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, along the undersurface of the inferior pubic ramus, seen on coronal fluid-sensitive MRI sequences or at symphyseal contrast injection. It indicates a microtear at the attachment of the short adductor muscles, adductor brevis, gracilis and pectineus, to the inferior pubic ramus, and is a marker of the athletic pubalgia and osteitis pubis spectrum, typically in footballers and other athletes performing repeated kicking, cutting and pivoting. It is distinct from the superior cleft sign, a parallel fluid cleft along the superior pubic ramus that marks a tear of the rectus abdominis-adductor longus aponeurotic plate, though the two frequently coexist. 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, symphyseal degeneration with irregularity, sclerosis and widening of the joint in chronic cases, and the associated inguinal wall deficiency seen in the sports hernia. 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 short adductor muscles, adductor brevis, gracilis and pectineus, take origin from the body and inferior ramus of the pubis just below the symphysis, and repetitive eccentric loading during kicking and pivoting shears this enthesis against the fixed bone. Microtears fill with fluid and extend from the primary cleft inferolaterally along the line of the short adductor origin, producing the secondary cleft. 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. A parallel process at the rectus abdominis-adductor longus aponeurotic plate on the superior pubic ramus produces the related superior cleft sign.

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

Other associated named signs: Osteitis pubis marrow oedema and the superior cleft sign of rectus abdominis-adductor longus aponeurotic plate injury

References

1. Cunningham PM, Brennan D, O’Connell M, MacMahon P, O’Neill P, Eustace S. Patterns of bone and soft-tissue injury at the symphysis pubis in soccer players: observations at MRI. AJR Am J Roentgenol. 2007;188(3):W291-6. PMID: 17312039.