Analysis of factors impacting interbody cage subsidence following stand-alone oblique lumbar interbody fusion

Abstract

Objective To investigate the factors influencing interbody cage subsidence after stand-alone oblique lumbar interbody fusion (OLIF). Methods A total of 65 patients (72 lumbar vertebrae) who underwent OLIF in our hospital from Ja-nuary 2019 to January 2023 were selected and divided into subsidence group (n=19) and non-subsidence group (n=53) according to the loss of disc height. The clinical data of the two groups were collected and compared, including gender, age, body mass index, number of lumbar vertebrae requiring surgery, responsible vertebral endplate sclerosis, cage height and length, preoperative CT values of the responsible vertebral body and its upper and lower endplates, preoperative multifidus muscle cross-sectional area at responsible vertebral body, degree of multifidus muscle atrophy, and degree of preoperative articular process degeneration. Logistic regression analysis was used to explore the factors influencing cage subsidence. Results There were significant differences between the two groups in the preoperative CT values of responsible vertebral body and its upper endplate, the proportion of patients with preoperative responsible vertebral body endplate sclerosis, the preoperative multifidus muscle cross-sectional area at responsible vertebral body, the proportion of patients with preoperative severe atrophy of the multifidus muscle, the proportion of patients with cage height 14 mm, the proportion of patients with cage length 55 mm, and the proportion of patients with articular process degeneration of degree 3 (t=2.332-3.097,χ2=4.545-6.246,P<0.05). Logistic regression analysis results showed that preo-perative CT value of responsible vertebral body ≤100.39 Hu, preoperative CT value of the upper endplate of the responsible vertebral body ≤103.80 Hu, preoperative multifidus muscle cross-sectional area ≤791.86 mm2, and cage height of 14 mm were risk factors for cage subsidence (P<0.05). Cage length of 55 mm and articular process degeneration of degree 3 were protective factors for cage subsidence (P<0.05). Conclusion In patients with OLIF, attention should be paid to the CT values of the responsible vertebral body and its upper endplate, the cross-sectional area of multifidus muscle at responsible vertebral body, and the degeneration of articular process. Moreover, the appropriate type of fusion cage should be selected to reduce the risk of cage subsidence.

Keywords

• lumbar vertebrae|spinal fusion|internal fixators|root cause analysis