Objective To evaluate the effectiveness of lumbar interbody fusion impacted bone grafts combined with regrafting in situ with spinous process and vertebral plate complex and pedicle screw fixation for lumbar degenerative instabil ity. Methods Between January 1998 and October 2010, 48 patients with lumbar degenerative instabil ity were treated by posterior decompression, lumbar interbody fusion impacted bone grafts combined with regrafting in situ with spinous processand vertebral plate complex and pedicle screw fixation. There were 26 males and 22 females, aged 52-76 years (mean, 62.4 years). The disease duration was 7 months to 25 years (mean, 6.5 years). One segmental instabil ity was located at L3, 4 in 1 case, at L4, 5 in 10 cases, and at L5, S1 in 11 cases; multi-segmental instabil ity was located at L3, 4, L4, 5, and L5, S1 in 5 cases, at L2, 3 and L3, 4 in 2 cases, at L3, 4 and L4, 5 in 10 cases, and at L4, 5 and L5, S1 in 9 cases. Of 48 patients, 32 complicated by lumbar disc herniation, 46 by lumbar spinal stenosis, and 16 by degenerative scol iosis. The cl inical results were evaluated by the Japanese Orthopaedic Association (JOA) score, recovery rate, disc height, and lumbar lordosis angles. Results The incisions obtained healing by first intention after operation. No nerve injury, rod or screw breakage, and infection occurred during and after operation. All 48 patients were followed up 1 to 6 years. The fusion time was 12-18 weeks (mean, 16.2 weeks). Vertebra sl i pping or degenerative scol iosis was corrected, and spinal column series became normal. At preoperation, 6 months after operation, and last follow-up, the disc heights were (5.2 ± 2.3), (11.9 ± 2.0), and (11.6 ± 2.1) mm, respectively; the JOA scores were 3.2 ± 2.1, 12.8 ± 1.6, and 13.6 ± 1.2, respectively; and the lumbar lordosis angles were (—20.5 ± 10.5), (30.5 ± 8.5), and (31.2 ± 5.6)°, respectively. The JOA scores, disc heights, and lumbar lordosis angles were significantly improved at 6 months after operation and last follow-up when compared with preoperative ones (P lt; 0.05), but no significant difference was found between 6 months after operation and last follow-up (P gt; 0.05). The recovery rate of JOA was excellent in 36 cases, good in 10 cases, and fair in 2 cases at 6 months after operation, with an excellent and good rate of 95.8%. Conclusion Lumbar interbody fusion impacted bone grafts combined with regrafting in situ with spinous process and vertebral plate complex and pedicle crew fixation for lumbar degenerative instabil ity can restore and maintain the intervertebral disc height effectively with high fusion rate. It is a plasty close to anatomic reconstruction.