Labral Injuries of the Hip: A Review of Diagnosis and Management

Labral Tears 

Data from cadaveric studies indicate that labral lesions are a common occurrence. Seldes et al,13 in a study of 55 hips, found 96% (53 of 55) to have gross labral tears. McCarthy et al1 explored 54 acetabulae and found 93% to have at least one labral lesion. Byers et al,17 in their investigation of 365 hips, found 88% of patients older than 30 years to have labral detachment from the articular cartilage. This so-called bucket handle lesion in which the labrum separates from the acetabular rim at the labral-cartilage junction was also most prevalent in the study of McCarthy et al.1

It is generally accepted that most labral tears occur in the anterior, anterior-superior, and superior regions of this acetabulum. Fitzgerald18 noted a 92% incidence of anterior or anterosuperior location of tears in 55 active adult patients reporting a slipping or twisting injury with catching-type pain. Seldes et al13 found 74% of tears to be in the anterosuperior quadrant. Byrd19 also reported a majority of lesions to occur at the anterosuperior portion. Interestingly, posterior tears of the labrum appear to have a higher incidence in Asian populations. McCarthy et al20 report that these posterior tears in Asian populations are associated with hyperflexion or squatting motions. Ikeda et al,21 in their arthroscopic investigation of 7 young patients reporting pain from frank trauma, found all but one labral tear to be posterosuperior in location. Further studies with larger sample sizes are needed to decipher whether Asian populations do, in fact, have a higher incidence of posterior labral tears. Patients with known posterior subluxation or dislocation also most frequently have posterior tears.20 The most common of all lesions to occur in the anterior labrum is what McCarthy et al20 term the watershed lesion. This is the typical appearance seen after minor trauma in which there is an anterior labral tear present concurrently with anterior acetabular chondral injury.

There are several reported ways to classify labral tears. In this discussion, labral tears are classified according to location, etiology, and morphology. In respect to location, tears are classified as anterior, posterior, or superior (lateral).20 In respect to etiology, McCarthy et al20 subclassify tears as degenerative, dysplastic, traumatic, and idiopathic. Degenerative tears may involve one or more regions of the labrum and can be seen in inflammatory arthritides.20 Labral tears and fraying are almost universal in patients older than 60 years.1 It has been suggested that labral tears predispose to osteoarthritis of the hip joint. If, in fact, the labrum is a weight-bearing structure, one would suspect that labral disruption would lead to nonsymmetric force distribution on the acetabulum and femoral head. It would be intuitive that such changes would lead to cartilage erosion, loss of joint space, sclerosis, and degenerative joint disease. This is an example of a labral tear causing degenerative joint disease; however, the high incidence of labral tears in patients older than 60 years may suggest that tearing is part of the normal aging process. Further studies are needed to discern whether all labral tears are symptomatic and whether tears are a part of the tissue aging process.

There have been many studies linking the presence of dysplasia to tears of the acetabular labrum. Dysplasias such as Legg-Calve-Perthes disease and congenital hip dysplasia (CHD) are now well known to predispose to labral tearing. McCarthy et al20 found tears to occur most frequently anterior in this population; however, they can be posterior or diffuse. They also found the labrum to be hypertrophic in the anterior portion causing infringement upon the anterior acetabulum. They conclude that the hypertrophy and tearing most likely cause impingement of the labrum between the acetabulum and femoral head, accounting for the mechanical symptoms frequently seen in this population. Patients in this category typically experience pain, clicking, and locking sensations of the hip joint.20

Labral tears with a known traumatic onset are usually confined to a particular region of the labrum depending on the forces involved. Axial loading of the femoral head into the acetabulum and posterior dislocation lead to posterior labral tears. Anterior labral tearing normally results from minor trauma without dislocation. Hyperextension combined with femoral external rotation is the injury pattern most commonly associated with the acute presentation of acetabular labral tears.7 It is thought that the labrum takes on a weight-bearing role at the extreme of motion with excessive forces leading to tearing. Sports involving repetitive twisting motions and movements to end-range hyperflexion, hyperextension, and abduction are at greater risk.

Tears of an idiopathic etiology do not fall into the above categories and are found commonly in athletes with intractable hip pain and occupational related hip pain with no evidence of trauma.20

Lage et al22 in arthroscopic evaluation of 267 hips provided a morphologic classification of labral tears. Radial flap tears and radial fibrillated tears involve the free margins of the labrum and are the most commonly encountered. Longitudinal peripheral tears of various length are seen at the acetabulum-labrum junction, whereas unstable tears followed no real pattern but caused mechanical symptoms.

