Summary: Pedicle subtraction osteotomy addressed the sagittal imbalance for patients fused short or long with improved SRS and ODI scores. However, increased kyphosis with loss of sagittal balance occured in patients fused short and should be monitored in the post‐op period.
Introduction: To assess the clinical and radiographic changes after PSO for the treatment of adult fixed sagittal imbalance. There is a paucity of information regarding the clinical outcome and its correlation with the level of proximal fusion and radiographic change after PSO.
Methods: Charts, x‐rays, post‐op SRS‐22 and ODI scores of 51 adult pts with fixed sagittal imbalance treated with lumbar PSO were reviewed. Long fusion was defined as proximal level greater than or equal to T8 and short fusion as less than T8. Radiographic parameters included thoracic kyphosis (TK), lumbar lordosis (LL), and sagittal balance (SVA). Statistical analysis included student's t test, chi‐square test, and Fisher's exact test. P value of <0.05 with confidence interval 95% was considered significant.
Results: There were 38f and 13m with mean age 52.5 yrs (21‐74 yrs) and mean f/u 5.8 yrs (2‐12 yrs). LL increased from 19.1° pre‐op to 52.8° post‐op and 52.0° at final f/u. C7PL decreased from 11.3cm pre‐op to 3.1cm post‐op and 6.3cm at final f/u. There were 26 short fusions and 25 long. SRS scores at latest f/u were: total 3.53, function 3.31, pain 3.40, self image 3.55, and mental health 3.59. 20 pts showed minimal disability, 18 pts showed moderate disability, and 4 pts showed severe disability in ODI score at final f/u (avg 70.2%). SRS and ODI scores were not different between the 2 groups (p=0.68, p=0.79). Increased SVA at final f/u was significantly larger in short fusion group compared to long fusion group (p=0.02). TK (T5‐T12) at final f/u also increased in pts having short fusion (p=0.001). Major complications occurred in 14 pts, 6 short (24%) and 8 long (31%) (p=0.754). 3 pts had additional PSO for the loss of correction in short fusion group.
Conclusion: Despite an increased SVA and high complication rate, PSO provided good sagittal balance and favorable clinical outcomes in both groups. The data suggests that loss of sagittal balance can be attributed to increased kyphosis in short fusion groups and should be monitored for long term outcomes.