ABSTRACT Muscle stiffness is a critical biomechanical property that influences joint function and neuromuscular control, with deviations often indicating underlying pathology. Two‐dimensional shear wave elastography (2D‐SWE) is a non‐invasive imaging technique that quantifies muscle stiffness and shows clinical promise in musculoskeletal assessment. The pectoralis major and minor muscles are of interest due to their roles in shoulder function and their susceptibility to treatment‐related changes, especially in breast cancer populations. Despite its potential, no systematic review has yet evaluated the reliability and validity of 2D‐SWE for assessing stiffness in these muscles. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines, using PubMed and Web of Science to identify relevant studies. The Consensus‐Based Standards for the Selection of Health Measurement Instruments (COSMIN) checklist was used to assess methodological quality. Five studies met inclusion criteria, all evaluating the reliability of 2D‐SWE for pectoralis muscle stiffness. Intra‐rater reliability ranged from moderate to excellent (ICC = 0.57–0.99), while inter‐rater reliability was consistently good (ICC = 0.85–0.89). No studies assessed validity, and most had doubtful or inadequate quality in key COSMIN domains. This review emphasizes that 2D‐SWE demonstrates moderate to excellent intra‐ and inter‐rater reliability for assessing stiffness of the pectoralis major and minor muscles in healthy individuals. However, the validity of SWE for these muscles has not been established. Given limited demographic diversity, future research should focus on validation in broader populations and protocol standardization to support clinical applicability.
Verbeelen et al. (Thu,) studied this question.