Does Bone Density Affect Outcomes in Lateral Lumbar Interbody Fusion? A Propensity Score-Matched Analysis of Preoperative Hounsfield Units

Background: This study aimed to assess whether preoperative Hounsfield unit (HU) values differ in short-term clinical outcomes after lateral lumbar interbody fusion (LLIF) surgery. Methods: In a retrospective analysis, 109 patients undergoing LLIF for lumbar degenerative diseases (LDD) were reviewed. Preoperative Computed Tomography (CT) scans measured HU values at the L1-L4 vertebrae, dividing patients into low and high HU groups. After conducting a cluster analysis of preoperative Hounsfield unit (HU) values, patients were categorized into low and high HU groups using propensity score matching (PSM). The outcomes measured one-year post-surgery included pain intensity (Numeric Rating Scales for Low Back Pain (NRS_LBP), Leg Pain (NRS_LP), and Leg Numbness (NRS_LN)) and quality of life (Japanese Orthopedic Association Back Pain Evaluation Questionnaire: JOABPEQ). Results: After PSM, there were 26 patients in each group. Significant improvements were noted in both low and high HU groups post-surgery, with the low HU group showing a decrease in NRS_LBP from 6.2 to 3.7, NRS_LP from 7.4 to 2.5, and NRS_LN from 6.4 to 3.0. The high HU group exhibited similar improvements (NRS_LBP: 6.5 to 3.6, NRS_LP: 6.3 to 2.5, NRS_LN: 6.2 to 2.4). JOABPEQ scores improved significantly in both groups across all domains, with no significant differences observed. Preoperative HU values have little correlation with the short-term outcomes of pain and quality of life in LLIF surgery. Conclusions: This study suggests reconsidering the role of HU values following indirect decompression via LLIF, particularly in evaluating pain and patient-reported outcome measures in patients with LDD.