In Reply: The Role of Pelvic Compensation in Sagittal Balance and Imbalance: The Impact of Pelvic Compensation on Spinal Alignment and Clinical Outcomes After Adult Spinal Deformity Surgery

To the Editor: First, we thank the editor for giving us an opportunity to respond to the letter written by Dr Noor et al.1 We appreciate the interest shown by Dr Noor and colleagues in our recent publication on the role of pelvic compensation in sagittal balance and imbalance.2 Their letter highlights significant points that complement and extend the findings of our study. We are pleased to provide detailed responses to their observations and suggestions. RECOGNITION OF THE STUDY'S CONTRIBUTIONS We are grateful for the acknowledgment of our work's importance in elucidating the role of pelvic compensation in surgical outcomes for patients with adult spinal deformity (ASD). Our study aimed to fill gaps in the current understanding of pelvic compensation's impact on sagittal balance (SB) and imbalance and to provide insights that can inform clinical practices and future research. SAGITTAL BALANCE OBSERVATIONS The authors correctly note that our study found analogous performance in the SRS-22r domains at baseline and follow-up for both failed pelvic compensation (FPC) and successful pelvic compensation groups under preoperative SB conditions. This finding underscores the complexity of sagittal alignment and the multifactorial nature of its clinical outcomes. Despite their more severe preoperative sagittal deformity, the superior postoperative alignment observed in the successful pelvic compensation group suggests that patients with effective pelvic compensation mechanisms are better positioned for favorable radiographic outcomes. These results support the need for individualized treatment plans that consider the unique compensatory capacities of each patient. RESTORING SPINOPELVIC BALANCE We concur with the emphasis on achieving optimal SB to enhance functional outcomes and health-related quality of life. The goal of spinal deformity surgery is not only to correct anatomic abnormalities but also to restore functional alignment that supports daily activities and reduces pain. The concept of “dynamic sagittal balance” introduced by the authors is particularly relevant as it highlights the importance of considering patient movement and postural changes in surgical planning.3,4 Future studies should focus on integrating dynamic assessments into preoperative evaluations to better predict and improve postoperative outcomes. DYNAMIC SAGITTAL IMBALANCE The authors' points about considering dynamic gait patterns and compensatory mechanisms are well-taken. Our study primarily focused on static radiographic parameters, but we recognize the significance of dynamic assessments. Parameters observed during walking, as compared with standing, can provide valuable insights into the compensatory mechanisms at play. Incorporating these dynamic factors into preoperative planning could help tailor surgical interventions to better address the functional needs of patients with ASD.5,6 MULTIFACTORIAL NATURE OF FPC We acknowledge the multifactorial nature of FPC and the need for comprehensive evaluation. The degeneration of paraspinal muscles, as highlighted by Dr Han et al,7 is one of many potential factors contributing to FPC. Our study identified a low Pelvic Tilt/Pelvic Incidence ratio as an indicator of FPC, but we agree that a holistic approach is necessary to fully understand and address the underlying causes. Future research should explore the interactions between muscular degeneration, spinal alignment, and pelvic compensation to develop more effective treatment strategies. FUTURE RESEARCH ON SEVERE DSI We appreciate the recommendation for further analysis of patients with severe dynamic sagittal imbalance. The criteria provided by Dr Kim et al offer a valuable framework for identifying and managing severe cases.8 We also thank Dr Md Moshiur Rahman and colleagues for their thoughtful letter and valuable contributions to the discussion. Their insights and suggestions will undoubtedly guide future research and improve clinical practices in the management of ASD.