Assessing Low Skeletal Mass in Patients Undergoing Hip Surgery: The Role of Sonoelastography

Abstract

Purpose: To analyze the utility of sonoelastography-a radiation-free procedure to characterize muscle properties-as an instrument to qualitatively and quantitatively assess the rectus femoris muscle.

Materials and methods: Fifty-one consecutive patients who underwent a pelvic computed tomography (CT) exam were enrolled prospectively. The final analysis was conducted using data from 39 patients after 12 were removed due to exclusion criteria (muscle strength could not be measured due to poor cognition [n=11]; too young [n=1]). The potential correlation between average Hounsfield unit (HFU) at the rectus femoris muscle (measured by CT) and muscle quality grade (determined by sonoelastography) was assessed along with a retrospective analysis of the relationship between hand grip strength, knee extensor power, history of intensive care unit stay, length of hospital day and sonoelastographic grade.

Results: There was a significant correlation between sonoelastographic grade and the average HFU (P<0.001). Furthermore, hand grip strength (P<0.001) and knee extensor power (P<0.001) decreased significantly as the sonoelastographic grade increased. The likelihood of an intensive care unit stay and prevalence of low skeletal mass increased significantly with an increase in sonoelastography grade (P=0.037, P<0.001, respectively). The sensitivity, specificity, and accuracy of sonoelastographic images for predicting low skeletal mass were 77.3%, 100%, and 87.5%, respectively.

Conclusion: Sonoelastography advantages, including the lack of radiation and greater accessibility, may make it a valuable alternative to qualitatively and quantitatively identify sarcopenia and low skeletal mass.

Keywords: Femur; Muscle strength; Sarcopenia; Sonoelastography.

Fig. 1. Conventional ultrasonographic (US) images of the rectus femoris muscle and sonoelastographic images using frozen US images. (A) The blue region is dominant and thus classified as grade 0. (B) When The blue region is relatively dominant (i.e., involved more than half of the muscle), it is classified as grade 1. (C) When the area occupied by the blue region is less than half, it is classified as grade 2.

RF: rectus femoris, VL: vastus lateralis, VI: vastus intermedius.

Fig. 2. Cross-sectional area of rectus femoris muscle was taken at three-fifths of the interval from the anterior superior iliac spine to the superior patellar border. By outlining the rectus femoris muscle using computed tomography images, average Hounsfield unit calculations and cross-sectional area of the rectus femoris was obtained.

Fig. 3. Positive correlation between sonoelastographic grade and average Hounsfield unit (HFU) calculation.

Fig. 4. Positive correlation between CSA_RF (sonoelastography) and CSA_RF (computed tomography).

SD: standard deviation.

Fig. 5. Significant differences in grip power and knee extensor power based on sonoelastography grade.

Fig. 6. Frequency of non-sarcopenia and sarcopenia by sonoelastography grade.