Diagnostic Considerations 

It is known that dysplastic conditions of the hip are correlated with labral tears; therefore, it is important to ask about childhood hip problems such as Legg-Calve-Perthes disease, CHD, and slipped femoral capital epiphysis. Questions targeting the location, duration, frequency, and distribution of pain as well as aggravating and relieving factors are of critical importance. True intra-articular hip pain will cause pain in the groin area with occasional radiation to the knee.20 A patient with a labral tear will typically present with pain and mechanical symptoms. The pain is usually confined to the anterior groin but may also refer to the proximal greater trochanter or buttocks.8 There is frequently a painful clicking sensation or unpredictable “locking” of the joint.20 It is common for the symptom presentation to be considerably more subtle, characterized by dull, activity-induced, or positional pain that typically fails to improve with time.7 Patients with acute tears often recall some form of twisting injury, slip, or fall. In the study of 55 patients by Fitzgerald,18 only 30 experienced trauma to the lower extremity. Thus, in patients with an insidious onset of symptoms and signs, it is important to determine whether there is a history of repetitive rotational motion strain.

Sports that entail repetitive hyperextension and external rotation, such as soccer, skating, hockey, tennis, and golf, may predispose susceptible individuals to labral tears.8 Other conditions mimicking the clicking associated with labral tears are the various snapping hip syndromes around the hip due to either intra-articular or extra-articular conditions. Intra-articular causes include loose bodies, synovial chondromatosis, hip subluxation, and osteocartilagenous exostoses.23 Extra-articular causes include the posterior border of the iliotibial band over the greater trochanter, the iliopsoas tendon over the iliopectineal eminence, or the iliofemoral ligaments over the femoral head.23

Differential Diagnosis 

The differential diagnosis of hip pain of labral origin includes local musculoskeletal structures, dysplasias, tumors (benign and malignant), herniations, and referred pain from the abdomen, sacroiliac joint, thoracolumbar spine, and other structures. A list of differential diagnoses can be found in Table 1.

Physical Examination 

The examination of a patient starts as the patient stands from their seat in the waiting room and walks to the examination room. Intra-articular disorders may be manifested by a Trendelenberg gait. If the hip is affected, the weight is lowered carefully on the affected side and the knee bends to absorb the shock.22 The step length on the affected side may be shorter than the normal side to minimize pain. Observation of the resting hip in flexion, abduction, or external rotation may indicate acute synovitis or joint effusion.20 Range of motion findings are often unrewarding.18 Fitzgerald18 has described a provocative maneuver to differentiate anterior from posterior labral tears. The sharp, catching pain with or without a click was reproduced in 54 (of 55) patients with the following: the hip is initially bought into acute flexion, external rotation, and full abduction, then extended with internal rotation and adduction. Pain with or without a click indicates an anterior tear. Moving from a fully flexed, internally rotated, and adducted position to an extended, abducted, and externally rotated position reproducing a sharp pain with or without a click indicates a posterior tear. McCarthy et al20 describes the McCarthy sign (with opposite hip flexed, the affected hip is extended first with internal then external rotation) in which a labral tear will reproduce a painful click. Suenaga et al24, in their study of 60 dysplastic hips, found the maximum flexion internal rotation test to be positive in 70% of patients with posterosuperior labral tears.

Imaging 

Plain x-ray is effective at diagnosing many intra-articular disorders. Signs of Legg-Calve-Perthes disease, CHD, and slipped femoral capital epiphysis are all easily diagnosed on plain film. Plain film x-rays are not useful in detecting labral tears, chondral defects, or unmineralized loose bodies.20 Routine measurements, including the center-edge Angle of Wiberg, should be made to assess for acetabular dysplasia.25

