Physeal bar

Physeal bars are interruptions of the normal growth plate cartilage, due to the formation of a bony or fibrous bridge between the epiphysis and metaphysis. Left untreated, physeal bars can cause abnormal bone angulation or limb length discrepancies.

Physeal bars are not initially clinically apparent, and may only be appreciated on imaging. If left untreated, they may cause limb shortening or abnormal bone angulation.

Physeal bars can be classified into three categories 1:

  • peripheral: causes angular deformity
  • linear: causes angular deformity
  • central: causes longitudinal growth retardation
Aetiology
  • trauma
  • infection
  • radiation
  • post-corticosteroid therapy
  • vascular insults
  • metabolic disorders
  • tumour infiltration
Plain radiograph

Plain film is an unreliable modality for evaluating physeal bars. Nevertheless, an established physeal bar can be demonstrated by the presence of focal bone density bridging across the normally lucent physis.

Sequelae of physeal bars, such as bone angulation, epiphyseal displacement and blurring of the physeal borders may also be seen 1.

CT

Physeal bars can be appreciated as high attenuation bone bridges present across the normally low attenuation physis on CT. Early formation of fibrous bars may be missed 1

Sequelae of physeal bars such as bone angulation can also be clearly seen. 

MRI

MRI can detect both early (fibrous) bars, and established bone bridges. 3D gradient echo sequences with T1 fat-sat weighting are used to perform physeal bar mapping 2,3.

Signal characteristics
  • T1
    • established physeal bars contain bone marrow and therefore appear as hyperintense bridges between the hyperintense epiphyseal and metaphyseal marrow
    • early fibrous bars appear as lower signal
  • T1 fat-sat
    • physeal bar appears as a focal low intensity bridge within the hyperintense growth plate
  • T2/T2*
    • physeal bar appears as a focal low intensity area within the normally high signal physeal cartilage

Accurate mapping and sizing of a physeal bar is important for directing management. The aim of treatment is to avoid deformity and limb length discrepancy.

Small bars (<30% of the physis) are managed conservatively. Medium sized bars (30-50%) require excision of the bar. Larger bars (>50%) are usually managed with more extensive surgery 4.

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Article information

rID: 47641
Section: Pathology
Tag: cases
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