Secondary cleft sign | Radiology Signs

Answer:

The secondary cleft sign is a linear fluid-signal cleft extending inferolaterally from the normal primary cleft of the pubic symphysis, seen on coronal fluid-sensitive MRI sequences or at symphyseal contrast injection. It indicates a microtear at the attachment of the adductor longus and the rectus abdominis aponeurosis to the pubis and is a marker of the athletic pubalgia and osteitis pubis spectrum, typically in footballers and other athletes performing repeated kicking, cutting and pivoting. Reporting should place the cleft in context with the rest of the pattern described in the imaging literature: bone marrow oedema in the pubic bodies, disruption or thickening of the rectus abdominis-adductor aponeurotic plate, tendinopathy or partial tearing of the adductor longus origin, and the associated inguinal wall deficiency seen in the sports hernia. Symphyseal degeneration with irregularity, sclerosis and widening of the joint is often present in chronic cases. The differentials that must be excluded before a diagnosis of athletic pubalgia are femoroacetabular impingement with labral tear, which frequently coexists and may be the true source of groin pain, stress fracture of the pubic rami or femoral neck, hip osteoarthritis, and inguinal or femoral hernia. Treatment is usually conservative with targeted rehabilitation, with surgery reserved for refractory cases.

Why is it called so?

The cleft is called secondary because it extends from the normal primary fibrocartilaginous cleft of the symphysis.

Pathophysiology

The pubic symphysis is a fibrocartilaginous joint with a normal central cleft in adults. The rectus abdominis and the adductor longus insert on the pubis as a common aponeurotic plate that crosses the anterior symphysis, and these two muscles pull in opposite directions, the rectus superiorly and the adductor inferolaterally. Repetitive eccentric loading during kicking and twisting shears this plate at its bony attachment, producing microtears that fill with fluid and extend from the primary cleft along the line of the adductor origin. The same shear stresses the subchondral bone, causing the marrow oedema and eventually the sclerosis and irregularity of chronic osteitis pubis, which is why the bony and soft tissue findings occur together.

Alternative names: Cleft sign of the symphysis; adductor microtear cleft

Other associated named signs: Osteitis pubis marrow oedema and the rectus-adductor aponeurotic plate injury of athletic pubalgia

References

1. Zoga AC, Kavanagh EC, Omar IM, Morrison WB, Koulouris G, Lopez H, et al. Athletic pubalgia and the “sports hernia”: MR imaging findings. Radiology. 2008;247(3):797-807. PMID: 18487535.