Improvement in spinopelvic parameters after laminectomy and complete factectomies above prior fusion facilitated by posterior arthroplasty: illustrative case.

backgroundPatients with adjacent segment degeneration after previous lumbar fusion often present with flat back posture. However, it is sometimes unclear if the flat back results from stenosis above the fusion or from structural spinal deformity. The authors illustrate the case of a patient who refused further fusion and asked for decompression only coupled with posterior arthroplasty. They demonstrate his change in sagittal alignment despite absence of a three-column osteotomy. OBSERVATIONS: A 72-year-old man with a previous lumbar fusion presented with 1 year of progressive neurogenic claudication and radiculopathy. Imaging revealed flat back syndrome with positive sagittal balance and adjacent segment disease with severe stenosis at L2-3. The patient was recommended to undergo a three-column osteotomy, but he refused another fusion surgery. He requested decompression and posterior arthroplasty at L2-3, with the understanding that his flat back syndrome would not be treated. Following surgery, the patient's preoperative symptoms improved, and, surprisingly, postoperative radiographs revealed a 6.7-cm improvement in sagittal balance. LESSONS: Alleviation of lumbar stenosis not only provided symptomatic relief but also improved this patient's sagittal imbalance, illustrating the contribution of lumbar stenosis to sagittal imbalance. Laminectomy with total factectomies was facilitated by the posterior arthroplasty device, which prevented pathological motion despite the destabilizing decompressive procedure. https://thejns.org/doi/10.3171/CASE25565.