Ischiopubic synchondrosis asymmetry

Last revised by Joshua Yap on 23 Apr 2023

Ischiopubic synchondrosis asymmetry (van Neck-Odelberg disease) is the characteristic enlargement of one of the ischiopubic synchondroses. It is largely considered an anatomic variant of skeletal development, given that it is a common and usually asymptomatic finding.

However, some cases are thought to be symptomatic and may correspond to MRI findings that suggest a stress reaction 7,8.

Occurs in all children before puberty during fusion of the pubic and ischial bones 3

Most cases of ischiopubic synchondrosis asymmetry are observed in asymptomatic patients. Symptomatic cases are described as presenting with groin or buttock pain in ambulatory, pre-pubertal children 7,8.

In younger children, the ischio-pubic synchondroses are symmetrically enlarged. Prior to fusion, enlargement may persist in the non-dominant leg due to greater mechanical stress. For example, in footballers, mechanical stresses are greater in the weight-bearing leg compared to the kicking leg. This causes a stress reaction in the synchondrosis. Similarly, preferential weight-bearing can cause asymmetrical enlargement contralateral to unilateral painful hip conditions 3

Recognition of an entity as a normal variant is important for radiologists when interpreting a pediatric pelvic radiograph. One of the key questions to ascertain is whether the region is painful or not:

  • if asymptomatic and there is no concerning antecedent history

    • it is unlikely to represent a sinister pathology other than just a developmental variant

  • if symptomatic or if there is a concerning antecedent history

    • it could still be a developmental variant although other important differential considerations should also be considered

Ischiopubic synchondrosis can be avid on bone scintigraphy 10 and FDG PET-CT.

On imaging alone, the condition can mimic many other pathological entities including:

The preceding clinical history is crucial in image interpretation.

The condition is named after M van Neck and A Odelberg who initially described these findings in 1924 4,5.

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