

Here are the postoperative instructions as developed by the senior author.

Here we list the complications that we previously discussed and the strategies we used to mitigate them.

The outcomes for hip arthroscopy are excellent, with 9 in 10 patients returning to sport.^4,7 Patient-reported outcomes are better than conservative treatment alone in indicated patients on a variety of hip function metrics.^4,7,9

These are our references.

Thank you for taking the time to learn about hip arthroscopy.