Radiographic Analysis of PEEK Cage and FRA in Adult Spinal Deformity Fused to Sacrum

Abstract

Retrospective radiographic study. To radiographically evaluate sagittal plane profile and fusion rates of polyetheretherketone (PEEK) cages versus femoral ring allografts (FRAs) in patients with adult spinal deformity fused to the sacrum. FRAs have been widely used in various degenerative lumbar spine disorders and in adult deformity to achieve interbody fusions with promising results. PEEK cages have gained increasing popularity of late; however, there is little documentation to the radiographic comparisons between PEEK cages and FRAs used in patients with adult spine deformity treated with long fusions to the sacrum. From March 2006 to February 2010, we analyzed 48 patients (mean age, 56.3±13.9 y) of 61 consecutive adult patients with global coronal and sagittal adult spine deformities who underwent first stage ALIF using PEEK cages or FRAs at L4-L5, L5-S1 segments followed by long (>6 levels) posterior instrumentation. PEEK cages and FRAs were used randomly according to surgeon's preference. Two independent observers retrospectively evaluated preoperative and postoperative disk height, foraminal height, segmental lordosis, and the interbody fusion rates at different postoperative intervals. Both PEEK cages and FRAs significantly (P<0.05) maintained disk space height at all follow-up times. PEEK cages maintained foraminal height and segmental lordosis, especially at L4-L5 better than FRAs at the final follow-up. At the final follow-up, PEEK cages achieved 94.9% of fusion rate, which was significantly (P<0.05) superior to FRA (84.2%), and PEEK cages were superior to FRAs in attaining earlier solid fusion. The Prolo functional scores of FRAs or/and PEEK cages were significantly improved at the final follow-up and did not show a significant difference between them. Both PEEK cages and FRAs can significantly increase disk space height and achieve similar clinical outcomes in treating adult spinal deformity fused to the sacrum. The radiographic results of PEEK cages were superior to FRAs in terms of an earlier solid fusion, and greater restoration of segmental lordosis.