Key points

Introduction

Acetabular labral tears are recognized as an important cause of hip pain in young, athletic individuals. Acetabular labral tears were first described by Paterson in 1957 after traumatic posterior hip dislocations, with a resulting bucket-handle labral tear serving as a block to a concentric reduction. Until recently, labral tears were thought to be relatively uncommon. However, advances in imaging and surgical techniques, as well as an improved understanding of hip pain, have led to increased awareness regarding labral tears and other pathologic conditions around the hip joint. The prevalence of labral tears in painful hips has been reported to be 22% to 55%, and Register and colleagues recently identified labral tears present in 69% of asymptomatic hips. Historically, treatment of labral lesions consisted of nonoperative measures or a partial excision performed through an anterior arthrotomy. Although Harris and colleagues suggested that an “intra-acetabular labrum” with degenerative labral changes could lead to the development of hip osteoarthritis, it was not until much later that Ganz and colleagues described femoroacetabular impingement (FAI), and the relationship of bony abnormalities of the acetabular rim and femoral head-neck junction with labral tears and hip osteoarthritis. The investigators theorized that repetitive bony impingement causes damage to both the acetabular labrum and articular cartilage. McCarthy and colleagues described a possible sequence of events that leads to joint degeneration, including excessive loading of the labrum through traction or impingement, fraying of the anterior margin of the labrum, articular cartilage delamination adjacent to the labrum lesion, and more global degenerative changes that occur in both the labrum and articular cartilage. The purpose of this article is to review the anatomy of the acetabular labrum, discuss the pathogenesis of labral tears, and discuss the various treatment options available, including arthroscopic labral repair and reconstruction.

Introduction

Acetabular labral tears are recognized as an important cause of hip pain in young, athletic individuals. Acetabular labral tears were first described by Paterson in 1957 after traumatic posterior hip dislocations, with a resulting bucket-handle labral tear serving as a block to a concentric reduction. Until recently, labral tears were thought to be relatively uncommon. However, advances in imaging and surgical techniques, as well as an improved understanding of hip pain, have led to increased awareness regarding labral tears and other pathologic conditions around the hip joint. The prevalence of labral tears in painful hips has been reported to be 22% to 55%, and Register and colleagues recently identified labral tears present in 69% of asymptomatic hips. Historically, treatment of labral lesions consisted of nonoperative measures or a partial excision performed through an anterior arthrotomy. Although Harris and colleagues suggested that an “intra-acetabular labrum” with degenerative labral changes could lead to the development of hip osteoarthritis, it was not until much later that Ganz and colleagues described femoroacetabular impingement (FAI), and the relationship of bony abnormalities of the acetabular rim and femoral head-neck junction with labral tears and hip osteoarthritis. The investigators theorized that repetitive bony impingement causes damage to both the acetabular labrum and articular cartilage. McCarthy and colleagues described a possible sequence of events that leads to joint degeneration, including excessive loading of the labrum through traction or impingement, fraying of the anterior margin of the labrum, articular cartilage delamination adjacent to the labrum lesion, and more global degenerative changes that occur in both the labrum and articular cartilage. The purpose of this article is to review the anatomy of the acetabular labrum, discuss the pathogenesis of labral tears, and discuss the various treatment options available, including arthroscopic labral repair and reconstruction.

Anatomy and function of the acetabular labrum

The hip is a ball-and-socket joint that is inherently stable, owing to highly constrained osseous anatomy. The labrum is a fibrocartilage structure that runs circumferentially around the margin of the acetabular rim and is attached to the transverse acetabular ligament both anteriorly and posteriorly. It has numerous functions, including maintenance of joint lubrication and the “suction-seal” effect, enhancement of joint stability, and protection of articular cartilage through improved distribution of pressure across the articulation between the femoral head and acetabulum. The labrum increases the effective depth of the bony acetabulum and provides stability to the femoral head while increasing the effective amount of femoral-head coverage. It contributes, on average, up to 22% of the acetabular surface area that articulates with the femoral head, and increases the volume of the acetabulum by up to 33%. The labrum, however, has limited healing capabilities. Kelly and colleagues studied the vascular supply of the labrum in a cadaveric study, showing that it is a relatively avascular structure with most vessels originating from the capsular periphery, with few reaching the more central articular-sided region. Furthermore, the distribution of vessels is not homogeneous through the labrum. The presence of free nerve endings has also been reported by Kim and Azuma, suggesting proprioceptive and nociceptive properties.

