The prevalence of PJK at 7.8 years postoperation was 39%. PJK progressed significantly within 8 weeks postoperation (59%) and between 2 years postoperation and ultimate follow-up (35%). Older age at surgery (>55 years) and combined anterior and posterior spinal fusion were identified as risk factors for developing PJK. The SRS outcome instrument was not adversely affected by PJK, except when PJK exceeded 20 degrees.

The overall prevalence of pseudarthrosis following long adult spinal deformity instrumentation and fusion to S1 was 24%. Thoracolumbar kyphosis, osteoarthritis of the hip joint, thoracoabdominal approach (vs. paramedian approach), positive sagittal balance > or = 5 cm at 8 weeks postoperatively, older age at surgery (older than 55 years), and incomplete sacropelvic fixation significantly increased the risks of pseudarthrosis to an extent that was statistically significant. Scoliosis Research Society 24 outcomes scores at ultimate follow-up were adversely affected when pseudarthrosis developed.

3.