The Clinical Significance of L5 Incidence in Patients with High Pelvic Incidence: A Case Report
Objective: To present a case of sagittal malalignment with high pelvic incidence and its surgical management. Summary of Background Data: Though rare, patients with high pelvic incidence (PI) around 90° without spondylolisthesis or spondylolysis often show sagittal malalignment with low back pain. However, little has been reported about the treatment of such cases. Methods: We report a case of a 15-year-old female complaining of severe difficulty in maintaining an upright position and gait disturbance due to back pain. Radiographs showed high PI of 88° and L5 incidence (L5I) of 67° combined with hyperlordosis of lumbar segments. A lower Lordosis Distribution Index (LDI; percentage of lordosis on segments L4–S1 in entire lumbar lordosis of L1-S1) was detected despite the high overall lumbar lordosis. The patient was surgically treated by two-stage combined posterior and anterior short fusion from the sacrum. Results: The surgical strategy was planned with attention to L5I instead of PI. L5I decreased to 49° and sagittal alignment of the whole spine—including cervical, thoracic, and lumbar spine—improved without any complications. Activity of daily living (ADL)improved preoperatively with relief of low back pain. Conclusions: Improvement of L5I by performing short fusion from L4 to S1 may be a strategy for patients with high PI complaining of low back pain due to sagittal malalignment.