Quiescent Andersson Lesion Simplifies Deformity Correction: A Case Report.

Case: We present a case of ankylosing spondylitis with sagittal imbalance and having a suspicious Andersson lesion (AL) on magnetic resonance imaging (MRI) at D12-L1. The segment did not reveal any potential mobility on erect radiographs and supine MRI. L2 pedicle subtraction osteotomy was planned. However, intraoperatively after positioning, the AL widely opened up. This made us reassess the treatment strategy; an interbody fusion was performed, and the correction was achieved using a cantilever mechanism without performing an osteotomy.

Conclusion: A quiescent AL can affect preoperative planning. However, understanding the pathology, reassessing the situation, and reformulating the plans intraoperatively resulted in a successful outcome.