Labral tears are one of the most frequent indications for performing hip arthroscopy, with most tears occurring in the anterosuperior location [4]. In 1998, Konrath reported that the labrum had little significance in load transmission of the hip [5], and three years later, McCarthy reported on the role of labral lesions in the development of early degenerative hip disease [6].

In contradistinction, more recent studies on hip labrum morphology and function have emphasized the importance of the labrum in maintaining joint stability [7, 8]. The sealing effect of the labrum on the hip not only enhances joint stability, but is also thought to more uniformly distribute compressive loads, thereby reducing peak cartilage stresses during weight-bearing [8]. In the normal hip joint, there is a seamless transition of articular cartilage to the labrum through a transitional zone at the periphery of the joint (Fig. 1).

Fig. (1) Anatomic drawing of hip depicting seamless transition of articular cartilage to the labrum through a transitional zone at the periphery of the joint.

Seldes has described two main types of tears in the adult acetabular labrum: Type I tears involve detachment of the fibrocartilaginous labrum from the articular hyaline cartilage at the transitional zone (Fig. 2a), while Type II tears consist of cleavage tears through the substance of the labrum (Fig. 2b) [9]. Both types of tears have been noted to be associated with an increased vascular response within the area of the tear, indicating a potential for healing (Fig. 3). The results from these studies and the promising early published results of arthroscopic labral repair in properly selected patients suggest that labral repair should be considered for patients who meet specific criteria, to be discussed below [10].

Fig. (2) a. Type I labral tear: Detachment of the fibrocartilaginous labrum from the articular hyaline cartilage at the transitional zone. The tear is indicated with an arrow. b. Type II labral tear: Cleavage plane is through the substance of the labrum. The tear is indicated with an arrow.

Fig. (3) Increased vascular response within the area of labral tears indicates a potential for healing.

FAI is caused by an impingement of the femoral head-neck junction against the acetabular rim. In 2003, Ganz et al., described FAI as a possible cause of early osteoarthritis [11], and several subsequent studies have supported this causal link [12-17]. These studies suggest that subtle and often unrecognized developmental abnormalities of the hip with alteration and malrotation of the femur and/or acetabulum may be responsible for secondary osteoarthritis of the hip [17]. There are two mechanisms of FAI: Cam impingement, which is caused by a non-spherical head, and Pincer impingement, which is the result of excessive acetabular coverage (Fig. 4) [18-22].

Fig. (4) There are two types of femoroacetabular impingement. Cam impingement is caused by a non-spherical head, while Pincer impingement is caused by excessive acetabular coverage. It is possible to have both types of impingement on a single joint.

Cam impingement most commonly occurs in young athletic men. The impingement of the Cam lesion occurs with flexion and internal rotation of the hip: the nonspherical deformity of the femoral head lifts up the labrum upon entering the joint, which can shear the articular cartilage from the subchondral bone and labrum (Fig. 5). The acetabular labrum undergoes partial undersurface tearing with fraying as it is pushed superiorly by the impingement lesion. An acetabular cartilage “wave sign” is often noted, demarcating delamination and shearing of the anterosuperior articular cartilage from the subchondral plate as the articular cartilage is compressed and pushed centrally (Fig. 6) [11, 17].

Fig. (5) In Cam impingement, the nonspherical deformity of the femoral head lifts up and tears the labrum upon entering the joint and shears the articular cartilage from the subchondral bone and labrum.

Fig. (6) Arthroscopic view of right hip of impinged hip. The articular cartilage is compressed and pushed inward. Delamination and shearing of the anterosuperior articular cartilage from the underlying bone can result in an acetabular cartilage “wave sign.”

In Cam impingement, the femoral head is considered aspherical if, on the cross table lateral, it protrudes outside of a best-fit circle and extends anteriorly in a convex shape onto the base of the femur [13, 18, 19]. If the alpha angle as described here is greater than 55 degrees it is considered abnormal and a possible source of FAI (Fig. 7). Cam lesions cause a decrease in the femoral head-neck offset resulting in a decreased clearance between the labrum and the femoral head neck junction. Over time, reduced clearance leads to tearing and pushing of the labrum away from the joint with delamination and separation of the articular cartilage at the chondrolabral junction.

Fig. (7) If the alpha angle of the femoral head is greater than 55 degrees, it is considered abnormal and a possible source of Cam-type femoroacetabular impingement. Any bone outside of a best fit circle can lead to femoroacetabular impingement.

