Effects of the Insulin‐like Growth Factor Axis and its Relationship in Nonsurgical Treatments in Patients with Lumbar Spinal Stenosis
Authors: Martin Brian J. , Beckner Meaghan E. , Sowa Gwendolyn A. , Schneider Michael J. , Flanagan Shawn D. , Dunn‐Lewis Courtenay , Poropatich Ronald , Nindl Bradley C. 
Published: June 2021

BackgroundLumbar spinal stenosis (LSS) is commonly caused by degenerative arthritis of the spine and is characterized by narrowing of the spinal canal and/or neural foraminae. It is prevalent in older adults and leads to limitations in physical function and activities of daily living. Insulin‐like growth factor I (IGF‐I) and insulin‐like growth factor binding proteins (IGFBPs) have been associated with osteoporosis, chronic musculoskeletal diseases and metabolic disorders. A potential relationship between LSS and the IGF axis is currently unknown.PurposeThe purpose of this study was to examine the effects of three nonsurgical treatment programs in patients with LSS to determine potential relationships with the IGF axis and outcome measures of pain and physical function.MethodsThe study was a secondary analysis of stored plasma from a previously conducted randomized controlled trial. The final data set consisted of 102 participants (39 medical care (MC), 26 community‐based group exercise (GE), and 37 clinic‐based manual therapy and individual exercise (MT). The primary outcome measures were IGF‐I and IGFBP 1–7. Secondary outcome measures consisted of the Swiss Spinal Stenosis (SSS) Questionnaire, physical activity (defined as amount of time spent in light/moderate/vigorous activity (> 1.5 METSs), and distance walked (meters) on a self‐paced walking test (SPWT). These outcome measures were collected at baseline, 2‐month, and 6‐month follow‐ups. IGF‐I and IGFBPs 1–7 were analyzed for within and between group differences across time using a two‐way repeated measures ANOVA. Correlation coefficients between the primary and secondary outcome measures were analyzed using Spearmans's rho. All data are means ± SD.ResultsThe two‐way ANOVA revealed a small group difference with IGFBP‐3 between GE and MT (6.81 ± 4.34 vs. 4.96 ± 1.79 ng/mL, respectively, p = 0.03), but not between GE and MC (6.81 ± 3.07 vs 5.45 ± 2.15 ng/mL, respectively, p = 0.18). No other differences between groups or other variables across time were observed (p > 0.05). Using Spearman's rho we observed a small but significant positive correlation between baseline IGF‐I and IGFBP‐7 with baseline SSS (rs = 0.20, p = 0.04 and rs = 0.21, p = 0.03) but neither correlation was apparent at the 2‐ or 6‐month follow‐up. Lastly, a small positive correlation was also observed between baseline IGFBP‐1 and physical activity time at the 2‐month follow‐up (rs = 0.21, p = 0.04).ConclusionThe present study examined the systemic effects of three different nonsurgical treatment modalities on concentrations of IGF‐I and IGFBPs 1–7 in patients with LSS. Both physical activity and muscle stretch have been shown to favorably alter the IGF axis, potentially improving muscle function and reducing risk of degenerative diseases. However, the present study did not observe any effects suggesting improvement in the IGF axis from any of the three interventions.Support or Funding InformationFunding provided by a pilot grant from Wabtec Corporation, through the Center for Military Medicine ResearchThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.