Quantitative MRI measurement of muscle atrophy and fatty infiltration after rotator cuff repair


 Background: It is not yet clear whether muscle atrophy and fat degeneration have improved after successful arthroscopic rotator cuff repair. Therefore, in this study, the quantitative MRI measurement was performed to evaluate the changes of muscle atrophy and fat degeneration before and after surgery more accurately and to analyze the correlation between changes in muscle atrophy and fat degeneration and clinical outcome.Materials and Methods: From March 2013 to March 2017, 40 patients who had no retear up to 1 year after rotator cuff repair were taken before surgery, 3 days after surgery, and 1 year after surgery. Supraspinatus muscle atrophy and fat infiltration were measured quantitatively in Conventional Y view and Supraspinatus origin view. The measurement items were muscle area , occupation ratio, degree of fat degeneration (%) and area of fat degeneration (㎣). Postoperative clinical results were measured by ASES score and Constant score at 1 year. Correlation between values and scores was analyzed. Results: Inter-measurement reliability was high (ICC = 0.933, Cronbach-α = 0.963). There was no significant change in muscle atrophy in Conventional Y-view at 1 year after surgery (Occupation ratio:P = 0.2770; Muscle area(㎣) P = 0.3049) and muscle atrophy in Supraspinatus origin view(Muscle area(㎣) P = 0.5953). Fatty Infiltration (%) and fat area (㎣) measured with conventional method on Y-view and showed significant difference (P = 0.0001). Fatty Infiltration (%) and fat area (㎣) measured with modify method on Y-view and SOV-view showed no significant difference (all P ＞0.05). Postoperative constant score and ASES showed significant improvement compared to preoperative (P = 0.0001), but there was no correlation between fat infiltration and muscle atrophy. (P = 0.653) Conclusion: Clinical outcome (ASES, Constant score) was significantly improved after rotator cuff repair surgery. Clinical outcome (ASES, Constant score) does not have correlation with FI & MA. Muscle Atrophy does not have change 1-year after surgery. Fatty Infiltration was improved in Y-view measured by conventional method. Keywords: Fatty infiltration, Muscle atrophy, Arthroscopic rotator cuff repair, Supraspinatus origin view, Y-view


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Rotator cuff tear is the most common diseases in shoulder with the high incidence of individuals over 60 31 years old. Arthroscopic rotator cuff repair (ARCR) leads to good midterm to long-term results in most cases and 32 become more and more popular [1,2], however, re-tear is the most common complication of arthroscopic repair 33 and poor outcomes also were reported .The re-tear rates of rotator cuff was from 10% up to 41% by in 6 months 34 base on recent studies [3,4]. irreversible [9][10][11][12]. Therefore, it is imperative to assess FI and MA using accurate methods.

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There are qualitative and quantitative parameters in the method of evaluating and classifying FI and MA.

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Quantitative parameters mainly use muscle area and occupation ratio [13]. Qualitative parameters of MA include

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There have been many studies on whether FI and MA are improved reversibly after surgery and no change as 52 an irreversible factor, and many studies have measured and compared serial MRI. It's controversial. While there 53 have been reports of improvement of FI and MA after surgery, some studies show that the reduction of FI and 54 MA is irreversible regardless of surgery.

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In the previous studies, the most problem was that the parameters measured in the oblique sagittal MRI before 56 and after the surgery were not measured at the exact same position, and that they did not accurately reflect the 57 tendon traction that occurred during the surgery.

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This study uses qualitative parameters, measured in Conventional Y-view and the supraspinatus origin view 59 with conventional method and modified method for muscle atrophy and fat infiltration before and after surgery.

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The purpose of this study was to investigate whether there was a significant change in degeneration and to 61 determine the correlation between the change of muscle atrophy and fatty infiltration and clinical outcome.

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All patients underwent same rehabilitation protocol, using abduction sling for 6 weeks. Pendulum exercise 152 was started 1 week after surgery, and active assisted range of motion exercise was followed for 6 weeks after  Institute, Cary, NC, USA). P-values< 0.05 were considered statistically significant.

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A total of 40 patients were included (male, n = 16; female, n = 24) with an average age of 60.9 ± 7.62 years.

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Our results focus on measuring FI and MA more accurately and quantitatively than previous studies. Rather,

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it was measured in the Supraspinatus origin view. In addition, follow-up observation was performed before,

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immediately after surgery, and 1 year after surgery. The correlation between the measured changes in FI and

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MA and the clinical outcome was also analyzed.

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FI was found to be significantly decreased in the study, but MA was significantly progressed. Most of the 215 previous studies were also analyzed using MRI measures using various methods and criteria, but the results

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from the Conventional Y-view and qualitative measurements were dominant.

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Chris et al. [17] have been reported that FI and MA of SST and IST recover after arthroscopic surgery. The between the constant score and the ASES score were compared according to the FI and MA changes, but the 238 qualitative comparison method was used, and the correlation was negative.

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The quantitative and qualitative parameters and measurement methods for FI and MA used in each study

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were not significantly different, and the measurement site was not significantly different with the Conventional The datasets generated during and analyzed during the current study are not publicly available due to ethical 289 concern but are available from the corresponding author on reasonable request