Download The Rotator Cuff and Shoulder Mechanics

The Rotator Cuff and Shoulder Mechanics
GEORGE RUSSELL, DC
Getting Better Community
1133 Broadway Suite 1125
New York, NY 10010
[email protected]
(646) 654 9529
Facebook: Getting Better Community
History: “It hurts in certain positions”. Pain while holding up arm for a fine motor task. Pain with
arm straight out (greatest stress on shoulder). Many locations in shoulder, down arm. Usually
diffuse (see Travell)
Palpation The ball and socket joint is very shallow. The shoulders will be off the table supine, and
may be forward in standing. It will look at first like a narrow chest/tight pecs. But it’s really that
the humeral head is forward and up. Test it going from the outside of the circle of the ball from AP to S-I, pressing at every location toward the center of the ball.
Ball and Socket Joint Mechanics In a ball and socket joint, the far end of the bone (elbow) is
moved by the big, external muscles (deltoid, pec, lat, etc.). They ROLL the ball out of the socket to
leverage the other end. The bone will dislocate if there isn’t an equal and opposite GLIDE back
toward the center of the joint. This is the most important role of the so-called ‘rotator cuff”.
Muscle “Actions” Are A Useful Fiction -- the “Rotator” Cuff. The anatomical “actions” of
muscles were determined by cutting up a cadaver and moving it around, and looking at the fiber
angles. Later, machines were developed to contract a muscle and watch what happened. At certain
angles, the rotator cuff muscles do rotate the humerus on the scapula. But both of these
“scientific” methods failed to assess human function, focusing instead on structure. So they missed
the role of the rotator cuff, which is to suck the humeral head into the center of the joint no matter
where the elbow goes in space. E.g., when you throw a baseball 90 miles per hour over home plate,
the rotator cuff prevents your arm from flying off your shoulderblade at the same speed.
Testing muscle “actions”
Here are some tests -- but why wouldn’t you just touch the muscles? :-). The most important
muscles in shoulder pain are the rotator cuff. Most of the others are secondary.
Supraspinatus “abduction” (except above 120 degrees :) test at 45 degrees between
flexion and abduction with thumb up, slowly. Codman’s test – in that position, challenge
by tapping arm down.
Infraspinatus “external rotation” from a position of internal rotation and forward flexion,
or elbow at side, arm at same 45 degree angle as above.
Subscapularis “internal rotation” – arm behind back, elbow low, lift arm off back.
Teres Minor “external rotation” – same as infraspinatus.
George Russell
Rotator Cuff and G-H Joint
Page 2
Shoulder Range of Motion – relationship of humerus to shoulder blade. Apley’s test for range of
motion – arm across front of neck, arm behind back, elbow low and elbow high. Apley’s is a
general test for shoulder dysfunction. It just tells you something about range of motion and if
something is wrong, but not what is wrong. You can have them move through the actions of the
shoulder, stopping before true pain. Range of motion is most important as a “before and after”
demonstration of how you helped the client.
Scapulohumeral Rhythm - - The sca pu la r eleva tors a nd u pwa rd rota tors help the
sca pu la su bstitu te for the glenohu m era l joint when it is lim ited or pa infu l in m otion.
In a n idea l world , the sca pu la sta rts m oving with the hu m eru s a t a bou t 20 d egrees of
a bdu ction a fter which the m ovem ent is ⅔ glenohu m era l a nd ⅓ sca pu la r u pwa rd
rotation (measured from acromion). Rehabbing the shoulder involves retraining that
relationship, and retraining the scapula to rotate upward rather than elevating. The
opposite of elevation here is not depression of the scapula, it’s upward and/ or
downward rotation.
The Rotator Cuff In Shoulder Dysfunction
In all shoulder pain and dysfunction – look for misalignment/muscle imbalance -- massage releases
and activates muscles, especially if you tap or scratch in fiber direction
Rotator cuff tendonitis – check the muscles and the alignment!!!!!!!!!!!!! Work muscles before
tendons – save the cross friction for later :)
Acromial bursitis
Acromial impingement syndromes –
“Frozen shoulder” – adhesive capsulitis v. subscapularis dysfunction
Rotator cuff tear
Myofascial pain syndrome
Pain on resisted movement – muscle or tendon
Pain on passive movement – ligament or capsule
Apprehension and autonomic symptoms – shoulder dislocation?
Shoulder instability – strengthen rotator cuff, shoulder blade stabilizers shoulderblade position is
crucial to proper function (catcher’s mitt and a baseball)
Ruling out nerve pain. Compression test for neck – push firmly/gently straight down on head. If
shooting, specific area arm pain results, it’s probably a nerve problem. Traction if possible. You
may want to refer to a chiropractor or physical therapist -- but why not try massage, home care and
ROM work first?. If there is a loss of strength in arm muscles that isn’t from pain, you should refer
them to a physiatrist, orthopedist or their general practitioner. If traction relieves pain, it’s further
evidence of a nerve impingement problem. Maximal foraminal compression test – more extreme
than compression. Do not do this test if compression test is positive – ipsilateral rotation and
lateral flexion. Add extension for fullest compression. (Dis)traction test – gently/firmly move
head and shoulder away from each other. If it causes shooting pain on the side being lengthened, it
may be a brachial plexus nerve problem or a scalene trigger point problem. Palpate the scalenes. If
scalene treatment doesn’t help, refer.
George Russell
Rotator Cuff
Page 3
Risk Factors For Rotator Cuff Strain
activities that require glenohumeral stabilization
the hairdresser and baseball pitcher
older people may have difficulty fixing hair
Case histories: “It hurts when I eat soup”; “my shoulder is breaking off when I swim”; “By the
way, I have a frozen shoulder and it can’t be thawed”
Frozen Shoulder and Menopause -- there are estrogen receptors on ligaments and muscles
Treatment
Supraspinatus
Infraspinatus/Teres Minor
Subscapularis
Mobilization of G/H, A/C, S/C and S/T articulations
Move the arm while you work
Having the patient move the arm while you hold a point
Retesting ROM periodically (diagnostic, therapeutic and cognitive effects)
Strengthening
I never use exercises for the classic anatomical actions in open chain, e.g. theraband.. If you do, tie
the band to the wrist to keep the finger muscles out of it.
Closed chain movement is best. Clasp hands behind buttocks with arms straight and punch
straight down while externally rotating the upper arm as much as possible. Therapist can resist
movement. Arms against wall, straight, chest facing foward. Then take one arm away and stay in
the same shape. Then try turning body, leaving arm EXACTLY where it was. Alternate back and
forth. Hold plank position. Walk around with hands. Walk up and down over blocks or books.
Turn muscles off completely between exercises. The element of surprise, responsiveness and
subtlety is important. The rotator cuff is Michael Jordan. The delt, pec and lat are Arnold
Schwarzenegger.
Partial Bibliography:
Great website for muscle information and stretches/techniques: www.drmarcheller.com
The classic myofascial pain reference: Travell, Janet and Simons, David. Myofascial Pain and
Dysfunction: The Trigger Point Manual. Williams & Wilkins, 1983.