Posterior shoulder capsules are thicker and stiffer in healthy
college baseball players: A quantitative assessment using shear-wave ultrasound

Takenage T, Sugimoto KS,
Goto H, Nozaki M, Fukuyoshi M, Tsuchiya A, Murase A, Ono T and Otsuka T. Am J Sports Med. 2
015. [Epub
Ahead of Print].

Home Message: Thickening of the posterior glenohumeral joint capsule is
correlated with lower ranges of glenohumeral internal rotation in collegiate baseball

The glenohumeral joint experiences significant distraction forces (1.5
times body weight) during the deceleration phase of overhead throwing. Current
research suggests that the posterior shoulder capsule thickens to accommodate this
stress. However, the relationship between capsule thickness and its effect on
glenohumeral internal rotation has not been conclusive. Therefore, Takenaga and
colleagues completed a cross-sectional study to assess the thickness and
elasticity of the posterior and posteroinferior capsule of the shoulder and its
relationship to glenohumeral internal rotation in collegiate baseball players. The
authors recruited 45 collegiate baseball players (male, ~20 years old, 13
pitchers) with no history of shoulder injuries. The authors evaluated posterior
capsule thickness using shear-wave ultrasound elastography in both a seated
position with the arm 0
º abduction and adduction
and 90
º of shoulder flexion.
Passive glenohumeral range of motion was assessed with a goniometer while the
participant laid supine with the shoulder at 90
º of
abduction. Overall, both posterior and posteroinferior capsule stiffness and
thickness in the throwing shoulder was greater than the non-throwing shoulder. Both
capsule thickness and elasticity were negatively correlated with glenohumeral
internal rotation. Hence, thicker capsules and greater stiffness were related
with less glenohumeral internal rotation.

Overall, the authors presented interesting findings for clinicians, especially
those dealing with
overhead throwing
athletes. The conclusions of the current study are in agreement with those of
Thomas and
which suggest that the repetitive
loading of overhead throwing may be a factor in the thickening of the posterior
and posteroinferior joint capsule. This change is most
likely a compensation to attempt to accommodate the large loads,
however to absorb these large loads, range of motion will logically be limited.
This would explain the second main finding that the increase in thickness would
be negatively correlated with glenohumeral internal rotation. If clinicians do
encounter patients with severely limited range of motion, they should seek to
treat the posterior capsule tightness. To avoid excessive stretching proper
assessments should precede this treatment strategy.   

Questions for Discussion: What treatments have you found to be effective in treating limited
range of motion in the shoulder of an overhead throwing athletes? Does this
treatment effect the joint capsule to restore motion?

Written by: Kyle Harris
Reviewed by:  Stephen Thomas

Related Posts:

Takenaga T, Sugimoto K, Goto H, Nozaki M, Fukuyoshi M, Tsuchiya A, Murase A, Ono T, & Otsuka T (2015). Posterior Shoulder Capsules Are Thicker and Stiffer in the Throwing Shoulders of Healthy College Baseball Players: A Quantitative Assessment Using Shear-Wave Ultrasound Elastography. The American Journal of Sports Medicine, 43 (12), 2935-42 PMID: 26473012