The labrum contributes to the suction-seal effect to improve fluid-film lubrication and maintain negative intra-articular pressure within the central compartment. A recent cadaveric study by Cadet and colleagues demonstrated significant efflux of fluid from the hip joint in the presence of a labral tear, suggesting disruption of the fluid seal effect. Although labral repair decreased the outflow of fluid from the hip joint, a repaired labrum was not shown to be as effective as the labrum-intact condition. The hip labrum has also been identified as an important secondary stabilizer in cases of simulated disruption of iliofemoral ligament, and large tensile forces have been measured in the anterior acetabular labrum during hip external rotation and abduction movements. Smith and colleagues showed that even a damaged labrum continues to provide hip stability and resist femoral-head dislocation after the creation of circumferential tears less than 3 cm in length or after creation of a 1-cm labrectomy.

Labral pathology

Labral tears are most common in the presence of a structural hip abnormality such as FAI or hip dysplasia. Recent retrospective studies have shown that between 49% and 87% of all patients with a labral tear have osseous changes consistent with FAI. In addition, although labral abnormality most commonly affects the anterosuperior labrum, the pattern of injury is highly dependent on the unique morphologic “fingerprint” present in the acetabulum and proximal femur, including the external mechanical loads and the arc of motion applied to the hip. In cases of pincer-type FAI with acetabular overcoverage, there is repetitive contact between the femoral neck and the acetabular rim, with compression of the labrum that leads to degeneration early in the process. The articular cartilage is relatively uninvolved, with chondral injury limited to a narrow margin along the acetabular rim. Eventually there is ossification of the labrum and further appositional bone formation that can exacerbate the magnitude of impingement, in addition to contre-coup lesions of the posteroinferior acetabular articular cartilage and the posteromedial aspect of the femoral head.

In cam-type FAI with loss of femoral head-neck offset, there is early damage to the articular cartilage, in contrast to the pattern seen with pincer-type FAI. During hip motion, the cam deformity is rotated into the acetabular socket with a shearing-type injury pattern and delamination of the articular cartilage. The damage is localized to the corresponding location where the abnormal head-neck junction ( Fig. 1 ) and acetabular rim make contact. Eventually there is separation of the labrum from the underlying subchondral bone, occurring at the transitional zone between the labrum and hyaline cartilage ( Fig. 2 ). Johnston and colleagues reported an association between the lack of femoral head-neck sphericity and the size of the cam lesion with the extent of acetabular chondral damage and delamination. The investigators noted more intra-articular damage in patients with a higher α angle, including detachment of the labrum and full-thickness delamination of the articular cartilage.

View of the femoral head-neck junction showing a typical cam deformity with loss of offset.

Anterosuperior labral tear with delamination of the articular cartilage at the transition zone.

Acetabular dysplasia is also responsible for pathologic changes to the labrum. The dysplastic hip is characterized by a shallow acetabulum with anterior and lateral acetabular undercoverage. In these cases, there is a shift in the normal center of contact between the femoral head and acetabulum to a more posterosuperior location, leading to pressure overload of the labrum and articular cartilage. This shift has been associated with the premature development of osteoarthritis as well as pathologic changes to the labrum, including hypertrophy, myxoid degeneration, and detachment from the acetabular rim.