Possible causes of the Cam lesion include slipped capital femoral epiphysis, previous trauma of the head-neck region of the hip, and epiphyseal overgrowth [20-23]. The Cam lesion is thought to be the cause of impingement rather than the result of repetitive trauma to the head-neck region. In younger patients without established osteoarthritis, FAI including Cam and Pincer lesions are not considered a disease entity in and of themselves but are part of a pathomechanical process that may lead to osteoarthritis. In the older patient with established osteoarthritis with little or no joint space remaining, Cam lesions along the femoral head-neck junction are considered osteophytes.

Pincer lesions result from an overcoverage of the acetabulum on the femoral head, resulting in “pinching” of the anterior superior labrum with resultant tear. Pincer leasions result from either global retroversion of the acetabulum or, more commonly, cranial retroversion of the acetabulum. This results in impingment of the femoral neck against the labrum and acetabular rim with resultant tearing of the labrum but little damage to the articular cartilage.

More commonly, patients with FAI have a combination of Cam and Pincer lesions which must both be addressed at surgery for labral repair to be successful.

Proper radiographic FAI evaluation is done with an AP radiograph x-ray beam centered on the pubis symphysis with the coccyx within two centimeters of the symphysis. A cross table lateral is performed to adequately evaluate for a Cam and/or Pincer impingement lesion, both of which produce an abnormal linear contact between the normal femoral neck and the overhanging acetabular rim with the mechanism described as Pincer impingement, as the labrum becomes trapped or pinched in between (Fig. 8).

Fig. (8) In Pincer impingement, excessive acetabular coverage can trap or pinch the labrum, resulting in a labral tear.

Radiographically the Cam lesion is visible as a bump at the superior lateral portion of the femoral head-neck junction on the AP radiograph and on the anterior head-neck junction on the lateral radiograph. Pincer lesion will appear as a cross-over sign on the AP radiograph.

In the radiographic evaluation of Pincer impingement, a crossover sign may be noted on AP radiographs noting cranial retroversion of the acetabulum caused by an anterolateral overhang of the rim [1]. In cases of global retroversion the acetabulum, the posterior wall will be noted to be medial to the center of the femoral head and is referred to as the “posterior wall sign”. Pincer impingement may also be caused by global retroversion of the acetabulum or by coxa profunda, where there is increased depth of the acetabulum (Fig. 9) [23].

Fig. (9) Pincer impingement may also be caused by retroversion of the acetabulum or by coxa profunda, where there is increased depth of the acetabulum.

In most cases of symptomatic FAI with possible concomitant labral tear, an MRI arthrogram is obtained to verify the labral tear and to evaluate any chondral damage. In cases of hip dysplasia or cases of global retroversion of the acetabulum, CT arthrograms with 3-d reconstruction can be extremely helpful in surgical planning.

Before we discuss specific aspects of the arthroscopic management of particular hip disorders, we will first provide a more general description of the technical aspects of hip arthroscopy. The structure of the hip joint presents salient differences from other joints approached arthroscopically, such as the knee and shoulder [10]. Notably, the deep confines of the joint itself necessitate the use of traction for gaining access to the central compartment. In addition, the joint is surrounded by a thick layer of soft tissue and muscle, which greatly increases the working distance from the surface of the skin to the tip of instruments, making triangulation more difficult (Fig. 10). The capsule of the hip joint is also thicker and less resilient than that of other joints, which reduces instrument maneuverability. Often, a capsulotomy is necessary to allow increased freedom of movement and to avoid damage to instruments. Because of these anatomic confines and the concomitant restriction of using rigid straight cameras, most viewing is accomplished with a 70-degree arthroscope with a short focal length, which can make orientation difficult.

Fig. (10) Hip arthroscopy is challenging because the hip joint is surrounded by a thick layer of soft tissue and muscle. This increases the working distance from the surface of the skin to the tip of the instrument, making triangulation more difficult.

The most common surgical positioning for hip arthroscopy is supine, however the procedure can also be performed in the lateral position and is contingent upon surgeon preference. Patients are positioned on a hip distraction table that allows variable amounts of traction to be applied to the operative leg to distract the hip an average of one centimeter. A slight amount of counter-traction is also applied to the contralateral leg to anchor the pelvis level and keep it from moving during hip distraction. The patient is placed against a well-padded perineal post that is lateralized to the surgical side. The resultant vector is in line with the femoral neck and facilitates distraction of the hip (Fig. 11). Traction times are kept below two hours to prevent nerve injury, the most common of which is pudendal neuropraxia, which can cause numbness to the scrotum or labia (Fig. 12) [2].

Fig. (11) In hip arthroscopy, the patient is placed against a wellpadded perineal post that is lateralized to the surgical side. The resultant vector is in line with the femoral neck and facilitates distraction of the hip.

