Labral Tears
See The Acetabular Labrum for more information regarding the anatomy and functions of the acetabular labrum.
To recap: The acetabular labrum is a fibrocartilaginous structure attached to the rim of the acetabulum. It deepens the socket, increases femoral-head coverage and contributes to hip stability. The labrum also forms a suction seal around the femoral head, helping maintain intra-articular fluid pressure, distribute load and protect the adjacent articular cartilage
An acetabular labral tear is a structural disruption of the labral tissue or its attachment at the chondrolabral junction, the interface between the labrum and acetabular articular cartilage.
Labral abnormalities range from:
- Mild fraying or degeneration
- Partial separation from the acetabular rim
- Intrasubstance cleavage
- Unstable flap tears
- Complete detachment
- Ossification or severe deficiency
Labral tears are not necessarily isolated lesions. They frequently occur secondary to an underlying structural abnormality of the hip and should therefore prompt consideration of the mechanical cause rather than treatment of the torn tissue alone.
FAIS is one of the most important causes of labral injury.
- Cam morphology produces shear at the chondrolabral junction and may separate the labrum and adjacent cartilage from the acetabular rim.
- Pincer morphology causes repetitive compression of the labrum between the acetabular rim and femoral neck.
- Combined morphology may produce features of both mechanisms.
Generalized ligamentous laxity, repetitive rotational loading, or capsular insufficiency may increase femoral-head translation and place excessive stress on the labrum. Although it is important to note that degenerative labral tearing may occur alongside progressive chondral damage and osteoarthritis. In this setting, the tear may represent part of generalized joint degeneration rather than an isolated, surgically correctable lesion.
Most clinically relevant tears occur in the anterosuperior region of the acetabulum, where mechanical stresses from flexion and rotation are commonly concentrated.
Location is conventionally described using an acetabular clock face:
- 12 o’clock: superior
- 3 o’clock: anterior
- 6 o’clock: inferior
- 9 o’clock: posterior
In addition, tears can also be classified as:
- Chondrolabral separation: detachment at the junction of the labrum and acetabular cartilage
- Intrasubstance tear: cleavage within the body of the labrum
- Radial or flap tear: a tear extending through the labral substance, sometimes creating an unstable fragment
- Degenerative tear: fraying, thinning or complex disruption of poor-quality tissue
- Complete or unstable detachment: substantial separation of the labrum from the acetabular rim
The classic Seldes classification broadly distinguishes:
- Type I: separation at the chondrolabral junction
- Type II: one or more intrasubstance cleavage planes
A torn labrum may become painful through mechanical instability and stimulation of sensory nerve endings within the labral tissue. The anterosuperior and posterosuperior labrum contain particularly abundant free nerve endings and sensory structures.
Structural disruption can also:
- Reduce the effectiveness of the suction seal and thus affect the intra-articular fluid pressurization
- Increase femoral-head translation
- Increase contact stress across the articular cartilage thus contributing to progressive chondral damage
The consequences depend on tear size, orientation, tissue quality and the underlying bony anatomy. Biomechanical studies suggest that radial tears may produce greater instability than a simple chondrolabral separation, although the clinical importance of each pattern must be considered in the context of the entire hip.
Labral pathology is commonly encountered during hip arthroscopy. The operative objective is not simply to remove visibly abnormal tissue, but to restore a stable labral attachment and functional suction seal while addressing the underlying cause of injury.
Broad arthroscopic options include:
- Labral repair
- Selective debridement
- Labral augmentation
- Labral reconstruction
Modern hip-preservation practice generally prioritizes preservation or restoration of viable labral tissue. Repair is preferred when sufficient healthy tissue remains. Reconstruction may be considered when the labrum is irreparable, severely deficient or extensively ossified. Detailed indications and techniques belong in the later chapters on labral repair and reconstruction.
A critical principle is that treatment of the labrum alone may fail when the causative morphology, instability, dysplasia or cartilage disease is not recognized and addressed.
References
- Seldes RM, Tan V, Hunt J, Katz M, Winiarsky R, Fitzgerald RH Jr. Anatomy, histologic features, and vascularity of the adult acetabular labrum. Clin Orthop Relat Res. 2001;(382):232-240. Read on Rounds
- Lage LA, Patel JV, Villar RN. The acetabular labral tear: an arthroscopic classification. Arthroscopy. 1996;12(3):269-272. Read on Rounds
- Groh MM, Herrera J. A comprehensive review of hip labral tears. Curr Rev Musculoskelet Med. 2009;2(2):105-117. Read on Rounds
- Kelly BT, Shapiro GS, DiGiovanni CW, Buly RL, Potter HG, Hannafin JA. Vascularity of the hip labrum: a cadaveric investigation. Arthroscopy. 2005;21(1):3-11. Read on Rounds
- Philippon MJ, Nepple JJ, Campbell KJ, et al. The hip fluid seal—Part I: the effect of an acetabular labral tear, repair, resection, and reconstruction on hip fluid pressurization. Knee Surg Sports Traumatol Arthrosc. 2014;22(4):722-729. Read on Rounds
- Alzaharani A, Bali K, Gudena R, et al. The innervation of the human acetabular labrum and hip joint: an anatomic study. Bone Joint J. 2014;96-B(1):38-43. Read on Rounds
- Hartigan DE, Perets I, Walsh JP, Domb BG. Biomechanics, anatomy, pathology, imaging and clinical evaluation of the acetabular labrum. SICOT J. 2018;4:16. Read on Rounds