Lage and colleagues described an arthroscopic classification for labral tears. Tears were divided into 4 categories based on the etiology: traumatic, degenerative, idiopathic, and congenital. In addition, 4 morphologic categories were used to classify labral tears: radial flap, radial fibrillated, longitudinal peripheral, and unstable. Seldes and colleagues also described 2 different histologic types of labral tears, include Type 1 tears whereby there is detachment of the labrum from the articular surface at the transition zone between labrum and articular cartilage, and Type 2 tears whereby there are 1 or more cleavage planes within the substance of the labrum. Capsular laxity and psoas impingement can also lead to the development of labral tears. It is important to understand the cause of the labral tearing and ensure that all pathologic aspects are properly addressed, as poor clinical outcomes can result from a failure to adequately decompress all bony impingement at the time of surgery. A summary of the various types of labral tears and the associated conditions is summarized in Table 1 .

Patient history and clinical evaluation

A thorough history is important in making the correct diagnosis and determining the cause of the complaint. Most commonly, patients with labral tears will present with groin pain that is exacerbated by hip flexion. The exact location of the pain and any exacerbating or relieving factors is important in helping to narrow the differential diagnosis. A characteristic sign in patients with labral tears and hip impingement is the “C sign,” whereby the patient holds his or her hand in the shape of a C proximal to the greater trochanter with the thumb directed posteriorly and the fingers pointing anteriorly toward the groin. This sign often indicates pain deep within the hip joint. The clinician must determine if there is a history of trauma that may have caused labral injury, or if the symptoms are insidious in nature. Young athletes may also complain of mechanical symptoms such as locking, catching, or clicking. Certain sporting activities are highly associated with labral tearing, including football, hockey, skiing, bicycling, and dancing. Pain may also be present with activities of daily living, such as putting on shoes and socks or getting in and out of a car. Radicular symptoms can also be confused with groin pain from a labral tear, and disorders of the gastrointestinal, genitourinary, and vascular systems can all cause referred pain to the hip and groin. Pain over the lateral aspect of the hip suggests greater trochanteric bursitis and possible tightness of the iliotibial band. The clinician must also recognize that in patients with hip laxity there is greater reliance on the surrounding hip musculature to act as secondary stabilizers; therefore, these structures may become overused and tender or weakened on physical examination.

In young patients with a suspected labral tear, the clinical examination should focus on evaluation of gait and posture, active and passive range of motion of the lower extremities, and an assessment of the neurovascular structures. In the standing position, the presence of a Trendelenburg gait indicates weakness of the hip abductor muscles. A shortened stance phase indicates an antalgic gait caused by a painful extremity. Range of motion and strength testing should be performed in the bilateral extremities, and any differences noted. Mechanical symptoms including catching, clicking, or popping suggest intra-articular abnormality, such as damage to the articular cartilage, labral damage, or a loose body. In addition, a snapping iliotibial band over the greater trochanter or the iliopsoas tendon over the pelvic brim can cause a popping sensation with a circumduction motion of the hip. Several special tests have been described for evaluation of the hip in the supine position, including the FADDIR test, whereby the hip is moved into flexion, adduction, and internal rotation to recreate the patient’s pain and to measure the amount of flexion and internal rotation; the Thomas test for psoas tightness; and the Patrick or FABER test to differentiate sacroiliac/lumbar spine abnormality from hip problems. Capsular laxity is assessed with the hip dial test, performed in the supine position. All patients should also be examined for signs of systemic ligamentous laxity according to the criteria of Beighton and colleagues. A thorough physical examination with provocative testing to recreate the location and intensity of the patient’s pain is critical in understanding the underlying abnormality, including labral tears and any associated injuries to the surrounding structures.

