Purpose: The aim of this study was to evaluate the radiographic characteristics of polyetheretherketone (PEEK) cages packed with adjacent vertebral autograft material in lumbar anterior lumbar interbody fusion (ALIF) in spinal deformity long fusion surgeries.
Methods: This is a retrospective radiographic study. From April 2008 to April 2012, 40 patients (5 males and 35 females, mean age 67 ± 9 years) with coronal and/or sagittal spine deformities underwent staged corrective surgery combined with lumbar ALIF using PEEK cages at the L3-L4, L4-L5 or L5-S1 segment with posterior long (≥ 4 levels) instrumentation. The mean follow-up time was 27.5 months (13-49 months). We examined the interbody fusion rate and cage subsidence at 3 months postoperatively and final follow-up. Additionally, we evaluated the distance of cage migration at final follow-up and the improvement in lumbar lordosis. The rate of "collapse" of the adjacent vertebra where the autograft was harvested was assessed at the final follow-up. Finally, we examined the cage-related postoperative complications in this series.
Results: Solid interbody fusion was achieved in 96.4 % (81/84) of the levels at the final follow-up. A mild forward cage migration was observed, and the mean migration distance at final follow-up was 0.83 mm in L3/4, 0.36 mm in L4/5 and 0.55 mm in L5/S1. There was cage subsidence observed in 8.3 % (7/84) of the levels. In all patients, the PEEK cage maintained a significant increase in segmental lordosis at all postoperative visits. However, a mild reduction in segmental lordosis still occurred with time. The adjacent lumbar vertebral bodies where the autografts were harvested appeared to be intact in height radiologically at the final follow-up. There were no postoperative complications due to bone harvesting or cage insertion. Proximal junctional kyphosis was found in one patient who underwent a subsequent revision surgery.
Conclusions: The use of lumbar ALIF with PEEK cages and adjacent vertebral autografts in spinal deformity long fusion surgeries is an effective and safe procedure. The allograft filler is safe and effective in maintaining the shape of harvested vertebrae. Additional long-term follow-up studies are needed to further justify its use.