Conventional MRI is not thought to be of use in the visualization of labral tears. Diagnostic confidence is limited by the normal variability in labral size and shape, by the joint capsule collapsed against the acetabular rim, and by the difficulty in distinguishing tears of the labrum from pseudotears caused by the normal labral articular cartilage interface.26 In an MRI study of 180 asymptomatic hips, significant differences between subjects with respect to labral shape were reported.11 It has also been documented that there is an age-related intensity increase on T1-weighted and T2-weighted gradient echo magnetic resonance images of the acetabular labrum. These asymptomatic patients may or may not exhibit labral tears. In the 2003 review of Narvani,27 it is stated that MRI features that may suggest a labral tear include irregular labral shape, a nontriangular labrum, a thickened labrum with no labral recess, labrum with increased signal intensity on T1 images, and labral detachment from the acetabulum. From the previously mentioned studies9, 10, 11 these findings may all be normal variants. In addition, Byrd19 states that partial separation of the labrum from the lateral aspect of the acetabulum has been found to be a normal anomalous variation. In the study of 56 hips by Fitzgerald,18 only 3 were found to have a tear from MRI. Most patients did, however, show a low-grade effusion. Magnetic resonance imaging was effective in eliminating osteonecrosis, pigmented villonodular synovitis, and synovial chondromatosis as causes of hip pain.

Magnetic resonance arthrography (MRA) is a modality available to image labral tears, and the use of contrast medium within the hip capsule makes this an invasive procedure. The principle of the procedure relies upon capsular distension, thereby outlining the labrum with contrast (usually gadolinium) and filling any tears that may be present.20 Labral tears manifest as an abnormal linear extension of high-intensity gadolinium solution into the labrum, labral blunting, or detachment from the underlying bone.26 The addition of intra-articular contrast has been shown to greatly increase the specificity and sensitivity of diagnosing labral tears.8 The normal recesses occurring at the labral-cartilage junction can make the normal labral sulcus difficult to distinguish from a labral tear.20, 26 In a study of 22 hips by Czerny et al,28 labral tears on MRA were confirmed surgically. In this study, MRA had a sensitivity of 90% and accuracy of 91%, compared with a sensitivity of 30% and accuracy of 36% with conventional MRI. Fitzgerald18 found a tear in 44 of 60 hips imaged with MRA. The injection of local anesthetic at the same time as arthrography was used to confirm the presence of intra-articular pathology or extra-articular source of pain. The average subjective pain relief (analog scale) experienced with marcaine injection at the end of the hip arthrography was 81% (range, 0%-100%). Although numerous studies have documented success of MRA in detecting labral tears, Hase and Ueo29 report a somewhat different experience. Ten patients were considered normal at arthroscopy. They conceded they could not visualize the posterior portion of the labrum as the femoral head obstructed its view. Considering most tears were posterior in location, this result was not surprising. McCarthy et al20 stated that the specificity of detecting anterior tears was 83% specificity and 78% accuracy. The detection of posterior tears (20%) and lateral tears (11%) is poor.

Arthroscopy, as a diagnostic tool, is reserved for those patients with an intra-articular source of pain without a clear diagnosis after careful history, physical examination, and radiographic studies.8 Arthroscopy will be discussed further in the treatment of labral tears.

Treatment of Labral Tears 

The diagnosis and treatment of acetabular labral tears are important not only for the relief of symptoms, but also to alter the progression of osteoarthritis.30 A trial of conservative treatment is indicated in cases of labral tears. To date, there has been no research on the efficacy of hip manipulation or mobilization in the treatment of labral injuries, despite indirect evidence that these procedures may be beneficial. In contrast, a small study has investigated the effect of hip manipulation or hip stretching on hip joint ROM in normal young adults or adult low back pain sufferers.31 Although these studies have shown improved hip joint ROM after treatment, the results cannot be extrapolated to a population of subjects suffering a labral tear. However, as manipulation has shown an improvement in function, further study should investigate the effect of manipulation on those with labral tearing. This is especially true for those that suffer from some catching or locking as a component of their symptom spectrum.

The labrum is an avascular structure and, therefore, receives nutrition and clears waste via imbibition. With restricted ROM comes lower rates of imbibition and compromised nutrition. Manual procedures aimed at restoring the rate of nutrient flow through increased joint ROM may promote labral healing. In cases of entrapped or folded labral portions, manual procedures, including hip joint tractional maneuvers, may be of benefit. Conservative treatment will usually consist of nonsteroidal anti-inflammatory drug administration and protected (partial) weight-bearing for 2 to 4 weeks. Ikeda et al21 reported 6 of 7 patients to respond to this regime. Fitzgerald,18 who had all patients (55 in total) partial weight-bearing for 4 weeks, found 7 patients experience complete relief of pain without recurrence. Hase and Ueo29 had two of their patients managed with bed rest and traction for a few weeks to find that both failed. It is unfortunate that most nonoperative interventions fail and patients report continued symptoms of painful catching particularly with activities.30 Conservative treatments often fail because labral tears are actually diagnosed on average of 2 to 3 years after injury.29 This delay in diagnosis is 2-fold: many patients cannot recall an antecedent injury or event, and many patients are initially misdiagnosed.17 It would be useful for further studies to investigate the effectiveness of protected weight-bearing on labral tears of recent onset. Other conservative approaches also warrant further investigation.

