Relationship between preoperative psoas major morphology and transient neuromuscular injury after oblique lumbar interbody fusion combined with anterolateral screw fixation

English Keywords:Oblique lumbar interbody fusion  Psoas major morphology  Lumbar plexus injury  Postoperative complications  Risk factors

English Abstract:

  【Abstract】 Objectives: To investigate the correlation between preoperative morphological characteristics of the psoas major muscle and the occurrence of transient neuromuscular injury in patients undergoing oblique lumbar interbody fusion(OLIF) combined with anterolateral screw fixation(AF). Methods: A retrospective analysis was conducted on the clinical data of patients with lumbar spinal stenosis(LSS) who underwent single-level L4/5 OLIF combined with AF via a left-sided approach at our hospital between June 2018 and April 2023. 22 patients who met the diagnostic criteria for postoperative transient lumbar plexus and psoas major muscle injury on the surgical side were included in group A. 35 matched patients without related injury symptoms were included in group B served as controls. General patient data including gender, age, body mass index(BMI), symptom duration, and American Society of Anesthesiologists(ASA) score, as well as surgery-related data were collected. Psoas major morphological parameters at the L4/5 disc level such as area, long axis, short axis, the distribution of the highest point(a-point) and the widest point(b-point) within the Moro zones were measured on the preoperative axial MRI, and the presence or absence of the space between lateral vertebral body edge and medial margin of the psoas major(cd space) on the left side was evaluated. Regression analysis was used to explore the relationship between preoperative psoas major morphological characteristics and postoperative transient neuromuscular injury. Results: There were no statistically significant differences in gender, age, BMI, symptom duration, or ASA score between the two groups, indicating comparability(P>0.05). All surgeries were successfully completed, with no significant differences in operative time, intraoperative blood loss, or hospital stay between the two groups(P>0.05). A total of 72 symptom events related to psoas/lumbar plexus injury were reported in group A, including anterolateral thigh paresthesia in 16 cases(22.2%), medial thigh paresthesia in 14 cases(19.4%), inguinal paresthesia in 11 cases(15.3%), hip adduction weakness in 12 cases(16.7%), knee extension weakness in 10 cases(13.9%), and hip flexion weakness in 9 cases(12.5%). There were no significant differences between the two groups regarding psoas major area, long axis, short axis, or a-point distribution. However, the rate of cd space absence and the proportion of the b-point located in Moro zone Ⅰ were 72.7% and 36.4% in group A, compared to 45.7% and 2.8% in group B, respectively, with group A showing significantly higher values(P<0.05). Regression analysis revealed that the absence of the cd space(OR=0.177, 95% CI: 0.037-0.852) and the distribution of the b-point in Moro zones Ⅰ-Ⅱ were independent risk factors for postoperative transient neuromuscular injury. Conclusions: Preoperative psoas major morphological characteristics are associated with the occurrence of transient neuromuscular injury after L4/5 OLIF combined with AF. Having the widest point of the psoas major cross-section located in Moro zones Ⅰ-Ⅱ and the loss of the space between the vertebral body and the medial psoas margin(cd space) are risk factors for transient neuromuscular injury after L4/5 OLIF combined with AF.