A gluteal muscle tear or strain frequently occurs during sports activities or while performing running or jumping activities. Its diagnosis is challenging and is often based on non-specific clinical findings [1,2]. In the current report, we describe the case of a patient with a gluteus maximus muscle tear that was confirmed by ultrasonography (US) and magnetic resonance imaging (MRI). Case This study was approved by the Institutional Review Board (IRB) of the Yeungnam University Hospital (IRB No: 2020-06-066). All authors declare that written informed consent was obtained from the patient for publication of this case report and accompanying images.

A 77-year-old woman having back pain due to an L2 vertebral body compression fracture took a lumbar spine magnetic resonance imaging (MRI). In MRI, in addition to the L2 vertebral body fracture, invagination of the small intestine into the intervertebral disc space at L5-S1 was found by chance. On a lateral lumbar spinal X-ray, the lordotic angle was markedly increased at the L5-S1 level. Additionally, the L5-S1 disc space had widened. These X-ray findings indicate the segmental instability at L5-S1. The spinal fusion operation on L3-4-5 seems to have resulted in overt mechanical loading on the inferior spinal segment (L5-S1). We think the instability damaged the anterior longitudinal ligament and caused a tear in the anterior portion of the annulus fibrosus. The defect in the L5-S1 intervertebral disc after the tear would have caused the vacuum, which is presumed to have pulled the patient’s small intestine into the empty space within the L5-S1 intervertebral disc. Although intervertebral invagination of intra-abdominal structures is not common, clinicians should be aware of the possibility of this complication in patients who have spinal segmental instability.