Pseudarthrosis and Instrumentation Complications at Long-Term Follow-Up of Long Fusions to Sacrum

Purpose: To describe the incidence and characteristics of pseudarthrosis and long-term complications associated with longfusions to the sacrum.

Methods: A retrospective chart and radiographic review with minimum five years follow-up to primary long fusions from the sacrum to T10 or higher was performed. Two-thirds of the fusions extended up to T2 through T4.

Results: 54 patients, average age at surgery 50 (18-72) and average follow-up 9.7 years (6-26), were included. Primary diagnosis was idiopathic scoliosis (31), degenerative scoliosis (10) or other (13). About half (46%) had iliac fixation. No death or paralysis occurred.

Pseudarthrosis occurred in 12 patients (23%), of whom 45% occurred at the lumbosacral level and three involved multiple levels (4 to 9). Pseudarthrosis was most commonly detected at 29 to 42 months post operatively (6) and 90 to 93 months post-operatively (3). Pseudarthrosis rate was higher in degenerative scoliosis (50% vs 16% in other diagnosis); with iliac fixation (31% vs 8% without); and in posterior alone fusions (75% vs 17% in AP). Pseudarthrosis rate was not affected by age, upper end vertebra of fusion, use of structural anterior graft or length of follow-up.

Instrumentation failure (breakage or loosening) occurred in 7 patients (12%), all cases having a pseudarthrosis. Symptomatic instrumentation occurred in 12 patients (21%), necessitating complete or partial instrumentation removal at which time two were found to have pseudarthrosis, one lumbosacral and one multiple level mid thoracic.

Conclusion: The risk of pseudarthrosis was higher in degenerative scoliosis or without an anterior fusion. Pseudarthrosis are common after long fusions to the sacrum in this population of average age 50, presenting late and more commonly at the lumbosacral area. All instrumentation failures occurred in cases with pseudarthrosis.