The hip joint is first accessed via the anterolateral portal located approximately 1–2 cm anterior and 1–2 cm proximal to the anterosuperior aspect of the greater trochanter (Fig. 9.2). This is the viewing portal for the majority of the procedure. An 18-gauge spinal needle is inserted under fluoroscopic guidance to ensure adequate portal placement, taking care to avoid labral penetration or iatrogenic femoral head chondral injury. Once intra-articular position is confirmed, the joint is distended with approximately 30 mL of normal saline. A guidewire is placed through the spinal needle, and a cannula is passed over the guidewire to enter the joint. After the arthroscope has been introduced, the anterior portal can be made using an 18-gauge spinal needle under direct visualization. Traditionally the anterior portal is made at the intersection between a line from the ASIS down the shaft of the femur and a horizontal line at the level of the superior aspect of the greater trochanter. However, we favor a modified anterior portal that is placed more laterally and distally to the standard anterior portal to increase margin of safety from the lateral femoral cutaneous nerve and improve trajectory for instrumentation of the labrum and acetabular rim.

A transverse interportal capsulotomy is made sharply to ensure adequate exposure (Fig. 9.3) [17]. Care is taken to remain between the labrum and femoral head to avoid iatrogenic labral or chondral injury. A blade is used rather than radio-frequency ablation to preserve full-thickness capsular margins for later repair [22]. A radio-frequency ablation wand is used to clear the extracapsular rim and expose the pincer lesion. The labral attachment and transitional zone cartilage are preserved whenever possible, but formal detachment and refixation may be required in certain cases of significant overcoverage (i.e., profunda) in which an extensive resection is required. A beaver blade is placed through the modified anterior portal, and the junction between the labrum and acetabular rim is identified. The labrum is detached from inferior to superior while taking care to avoid damage to the adjacent articular cartilage or labral amputation (Fig. 9.4). A thorough examination of the central compartment and pincer lesion is useful to define the type and extent of the pathology [4, 23]. The indirect head of the rectus femoris originating from the lateral acetabular rim uses a useful landmark for guiding rim resection (Fig. 9.5). Intraoperative findings consistent with pincer-type FAI include labral ecchymosis, ossification, and cystic degeneration; anterosuperior acetabular wave sign; posterior linear acetabular wear; extension of the acetabular rim at least 3–5 mm beyond the labrochondral junction; and anterior or superior acetabular rim fractures or os acetabuli [14]. The interportal capsulotomy can be extended posteriorly to the piriformis tendon or anteromedially to the psoas tendon depending on the extent of the pathology encountered [22]. Delaminated cartilage should be debrided to a stable edge. Microfracture may be selectively employed for focal full-thickness defects with well-shouldered margins. When small os acetabuli or rim fractures are encountered, typically they may be excised to help resolve the pincer-type impingement (Fig. 9.6). However, larger fragments or those involving weight-bearing portions of the acetabulum may be treated with arthroscopic reduction and cannulated screw fixation to avoid iatrogenic dysplasia [24, 25].

A thorough assessment of the labrum is crucial to determine the need for labral preservation, debridement, or excision. Preservation is preferred, but debridement may be necessary in the presence of significant intrasubstance cystic degeneration or ossification. If the labrum appears relatively normal with an intact labrochondral junction, smaller areas of bony prominence of the acetabular rim may be resected via extracapsular exposure without formal detachment of the labrum. When a greater area of pathology is present, labral takedown is recommended prior to rim resection. Rim resection is performed with a burr placed via the modified anterior or lateral portal based on preoperative imaging and arthroscopic findings, with the goal being to contour the rim to correct the focal coverage or extra-articular subspine deformity extending to or caudal to the acetabular margin (Fig. 9.7). Fluoroscopy is used to identify the starting point for resection, which is typically just inferior to the location of the crossover sign. For focal anterior overcoverage, rim resection is performed to correct the area of focal retroversion as templated on preoperative imaging; the width of the burr can help to estimate the magnitude of resection. The amount of the bony resection should be sufficient to eliminate rim extension beyond the labrochondral junction and to eliminate the crossover sign and restore a lateral center-edge angle of 25–40° on fluoroscopic imaging. The deepest area of resection should occur at the midpoint of the pincer lesion with more gradual resection occurring peripherally. Resection of the harder, yellowish, pincer lesion should reveal the underlying softer, pinkish cancellous bone [17]. Some surgeons recommend microfracture of the subchondral bone until punctate bleeding occurs [4]. The amount of rim resection is confirmed and/or adjusted by comparing intraoperative fluoroscopy with preoperative imaging. Intermittent release of traction, fluoroscopic evaluation of acetabular coverage, and intraoperative assessment of range of motion may be useful to assess the extent of the correction.

The presence of subspine impingement should also be recognized and addressed as needed. This is best appreciated on false-profile plain radiographs and three-dimensional CT imaging [11]. Adequate visualization may require reflection of the joint capsule proximally up to the AIIS or creation of a window through the direct head of the rectus tendon. Decompression should be considered when there is AIIS extension to the level of, or caudal to, the anterior acetabular rim (Fig. 9.8). Other intraoperative findings suggestive of AIIS impingement include calcific deposits within the proximal rectus femoris and synovitis or peripheral labral ecchymosis anteriorly at the level of the AIIS [12]. An adequate resection may require making a small longitudinal split in the rectus femoris; however, detachment of the tendon should be avoided to prevent postoperative hip flexion weakness. Studies have shown that the broad footprint of the rectus tendon is protective, and a large series of arthroscopic resections performed for symptomatic deformity with this technique yielded excellent clinical outcomes with no cases of postoperative avulsion [26].