Rehabilitation 

There are currently no studies investigating the effects of rehabilitation on pre- or postarthroscopic patients. However, graded rehabilitation is generally prescribed to arthroscopy patients for several reasons. The authors here recommend a conservative trial of care presurgically. The search for biomechanical predisposing factors may be of benefit in cases of labral tears. Janda32 has described a predictable pattern of muscular imbalance in the pelvis, known as the lower crossed syndrome. Tightness of the hip flexors and lumbar erector spinae and weak, inhibited gluteal and abdominal muscles characterize lower crossed syndrome. The resultant imbalance leads to anterior pelvic tilt, increased hip flexion, and a hyperlordosis of the lumbar spine. Hip flexion contracture might lead to increased weight-bearing upon the anterior acetabulum and labrum predisposing to tearing. Many patients presenting in the primary setting with low back pain due to lower crossed syndrome can be rehabilitated to correct these aberrant pelvic mechanics. If the patient is participating in high-risk sports, they may be in a position to distribute forces more evenly around the labrum and acetabulum, reducing the risk of tearing.

Dirocco et al33 have noted many impairments after arthroscopy; these include inflammation, pain, swelling, decreased joint mobility, altered muscle extensibility, impaired muscle strength, altered proprioception, and decreased muscle endurance. Rehabilitation protocols should be designed to address these impairments. Manual therapy should be included, given its effects of increasing joint mobility, stretching muscles, and increasing proprioception. It is important to maintain a flexible approach, however, as all patients will have varied needs. The initial period after surgery is focused to decrease pain, decrease effusion, prevent muscle inhibition, promote tissue nutrition and wound healing, maintain proper static joint alignment, increase awareness of joint protection, allow an independent and safe gait with assistive device on all level surfaces and elevations, and increase sitting tolerance.33

An aquatic program is often beneficial allowing early joint mobilization and gentle strengthening in a reduced-weight environment.34 After initial pain relief, all efforts should be focused toward restoring hip ROM through muscle stretch procedures and capsular mobilization. Small accessory oscillation movements stimulate joint mechanoreceptors and assist in pain modulation.34 Faulty movement patterns should also be addressed while improving muscle strength and endurance. Griffin34 states that proprioceptive deficits routinely occur in conjunction with injury to the joint surfaces. This inhibits normal motor response and decreases neuromuscular stabilization of the joint. Thus, proprioceptive retraining is important to restore these deficits and assist in re-establishing neuromotor control. Altered gait and weight-bearing mechanics are likely to predispose to sacroiliac and lumbar spine dysfunction. The lumbopelvic rhythm must be assessed in all patients with altered hip mechanics. Spinal manipulative therapy is likely to be of use in those patients with sacroiliac joint and lumbar spine dysfunction. Abdominal core (transverses abdominus) stabilization exercises are also likely to be of use in restoring correct lumbopelvic biomechanics. With functional progression of the patient comes the introduction of activity-specific exercises and plyometric training with slow return to work or sporting activity. Patients with resection of a labral tear without evidence of articular cartilage involvement may progress more quickly to closed kinematic-chain, weight-bearing exercise and return more quickly to sports or to physically demanding jobs.33 Return to sport is usually possible in 2 to 4 months.

Arthroscopy 

Arthroscopy currently represents the gold standard in both the diagnosis and treatment of labral tears. It is now considered minimally invasive owing to more advanced knowledge of the labrum as well as technique and instrument development. Visual inspection of all quadrants of the joint is possible with arthroscopy.20 Table 2 lists arthroscopic indications and contraindications.

