Diagnosis and Treatment of Labral Tear

Diagnosis and Treatment of Labral Tear

The acetabular labrum is a critical structure in the hip joint, playing a significant role in joint stability, lubrication, and the prevention of premature arthritis. Labral tears, which can result from various etiologies such as femoroacetabular impingement (FAI), trauma, dysplasia, capsular laxity, and degeneration, have become increasingly diagnosed with advancements in imaging techniques and arthroscopy. This article provides a comprehensive review of the anatomy, function, etiology, diagnosis, and management of acetabular labral tears, drawing from a systematic review of the literature.

Anatomy and Function of the Labrum

The acetabular labrum is a triangular fibrocartilage structure attached to the acetabular rim almost circumferentially, transitioning into the transverse acetabular ligament at the acetabular notch. The anterior portion of the labrum is wider and thinner, while the posterior labrum is thicker, forming a sulcus that can be mistaken for pathology. The labrum is innervated, with the most concentrated innervation in the anterosuperior part, consisting of free nerve endings and sensory nerve end organs. The blood supply to the labrum is circumferential, originating from the obturator, superior gluteal, and inferior gluteal arteries, with the peripheral one-third being vascular and the articular side avascular.

The labrum deepens the acetabulum, increasing the articular surface by 22% and the acetabular volume by 33%. It creates a vacuum with negative pressure, enhancing joint stability and retaining fluid within the central compartment to lubricate the joint and distribute contact forces evenly across the articular surface, preventing early arthritic wear.

Etiology of Labral Tears

Labral tears are most commonly secondary to FAI, a condition characterized by deformity of the acetabulum, femoral head, or both. FAI is classified into cam, pincer, and mixed types. Cam type involves a bony protrusion at the anterolateral head-neck junction, causing shear force on the adjacent articular cartilage and leading to chondrolabral delamination. Pincer type involves over-coverage of the femoral head by the acetabulum, leading to linear contact and breakdown of the labrum and adjacent cartilage. Mixed type presents deformities of both the femur and acetabulum.

Other causes of labral tears include significant trauma, capsular laxity, dysplasia, and degeneration. Trauma can cause subluxation or dislocation of the femoral head, often associated with chondral injuries. Capsular laxity, related to collagen disorders or hormonal influences, can lead to rotational instability and increased pressure on the anterior superior labrum. Dysplasia involves bony abnormalities such as a shallow acetabulum, reduced acetabular or femoral anteversion, acetabular retroversion, and decreased head offset, leading to decreased joint surface area and increased stresses on the labrum. Degeneration is a natural history of aging joints.

Symptoms and Physical Examination

Patients with labral tears commonly complain of anterior hip or groin pain, which may radiate to the knee. The pain is often gradual in onset, occurring at night and described as a constant dull ache that worsens with activities such as walking, pivoting, prolonged sitting, and running. Mechanical symptoms include clicking, locking, catching, or giving way.

The most specific physical examination finding is a positive anterior hip impingement test, performed with the hip and knee flexed to 90°, adduction, and internal rotation of the symptomatic hip. Pain in the anterolateral hip or groin suggests an anterior labral tear. Other less-specific tests include the Patrick/Faber test, resisted straight leg raise test, Log-roll test, and apprehension test.

Imaging Evaluation

Radiographic evaluation is essential to identify underlying structural abnormalities. Standard radiographs include an AP pelvis and a cross-table lateral view of the affected side. The AP pelvis radiograph helps evaluate dysplasia and pincer FAI, while the cross-table lateral view provides an accurate view of femoral head-neck offset.

Magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) are used to evaluate chondral and labral lesions. Standard MRI has low sensitivity and accuracy for labral pathology, while MRA, with intra-articular or systemic gadolinium infusion, provides better detail. Radial MRI, performed with a plane perpendicular to the acetabular rim, is also utilized to evaluate the labrum.

Conservative Treatment

Initial conservative treatment for suspected labral tears includes rest, non-steroidal anti-inflammatory medication, pain medications, activity modification, physical therapy (PT), and intra-articular injection (IAI). A 12-week PT protocol focusing on pain control, trunk stabilization, muscle strengthening, and movement correction has shown good outcomes in some patients. IAI, containing an anesthetic agent and corticosteroid, can provide diagnostic and therapeutic benefits, with studies showing positive responses in a significant percentage of patients.

Surgical Treatment

When conservative treatment fails, surgical intervention is often indicated. Surgical options include labral debridement, labral repair, and labral reconstruction.

Labral Debridement

Labral debridement involves removing the torn portion of the labrum to alleviate pain. While short-term outcomes have been favorable, labral debridement is generally inferior to labral repair due to the loss of the suction seal effect. Selective debridement with labral preservation (SDLP) has shown favorable outcomes in specific cases, particularly when the labral base is stable and the labral width is at least 4mm.

Labral Repair

Labral repair is increasingly favored over debridement due to the importance of preserving the labrum’s role in joint stability and preventing premature arthritis. Techniques include looped repair and labral base refixation, with studies showing no significant difference in outcomes between the two. An eversion-inversion labral repair technique has been introduced to optimize the suction seal effect, with favorable outcomes reported.

Labral Reconstruction

Labral reconstruction is indicated when the labrum is deemed irreparable due to insufficient tissue or previous debridement. Reconstruction can be performed using autografts (e.g., iliotibial band, ligamentum teres capitis, gracilis tendon) or allografts. Surgical dislocation and arthroscopic techniques are used, with all-arthroscopic harvest and reconstruction showing potential advantages in reducing scarring and post-operative pain. Studies have reported good outcomes with labral reconstruction, though long-term follow-up is needed to confirm its efficacy.

Summary

The acetabular labrum is crucial for hip joint stability and preventing premature arthritis. Labral tears, often secondary to FAI, trauma, dysplasia, capsular laxity, and degeneration, require accurate diagnosis and appropriate management. Conservative treatment includes rest, PT, and IAI, while surgical options range from debridement to repair and reconstruction. Labral repair is increasingly preferred for preserving the labrum’s function, while labral reconstruction shows promise for irreparable tears. Further research is needed to establish long-term outcomes and optimize treatment strategies for labral tears.

doi.org/10.1097/CM9.0000000000000020

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