Single-Level Posterior Lumbar Interbody Fusion for Scoliosis Associated With Postural Imbalance and Low Back Pain: A Case Report.

Elderly patients often experience a severely impaired quality of life due to chronic pain and truncal shift. While spinal deformities primarily caused by radiculopathy secondary to degenerative diseases can often be managed with focal intervention, they are frequently misdiagnosed as permanent structural issues. This radiculopathy-induced "antalgic scoliosis" presents a significant diagnostic challenge; identifying and treating the localized pain trigger may allow patients to avoid extensive reconstructive surgery. We report the case of a 66-year-old female with pre-existing degenerative scoliosis who presented with an acute, severe exacerbation of coronal imbalance. A diagnostic selective nerve root block provided transient but complete relief of both pain and truncal tilt, confirming the L4 nerve root as the primary antalgic driver of the coronal malalignment. A single-level posterior lumbar interbody fusion (PLIF) at L4/5 achieved immediate restoration of global coronal and sagittal alignment and significant improvement in radiographic parameters. Identifying focal triggers of antalgic posture via selective blocks is crucial; targeted single-level fusion can occasionally resolve global imbalance, sparing elderly patients from the significant morbidity associated with extensive reconstructive surgery.