Table 2. Indications/contraindications of hip arthroscopy for a labral lesion

	Indications for hip arthroscopy	Contraindications
	• Loose bodies	• Femoral neck stress fracture, pelvic insufficiency fracture
	• Synovial chondromatosis	• Transient osteoporosis
	• Labral tears	• Osteonecrosis and synovitis without mechanical symptoms
	• Chondral flap lesions of the acetabular or femoral head	• Acute skin lesions
	• Osteonecrosis of the femoral head	• Sepsis with osteomyelitis or abcess formation (open surgery)
	• Ruptured or impinging ligamentum teres	• Joint ankylosis, protrusio limiting hip distraction
	• Collagen disease (RA, SLE, etc) with impinging synovitis	• Advanced osteoarthritis
	• Foreign body removal	• Obesity (relative contraindication)
	• Crystalline hip arthropathy (gout, pseudogout etc)
	• Capsular shrinkage (Ehler-Danlos, etc)
	• After trauma (dislocation, Pipkin fracture, bullet etc)
	• After total hip arthroplasty
	• Intractable pain with positive physical findings
	• Osteoarthritis

For the procedure, the patient is usually placed in either the supine or lateral position, depending on which position the surgeon finds more comfortable. Huffman and Saffran8 and Byrd35 describe their preference of the supine position. McCarthy20 prefers the lateral decubitus position. Once the patient is positioned correctly, the operative leg is distracted in a longitudinal, slight lateral, and caudad vector in line with the femoral neck.8 Byrd35 describes 3 portals in the supine position. The anterior portal lies (on average) 6.3 cm distal to the anterior superior iliac spine and penetrates the muscle belly of the sartorius and rectus femoris before entering through the anterior capsule. The anterolateral portal penetrates the gluteus medius before entering the lateral aspect of the capsule at its anterior margin. The posterolateral portal penetrates both the gluteus medius and minimus before entering the lateral capsule at its posterior margin. The anterior capsule is best visualized through the anterior portal, whereas the posterior labrum is best seen through the posterolateral portal. The initial portal placement is usually the anterolateral portal, as this is located in the so-called safe zone of the hip. In this position, there is limited chance of neurovascular compromise. Once in place, the anterolateral portal can assist in directing the remaining portals. Once labral tears are identified, the surgical portion of the operation is used, which involves minimal debridement of the torn labral segment. It should be noted that there is considerable confusion in the orthopedic literature regarding nomenclature of portals. It would be useful to report a standardized definition of each portal placement.

The short-term results of arthroscopic debridement of labral tears have been favorable. O'leary et al36 reported a 91% success rate in relief of symptoms in a series of 86 patients undergoing arthroscopy. Santori and Villar37 reported more than two thirds of their patients having positive symptomatic relief. Byrd and Jones38 documented the Harris hip score as an outcome measure after arthroscopic labrectomy. It should be noted that the Harris hip score is traditionally used and was designed to assess patients after arthroplasty. They found an average increase of 27 points. Hase and Ueo29 performed arthroscopic surgery to remove the torn and unstable portion of the labrum to note a prompt resolution of symptoms in all patients. McCarthy et al20 related labral tears with relationship to outcome in 62 hips. They classified labral tears according to severity and then correlated this with outcome 2 years after surgery. For minor lesions, they reported 91% to have good to excellent results. The more severe lesions involving labral tearing and subadjacent degrees of acetabular cartilage damage did not fair nearly as well. In hips with marked degenerative change, 78% were associated with a poor result in follow-up, and 43% went on to total joint arthroplasty within 2 years of arthroscopy. Farjo et al39 reported 71% success in patients without evidence of osteoarthritis, and only 21% of arthritic patients reported good results. The poor results of advanced labral tears with diffuse osteochondral defects highlight the need for early diagnosis of labral tears. All of these studies document the arthroscopic short-term outcome. Future research needs to focus on the long-term consequences of partial labrectomy. Because a section of the labrum is excised, the mechanical properties of the structure are altered. Although symptomatic relief is important, partial labrectomy could itself still lead to progression of hip osteoarthritis. Arthroscopic surgery still carries risks; various complications are noted in Table 3. Complications after hip arthroscopy are stated to occur in 1.6% to 5% of cases.35

Table 3. Complications of hip arthroscopy38

	Traction injuries	Distraction type
		Neuropraxia
		Femoral nerve
		Sciatic nerve
		Lateral femoral cutaneous nerve
		AVN femoral head
		Compression type
		Neuropraxia
		Pudendal nerve
		Scrotal necrosis
		Labia majora hematoma
	Inadequate traction injuries	Cartilage scruffing (gouging)
		Labral avulsion
	Fluid injuries	Extravasations
		Intra-abdominal/thigh
	Infection	Deep
		Superficial
	Instruments	Breakage
	Late	Heterotopic ossification

AVN, avascular necrosis.