Fig. (12) Traction times for arthroscopic surgery are kept below two hours to prevent nerve injury, the most common of which is pudendal neuropraxia, which can cause numbness to the scrotum or labia.

The contralateral leg is abducted to allow for passage of the fluoroscopic C-arm. Attention to portal placement during hip arthroscopy is critical to avoid damaging surrounding neurovascular structures and to facilitate access to all parts of the central and peripheral compartments (Fig. 13).

Fig. (13) Attention to portal placement during hip arthroscopy is critical to avoid damaging surrounding neurovascular structures and to facilitate access to all parts of the central and peripheral compartments.

At the start of the procedure, traction is applied to obtain approximately one centimeter of joint clearance. The safe zone for establishing portals lies lateral to the sagittal plane distal to the ASIS. Portal placement medial to this plane can result in catastrophic neurovascular injury and must be avoided (Fig. 14).

Fig. (14) The safe zone for establishing portals lies lateral to the mid-sagittal plane distal to the ASIS. Portal placement medial to this plane can result in catastrophic neurovascular injury.

There are two compartments of the hip that are contained by the joint capsule. The central hip compartment provides the articulation between the femoral head and acetabulum and requires hip distraction for access. The peripheral compartment of the hip does not require traction to access. It lies along the femoral neck and extends from the hip joint to the capsular reflection on the intertrochanteric junction to the medial and lateral gutters and the inferior recess of the joint (Fig. 15). The labrocapsular junction, acetabular rim and femoral neck can be accessed through the peripheral compartment, as well as through the psoas tendon when tendon recession is required [3].

Fig. (15) There are two compartments of the hip that are contained by the joint capsule. The central hip compartment provides the articulation between the femoral head and acetabulum and requires hip distraction for access. The labrocapsular junction, acetabular rim and femoral neck can be accessed through the peripheral compartment without traction.

Outside of the hip joint, the superficial and deep paratrochanteric spaces are potential spaces that can be insufflated with fluid and accessed endoscopically to treat disorders of the iliotibial band, trochanteric bursa, iliopsoas tendon, and gluteal tendon reattachments.

The ideal surgical candidate is a patient with well-documented symptomatic labral tear and FAI whose symptoms go back at least one month and who has failed respond to conservative therapy. Patients should have mechanical symptoms, including activity-related hip pain localized around the groin, worse with flexion and internal rotation. The physical exam should reveal limited hip flexion and internal rotation, particularly in the setting of Cam lesions, with positive impingement tests. Patients should have a radiographically well-defined Cam or Pincer deformity with little or no secondary osteoarthritis and a lack of global retroversion or severe dysplasia. Patients should have an identifiable labral tear with a correctable impingement deformity defined by radiology and MRI with absence of grade IV chondral defects and less than two millimeters of joint space narrowing. Patients meeting these criteria will generally be less than 55 years old, as older patients will usually have a greater extent of hip osteoarthritis [28].

The goals of surgery are to eliminate the impingement lesion while preserving the joint and protecting the function of the labrum. The appropriate timing for surgical intervention in treating FAI continues to evolve. The only caveat in delaying surgical intervention is that disease progression may continue to the point where joint preservation is no longer possible, as joint space narrowing of greater than two millimeters is associated with inferior results [30, 31].

Open surgery for the treatment of FAI and labral tears is a more invasive surgical procedure that requires admission with resultant increased costs of hospitalization. The open surgical exposure requires dislocation of the femoral head, which can lead to injury of the blood supply to the femoral head with resultant avascular necrosis which has never been reported in the literature with arthroscopic treatment. Open treatment can also lead to greater stiffness from surgical scarring and an increased risk of heterotopic bone deposition compared with arthroscopic treatment. Arthroscopic treatment is done as a day surgery, is minimally invasive with small incisions, and causes minimal trauma to the soft tissues. Arthroscopic treatment facilitates rehabilitation with quicker return of muscles strength and less pain from soft tissue damage.

Treatment of labral tears of the hip is decided based on patient age, symptoms, failure of conservative therapy, and minimal osteoarthritis with less than two millimeters of joint space narrowing. The final decision on possible labral repair versus debridement is made at the time of surgery and depends on the condition of the labrum, which must have good tissue viability that will support sutures without pulling through.

Arthroscopic labral repair is usually accomplished utilizing the anterolateral, midanterior, and anterior portals [7, 32]. Suture anchors are placed using accessory portals. Anchor placement must be into the acetabular rim, taking care to avoid violating the articular surface of the acetabulum. Single- or double-loaded anchors may be used with knots tied on the capsular surface away from the joint surface (Fig. 16).

