Study Design:​ This was a 3-part, retrospective, observational, cross-sectional study.

Objective:​ The objective of the study was to examine the association between muscle morphometry of selected trunk and hip muscles, and various measures of low back pain (LBP) in adult males and females.

Background:​ LBP is a huge cause of human suffering and expense in the United States and worldwide. Understanding the causes of, and developing successful interventions to address LBP, requires an understanding of certain morphometric and LBP-related variables, and how they interact with each other.

Methods:​ Muscle cross-sectional area (CSA) was measured using computed tomography and magnetic resonance imaging scans of selected hip and trunk muscles in a cadaver model, and in living human participants through retrospective review of patient records. LBP-related variables were obtained from medical records and correlated with muscle CSA and with LBP surgical outcomes.

Results:​ Multifidus (MF), gluteus maximus (GM), and erector spinae (ES) CSAs showed a correlation with LBP incidence and severity. Psoas major (PM), while correlated with MF atrophy in one component of the present research, overall did not demonstrate a relationship to LBP. Pre-surgical MF CSA was positively correlated with 6-month post- surgical outcomes. Pre-surgical Oswestry Disability Index (ODI) scores demonstrated the iiability to differentiate between surgical and non-surgical participants, and were correlated with post-surgical outcomes.

Conclusion:​ This research supports prior research indicating MF and ES vary with LBP. A previously unexplored relationship between GM and LBP was demonstrated. Pre-surgical ODI scores may have clinically useful predictive value for post-surgical outcomes.