[Instability of lower lumbar treated with posterior lumbar interbody fusion with autologous iliac crest or interbody fusion cage: a comparative study]

Abstract

Objective: To compare the curative effect of posterior lumbar interbody fusion with autologous iliac crest to that of interbody fusion cage for adult instability of lower lumbar.

Methods: From February 2003 to October 2006, 60 inpatients with lower lumbar instability were treated. Patients were randomized into 2 groups: bone-graft group (n=28) was treated with posterior lumbar interbody fusion with two autologous iliac crests, while cage group (n=32) was treated with posterior lumbar interbody fusion with two quadrate cages. In the bone-graft group, 17 males and 11 females aged (52.78 +/- 10.50) years with 3-16 months of disease course, there were 12 cases of degenerative instability, 14 isthmus slit olisthe and 2 iatrogenic instability, including 1 case of L3,4, 17 cases of L4,5 and 10 cases of L5, S1. Relative disc space height was (23.24 +/- 6.62) mm, disc space activity was (10.50 +/- 5.07)degrees, sagittal saw slippage distance was (4.50 +/- 1.15) mm and the JOA score was 18.56 +/- 2.68. In the cage group, 19 males and 13 females aged (51.75 +/- 10.44) years with 3.5-14.0 months of disease course, there were 16 cases of degenerative instability, 14 isthmus slit olisthe and 2 iatrogenic instability, including 16 cases of L4,5 and 16 cases of L5, S1. Relative disc space height was (24.34 +/- 7.22) mm, disc space activity was (11.12 +/- 5.67)degrees, sagittal saw slippage distance was (4.38 +/- 0.75) mm and the JOA score was 19.00 +/- 4.12. There was no significant difference between the two groups in terms of age, gender, JOA score, disc space activity and relative disc space height preoperatively (P > 0.05).

Results: All patients received the follow-up at the 1st, 3rd, 6th and 12th month postoperatively. There was no significant difference in operation time and hemorrhage amount between the two groups (P > 0.05), but significant difference in the cost of operation (P < 0.01). Two cases in the bone-graft group suffered donor site pain and received no treatment. Three cases in the bone-graft group and 2 cases in the cage group had symptom of nerve injury 1-2 days after surgery, which were cured after expectant treatment. There were no pseudoarticulation formation, intervertebral space infection and cage aversion in both groups. Significant difference of relative disc space height was found in each group pre- and post- operatively (P < 0.01) and significant differences were evident between the two groups at any of the time points (P < 0.01). One month after operation, there was significant difference between the two groups (P < 0.05). There was also significant difference at the 3rd, 6th and 12th month after operation (P < 0.01). No sign of fusion was found in each group at the 1st and 3rd month after operation. In bone-graft group, there were 7 vertebral fusion cases 6 months after operation and 23 vertebral fusion cases 12 months after operation. In cage group, there were 8 vertebral fusion cases 6 months after operation and 29 vertebral fusion cases 12 months after operation. There was no significant difference in the rate of fusion at 6 and 12 months follow-up between the two groups (P > 0.05). Significant difference of JOA scores was found in each group pre- and post- operatively (P < 0.05). And no significant difference in JOA scores at 1, 3, 6, and 12 months follow-up was evident between the two groups (P > 0.05).

Conclusion: There is no significant difference between the two groups in the fusion time, the fusion rate and the clinical symptoms alleviation, indicating autologous iliac crest is applicable to interbody fusion for the treatment of adult instability of lower lumbar and good therapeutic effect can be achieved with no immunoreaction and lower cost.