Fig. (16) Arthroscopic labral repair may involve single- or double-loaded anchors, with knots tied on the outer capsular surface away from the joint surface.

Successful labral repair requires proper patient selection, adequate tissue, and a secure repair. Preserving as much viable hip labrum as possible appears to be critical for joint preservation and the maintenance of normal hip function. Loss of labral tissue has been associated with the development of hip arthritis over time [6, 8].

Although there have been many publications on labral debridement, reports of the results of labral repair have been sporadic. Espinosa et al., found patients undergoing open debridement for FAI with refixation of labral repairs did better than those with labral resection [33]. In a series of patients treated with labral debridement, Robertson et al., reported 67% of 58 patients and 91% of 22 patients were satisfied with their results at 3.5 years [33, 34].

Surgical management of a patient with labral tear and FAI involves addressing both the labrum – repair or debridement, as described above – and the underlying bony abnormality. If the FAI is not addressed surgically, the problem may simply recur. Thus, the goals of surgical treatment for FAI include labral preservation and correction of any underlying abnormal bone morphology.

The arterial blood supply to the femoral head is through an anastomosis of a branch of the obturator artery in the ligamentum teres, and branches from the medial and lateral circumflex arteries from the deep femoral artery. The principal supply comes from the retinacular vessels from the medial femoral circumflex artery along the posterior inferior and posterior superior femoral neck [24]. The vessels arise within the lateral synovial retinaculum, which is a reflection of the capsule onto the neck of the femur (Fig. 17). During femoral neck osteoplasty, great care must be taken to avoid these vessels. Failure to do so can lead to avascular necrosis of the femoral head and joint collapse.

Fig. (17) During femoral neck osteoplasty, great care must be taken to avoid important blood vessels like the retinacular vessels from the medial femoral circumflex artery along the posterior inferior and posterior superior femoral neck.

In restoration of the femoral head-neck contour to address Cam impingement, care must be taken during osteoplasty to stay proximally in the safe anterolateral and anterior regions, away from the retinacular vessels (Fig. 18). Mardones et al., have shown that resection of anything more than 30% the surface area of the femoral head-neck junction may be excessive and can lead to femoral neck fracture postoperatively [35]. In addition, over-resection of the femoral neck-head junction can lead to a loss of the labral seal during hip movement.

Fig. (18) In surgical correction of Cam impingement, it is important to avoid the retinacular vessels by staying in the safe decompression area.

In the case of Pincer impingement, surgical treatment involves carefully trimming the excess acetabular bone away from the labrum using a high-speed burr, using fluoroscopy to guide the amount of resection. Fluoroscopic guidance is essential during acetabular rim trimming to prevent excessive resection of the acetabular rim, which can lead to instability of the hip. This technique preserves and recesses the labrum back to a normal anatomic acetabular rim without violating the chondrolabral junction (Fig. 19). The labrum is then reattached using bone anchors loaded with non-absorbable sutures. Care must be taken not to trim any more acetabular bone than is necessary, as excessive over-resection of the acetabular rim may lead to undercoverage of the femoral head and a resulting tendency for superolateral migration.

Fig. (19) Correcting Pincer impingement involves trimming the excess acetabular bone with a high-speed burr, while preserving the labrochondral junction and then reattaching the labrum using bone anchors loaded with non-absorbable sutures.

It is important to recognize that FAI is most often caused by a combination of acetabular and femoral head-neck impingement lesion. Both bony abnormalities must be addressed at surgery for the procedure to be successful [1].

Overall results of arthroscopic treatment for FAI show predictable functional improvement with good pain relief, equaling the results of open decompression with labral repair [36-45]. For the procedure to be successful, it is imperative to treat patients prior to the onset of significant joint space narrowing and degenerative changes. Labral preservation appears to improve the results and should be attempted in properly selected patients [31].

In a 2007 publication, Espinosa et al., reported the preliminary results for the treatment of FAI with labral reattachment. The authors found that patients who had reattachment of the labrum recovered earlier and had superior radiographic results when compared with patients who had resection of the labrum [33]. Other authors have reported similar results with arthroscopic treatment of FAI with concomitant labral repair [31, 40]. In addition, a recent prospective study of the surgical treatment of FAI with chondrolabral dysfunction revealed good to excellent results in 112 patients when there was less than two millimeters of joint space narrowing. In the same study, patients who had labral repair did better than those with labral debridement [28]. Currently there are no randomized, prospective studies of young active patients with FAI and labral tears [30].