Comparing the early efficacies of autologous bone grafting and interbody fusion cages for treating degenerative lumbar instability in patients of different ages.

PURPOSE: The aim of this study was to compare the early efficacies of interbody fusion using autologous bone graft or an interbody fusion cage in a modified transforaminal lumbar interbody fusion (TLIF) in patients of different ages with degenerative lumbar instability.
METHODS: Data from 33 patients with double-segment degenerative lumbar instability treated with a modified TLIF combined with a posterior fixation system from December 2008 to June 2014 were retrospectively analyzed. The two segments separately received an interbody bone graft fusion and an interbody fusion cage. Patients were divided by age into group A (middle-aged and elderly group, age ≥ 55 years, n = 13) and group B (young adult group, age < 55 years, n = 20). The clinical efficacy of the modified TLIF combined with a posterior fixation system was assessed using the Japanese Orthopaedic Association (JOA), Oswestry Disability Index (ODI), and Visual Analogue Scale (VAS) scores obtained before and after surgery, and at final follow-up. We measured the mean intervertebral space height, intervertebral foramen height, lumbar lordosis angle, and inter-technique differences in the mean intervertebral space height and intervertebral foramen height. Interbody fusion was evaluated using the Suk standard.
RESULTS: Patients in group A followed-up for 19.15 ± 8.01 months. Patients in group B followed-up for 14.80 ± 5.47 months. The post-operative JOA, ODI, VAS, and lumbar lordosis angle were improved significantly. Moreover, the early clinical follow-up effect was good. In group A, significant differences in the intervertebral foramen height post-surgery and at final follow-up, and the mean intervertebral space height at final follow-up were noted. The intervertebral foramen and space heights were increased in the interbody cage group. In group B, a significant difference in the intervertebral foramen height at final follow-up was noted. The mean intervertebral space height post-surgery and at final follow-up was significantly increased between the two fusion methods. Bony fusion was achieved in all cases. The fusion time of autologous bone graft and interbody fusion cage was 5.46 ± 1.20 months and 6.77 ± 1.01 months respectively in group A, and 5.50 ± 1.28 months and 6.35 ± 1.76 months respectively in group B, the difference in fusion time between techniques was significant.
CONCLUSION: At different ages, the interbody fusion cages can better preserve the intervertebral space and the intervertebral foramen height. However, autologous bone graft can rapidly achieve a bony fusion. Interbody fusion cages are therefore ideal for young adults, while autologous bone grafting is ideal for middle-aged and elderly patients who receive a modified TLIF.