Does the presence of proximal humerus growth plate changes in young baseball pitchers happen only in symptomatic athletes? Anxray evaluation of 21 young baseball pitchers

Abstract

Radiographic changes in the proximal humerus growth plate were found in 66% of the cases, but 64% were asymptomatic. These changes indicate possible evolution, in the future, to a greater degree of retroversion in pitchers' dominant shoulders.

The Human Shoulder Suspension Apparatus: A Causal Explanation for Bilateral Asymmetry and a Fresh Look at the Evolution of Human Bipedality

“…Our biomechanical model of the shoulder suspension apparatus in a right‐handed individual incorporates our general morphometric data and makes explicit predictions about the functioning of its muscles, which can be tested by functional analytical methods (Homberger, ; Bock and Homberger, ), such as electromyography to test the predicted synchronization of contractions by different muscles (see, e.g., Basmajian, ; Loeb and Gans, ), strain gauges to test the predicted relative strains in different muscles and tendons (see, e.g., Herring et al, ), or piezoelectric crystals to test the predicted changes in the length of muscles and, thereby, of the distance between the skeletal elements to which they attach (see, e.g., Griffiths, ). It also corroborates the classic theories of Virchow (), Roux (), and Wolff () concerning the influence of muscle forces on bone formation and supports recent observations that muscle forces influence the shape and size of bone (e.g., Krahl, ; Cowgill, ; Sládek et al, ; Auerbach and Raxter, ; Murachovsky et al, ; Preuschoft et al, ; Blackburn, ; Sanchis‐Moysi et al, ; Wyland et al, ). More specifically, our model explains the causal interplay between greater musculo‐fascial forces, better developed musculo‐fascial components of particular muscles, and the size and shape of bony features serving as muscle attachments.…”

“…The variability in composition of bilateral asymmetries within an individual and between individuals that is shown in our study suggests that the biomechanical causes of asymmetries are complex, affecting each bony feature in each individual in a different way (Auerbach and Ruff, ; Barros and Soligo, ; Cashmore and Zakrzewski, ). This variability is likely due to a variety of underlying causes, such as idiosyncratic behaviors, occupations that require habitual postures (e.g., the stoop of a dentist or the forward head posture of a data entry specialist or microscopist) or repetitive movements (e.g., the throwing of baseballs by a pitcher or the throwing of pots by a ceramicist; (see also Pieper, ; Murachovsky et al, ; Wyland, ), besides variations in the morphology and location of muscle attachments due to genetic and epigenetic causes.…”

“…And because the mastoid processes begin to acquire their distinctive size and shape postnatally (Cinamon, ), we hypothesized that the characteristic configuration of the human mastoid process and clavicle may at least partly be a function of the forces acting on them during postnatal development as an infant starts to sit up, stand up, and walk and, by extrapolation, during the evolution of a shoulder suspension apparatus as ancestral humans acquired an upright posture and bipedality. About 70–90% of humans use one hand preferentially, which results in bilateral asymmetries in the soft and bony tissues (see, e.g., Ruff, ; Steele and Mays, ; Sanchis‐Moysi et al, ; Volpato et al, ; for additional references, see Osborn, ); like the size of the mastoid process, these asymmetries also increase during development (Murachovsky, ; Blackburn, ). Thus, our hypothesis is testable by ascertaining whether asymmetries in the forces that are naturally applied to the shoulder suspension apparatus are causally correlated with asymmetries of the bony features.…”

Bilateral Asymmetry of Humeral Torsion and Length in African Apes and Humans

“…Adult humeral torsion values in humans develop during growth in the proximal epiphysis (where 80% of humeral growth takes place [Pritchett, 1991]) as a result of repetitive rotational stresses, which lead to the deformation of the epiphyseal cartilage, thus resulting in reduced torsion values [Mair et al, 2004;Murachovsky et al, 2010;Thomas et al, 2012;Wyland et al, 2012]. Although the exact timing of the cessation of humeral torsion development is unknown [Cowgill, 2007], it is thought to occur at the time of epiphyseal fusion, between the ages of 16 and 20 [Krahl, 1976;Edelson, 2000].…”

Solutions for swimmer’s shoulder, baseballer’s elbow and runner’s upper respiratory tract infection

“…Normal variant or pathology? This paper from Brazil2 (see page 90 ) helps to clarify that issue. And if you are treating paediatric sports injuries remember to check back to the January 2010 issue (http://bjsm.bmj.com/content/vol44/issue1/?etoc), which raised lively debates (http://blogs.bmj.com/bjsm/) about kids, their treatment, and their injuries.…”