Abstract: BACKGROUND: The advantage of oblique lumbar interbody fusion for lumbar degenerative diseases is affected by the cage settlement. Supplementary fixation can provide extra biomechanical stability and may reduce the occurrence of settlement. Among them, oblique lumbar interbody fusion combined with lateral plate fixation can avoid the damage caused by the posterior approach.  
OBJECTIVE: To analyze the early clinical and radiological results of oblique lumbar interbody fusion combined with lateral plate in the treatment of lumbar degenerative diseases, and to combine with bilateral pedicle screws to analyze whether there is a difference in the degree of cage settlement.
METHODS:  Fourteen patients (17 segments) with oblique lumbar interbody fusion combined with lateral plate fixation (lateral plate group) and 12 patients (15 segments) with oblique lumbar interbody fusion combined with bilateral pedicle screw fixation (bilateral pedicle screw group) were included. The clinical and radiological data of patients before operation, 3 days and 6 months after operation were recorded. The clinical evaluation included low back pain and lower limb pain visual analogue scale scores and Oswestry disability index score. Radiological evaluation included measurement of disc height, segmental lordosis, and degree of cage settlement. 
RESULTS AND CONCLUSION: (1) There was no significant difference between the two groups in age, gender, body mass index, quantitative CT bone mineral density, and preoperative diagnosis. The operation time of the bilateral pedicle screw group was significantly higher than that of the lateral plate group (P=0.025). The complication rate was 43% in lateral plate group and 33% in bilateral pedicle screw group. There was no significant difference between the two groups in operation segment, blood loss, and complication rate. (2) There was no significant difference in low back pain and lower limb pain visual analogue scale scores and preoperative Oswestry disability index scores between the two groups. The Oswestry disability index score of the bilateral pedicle screw group was significantly lower than that of the lateral plate group at 6 months after operation (P=0.007). At 6 months after operation, the visual analogue scale scores and Oswestry disability index scores were significantly improved in both groups compared with those before the operation (P < 0.05). (3) At 3 days after operation, disc height and segmental lordosis were significantly improved compared with before operation, but there was a significant loss of disc height in both groups at 6 months after operation (P < 0.05). There was no significant difference in disc height between the two groups before and 3 days after the operation. The disc height of the lateral plate group was significantly lower than that of the bilateral pedicle screw group at 6 months follow-up (P=0.044). (4) No statistical difference was found in segmental lordosis between the two groups. (5) There was no significant difference in the cage settlement rate between the two groups at 6 months follow-up. There were two cases of severe subsidence in the lateral plate group and none in the bilateral pedicle screw group. (6) Compared with oblique lumbar interbody fusion combined with bilateral pedicle screws, oblique lumbar interbody fusion combined with lateral plate fixation in the treatment of lumbar degenerative diseases is less effective in preventing early cage settlement. Both have similar pain relief effects at the early stage, but in terms of quality of life, oblique lumbar interbody fusion combined with bilateral pedicle screw fixation is better than oblique lumbar interbody fusion combined with lateral plate fixation.

Key words: oblique lumbar interbody fusion, lumbar degenerative disease, lateral plate, pedicle screw, cage settlement