Late Complications of Adult Idiopathic Scoliosis Primary Fusions to L4 and Above – The Effect of Age and Distal Fusion Level
Purpose: Few reports describe complications related to primary long fusions in the treatment of adult idiopathic scoliosis (IS). This is an analysis of primary cases of adult IS treated with long instrumented fusions from the thoracic spine to L4 and above by two surgeons between 1985 to 1999.
Methods: 69 patients with adult IS with 2-year min. follow-up (ave. 5.6 yrs., 32 pts. with >5 year follow-up) were analyzed. All non-primary cases were excluded. Patients were divided into groups based on age and level of last instrumented vertebrae (LIV) (summarized in Table 1 with type of fusion performed). Patients were analyzed with upright radiographs and SRS-24 questionnaires from the latest follow-up date.
| Table 1 | n | Age | ASF (inst) | ASF/PSF | ASF(inst)/PSF | PSF |
| <40 y (Gr.A) | 40 | 29+4 y | 4 | 2 | 5 | 29 |
| >40 y (Gr. B) | 29 | 47+8 y | 0 | 5 | 4 | 20 |
| T11-L2 (Gr. 1) | 30 | 34+9 y | 2 | 1 | 1 | 26 |
| L3-L4 (Gr. 2) | 39 | 38+10 y | 2 | 5 | 8 | 24 |
Results: When analyzing age, Gr. A’s complications included pseudarthrosis (3), instrumentation dislodgement (1), symptomatic inst. requiring removal (2), coronal decomp. >3cm. (1), and sagittal decomp.>5cm. (4). In Gr. B, complications included pseudo (4), coronal decomp. >3cm. (2), and sagittal decomp.>5cm. (2). SRS-24 scores were similar in both groups, averaging a total score (TS) of 99 in Gr. A and 95 in Gr. B. When analyzing LIV, in Gr. 1 there was 1 case of pseudo, 2 cases of coronal decomp. >3 cm., 4 cases of sagittal decomp. >5 cm, and 2 cases of symptomatic inst. requiring removal. The complications related to Gr. 2 include pseudo (6), coronal decomp (1), sagittal decomp (2), and inst. dislodgement (1). SRS- 24 scores were higher in TS in Gr. 1 (ave. 103) as compared to Gr. 2 (ave. TS=90). Patients with pseudarthrosis had lower TS (ave. 80.5) than those without (ave. TS=90) (p=0.04).
Conclusions: Patients with adult IS and long fusions had higher pseudo rates but not higher sagittal/coronal decomp. rates when LIV is L3 – L4 relative to levels T11-L2. When separated by age, patients >40y had more ASF/PSF, but late complication rates were similar to the <40Y group. Pts. with pseudos had lower SRS-24 TS than those without (p="0.04)."