A thorough and systematic radiographic examination is performed in all patients with hip pain and suspected labral disorder, including anteroposterior (AP) pelvis, cross-table lateral, and false-profile plain radiographic views of the involved hip. The AP pelvis is evaluated for the outline of the acetabular lines, and any pathologic features such as the presence of a crossover sign, whereby the outlines of the anterior and posterior acetabular wall cross to form a figure-of-8 pattern. This sign indicates relative anterior acetabular overcoverage. Global acetabular overcoverage, as seen in coxa profunda and coxa protrusio deformities, is suspected when the floor of the acetabular fossa touches or passes medially to the ilioischial line. On the cross-table lateral view, the α angle is measured to evaluate for cam-type FAI and any loss of femoral head-neck offset. Anterior acetabular overcoverage or undercoverage and joint-space narrowing in the posteroinferior acetabular are assessed on the false-profile view. Magnetic resonance imaging (MRI) or magnetic resonance arthrography is often used in young patients with a painful hip to evaluate the acetabular labrum, joint capsule, articular cartilage, and periarticular structures.

Nonoperative treatment

There is a paucity of evidence to support the nonoperative treatment of acetabular labral tears in young patients. Philippon and colleagues reported that early intervention for labral abnormality may lead to improved results, as shown in a cohort of professional hockey players where those who underwent intervention within 1 year from the time of injury returned to play earlier than those who waited. Simple measures such as activity modification and preventing provocative positions such as hip flexion and interior rotation can improve pain and prevent further episodes of impingement. Focused physical therapy and nonsteroidal anti-inflammatory drugs (NSAIDs) can be used initially, and can be combined with physical therapy for 10 to 12 weeks. Greater trochanteric bursitis and a snapping iliopsoas are managed with rest/activity modification, NSAIDs, and stretching. Corticosteroid injections into the bursa can be administered if needed. Intra-articular steroid injections may also be beneficial, especially in patients who have pain that is not responsive to nonoperative treatments.

Physical therapy can be used in patients with hip pain and labral tears to decrease pain and improve function. Casartelli and colleagues compared hip-muscle strength testing and hip-flexor electromyography in 22 patients with FAI and compared the results with those of healthy, age-matched controls during active hip flexion. Whereas there was significant weakness in the FAI group when compared with the healthy controls, in particular of the abductions, adductors, hip flexors, and external rotators, there was no significant difference in the strength of hip internal rotators and extensors. Although the weakness observed could be due to many factors (eg, atrophy, reduced muscle activation, pain), these results may aid in the development of specific rehabilitation and therapy protocols to improve strength in those with FAI. Yazbek described a nonsurgical therapy program used in 4 patients with clinical and MRI findings consistent with a labral tear. The rehabilitation protocol emphasized stabilization of the hip and lumbopelvic regions with correction of muscular imbalance, biomechanical control, and sport-specific functional progression. All patients showed an overall decrease in pain and an increase in function, correction of muscular imbalances, and improved muscle strength of the hip flexors, abductors, and extensors. Patients who fail to improve after a trial of nonoperative treatment are candidates for arthroscopic treatment.

Operative treatment

There are several surgical treatment options available for the young patient with FAI. Both open surgical dislocation and arthroscopic procedures have demonstrated excellent short-term and mid-term results, including the ability to return to sports. It is critical that the clinician perform a thorough history and physical examination, and obtain the necessary imaging studies to identify not only labral abnormality but also osseous abnormalities such as FAI or dysplasia, in addition to damage to the articular cartilage, the ligamentum teres, and surrounding soft-tissue structures. The concomitant pathologic features must be addressed to achieve a successful outcome. The goal of arthroscopic surgery is to correct the labral abnormality and relieve mechanical impingement, as well as address associated intra-articular abnormality.

