October Newsletter
Erik Dalton, PhD, Certified Advanced
Rolfer
| Acknowledging the
A/C
The Acromioclavicular or A/C joint sits on the
point of the shoulder lateral to the sternoclavicular and proximal to the
glenohumeral. Like its brother the sternoclavicular joint discussed in our
last issue, this oft-overlooked bony articulation receives little respect
from most manual therapists…a regrettable omission, indeed. Both the A/C
and S/C joints play vital roles in the biomechanics of throwing and other
upper-limb activities. A/C joint injuries typically occur from falling
directly on the point of the shoulder. In competitive sporting events a
direct clash of shoulders between players often displaces or completely
subluxes this joint. Some authors believe that since the A/C is such a
small joint, the human shoulder (under normal circumstances) could
actually function adequately without it. However, long-term A/C
restrictions can have devastating effects on all upper limb
functioning.
Since the acromioclavicular is a planar joint,
small movements occur in all three planes. Arm elevation causes the
acromion to glide superiorly on the distal clavicle. To test movement of
this joint on yourself, simply glide your right index finger laterally
along the superior surface of your left clavicle beginning at the
sternoclavicular joint. Just before you contact the acromion you should
feel a bump or a notch. Since arm elevation raises the acromion in
relation to the clavicle, left arm abduction should allow your finger to
palpate a “dip” as the acromion rises on the clavicle.
Approximately 20° of motion occurs at the AC
joint during arm abduction with 10° occurring between 0° and 30° of arm
elevation and the last 10° occurring during the last 45° of the normal
range (180°) of arm elevation. At both the AC and SC joints, the clavicle
posteriorly rotates approximately 45° during arm elevation. This motion is
allowed by the planar configuration at the A/C joint and the
fibrocartilaginous articulating disc between the sternum and proximal
clavicle as discussed in the last “Sternoclavicular”
newsletter. |
 |
The most common three restrictions at the
acromioclavicular joint involve limited internal and external rotation and
abduction. To test for restrictions of internal and external rotation, the
client’s elbow is flexed 90 degrees, arm horizontally abducted 90 degrees, and
horizontally adducted 30 degrees. Adducting the arm 30 degrees close-packs the
glenohumeral joint allowing the therapist to isolate and test only for A/C
restrictions.
 |
Assessing for Internal Rotation
Restrictions
To test for limitations
in internal rotation the therapist’s left hand braces medial to the A/C
joint, shoulder braces elbow, and his right hand brings client’s arm to
the first internal rotation barrier. The client attempts external rotation
(pushes up) with a 20% effort to a count of six and relaxes. The therapist
then brings the arm down into more internal rotation to the next
restrictive barrier and repeats the same procedure until full 90 degrees
of internal rotation is restored. |
 |
Assessing for External Rotation
Restrictions
The therapist’s right
hand braces the AC, arm braces the elbow, and his left hand brings
client’s arm to the first external rotation barrier. Therapist resists
clients attempt to internally rotate (pushing arm down) to a count of six
and relaxes. Client’s arm is then brought up to meet the new external
rotation barrier and procedure is repeated until 90 degrees of external
rotation is achieved. The key to success in this maneuver requires that
therapist always maintain the arm in 30 degrees of horizontal adduction so
the glenohumeral does not come into play. |
 |
Testing Arm
Abduction
Now it is time to test the
ability of the arm to abduct in a smooth 180 degree pain-free arc. In this
test, the client’s right arm rests on therapist’s left shoulder and is
brought into 30 degrees if horizontal abduction. Therapist bends knees and
hands grasp medial to the acromion. As the therapist slowly straightens
his legs while bracing with his hands, a counter-force is created that
brings the client’s arm to the first abduction restrictive barrier. Client
is asked to press down on therapist’s shoulder to a count of six and
relax. Therapist again straightens legs bringing client’s arm up to the
new restrictive barrier. This continues until 180 degrees of smooth,
pain-free abduction is attained. |
AC joint restrictions typically limit
end-range elevation and cross-body adduction. Often seen in long-standing
rotator cuff and frozen shoulder dysfunctions, sternoclavicular and
acromioclavicular restrictions are typically the first joints affected by
postural asymmetries (upper crossed syndrome) in the upper quadrant. As a
result, even minor restrictions at these primary upper extremity joints set off
mechanoreceptive muscle/joint reflex arcs that quickly travel down the kinetic
chain producing sympathetic protective muscle guarding (splinting) in all soft
tissues and associated joints of the shoulder. Pain-spasm-pain cycles are often
difficult to correct until full range of motion is restored to these commonly
overlooked bony articulations.
Note: In all the ‘so-called’ joint
mobilization routines presented during our tour through the upper extremities,
please keep in mind that although we are speaking in terms of bony restrictions,
our intent is to release myofascial adhesions limiting joint movement.
Look forward to November’s E-newsletter as
we embark on an adventure through the most mobile and arguably the most complex
joint of the body. Try and catch this month’s issue of Massage and
Bodywork magazine. Tom Myers and I have a couple interesting articles on
Posture. Remember that many of my past magazine articles are posted on my
website at: http://erikdalton.com/massagearticles.htm See you
soon!
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