Acetabular labral tears are a major cause of hip dysfunction in young patients and a primary precursor to hip osteoarthritis. In addition, labral disease more commonly occurs in women and can present with nonspecific symptoms. It is possible to diagnose, quantify, and treat labral tears before the onset of secondary joint deterioration. However, the diagnosis requires a high index of suspicion, special attention to subtle patterns of presentation, and timely consideration for imaging studies. Treatment options are still evolving and include a wide array of nonsurgical and surgical techniques. Treatment should also address secondary dysfunction that can be associated with hip pathology. An initial trial of conservative management is recommended and failure to progress is an indication for surgical consultation.
The differential diagnosis of anterior hip, groin, and pelvic pain spans many health care specialties from gynecology to general surgery to musculoskeletal medicine and orthopedic surgery. The list of possible causes of pain and dysfunction is extensive. These include causes involving osseous structures and their related soft tissues, as well as pelvic and intraabdominal organs. Structural disorders involving the hip joint itself is a known cause of anterior hip and groin pain. However, many extraarticular structures should also be considered when attempting to elucidate structural and physiological causes of pain. Furthermore, secondary pain and dysfunction may be associated with the complex relationship among the pelvis, spine, and hip, further complicating the diagnostic process and the task of achieving a resolution.
An increasing number of reports suggest acetabular labral tears to be a frequent cause of anterior hip and groin pain. Acetabular labral tears were first described in 1957 . In the last decade, labral disease has been increasingly studied. In addition to hip arthroscopy, better technology related to imaging has been a significant factor in improving the recognition of labral tears. Despite these improvements, patients with labral tears commonly go undiagnosed for several months and patients are often seen by multiple health care providers before obtaining a definitive diagnosis . The diagnosis may go unrecognized because the clinical presentation of labral tears varies, especially once secondary changes occur in associated structures, such as the pelvis, the sacroiliac joint, and the related pelvic-floor musculature. A high index of suspicion is necessary to investigate and appropriately treat patients in a timely fashion. The evaluation of patients with anterior hip and groin pain begins with a thorough history, physical examination, radiographic evaluation, and appropriate imaging studies.
The anatomy of the acetabular labrum
The acetabular labrum is a ring of fibrocartilage and dense connective tissue that surrounds the hip joint. It is a continuous, triangular structure that attaches to the boney rim of the acetabulum and is completed at the inferior portion by the transverse acetabular ligament over the acetabular notch ( Fig. 1 ) . The labrum is wider and thinner in the anterior region and thicker in the posterior region. The labrum attaches to the articular side of the acetabulum through a 1- to 2-mm transition zone of calcified cartilage that becomes the hyaline cartilage of the acetabulum. On the nonarticular side, the labrum attaches directly to the acetabular bone ( Fig 2 ) .
The outer one third of the acetabular base of the acetabular labrum is vascular, while the remaining majority is avascular . This is somewhat controversial as McCarthy and colleagues found no areas of relative hypovascularity to the labrum. The vascular supply is provided by the obturator, superior gluteal, and inferior gluteal arteries. These are the same arteries that supply the bony acetabulum . The anterior and superior aspect of the labrum is thought to be the most innervated portions, consisting of free nerve endings and sensory nerve end organs. These structures produce pain, pressure, and deep sensation. As a result, one can conclude that a tear of the labrum could be a source of hip pain .
The function of the acetabular labrum remains debatable. It is thought to add stability and protection to the hip joint. The labrum aids in stability by deepening the joint. Some studies show that it deepens the acetabulum by 21% . Additionally, the labrum increases the surface area of the acetabulum by 28% , which helps distribute load and therefore decrease contact stress on articular surfaces. The labrum also provides a seal for the joint that helps to maintain the synovial fluid and fluid pressure. This allows some of the load to be transferred to the pressurized joint fluid and off of the femoral and acetabular articular cartilage . Without the labrum, the articular cartilage must withstand significantly increased pressure and a compromise of this system could lead to early joint deterioration. A study testing a labrum-free model of the hip showed that, without the labrum, contact stress may increase by as much as 92% .
