Do Shoulder Vibration Signals Vary Among Asymptomatic Volunteers

Numerous studies document vibrations emanating from joints during active or passive motion. It has been proposed these vibrations, termed vibroarthrographic signals, are associated with changes in the shape or quality of tissues in and around the joint. Vibroarthrographic signals in articular joints have been tested to correlate a particular signal with a particular feature of a joint such as a specific lesion. Because of the limited morphologic changes noted in dominant and nondominant articular joints, we hypothesized shoulder vibroarthrographic signals would be similar between subjects. We determined vibroarthrographic signals in young, adult, asymptomatic volunteers evaluated by 21 different active physician-assisted physical examination tests. Comparisons of data from both shoulders with a two-sample statistical test and a neural network demonstrated difficulty distinguishing the dominant and nondominant shoulder. Four percent of the comparisons were different, and the sensitivity of the neural network averaged 50% for most physical examination tests when classifying shoulder signals as dominant or nondominant. Our findings suggest future studies investigating vibroarthrographic signals from symptomatic shoulders can be compared with asymptomatic shoulders from young patients with little regard to limb dominance for most physical examination tests.