Introduction: Sagittal balance in adult spinal deformity is a major predictor of preoperative clinical symptoms and postoperative improvement in quality of life. Factors that influence postural control may influence sagittal balance. A temporary loss of paraspinous muscle force and postoperative somatic pain may limit the ability to maintain erect posture. We sought to assess the evolution of sagittal balance and clinical outcomes during recovery from adult spinal deformity surgery.

Methods: A prospective database identified a consecutive series of patients undergoing surgery for adult deformity with a SVA >40mm. Radiographic parameters and clinical outcomes were measured preoperatively, postoperatively and at 6 weeks, 3 months, 6 months, one year and two year.

Results: 113 consecutive patients met inclusion criteria. Mean preoperative SVA was 90.3mm,increased to 104.6mm in the first week, then gradually reduced at each follow-up interval to 59.2mm at 6 weeks, 45.0mm at 3 months, 38.6mm at 6 months, and 34.1mm at one year (all p<0.05). The change in SVA between one and two years was not statistically significant (34.6 mm to 36.1 mm, p=0.83). Mean VAS back and leg pain decreased from 7.05 and 5.51 to 2.91 and 2.86 at one year, respectively (both p<0.01). Mean modified ODI decreased from 47.1 to 18.6 at one year (p < 0.01). Mean SF-36 PCS and MCS scores at one year improved from 32.3 to 43 (p<0.01) and from 43.7 to 51.2 (p<0.01) respectively. There was no statistically significant change in VAS, ODI or SF-36 scores between one and two years.

Conclusions: Sagittal balance initially worsened then steadily improved at each interval over the first year postoperatively. At one year, all clinical outcomes were significantly improved. Improvement in pain occurred early, while functional improvement was delayed compared to radiographic correction. Radiographic restoration of global sagittal alignment did not fully reflect surgical correction until six months postoperatively.

Patient Care: This study allows deformity surgeons to better counsel patients regarding expectations and a time course for radiographc and clinical improvement after surgical intervention for spinal deformity. Further, this study suggests that residual or exaggerated sagittal imbalance in the immediate to subacute postoperative period may be a normal part of the recovery process.

Learning Objectives: 1. To better understand the evolution of sagittal balance following surgical correction of adult spinal deformity. 2. To delineate improvement in clinical outcomes in relationship to radiographic outcomes over time.

References: Blondel B, Schwab F, Ungar B, Smith J, Bridwell K, Glassman S, et al: Impact of magnitude and percentage of global sagittal plane correction on health-related quality of life at 2-years follow-up. Neurosurgery 71:341-348; discussion 348, 2012 Glassman SD, Berven S, Bridwell K, Horton W, Dimar JR: Correlation of radiographic parameters and clinical symptoms in adult scoliosis. Spine (Phila Pa 1976) 30:682-688, 2005 Glassman SD, Bridwell K, Dimar JR, Horton W, Berven S, Schwab F: The impact of positive sagittal balance in adult spinal deformity. Spine (Phila Pa 1976) 30:2024-2029, 2005