Different Moro Zones of Psoas Major Affect the Clinical Outcomes after Oblique Lumbar Interbody Fusion: A Retrospective Study of 94 Patients

Abstract

Oblique lumbar interbody fusion (OLIF) has been driven to the maturity stage in recent years. However, postoperative symptoms such as thigh paresthesia resulting from intraoperative retraction of the psoas major (PM) have sometimes occurred. The aim of this study was to assess the different positions and morphology of PM muscles and their relationship with clinical outcomes after OLIF by introducing the Moro zones. Patients who underwent L4-5 OLIF at our institution between April 2019 and June 2021 were reviewed and all data were recorded. All patients were grouped by Moro zones into a Moro A cohort and a Moro I and II cohort based on the front edges of their left PM muscles. A total of 94 patients were recruited, including 57 in the Moro A group and 37 in the Moro I and II group. Postoperative thigh pain or numbness occurred in 12 (21.1%) and 2 (5.4%) patients in the Moro A group and the Moro I and II group, respectively. There was no difference in the psoas major transverse diameter (PMTD) between groups preoperatively, while longer PMTD was revealed postoperatively in the Moro A group. The operating window (OW) and psoas major sagittal diameter (PMSD) showed significant differences within and between groups. Thirteen patients had teardrop-shaped PM muscles, with 92.3% in the Moro A group showing significantly worse clinical scores at 1-week follow-up. The Moro zones of the PM affected the short-term outcomes after OLIF. Preoperative measurements and analysis of OW, PMSD and PM morphology should be performed as necessary to predict short-term outcomes.

Evaluation and analysis of surgical treatment for single-level or multi-level lumbar degenerative disease based on radiography

“…With the aging of the population, the incidence of lumbar degenerative disease (LDD) is increasing ( 1 ). Transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF) have become the standard and widely accepted treatments for patients with LDD, which includes spinal stenosis, lumbar spondylolisthesis, lumbar disc herniation, and degenerative scoliosis ( 2 , 3 ) when conservative measures have failed for at least six months ( 4 ). Many researchers have identified risk factors affecting surgical treatment, including old age, obesity, and anatomical structure, but no consensus has been reached ( 5 ).…”

Psoas Major Swelling Grade Affects the Clinical Outcomes after OLIF: A Retrospective Study of 89 Patients

“…The morphology of the PM can significantly influence the surgical approach for the OLIF procedure. PM swelling may result in pain or numbness in the anterior thigh, potentially compromising short‐term postoperative outcomes 9 . Consequently, examining the morphology and swelling of the PM is crucial for predicting complications.…”

“…PM swelling may result in pain or numbness in the anterior thigh, potentially compromising short‐term postoperative outcomes. 9 Consequently, examining the morphology and swelling of the PM is crucial for predicting complications. This study primarily focused on the PM and innovatively introduced a new grading method named Psoas Major Swelling Grade (PMSG), classifying the degree of swelling into three levels—I, II, and III—based on PM swelling severity on MRI scans.…”