Hip Arthroscopic Approach for Femoroacetabular Impingement Treatment

BACKGROUND

Hip arthroscopy is being increasingly utilized to manage femoroacetabular impingement.¹ It provides excellent access to the central compartment as well as the ability to resect bone from the peripheral compartment. As discussed previously, the benefits of hip arthroscopy compared to more traditional open approaches include a more limited surgical dissection with resultant decreased perioperative discomfort and a more rapid recovery. The potential benefits of hip arthroscopy also serve as its limitations. With a more limited approach, obtaining safe, reliable access to the deformities associated with femoroacetabular impingement is dependent on surgical technique and experience.² In this chapter, we will discuss the indications and limitations of the arthroscopic approach, surgical technique, postoperative management, complications, and reported results.

Clinical Scenario

SL is a 22-year-old male with persistent left hip pain for more than 6 months. He did finish a course of physical therapy to alter his posture and body mechanics to relieve his hip pain but without much relief. On physical exam, his left hip flexes from 0° to 90° with flexion/internal rotation (IR) of 15° and flexion/external rotation (ER) of 45° with a positive impingement sign. In full extension, his abduction is 35° and adduction is 15°. His radiographs (Figure 13.1A) show a cam deformity
visible on the anteroposterior (AP) pelvis view with normal acetabular coverage and acetabular version. On the false-profile view (Figure 13.1B), there is normal coverage but a prominent inferior iliac spine, and on the modified Dunn lateral view (Figure 13.1C), the cam deformity is clearly visible. The magnetic resonance imaging (MRI) (not shown) did not show significant chondral damage and femoral anteversion of 19°, and the patient underwent an arthroscopic cam decompression (Figure 13.2) with excellent pain relief and returned to all activities in 4 months.

FIGURE 13.1. 22-year-old male with symptomatic left hip impingement. The anteroposterior pelvic radiograph (A) shows normal acetabular coverage and normal acetabular version. The decreased head-neck offset is visible. The false-profile view (B) shows normal anterior coverage but a prominent anterior inferior iliac spine, which may cause subspine impingement. The modified Dunn lateral view (C) is the best view to show the cam deformity.

FIGURE 13.2. Intraoperative Dunn lateral view of the proximal head-neck junction before (A) and after (B) after arthroscopic cam decompression in a 22-year-old male.

This case represents a good candidate for arthroscopic cam decompression that has normal acetabulum, minimal joint damage, no proximal femoral retroversion, and limited motion and pain likely on account of the cam deformity.

INDICATIONS

What deformity does well with arthroscopic approach?
- Anterior-superior cam deformity with normal acetabular coverage
- Peripheral rim osteophytes limiting hip flexion/IR and flexion/ER
How much deformity is too much?
- Hip flexion/IR <0°³
- Acetabular dysplasia (LCE <15°)⁴
- Excessive femoral retroversion⁵
- Circumferential femoral osteophytes³

TECHNIQUE

Patient Positioning and Prep (Figure 13.3; Table 13.1)

Traction

Limiting the duration of operative traction is important and can be influenced by numerous factors prior to starting the surgical procedure. The following is a list of steps recommended prior to applying traction (Table 13.2).

Traction Process

Gentle traction is placed on the contralateral hip as a means of stabilizing the pelvis.

Operative hip is moved to a position of flexion (20°), abduction (20°), and maximal internal rotation. (The greater trochanter should be maximally prominent.) This position serves to relax the iliofemoral ligament and facilitates traction application.⁶ Approximately 30 to 50 lbs of gross traction is applied in this position and held in place. The leg is then brought to a position of neutral flexion/extension and abduction/adduction. Fluoroscopy can confirm the degree of distraction (Figure 13.4).

Draping

Drapes

Sticky towels × 4 in a block-drape configuration (Figure 13.5). Hip arthroscopy drape placed such as to ensure adequate access to all relevant portal sites. A sterile mayo stand should be placed cranial to hold commonly used instruments (Table 13.3).

