Oppenheimer ossicle

Last revised by Matt Skalski on 31 Oct 2022

Oppenheimer ossicles are accessory ossicles associated with the facet joints and are found in ~4% (range 1-7%) of lumbar spines 1

Oppenheimer ossicles predominantly occur as a single, unilateral ossicle of the inferior articular processes of the lumbar spine although they can also occur at the superior articular process ref.

Best seen on sagittal CT and MR images and can be easily mistaken on thick axial slices. 

Oppenheimer ossicles are seen in the lumbar spine, most notably at L2 and L3 levels 2. They appear as smoothly corticated structures that may sometimes be lined by articular cartilage. The synovial space of the adjacent facet joint may communicate with the cleft between the ossicle and the articular process 2

They may be associated with other neural arch malformations, such as articular process hypoplasia 2

Oppenheimer ossicles are thought to arise as a result of the non-union of an articular process secondary ossification center. These ossicles should fuse between the ages of 17 and 25 years ref

Oppenheimer nodules were first described by Albert Oppenheimer in 1942 3.

  • usually asymptomatic and discovered incidentally on imaging 2.
  • not to be confused with an articular process fracture: an Oppenheimer ossicle will demonstrate regular, well-defined corticated margins

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Cases and figures

  • Figure 1: illustration
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  • Case 1: arrowed
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  • Case 2
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  • Case 3
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  • Case 4a: sagittal (arrowed)
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  • Case 4b: coronal (arrowed)
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  • Case 5
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