Shoulder Pain in Competitive Swimmers: A Multi-Site Survey Study.

Background: There are 2.8 million youth competitive swimmers in the United States (US), and shoulder pain is the most common complaint among swimmers. Purpose: To determine prevalence of shoulder pain, disability, and dissatisfaction in youth competitive swimmers. A secondary purpose was to determine influence of age, competitive swimming experience, and previous history of shoulder pain or injury on shoulder pain, disability, and dissatisfaction, and finally to determine if sex, geographic area, and participation in a second sport relate to shoulder pain, disability, and dissatisfaction. Study Design: Multi-site cross-sectional design. Methods: Six-hundred and seventy-one swimmers aged 9-17 years from six states in the US completed surveys which included demographics, the Penn Shoulder Score (PSS), and the Disability of Arm Shoulder Hand (DASH) Sports. Independent t-tests were used to compare pain, disability, dissatisfaction, the influence of age, sex, participation in second sport, geographic region, and history of shoulder pain. Linear regression analyses were performed to determine the interaction of these variables with reported pain and disability. Results: Forty-nine percent of swimmers had shoulder symptoms. Greater shoulder pain and disability were reported in 15 to 17-year-olds compared to 9 to 10-year-olds (pain and disability: p<0.001), in swimmers with greater versus less years of experience (pain and disability: p<0.001), and in swimmers from eastern versus western states (pain: p=0.001, disability: p=0.0014). Swimmers not participating in a second sport had higher shoulder dissatisfaction (p=0.002). History of prior shoulder pain/traumatic injury was the best indicator of increased pain, disability, and dissatisfaction (p<0.001). Conclusion: Almost half of swimmers surveyed had shoulder pain, with a higher prevalence found in older age groups, those with greater experience, and in those with prior shoulder pain or traumatic injury. Further research should investigate shoulder pain prevention programs, and surveillance methods are recommended to identify symptomatic swimmers who may benefit from referral to prevent further pain and disability. Level of Evidence: III.

Parcellation of Human Amygdala Subfields Using Orientation Distribution Function and Spectral K-means Clustering.

Amygdala plays an important role in fear and emotional learning, which are critical for human survival. Despite the functional relevance and unique circuitry of each human amygdaloid subnuclei, there has yet to be an efficient imaging method for identifying these regions in vivo. A data-driven approach without prior knowledge provides advantages of efficient and objective assessments. The present study uses high angular and high spatial resolution diffusion magnetic resonance imaging to generate orientation distribution function, which bears distinctive microstructural features. The features were extracted using spherical harmonic decomposition to assess microstructural similarity within amygdala subfields are identified via similarity matrices using spectral k-mean clustering. The approach was tested on 32 healthy volunteers and three distinct amygdala subfields were identified including medial, posterior-superior lateral, and anterior-inferior lateral.