2023, Vol. 27 ›› Issue (13): 1975-1980

Biomechanical characteristics of integrated expandable repositionable cage through lateral anterior approach

Zhang Hong1, 2, Wu Aimin3, 4, Li Junwei1, 2, Cai Xinyi1, 2, Ren Yanan1, 2, Du Chengfei1, 2   

Abstract: BACKGROUND: In vitro experiments have confirmed that although the integrated interbody cage can be implanted from the side, it does not have the ability to adjust the height of the intervertebral cage and adjust the reduction function of lumbar spondylolisthesis after implantation. Therefore, the present study designed a new lumbar surgical procedure: oblique lumbar interbody fusion with an integrated expandable repositionable cage fixation (OLIF+IERC), and studied the biomechanical performance of OLIF+IERC.  
OBJECTIVE: To explore the biomechanical performance differences of the OLIF+IERC surgical model in this study, compared with the normal lumbar spine finite element model, OLIF stand-alone without fixation system (stand-alone OLIF) model, and OLIF with posterior bilateral pedicle screws fixation (OLIF+BPS) model.
METHODS:   The established and validated normal model (L3-S1) was suitably modified to establish three kinds of OLIF surgical models: stand-alone OLIF, OLIF+BPS, and OLIF+IERC designed in this study. By applying a 500 N follower load and a moment load of 7.5 N·m in different directions (flexion, extension, lateral bending, and axial rotation) to each model, the various biomechanical indicators of the different models were compared.  
RESULTS AND CONCLUSION: (1) For range of motion, maximum cage stress, and maximum endplate stress at L4-L5, OLIF+IERC was lower than other surgical models in axial rotation; stand-alone OLIF was highest in all motion postures; OLIF+BPS was lowest in flexion, extension, and lateral bending. (2) Taken together, the biomechanical stability, resistance to cage subsidence, and disc height reduction of OLIF+IERC were superior to stand-alone OLIF in all motion postures and superior to OLIF+BPS in motion posture of axial rotation. (3) This study suggests that OLIF+IERC may be considered as a surgical procedure for future surgical treatment of patients with degenerative disease of the lumbar spine. This study provides a valuable reference for the treatment of lumbar degenerative diseases.
Key words: oblique lumbar interbody fusion, integrated expandable repositionable cage, lumbar slippage, biomechanics, finite element