Introduction: ALIF is commonly performed at caudal segments of long posterior fusions to the sacrum. In patients over age 60, we hypothesized that PAs would result in equally high fusion rates as TMCs and perhaps less settling.
Methods: Patients over 60 who had a long (>6 levels) posterior fusion to the sacrum between 2002–2005 were studied. A matched cohort analysis was performed comparing ALIFs with TMCs to PAs. ALIFs were performed through a mini‐open approach. In addition to either a TMC or PA, 4‐mg of rhBMP‐2 was used at each level. Minimum f/u for all patients was 2 years.
Results: 35 patients (9M/26F), mean age of 69.7±5.5 years, had a total of 72 ALIFs performed (41 TMC/28 PA). Mean f/u 4.7±0.9 years. The TMC cohort had 18 patients and 37 ALIFs (2.1±0.8 levels/pt). The PA cohort had 17 patients and 35 ALIFs (2.1±1.2 levels/pt). Mean number of posterior fusion levels were similar (TMC=11.6±5.2 vs PA=9.5±4.2). Final improvement in lumbar lordosis (TMC=8.41° vs PA=10.6°) and sagittal vertical axis (SVA) (TMC=25.2 mm vs PA=31.9 mm) were also similar. There was no statistical difference in loss of lumbar lordosis prior to solid fusion (TMC=4.75° vs PA=2.26°, P=0.452). A greater number of ALIFs in the PA group were “definitely fused” (TMC=54.1%vs PA=91.4%, P=0.005); a similar number were “definitely fused” or “probably fused” (TMC=94.6% vs PA= 100.0%) according to Bridwell's fusion assessment. There was no case of PA graft resorption. There was a greater prevalence of graft settling in the TMC population (TMC=51.4% vs PA=17.1%, P=0.003). The amount of graft settling was also greater in the TMC group (TMC=5.35±1.8 mm vs PA=2.51±1.2 mm, P=0.012).
Conclusion: Both TMCs and PAs are viable ALIF grafts at the caudal segments of a long fusion to the sacrum in patients over age 60. PAs, however, are more easily judged to be fused and result in significantly less graft subsidence than TMCs.
Significance: An ALIF graft with a modulus of elasticity closer to that of native bone, such as a PA, may be a better option in the aging spine than TMCs. Additionally, the ease of fusion assessment and revision makes PA an attractive structural graft option for ALIF.