Jose H Trevino Iii1, Takuma Yuri1,2, Taku Hatta3, Yoshiro Kiyoshige2, Philip M Jacobs4, Hugo Giambini5,6. 1. Department of Biomedical Engineering and Chemical Engineering, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA. 2. Graduate School of Health Sciences, Yamagata Prefectural University of Health Sciences, Yamagata, Japan. 3. Department of Orthopedic Surgery, Tohoku University School of Medicine, Sendai, Japan. 4. Department of Orthopedics, The University of Texas Health Science Center, San Antonio, TX, USA. 5. Department of Biomedical Engineering and Chemical Engineering, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA. hugo.giambini@utsa.edu. 6. Department of Orthopedics, The University of Texas Health Science Center, San Antonio, TX, USA. hugo.giambini@utsa.edu.
Abstract
INTRODUCTION: Rotator cuff tears are common in the older population. Atrophy and fat infiltration develop un-evenly in torn supraspinatus (SSP) muscles leading to pre- and post-surgical complications. The purpose of the current study was twofold: first, to implement a volumetric and quantitative magnetic resonance imaging (MRI) approach to quantify the degree of muscle atrophy and fat infiltration within the SSP muscle and its four sub-regions (AS, PS, AD, and PD); second to compare 3-D MRI outcomes to the standard 2-D assessment and investigate their relationship with tear size. MATERIALS AND METHODS: Fifteen cadaveric shoulders were obtained and MRI performed. Quantitative 3-D outcomes included SSP muscle volume, fossa volume, fat-free muscle volume, and fat fraction for the whole SSP muscle and its four sub-regions. 2-D and qualitative measurements included tear size, 2-D fat infiltration using the Goutallier classification, tangent sign, and occupation ratio. RESULTS: Linear regression outcomes with tear size were not significant for both cross-sectional area (r = - 0.494, p = 0.061) and occupation ratio (r = - 0.011, p = 0.969). Tear size negatively correlated with fat-free muscle volume for both AS and PS sub-regions (AS: r = - 0.78, p < 0.001; PS: r = - 0.68, p = 0.005, respectively) while showing no significant correlation with fat fraction outcomes. AD and PD sub-regions positively correlated with tear size and fat fraction outcomes (AD: r = 0.70, p = 0.017; PD: r = 0.52, p = 0.045, respectively), while no significant correlation was observed between tear size and fat-free muscle volumes. CONCLUSION: Quantitative 3-D volumetric assessment of muscle degeneration resulted in better outcomes compared to the standard 2-D evaluation. The superficial supraspinatus muscle sub-regions primarily presented muscle atrophy, while the deep sub-regions were mainly affected by fat infiltration. 3-D assessments could be used pre-surgically to determine the best course of treatment and to estimate the muscles' regenerative capacity and function.
INTRODUCTION: Rotator cuff tears are common in the older population. Atrophy and fat infiltration develop un-evenly in torn supraspinatus (SSP) muscles leading to pre- and post-surgical complications. The purpose of the current study was twofold: first, to implement a volumetric and quantitative magnetic resonance imaging (MRI) approach to quantify the degree of muscle atrophy and fat infiltration within the SSP muscle and its four sub-regions (AS, PS, AD, and PD); second to compare 3-D MRI outcomes to the standard 2-D assessment and investigate their relationship with tear size. MATERIALS AND METHODS: Fifteen cadaveric shoulders were obtained and MRI performed. Quantitative 3-D outcomes included SSP muscle volume, fossa volume, fat-free muscle volume, and fat fraction for the whole SSP muscle and its four sub-regions. 2-D and qualitative measurements included tear size, 2-D fat infiltration using the Goutallier classification, tangent sign, and occupation ratio. RESULTS: Linear regression outcomes with tear size were not significant for both cross-sectional area (r = - 0.494, p = 0.061) and occupation ratio (r = - 0.011, p = 0.969). Tear size negatively correlated with fat-free muscle volume for both AS and PS sub-regions (AS: r = - 0.78, p < 0.001; PS: r = - 0.68, p = 0.005, respectively) while showing no significant correlation with fat fraction outcomes. AD and PD sub-regions positively correlated with tear size and fat fraction outcomes (AD: r = 0.70, p = 0.017; PD: r = 0.52, p = 0.045, respectively), while no significant correlation was observed between tear size and fat-free muscle volumes. CONCLUSION: Quantitative 3-D volumetric assessment of muscle degeneration resulted in better outcomes compared to the standard 2-D evaluation. The superficial supraspinatus muscle sub-regions primarily presented muscle atrophy, while the deep sub-regions were mainly affected by fat infiltration. 3-D assessments could be used pre-surgically to determine the best course of treatment and to estimate the muscles' regenerative capacity and function.