In this case series, we evaluated the potential of ligament reconstruction combined with open midline decompression following lumbar fusion surgery to mitigate adjacent segment disease (ASD). The focus is on its capacity to reduce mechanical stress on adjacent segments and support spinal biomechanics. This retrospective case series included 32 patients with a mean follow-up of 19 months. Radiological ASD was observed in 4 cases (12.5%), while no ASD was detected in 28 cases (87.5%). Among the cases of ASD, none required reoperation, and only 1 patient underwent additional surgery. Postoperative clinical outcomes showed significant improvement. Facet arthrodesis was identified in 7 cases (21.9%), and cortical calcification around the facet joint was noted in 5 cases (15.6%). Ligament reconstruction and open midline decompression provide dynamic stabilization by reducing hypermobility and mechanical stress on adjacent segments, which may help to mitigate the risk of adjacent segment disease (ASD) following lumbar fusion surgery. This case series demonstrated a lower-than-expected incidence of radiological ASD and favorable clinical outcomes, suggesting that ligament reconstruction could serve as an effective motion-preserving alternative to traditional fusion, particularly for patients with high ASD risk.