Stretching positions for the posterior capsule of the glenohumeral joint: strain measurement using cadaver specimens.
BACKGROUND
Various stretches have been introduced for the posterior shoulder; however, little quantitative analysis to measure stretching of the posterior capsule has been performed.


OBJECTIVE
The current shoulder stretching program is not sufficient to stretch the entire posterior capsule.


METHODS
Controlled laboratory study.


METHODS
Using 8 fresh-frozen cadaver shoulders (average age, 82.4 years), 8 stretching positions for the posterior capsule were simulated by passive internal rotation. Stretching positions of 0 degrees , 30 degrees , 60 degrees , and 90 degrees of elevation in the scapular plane; 60 degrees of flexion; 60 degrees of abduction; 30 degrees of extension; and 60 degrees of flexion and horizontal adduction were adopted. Strain was measured in the upper, middle, and lower parts of the capsule. The measurement of strain was instituted from reference length.


RESULTS
With internal rotation, mean strain on the upper capsule was 3.02% at 0 degrees of elevation and 3.35% at 30 degrees of extension. Strain on the middle capsule at 0 degrees and 30 degrees elevation was 0.78% and 4.77%, respectively; on the lower capsule, it was 5.65% and 2.24% at 30 degrees and 60 degrees of elevation, respectively, and 2.88% at 30 degrees of extension. Increase in strains of the upper, middle, and lower capsule with internal rotation at 0 degrees , 30 degrees , and 60 degrees of elevation were statistically significant, respectively (P < .01). Other shoulder positions demonstrated no positive strain values.


CONCLUSIONS
Based on the results of this cadaver study, large strains on the posterior capsule of the shoulder were obtained at a stretching position of 30 degrees of elevation in the scapular plane with internal rotation for the middle and lower capsule, while a stretching position of 30 degrees of extension with internal rotation was effective for the upper and lower capsule.


CONCLUSIONS
The current posterior capsule stretching program of the shoulder was not sufficient to stretch the entire posterior capsule.
Department of Physical Therapy, Sapporo Medical University School of Health Sciences, Sapporo, Japan.
Tomoki
T
Izumi
Mitsuhiro
M
Aoki
Takayuki
T
Muraki
Egi
E
Hidaka
Shigenori
S
Miyamoto
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006801:Humans; D017746:Joint Capsule / Q000502:physiology*; D008297:Male; D052580:Muscle Stretching Exercises / Q000379:methods*; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D012785:Shoulder Joint / Q000502:physiology*; D013314:Stress, Mechanical