Does a long-fusion "t3-Sacrum" portend a worse outcome than a short-fusion "t10-Sacrum" in primary surgery for adult scoliosis?

STUDY DESIGN.: Retrospective clinicoradiographic analysis. OBJECTIVE.: To compare the upper thoracic (UT) and lower thoracic (LT) spines as the upper instrumented vertebra in primary fusions to the sacrum for adult scoliosis. SUMMARY OF BACKGROUND DATA.: The optimal level at which a fusion to the sacrum is terminated proximally for adult scoliosis remains controversial. We hypothesized that (1) UT spine would have an increased pseudarthrosis, more perioperative complications, and worse outcomes and (2) LT spine would have more proximal junctional kyphosis. METHODS.: Patients who underwent primary surgery for adult scoliosis between 2002 and 2006 were studied. UT and LT groups were matched cohorts. Minimum follow-up for all patients was 2 years. Scoliosis Research Society scores and Oswestry Disability Index were the clinical outcome measures. RESULTS.: Fifty-eight patients (UT = 20, LT = 38) with a mean age of 55.7 years were followed for an average of 3.0 ± 1.1 years. The UT group had greater preoperative thoracic kyphosis and coronal Cobb values (P < 0.05). Diagnoses were idiopathic scoliosis (75.9%) and degenerative scoliosis (24.1%). The UT cohort had a greater number of levels fused (15.8 vs. 8.6) and higher blood loss (1350 mL vs. 811 mL). Operative time, recombinant human bone morphogenetic protein-2 per level, and caudal interbody grafting (80.0% UT vs. 89.5% LT) were similar. The UT group experienced an increased number of perioperative complications (30.0% vs. 15.8%), more pseudarthrosis (20.0% vs. 5.3%), and a higher prevalence of revision surgery (20.0% vs. 10.5%). The LT group had more proximal junctional kyphosis (18.4% vs. 10.0%). Scoliosis Research Society scores and Oswestry Disability Index were improved in both cohorts in all domains (P < 0.001), except function (P = 0.07) and mental health (P = 0.27), which were not significantly improved in the UT group. CONCLUSION.: With long fusions to the sacrum, one should anticipate more perioperative complications, a higher pseudarthrosis rate, and perhaps more revision surgery than short fusions. Short fusions may result in a more proximal junctional kyphosis, only rarely requiring revision surgery.