Etiology
Tears of the acetabular labrum are increasingly recognized as a source of hip pain and dysfunction, especially in young adult and middle aged patients . Historically, labral tears were associated with slipped capital epiphyses, Legg-Calve-Perthes disease, major structural abnormalities of the hip, or high-velocity trauma, such as motor vehicle accidents or falls . Athletic activities that involve repetitive pivoting motions on a loaded femur have also been associated with damage to the acetabular labrum . Specific sporting activities, such as soccer, hockey, golf, and ballet, have been linked to labral abnormalities . The end-range motion in positions of hyperabduction, hyperextension, and external rotation is thought to contribute to the higher incidence of labral tears seen in this population of active individuals . However, most labral tears have recently been reported to be insidious in onset, without a specific inciting event . In these cases, the underlying inciting event is thought to be repetitive microtrauma .
Hip dysplasia and femoroacetabular impingement are widely accepted as major initiators of early hip disease and secondary osteoarthritis and are now also thought to contribute to acetabular labral tears . Both of these structural abnormalities predispose the hip to abnormal articular loading. This results in progressive labral and chondral injury, and can lead to the development of acetabular labral tears, articular cartilage delamination, and eventual secondary osteoarthritis.
Recent literature correlates subtle bony changes of the acetabulum and femur to acetabular labral and chondral abnormalities . These abnormalities include mild or subclinical hip dysplasia and femoroacetabular impingement. Peelle and colleagues studied the radiographs of 78 patients treated arthroscopically for labral tears. Forty-nine percent of patients with symptomatic labral tears were found to have at least one radiographic abnormality: 17% occurred at the acetabulum, 14% at the femur, and 18% at both anatomic sites. These changes contribute to joint incongruency and are postulated to increase stress on the acetabular labrum. These data emphasize the common association of intraarticular hip disease and structural abnormalities.
Some researchers believe that labral fraying and tears represent the natural history of the aging hip joint. In cadaver studies, labral tears and abnormalities were found in 93% of hips with the average age of 78 and range of 48 to 102 years . Labral abnormalities have also been found in patients without hip pain with the incidence increasing with age .
Etiology
Tears of the acetabular labrum are increasingly recognized as a source of hip pain and dysfunction, especially in young adult and middle aged patients . Historically, labral tears were associated with slipped capital epiphyses, Legg-Calve-Perthes disease, major structural abnormalities of the hip, or high-velocity trauma, such as motor vehicle accidents or falls . Athletic activities that involve repetitive pivoting motions on a loaded femur have also been associated with damage to the acetabular labrum . Specific sporting activities, such as soccer, hockey, golf, and ballet, have been linked to labral abnormalities . The end-range motion in positions of hyperabduction, hyperextension, and external rotation is thought to contribute to the higher incidence of labral tears seen in this population of active individuals . However, most labral tears have recently been reported to be insidious in onset, without a specific inciting event . In these cases, the underlying inciting event is thought to be repetitive microtrauma .
Hip dysplasia and femoroacetabular impingement are widely accepted as major initiators of early hip disease and secondary osteoarthritis and are now also thought to contribute to acetabular labral tears . Both of these structural abnormalities predispose the hip to abnormal articular loading. This results in progressive labral and chondral injury, and can lead to the development of acetabular labral tears, articular cartilage delamination, and eventual secondary osteoarthritis.
Recent literature correlates subtle bony changes of the acetabulum and femur to acetabular labral and chondral abnormalities . These abnormalities include mild or subclinical hip dysplasia and femoroacetabular impingement. Peelle and colleagues studied the radiographs of 78 patients treated arthroscopically for labral tears. Forty-nine percent of patients with symptomatic labral tears were found to have at least one radiographic abnormality: 17% occurred at the acetabulum, 14% at the femur, and 18% at both anatomic sites. These changes contribute to joint incongruency and are postulated to increase stress on the acetabular labrum. These data emphasize the common association of intraarticular hip disease and structural abnormalities.
Some researchers believe that labral fraying and tears represent the natural history of the aging hip joint. In cadaver studies, labral tears and abnormalities were found in 93% of hips with the average age of 78 and range of 48 to 102 years . Labral abnormalities have also been found in patients without hip pain with the incidence increasing with age .
