Fact-sheet: Acetabular labral tear
Updated on 09/30/2019 at 6:17 PM
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Definition
The acetabular labrum is a triangular fibrocartilaginous structure, presenting:
- a base adherent to the acetabular bone with a direct insertion onto the periosteum,- an articular edge, extending the acetabular articular surface, in continuity with the hyaline cartilage,- a capsular edge corresponding to the supralabral recess and the capsular insertion,- a free edge in contact with the femoral head.
No tendinous or ligamentous insertion.
The labrum measures between 6 and 12 mm, and is wider in its posterosuperior portion. It is richly innervated.
Acetabular labral tear may be partial or full-thickness.
Etiologies:
- Hip dysplasia,- Femoroacetabular impingement, - Hip trauma,- Degenerative lesions,- Conflict with the iliopsoas tendon, - Hypermobility, laxity: controversial.- Young patients with no history or predisposing factors.
- Various conditions: arthritis, femoral head osteonecrosis, Legg-Calvé-Perthes disease, slipped capital femoral epiphysis
Clinical features
Mainly affects athletes aged 20 to 50.
Beyond 50 years of age, lesions are common, mainly related to degenerative changes.
Clinical presentation: Anterior groin pain of mechanical rhythm, with perception of an audible or palpable click. Pain reproduced on moving from flexion, external rotation and abduction toward extension, internal rotation and adduction when the lesion involves the anterior portion of the labrum.
Opposite movement when the posterior portion of the labrum is affected.
Radiography
Near-normal radiograph.
Search for associated lesions (fracture, osteoarthritis)
or predisposing causes (hip dysplasia, femoroacetabular impingement).
MRI
MR arthrography or CT arthrography +++
4 quadrants:
- anterosuperior (0–3 o'clock),
- anteroinferior (3–6 o'clock),
- posteroinferior (6–9 o'clock),
- posterosuperior (9–12 o'clock).
A labral tear corresponds to a discontinuity of the labrum, partial or complete, simple or complex, opacified by contrast material.
Radial: perpendicular to the axis of the labrum.
Longitudinal: parallel, cleavage type. Longitudinal tears at the base of the labrum are referred to as detachment.
Location: anterosuperior labrum, between 1 and 2 o'clock, i.e., in the area of maximal mechanical stress.
Posterosuperior tears are mainly observed in young, athletic patients, likely posttraumatic in origin.
Isolated labral tear at 3 o'clock: suggestive of conflict with the psoas tendon.
Pitfalls:
- Perilabral recess: groove between the transverse ligament and the anterior labrum.
- Sublabral recess: at the base of the posteroinferior labrum.
- Os acetabulare: nonfusion of one of the epiphyses of the acetabular rim. No passage of contrast material between the os acetabulare and the acetabulum.