Lumbar Arthroplasty Core Herniation Presenting With Cauda Equina Syndrome: Case Report of a Rare Complication

BACKGROUND: Treatment failures of artificial disc implantation are well-described, but posterior herniation of the arthroplasty core is rare. We present a case of posterior herniation of the arthroplasty core resulting in cauda equina syndrome in a 36-yr-old woman. Preoperative imaging studies including computed tomography (CT), magnetic resonance imaging (MRI), and CT Myelogram were performed; only the CT Myelogram demonstrated the severe compression well. This report highlights the radiographic findings on multiple imaging modalities, clinical implications, and management considerations of posterior arthroplasty failures. OBJECTIVE: To demonstrate a rare complication of lumbar arthroplasties. The biomechanical considerations, surgical management, and thorough radiographic work-up demonstrate successful diagnosis and treatment of this unusual complication. METHODS: The patient's chart was reviewed for medical history, laboratory and radiographic studies, and outpatient clinical follow-up. RESULTS: After imaging work-up, this patient was found to have a herniation of the arthroplasty core at L5-S1. She was taken emergently to the operating room for a decompression at L5-S1 and arthroplasty core removal. She made some recovery neurological, but over 3 mo time, she developed a spondylolisthesis with new back pain and radiculopathy. This ultimately responded well to an L5-S1 instrumented posterior fusion. CONCLUSION: Posterior herniation of the lumbar arthroplasty core is a rare complication from implantation of an artificial lumbar disc. Confirmation of the diagnosis is best confirmed with a CT Myelogram. Furthermore, this case underscores the biomechanical importance of the artificial disc given the development of the spondylolisthesis after removal, and fusion after arthroplasty core removal should be considered.