Demographics
Most studies report that symptomatic labral tears occur more frequently in women than in men . This may partly be due to the increased incidence of hip dysplasia in women , especially between the ages of 15 to 41 years ( Table 1 ) . It is unknown if women with increased joint laxity are predisposed to labral injuries.
| Study | N | Population | Male | Female | Dysplasia | Age range (y) | Average age (y) |
|---|---|---|---|---|---|---|---|
| Suzuki and colleagues | 5 | Patients with hip pain of unknown origin; labral tear, undiagnosed by arthrography, noted at arthroscopy | 60% | 40% | 0% | 13–16 | 15 |
| Ikedo and colleagues | 7 | Patients with hip pain and normal radiographs | 42.8% | 57.1% | 14.3% | 13–26 | 16.7 |
| Hase and Ueo | 10 | Patients with arthroscopically diagnosed and treated labral tears | 30% | 70% | 10% | 13–67 | 28.7 |
| Dorrell and Catterall | 11 | Patients in which acetabular dysplasia was associated with labral tears | 0% | 100% | 100% | 13–47 | 32.6 |
| Farjo and colleagues | 28 | Patients who underwent hip arthroscopy and were found to have labral tears | 53.6% | 46.4% | 50% had arthritis or dysplasia | 14–70 | 41 |
| Fitzgerald | 55 | Patients with a diagnosis of labral tears | 45.5% | 54.5% | Not reported | 18–75 | 36.5 |
| Sanlori and Villar | 58 | Patients with labral tears that were arthroscopically detected and treated with partial resection of the labrum | 43.1% | 56.9% | Not reported | 8–70 | 36.7 |
| Burnett and colleagues | 66 | Patients with labral tears that were confirmed by hip arthroscopy | 29% | 71% | 22.7% | 15–64 | 38 |
| McCarthy and colleagues | 241 | Patients with labral tears and mechanical hip symptoms | 45.6% | 54.4% | Not reported | 14–72 | 39.9 |
Presentation
More than 90% of patients diagnosed with acetabular labral tears complain of anterior hip or groin pain . Burnett and colleagues studied 66 patients found to have labral tears by arthroscopy and reported 92% had predominant localized groin pain, 52% had associated anterior thigh pain, and 59% described lateral hip pain. Fewer patients, 38%, reported associated buttock pain. No patient presented with isolated buttock pain.
The onset of symptoms was described as insidious in 61% of patients. Many patients with labral tears describe a constant dull pain with intermittent episodes of sharp pain that worsens with activity. Walking, pivoting, prolonged sitting, and impact activities, such as running, often aggravate symptoms. Seventy-one percent of patients describe night pain, 53% report mechanical symptoms of popping or snapping, while 41% report true locking or catching ( Table 2 ). The data on functional limitations of patients with acetabular labral tears is scarce. Burnett and colleagues found 89% of patients with labral tears reported limping, 67% required the use of banister with stairs, 36% reported limited walking to six blocks, and 32% reported difficulty donning and doffing socks ( Table 3 ).
