Scapular Dyskinesis

The Key Link in Neck and Shoulder Pain

I can’t say that all (non traumatic) neck/shoulder pain is related to scapular dyskinesis, but 60% of the time, it is every time. Scapular dyskinesis means an odd or uncontrolled movement of the scapula, also known as decentration. This can overload tissues that are working too hard, or cause structures to be impinged or pinched.

Our shoulder is an extremely unique structure, not just in our bodies but truly in the entire animal kingdom.  No other creatures swing their arms to walk upright or run, throw with precision and speed, or reach even over head with palms facing inwards (other primates palms face outwards when reaching overhead). Let’s explore some anatomy and the requirements of the shoulder complex.

Anatomy

Like Spider-Man and Uncle Ben say: “With great power comes great responsibility.”  Our shoulder joint has the greatest mobility of all our joints and the least natural stability.  Hence the great responsibility.

The shoulder itself is actually 4 joints. The glenohumeral (GH) joint is a ball and socket, the arm bone (humerus) and the shoulder socket portion (glenoid) of the scapula.  This is the main mover, the one that dislocates and the site of rotator cuff injuries. The GH joint is largely stabilized against the scapula (socket) by the rotator cuff as well as ligaments and cartilage. Our scapula, is an amazing piece of engineering.  Its bony attachments to the body are via the collar bone (clavical) at the AC (acromioclavicular), and the SC (sternoclavicular) joints.  Then the gliding joint of the scapula and rib cage. It is stabilized and controlled by the 17 muscles that attach to it.

The scapula plays roughly the same role as the pelvis and hip socket in regards to force transmission between the axial (spine, skull and chest) appendicular (extremities) skeleton. They are both referred to as “girdle joints.”  The pelvis moves some with leg motion, the scapular moves way more. This coordinated motion plays a huge roll in all upper extremity cases.

Socket?

It is almost unfair to call your shoulder socket, truly a socket when compared to the hip. This is why many of us have had a shoulder dislocations, but a hip dislocation is very rare outside of autoaccidents. Even in a car crash the femur or pelvis fracture more often than they dislocate. So no, the “my hip is out” is not an accurate statement, and why you might see me cringe on the inside if you say it to me.

To be fair the glenoid is made larger and more socket-like via the labrum, a piece of cartilage that increases the surface area and depth helping provide stability.

Our amazing shoulder

The shoulder has a tiny little socket, and a big range of motion.  It has the ability to move crazy fast, an angular momentum of 7700 degrees per second internal rotation in pitching for instance, and to be incredibly precise while doing so.  Seventeen muscles helping provide impressive strength. The world record for an overhead press is an astonishing 217Kg (some 430lbs), the record for pull ups in a 24hr period is 4300! The shoulder can bear some pretty wild forces.

All thanks to a shoulder blade that can do these three key things:

  1. Move the socket and ball together
  2. Keep the scapula eficiantly anchored to its power supply  (the core and axial skeleton)
  3. Maintaining the safety of all the nerves, muscles and blood vessels that pass through it

The ability of the scapula to move with the arm is comparable to a seal moving with the ball to keep it balanced.

Scapular Dyskinesis

The coordinated movement (stability) of the scapula is central to shoulder and neck pain.  Due to life, injury, development, habits, postures, work, training and more, our shoulder muscle balance can vary.  With 17 muscles attaching to the scapula, it literally gets pulled in all directions.  And two of the biggest shoulder muscles, the lats and pecs, mostly attach to the axial skeleton (all but skipping the scapula) and attach directly to the humerous.   Intersting (small scale) study on the lat here:

A study found that, of 100 cadavers dissected:

  • 43% had “a substantial amount” of muscular fibers in the latissimus dorsi originating from the scapula.
  • 36% had few or no muscular fibers, but a “soft fibrous link” between the scapula and the latissimus dorsi
  • 21% had little or no connecting tissue between the two structures.

Scapular motion can vary from person to person. Just look at different PGA golfers for instance, all unique patterns, all skilled.  Subtle differences in how they do it, but they all get the job done.  And that job is to keep the ball and socket together (not pinching itself in the process), and connect the scapula to its power source (the core). All while not wrenching the core in the process. The PGA guys move well creating tremendous speed and precision, yet even they can break. And for us mere mortals, it can be the mundane that breaks us.

Injuries:

  • Soft Tissue conditions
    • Over training, Breathing patterns, muscle compensations and imbalance
      • Shoulder Bursitis
      • Trigger point pain
      • Muscle adhesions or spasm
      • Cervicogenic headache
  • Muscle entrapment
    • Rotator Cuff Tears
    • Impingement syndrome
  • Spine injuries
    • Join Decentration (odd alignment and compression)
      • Cervical disc injuries
      • Costochondritis
      • Mid back pain
      • Headaches
  • Nerve and Blood Compromises
    • Thoracic Outlet Syndrome

Scapular motion

Scapular motion doesn’t have to be perfect, it has to be good enough for the tasks asked of it. When it’s not, irritation and injury can occur. Treatment that only focuses on the site of pain; be it manipulation, e-stim, ultra sound, hot/cold, massage, soft tissue therapies, or needling, will have less results than treatment that looks at the whole person.  This might mean looking down the chain from the scapula.  Looking at the core, pelvis or feet even.  At the very least, in neck cases, a thorough scapular and shoulder assessment should be performed.

The assessment of scapular dyskinesis involves observing and feeling how the scapula rest, and how it moves during tasks.  Such as how it moves when the arm/hand moves, and how it functions when the arm/hand is supporting the body.  We would also assess what happens during respiration.  You breath some 20K times a day, lots of people walk around shrugging their shoulder every time they breath, that adds up! Our interventions will vary based on these assessments.  As a general rule, what is tight is stretched/mobilized, and what is weak is strengthened.

If your having issues that you want looked at let us know.  In the meantime, here are some interventions I use often:

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