Once labral takedown and adequate rim resection is complete, labral refixation is indicated to reestablish femoral stability and physiologic joint seal (Fig. 9.9) [6, 27]. Preparation of the labrum and acetabulum may be completed with a motorized shaver and burr, respectively, to promote labral healing. Anchors should be placed with a distal-to-proximal trajectory to prevent intra-articular penetration. Fluoroscopy may be used to confirm that the drill is superior to the acetabular sourcil. We frequently utilize an accessory distal anterolateral portal to improve trajectory and safety. To avoid iatrogenic cartilage damage, the anchor should be placed 2 mm off the articular margin on the acetabular rim. During drilling and suture anchor placement, direct visualization of the articular surface is recommended to ensure that the articular surface is not penetrated. Labral base fixation stitches are utilized when possible to minimize eversion and preserve the suction seal, but formal detachment of the labrum or marginal tissue quality may necessitate simple “loop around” stitch configuration [14]. The suture is tied using standard arthroscopic knot-tying technique. The arthroscope is then moved to the anterolateral portal, and an anterior suture anchor is placed using the same technique. In total, at least one and as many as eight anchors may be required depending on the extent of the labral takedown.

To address superior and superoposterior pathology, the arthroscope is placed through the anterior portal. The beaver blade and burr are placed through the anterolateral portal as needed for additional labral takedown and rim resection. Again, fluoroscopy should be used to correlate intraoperative rim resection with preoperative imaging. When pincer-type FAI extends more posteriorly than is accessible through the anterior or anterolateral portals, a posterolateral portal may be established approximately 2 cm proximal to the greater trochanter at its posterosuperior margin. During placement of the posterolateral portal, the leg should be internally rotated to further protect the sciatic nerve.

At this point, thorough fluoroscopic and dynamic evaluation of the hip is crucial to assess for areas of residual impingement (Fig. 9.10). Fluoroscopic evaluation should include AP, cross-table lateral, and 45° and 90° Dunn lateral views to confirm improved acetabular morphology. While the presence or absence of cam-type pathology should be confirmed during preoperative evaluation and imaging, “around the world” fluoroscopic views should confirm normal head-neck junction and femoral head sphericity. Ross et al. [28] described the six critical fluoroscopic images to assess the most common zones of proximal femoral deformity and assure a thorough correction in all of these planes. Dynamic evaluation should assess for residual impingement in extension, abduction, internal rotation, external rotation, FABER (maximum flexion, abduction, external rotation), and FADIR (maximum flexion, adduction, internal rotation). Once it is confirmed that no additional bony work is required, the motorized shaver should be reintroduced into the joint to remove bony debris to decrease the risk of postoperative heterotopic bone formation. Portal incisions are closed using simple interrupted nylon suture, and a soft dressing is applied.

Postoperative management and rehabilitation involve protecting any repaired or reconstructed structures while progressing with range-of-motion and strengthening exercises to minimize joint stiffness and muscle weakness, respectively (see Chap. 16 – Rehabilitation after FAI Surgery). In the early postoperative period, we restrict weight bearing and range of motion, particularly hip flexion and rotation. Passive range of motion begins immediately after surgery, followed by formal physical therapy guided by a therapist familiar with managing patients after hip arthroscopy.

To our knowledge, no studies report exclusively the results of arthroscopic treatment of isolated pincer-type FAI. This is not surprising as most patients presenting with FAI have mixed-type morphology involving both cam and pincer lesions. Level III and IV studies of arthroscopic treatment of FAI report good to excellent results among outcome measures, including modified Harris Hip Score (HHS), Hip Outcome Score (HOS), visual analog pain score, hip morphology, patient satisfaction, quality of life, and return to activity [29–34]. A study by Bedi et al. [20] confirmed that arthroscopic cam and/or rim osteoplasty results in significant improvement in hip kinematics and range of motion in symptomatic patients. Although it has not been shown that arthroscopic treatment of FAI changes natural history or progression to osteoarthritis, elimination of impingement lesions hopefully decreases associated chondral injuries and preserves labral function to improve load transmission and joint-loading mechanics. Studies have also reported good clinical outcomes with labral preservation or repair, as compared with debridement or excision, during arthroscopic treatment of combined- and pincer-type FAI [35–40]. Hetsroni et al. [10] found significantly improved hip flexion and HHS in ten patients with AIIS impingement at an average follow-up of 14.7 months. In nine patients with an ipsilateral anterior cam lesion, a preoperative intra-articular anesthetic injection did not relieve anterior hip pain. The authors interpreted this finding as being indicative of an extra-articular etiology of their symptoms. These studies support our preferred technique of arthroscopic acetabular rim osteoplasty, labral preservation or repair, and AIIS decompression in the setting of focal pincer-type FAI.