| Clinical parameter | Number of patients |
|---|---|
| Onset of symptoms | |
| Insidious | 40 (61%) |
| Acute | 20 (30%) |
| Trauma | 6 (9%) |
| Moderate or severe symptoms | 57 (86%) |
| Location of Pain | |
| Groin | 61 (92%) |
| Anterior thigh or knee | 34 (52%) |
| Lateral hip | 39 (59%) |
| Buttock | 25 (38%) |
| Quality of pain | |
| Sharp pain | 57 (86%) |
| Dull pain | 53 (80%) |
| Combination of sharp and dull pain | 46 (70%) |
| Activity-related pain | 60 (91%) |
| Constant pain | 36 (55%) |
| Intermittent pain | 30 (45%) |
| Night pain | 47 (71%) |
| Mechanical snapping, popping, or locking | 35 (53%) |
| Mechanical locking | 27 (77%) |
| Painful mechanical locking | 24 (89%) |
| Pain during walking | 46 (70%) |
| Pain during pivoting | 46 (70%) |
| Pain during impact activities | 41 (62%) |
| Pain during sitting | 40 (61%) |
| Limitation | Number of Hips (N = 66) |
|---|---|
| Limp at any time during symptoms | 59 (89%) |
| Severity of limp | |
| Slight or mild | 51 (77%) |
| Moderate | 5 (8%) |
| Severe | 3 (5%) |
| Use of cane, crutches, or assistive device at any time during symptoms | 6 (9%) |
| Limitation in walking distance | 24 (36%) |
| Limited to six blocks | 10 (15%) |
| Limited to two blocks | 11 (17%) |
| Limited to household | 3 (5%) |
| Stairs | |
| Requires use of banister | 44 (67%) |
| Unable | 1 (2%) |
| Sitting | |
| <30 min | 17 (26%) |
| Unable or short duration | 3 (5%) |
| Donning shoes and socks | |
| Difficult | 21 (32%) |
| Unable | 3 (5%) |
| Unable to use public transportation | 6 (9%) |
Unique in women is the possible concomitant pelvic-floor pain that may occur in association with labral tears, hip impingement, dysplasia, and early and late arthritis. Because these hip disorders are more common in women, a thorough history should include the discussion of pelvic-floor symptoms. The obturator internus is considered one of the primary musculature sources of pelvic-floor pain that often presents with the complaint of deep vaginal pain. Because the obturator internus is a primary hip rotator, a hip-related cause of pelvic pain should be considered in the differential diagnosis when the pain is determined to be originating from this muscle and when other causes have been excluded.
In an unpublished case series (Prather H, Hunt D. Unpublished data, 2006.), the investigators found that an acetabular labral tear was the source of pain in five women with groin and vaginal pain after a vaginal hysterectomy or attempted vaginal hysterectomy. It is unknown if these women had the labral tears before surgery and became symptomatic after surgery or if the tears occurred during surgery. Regardless, the investigators speculate that hip positioning in flexion and external rotation required to perform a vaginal hysterectomy may have exacerbated or caused the symptoms related to the labral disease.
In the article by Dugan and Prather specifically on pelvic-floor pain elsewhere in this issue, a more in-depth discussion includes information regarding the presentation and evaluation of pelvic-floor disorders.
Diagnosis and physical examination
The diagnosis of a labral tear relies on a high index of suspicion based on recognition of a specific pattern of presentation as well as a thorough physical examination. Determining that a labral tear is the cause of the patient’s symptoms can be difficult and many patients experience a delay in diagnosis due to the elusive nature of the signs and symptoms. Fig. 3 presents an algorithm helpful in assessing the structural causes of hip and groin pain. The first step is to discern between an intra- and extraarticular problem, which can be challenging because dysfunction in extraarticular structures coexist or are secondary to intraarticular disorders. An assessment of spine motion and positions of provocation of symptoms is important in determining if a spine issue is contributing to the patient’s pain. A thorough neurological examination with neural tension provocative maneuvers in the lower extremity can help discern a neurological component. Evaluation of muscle length and strength, particularly in the core muscles, including the hip and abdominal musculature, is key to identifying areas of system breakdown that may contribute or cause the dysfunction and pain. Extraarticular muscle imbalances between posterior hip abductors and external rotators in combination with shortened hip flexors and iliotibial band can lead to groin and lateral hip pain. Hip range-of-motion parameters are variable in the literature and are described in normal asymptomatic volunteers. For young adults with early hip disorder, range-of-motion parameters have not been developed. The evidence regarding evaluation and management of early intraarticular hip disorders is emerging. For this reason, reliable values for range of motion of the hips in asymptomatic individuals are needed. The influence of age, gender, position, and active or passive movement on range of motion of the hip has not been adequately documented . Simoneau and colleagues found that measurements of active hip internal rotation were not significantly affected when subjects were in the prone, rather than seated, position. However, prone positioning significantly affected external rotation. Women also had statistically greater active hip internal and external rotation than men had. More studies are needed to establish the factors that influence range of motion in healthy individuals.
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