45. Associations between preoperative multifidus and psoas muscle qualities and postoperative patient-related outcomes after anterolateral lumbar interbody fusion: predictors for chronic disability and pain

BACKGROUND CONTEXT To date, a small number of studies have examined the multifidus muscle and psoas muscle quality effects on patient-reported outcomes in anterolateral lumbar interbody fusion; however, their relationships with chronic disability and back pain remain questionable. The variability of clinical outcomes during a lumbar lateral interbody fusion and the possibility of developing transient iliopsoas weakness and femoral neuropraxia promotes the need for predictor factors before surgery. PURPOSE Due to the variability of clinical outcomes following anterolateral lumbar interbody fusions, the need for predictive factors before spine surgery becomes relevant. The predictive powers of preoperative multifidus and psoas muscle qualities in terms of patient-reported outcomes (PROS) related to lumbar surgery remain unknown. STUDY DESIGN/SETTING Retrospective Observational cohort. PATIENT SAMPLE One hundred. OUTCOME MEASURES Multivariate analysis Pearson correlation multiple linear regression analyses. METHODS After IRB approval, this study retrospectively reviewed the records of 100 patients who underwent anterolateral lumbar interbody fusion, between L1 to S1 vertebras during a mean follow-up period of ≥ one year. Preoperative MRI scans were collected to analyze multifidus and psoas muscle qualities using two image analysis systems (Ambra and Image J); studied parameters included cross-sectional area (CSA) and fat infiltration indices (MFI) at the level of the superior endplate of L5. Pearson correlation analysis was utilized to investigate the univariate relationships between muscle qualities and PROS. Multiple linear regression analyses were used to study the potential confounding effects of independent variables, including age, history of prior spine surgery, gender, body mass index, smoking, and patient comorbidities. RESULTS A total of 100 patients with a median age of 68.1 years (43%, males and 57%, females) with a mean follow-up period of 1.07 years (ranged 0.82-5.42 years) were evaluated. 207 surgical levels were analyzed; L1-L2 (n = 9), L2-L3 (n = 39), L3-L4 (n = 68), L4-L5 (n = 61), and L5-S1 (n = 30) with 42 surgeries as stand-alone procedures and 58 required posterior instrumentation. A total of 42 patients had a prior history of a lumbar procedure. Univariate analyses including all data showed that decreased multifidus cross-sectional area (CSA) was significantly related to increased preoperative disability and preoperative back pain (p 0.2). Multifidus fat infiltration indices and psoas muscle morphology did not demonstrate any effect on PROs either pre- or postoperatively (p > 0.05). Stratification by surgical history showed that patients with prior surgery (n = 42) with greater multifidus CSAs had higher magnitudes of improvement in VAS back scores (p = 0.019 [ImageJ]; p = 0.039 [Ambra]). CONCLUSIONS We demonstrated significant relationships between multifidus CSA and preoperative disability and back pain prior to anterolateral lumbar interbody fusions; at the same time, in patients with prior surgery, increased multifidus CSA was significantly related to improvement in VAS back delta (ImageJ and Ambra). Psoas muscle features including fatty infiltration and CSA were not predictive of pre- or postoperative outcomes. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. To date, a small number of studies have examined the multifidus muscle and psoas muscle quality effects on patient-reported outcomes in anterolateral lumbar interbody fusion; however, their relationships with chronic disability and back pain remain questionable. The variability of clinical outcomes during a lumbar lateral interbody fusion and the possibility of developing transient iliopsoas weakness and femoral neuropraxia promotes the need for predictor factors before surgery. Due to the variability of clinical outcomes following anterolateral lumbar interbody fusions, the need for predictive factors before spine surgery becomes relevant. The predictive powers of preoperative multifidus and psoas muscle qualities in terms of patient-reported outcomes (PROS) related to lumbar surgery remain unknown. Retrospective Observational cohort. One hundred. Multivariate analysis Pearson correlation multiple linear regression analyses. After IRB approval, this study retrospectively reviewed the records of 100 patients who underwent anterolateral lumbar interbody fusion, between L1 to S1 vertebras during a mean follow-up period of ≥ one year. Preoperative MRI scans were collected to analyze multifidus and psoas muscle qualities using two image analysis systems (Ambra and Image J); studied parameters included cross-sectional area (CSA) and fat infiltration indices (MFI) at the level of the superior endplate of L5. Pearson correlation analysis was utilized to investigate the univariate relationships between muscle qualities and PROS. Multiple linear regression analyses were used to study the potential confounding effects of independent variables, including age, history of prior spine surgery, gender, body mass index, smoking, and patient comorbidities. A total of 100 patients with a median age of 68.1 years (43%, males and 57%, females) with a mean follow-up period of 1.07 years (ranged 0.82-5.42 years) were evaluated. 207 surgical levels were analyzed; L1-L2 (n = 9), L2-L3 (n = 39), L3-L4 (n = 68), L4-L5 (n = 61), and L5-S1 (n = 30) with 42 surgeries as stand-alone procedures and 58 required posterior instrumentation. A total of 42 patients had a prior history of a lumbar procedure. Univariate analyses including all data showed that decreased multifidus cross-sectional area (CSA) was significantly related to increased preoperative disability and preoperative back pain (p 0.2). Multifidus fat infiltration indices and psoas muscle morphology did not demonstrate any effect on PROs either pre- or postoperatively (p > 0.05). Stratification by surgical history showed that patients with prior surgery (n = 42) with greater multifidus CSAs had higher magnitudes of improvement in VAS back scores (p = 0.019 [ImageJ]; p = 0.039 [Ambra]). We demonstrated significant relationships between multifidus CSA and preoperative disability and back pain prior to anterolateral lumbar interbody fusions; at the same time, in patients with prior surgery, increased multifidus CSA was significantly related to improvement in VAS back delta (ImageJ and Ambra). Psoas muscle features including fatty infiltration and CSA were not predictive of pre- or postoperative outcomes.