Complications and Results of Long Adult Deformity Fusions Down to L4, L5, and the Sacrum

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Abstract
This is a consecutive study of patients having undergone surgical treatment of adult lumbar scoliosis. Follow-up ranged from 2 to 13 years (average 5 years). To assess the complications and outcomes of patients with long fusions to L4 (n=23), L5 (n=21), or the sacrum (n=15) and determine if a “deeply seated” L5 segment is protective. Few studies assess outcomes and complications in adults fused from the thoracic spine to L4, L5, or the sacrum with minimum 2-year follow-up. Fifty-eight patients (59 cases; average age 43 years; range 21 to 60) with minimum 2-year follow-up were analyzed for subsequent spinal degeneration and complications. Outcomes were assessed from questionnaires administered at latest follow-up. Sixteen percent of cases (7 of 44) fused short of the sacrum displayed subsequent postoperative distal spinal degeneration, although only three patients were symptomatic. Compared with the group with no subsequent degeneration, this group had a lower improvement in function and pain relief. Other complications for patients fused short of the sacrum included two cases with crosslink breakage, one with neurologic deficit, three with pseudarthroses, one with hook pullout, and one with L5 screw pullout. For cases fused to the sacrum, two cases with deep wound infections and one with loose iliac screw requiring removal were observed. Because two of four cases fused to L5 with subsequent degeneration at L5–S1 were observed to have “deeply seated” L5 segments and two of the four did not, the authors could conclude only that “deep seating” of L5 is not absolute protection. Fusions short of the sacrum did not have predictable long-term results. Those fused short of the sacrum who developed distal spinal degeneration had worse outcomes. Patients fused to the sacrum did not have a higher complication rate. A “deeply seated” L5 segment does not necessarily protect the L5–S1 disc.