There are several surgical options available to address labral lesions, including debridement, repair, or reconstruction. Improved clinical outcomes have been reported after either open or arthroscopic labral debridement. Encouraging results for labral refixation have also been published. Espinosa and colleagues retrospectively reported the results after labral resection or labral refixation in a series of patients who underwent open surgical dislocation for symptomatic FAI. Patients treated with labral refixation recovered earlier and had superior clinical and radiographic outcomes when compared with the patients who had resection of the torn acetabular labrum. In 2009, Larson and Giveans performed a similar study to compare the outcomes after arthroscopic labral debridement with those after labral repair. At the 1-year follow-up visit the investigators demonstrated improved subjective outcomes in both groups, although the modified Harris Hip Scores (mHHS) were superior in those with refixation when compared with the debridement group. The percentage of good to excellent results was also significantly improved in the labral repair group. More recently, Larson and colleagues reported results of arthroscopic labral repair at a mean 3.5 years’ follow-up. While the subjective scores improved for both the repair and debridement groups, the mHHS and visual analog scale (VAS) for pain were significantly better for the refixation group at all time points, with good to excellent results noted in 92% of patients in the refixation group. In addition, Philippon and colleagues performed an experimental study in an ovine model, and showed that labral repairs are capable of healing through a fibrovascular scar that originates from the joint capsule or the exposed bony attachment of the labrum. The investigators noted, however, that labral healing was incomplete in all specimens, and degenerative changes were present in 89% of the hips after 24 weeks.

Labral reconstruction is another technique that may be used to treat patients with extensive labral damage that is not amenable to debridement or repair. Techniques using autologous iliotibial (IT) band and ligamentum teres grafts have been described. Early results on the use of labral reconstruction to improve both the mechanical environment of the hip and clinical outcomes are promising.

Surgical Technique: Labral Repair

The senior author (M.J.P.) performs hip arthroscopy in the modified supine position, although it may also be performed in the lateral position as described by Glick and colleagues. A combined spinal-epidural is used routinely for anesthesia and postoperative analgesia. All prominences are well padded, and a wide perineal post is used to distribute pressure during traction and prevent iatrogenic injury. The hip is then placed in a position of 10° flexion, 15° internal rotation, 10° of lateral tilt, and neutral abduction. Traction is then applied to the operative leg on the magnitude of 25 to 50 lb (11.3–22.7 kg), with gentle countertraction being applied to the nonoperative extremity. After traction is applied, the operative leg is slightly adducted to force the femoral head laterally. The leg is internally rotated to align the femoral neck parallel to the floor. Fluoroscopy is used to confirm a “vacuum sign” and approximately 8 to 10 mm of distraction. Anatomic landmarks are identified, including the outline of the greater trochanter and the anterior inferior iliac spine (AIIS). The portals are then marked, and the hip area prepped and draped.

It is important to create arthroscopic portals in a reliable and safe fashion to avoid injury to nerves and blood vessels, in addition to the labrum and articular cartilage. Improper placement can also compromise adequate visualization during the procedure. The senior author uses 2 arthroscopic portals routinely, the anterolateral and mid-anterior portals. The anterolateral portal is established 1 cm proximal and 1 cm anterior to the tip of the greater trochanter. The mid-anterior portal is established 6 to 7 cm distal to the anterolateral portal at a 45° to 60° angle with respect to the longitudinal line passing through the anterolateral portal. The anterolateral portal is established first, followed by the mid-anterior portal, under direct arthroscopic visualization using a 70° arthroscope.

An interportal capsulotomy is performed next to improve passage of instruments and mobility within the joint. Care is taken to limit the medial extension of the capsulotomy to preserve the integrity of the iliofemoral ligament and prevent destabilization of the joint. The nature of the labral tear and the quality of the tissue are then assessed. Nonviable tissue can be removed with an arthroscopic shaver to improve visualization; often, a previously unrecognized flap or area of chondral delamination becomes visible. A treatment decision is then made ( Table 2 ) based on the intraoperative findings. In all cases, as much labral tissue as possible is preserved. Isolated labral debridement is used only in cases of a small peripheral tear where enough tissue can be retained to preserve normal labral function.

Table 2

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

Trauma Section Prevention of Overuse Sports Injuries in the Young Athlete Os Acromiale Management of Labral Tears of the Hip in Young Patients Spectrum of Shoulder Injuries in Skeletally Immature Patients Lateral Epicondylitis

Stay updated, free articles. Join our Telegram channel

Join