Hip Access

Skin Marking

Prior to starting the procedure, the anterior-superior iliac spine (ASIS) and greater trochanter should be marked to assist portal placement. In our technique, we prefer to use the anterolateral (AL) and midanterior (MA) portals
as our working portals. The posterolateral (PL) and distal anterolateral accessory (DALA) portals are used on a much less frequent basis (Figure 13.6).

FIGURE 13.3. Traction table set up for right hip arthroscopy (A). The right arm is folded over the chest over gel rolls (B). The left arm is positioned on arm holders (C).

TABLE 13.1 Equipment Needed for Patient Positioning

Site	Needs
FEET	ABD × 4 (2 per side) Webril × 2 (1 per side)
HIP	POST and PAD Plastic U-Drape × 1 Plastic Strips × 2
ARMS	Contralateral—Armboard @ 90° Ipsilateral—Foam/Gel Pad × 2 Belt/Tape

TABLE 13.2 Surgical Checklist Prior to Traction

• Anesthesia team completed with airway management/sedation

• Patient translated onto hip post and plastic drapes applied

• Arms secured onto arm-board/across chest

• Feet well padded and secured within traction apparatus

• C-Arm is in the room and turned on (ready for imaging)

• Fine traction mechanism is set at zero (ie fully shortened)

• Skin is ready for prep application

AL Portal Access

Steps for AL access to hip joint:

Switching stick at proposed AL portal site is used to identify the ideal starting point. (Figure 13.7) The following should be considered:
- Cranial/caudal location should start at the level of or just proximal to the greater trochanter on fluoroscopic imaging.
- Antero/posterior location depends on the femoral version. A normal version femoral starting point should be midway between the tip and the anterior border by skin marking/palpation. In anteverted femurs, this position will move further anterior, whereas in retroverted femurs this will move posterior.
18 gauge needle is inserted to the level of the capsule under fluoroscopy. Typically, the trajectory is 10° to 15° cranial and posterior from the starting point in order to pierce the capsule at the 12 o’ clock position. The targeted space lies between the femoral head and the acetabular labrum. The needle tip should face away from the labrum during capsular penetration, then reversed (away from the femoral head) if inserted further (Figure 13.8A, B).
Needle trochar is removed, and air (˜15 cc) is injected into the joint. The air arthrogram will break the fluid seal of the hip and permit fine-tuned traction if needed at this stage. Fluoroscopic imaging of this air arthrogram should show the inferior border of the labrum “float” away from the needle. In cases where this is not observed, repositioning the needle should be considered. Figure 13.8C shows the labrum and femoral head moving out of the way after injection of air into the joint.
Nitinol wire is inserted. When judging portal placement, the nitinol wire should cross the entire sourcil to the cotyloid fossa. If the wire stops short of the fossa, the portal is likely malpositioned in the anteroposterior plane (typically aimed too posterior). The needle should be repositioned. Figure 13.8D shows correctly placed nitinol wire.
Once the nitinol is well positioned, the needle is removed and a skin incision is made. The 4.5-mm cannula with blunt entry trochar is then inserted to the level of the capsule. Entry through the capsule is made with a twisting motion of the trochar/cannula along the axis of the nitinol wire until a “give” is felt. The cannula’s position within the joint can be confirmed by imaging (Figure 13.8E).
The trochar can be disengaged and replaced with the arthroscope at this point. Water should not be started until the second portal has been established. The camera’s lens should be directed anteriorly to bring the anterior capsular window between the acetabular labrum and femoral head into view. This provides the intra-articular view needed to safely place the MA portal cannula (Figure 13.9A).

FIGURE 13.4. The leg is initially placed into some abduction and neutral rotation (A) to place the plastic drapes. For traction, the leg is maximally internally rotated (B) to place the femoral head deep in the acetabulum and to place the trochanter laterally.

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