Index-level fusion and adjacent segment disease following dynamic stabilization for lumbar degenerative disc disease: illustrative case

BACKGROUND Dynesys dynamic stabilization (DDS) is an alternative to surgical fusion for the operative management of degenerative lumbar spondylosis. Compared to rigid instrumentation and fusion, DDS is purported to preserve a higher degree of spinal range of motion and reduce the risk of developing adjacent segment disease (ASD). OBSERVATIONS A 60-year-old female presented with severe back pain and bilateral leg pain, which had progressed over the prior 4 years. Nine years earlier, she had undergone DDS system implantation at L5-S1 for lumbar stenosis and spondylosis. Repeat imaging revealed an unintended fusion at the index level (L5-S1) and ASD causing severe lateral recess stenosis at L4-5. She underwent DDS system removal, decompression at L4-5, and extension of the fusion to L4. LESSONS Although DDS has been marketed as a motion-preserving system that avoids fusion and reduces the risk of ASD, unintended index-level fusion and ASD can still occur after DDS system surgery. These potential complications should be assessed when determining the optimal primary surgical treatment for patients with lumbar degenerative disc disease.