Study design:

Retrospective case series.

Objective:

This study aimed to investigate the effects of lateral lumbar interbody fusion (LLIF)-induced unintended tissue damage, including cage subsidence, cage malposition, and hematoma in the psoas major muscle, on the development of thigh symptoms.

Summary of background data:

Thigh symptoms are the most frequent complications after LLIF and are assumed to be caused by lumbar plexus compression and/or direct injury to the psoas major muscle. However, the causes and risk factors of thigh symptoms are yet to be fully understood.

Methods:

Adult patients with spinal deformity who underwent two-stage surgery using LLIF and a posterior open fusion for the first and second stages, respectively, were included. Computed tomography and magnetic resonance imaging were routinely performed after LLIF before posterior surgery to investigate cage subsidence, cage malposition, and hematoma in the psoas muscle. We evaluated the development of thigh symptoms after LLIF and examined the effects of tissue injury on the occurrence of thigh symptoms. The differences in demographics and surgical and tissue damage parameters were compared between the groups with and without thigh symptoms using unpaired t-tests and chi-square tests. Factors associated with the development of thigh symptoms and muscle weakness were also assessed using logistic regression analysis.

Results:

Overall, 130 patients (17 men and 113 women; mean age, 68.7 [range, 47-84]) were included. Thigh symptoms were observed in 52 (40.0%) patients, including muscle weakness and contralateral side symptoms in 20 (15.4%) and 9 (17.3%) patients, respectively. The factors significantly associated with thigh symptoms identified following multiple logistic regression analysis included hematoma (odds ratio 2.27, 95% confidence interval (CI) 1.03-5.01) and approach from the right side (odds ratio 2.64, 95% CI 1.21-5.75). The presence of cage malposition was the only significant factor associated with muscle weakness. (odds ratio 4.12, 95% CI 1.37-12.4).

Conclusions:

We found unintended tissue injury during LLIF was associated with thigh symptoms. We found that hematoma in the psoas major muscle and cage malposition were factors associated with thigh symptoms and muscle weakness, respectively.

Level of evidence:

4.