Scapular Dyskinesis & SAPS

what are the 4 key points to know about force couples?

• a force couple is when two forces act in opposite directions to create rotation of a joint in a specific direction

• when the forces are equal and opposite, the instantaneous center of rotation is maintained

• maintaining the instantaneous center of rotation allows for dynamic stability of a joint

• dynamic stability is preserved throughout the full ROM

what are the 4 main force couples in the shouder complex and their roles?

1. Centering of humeral head: anterior and posterior cuff (subscap relataive to infraspinatus and teres minor)

2. Arm elevation: rotator cuff + deltoid

3. scapular upward rotation: lower trap + upper trap + serratus anterior

4. scapular downward rotation: levator scapula + rhomboid + pectoralis minor

during shoulder elevation, if the rotator cuff is not working properly or the deltoid is left unchecked, what would happen?

superior migration of the humeral head

what are the roles of the force couples during upward and downward rotation?

1. keep the glenoid oriented for optimal function

2. efficient length-tension for the deltoid

3. prevents impingement of the rotator cuff muscles

4. provide a stable scapular base

what happens if any of the force couples in our shoulder become imbalanced?

scapular dyskinesis

what is scapular dyskinesis?

altered dynamic control of the scapula

what are various patterns of scapular dyskinesis?

• winging of the medial scapular border— possibly due to SA weakness or pec minor tightness

• winging of the inferior angle of the scapula— possibly due to pec minor length issue or weak lower trap

• excessive elevation aka hiking— possibly due to tight upper trap

what are common muscle imbalances that can lead to scapular dyskinesis?

• overactivity of upper trapezius

• delayed or decreased activation of lower and middle traps

• delayed or decreased activation of the serratus anterior

what are possible causes of scapular dyskinesis?

neurological:

• lesion to the long thoracic nerve

• lesion to the spinal accessory nerve

• cervical radiculopathy

muscular:

• neuromuscular control

• rotator cuff strength

• muscle tightness or stiffness

• increased thoracic kyphosis

what muscles are more prone to tightness?

upper trap, levator scapula, pecs, SCM, scalenes, subscapularis, upper cervical extensors

what muscles are more prone to weakness?

middle trap, lower trap, rhomboids, SA, deep neck flexors, supraspinatus, infraspinatus

how do we go about a scapular assessment?

• observation

• assess AROM

• assess muscle length

• assess muscle strength

• try to adjust scapular positioning and assess for changes in symptoms

what are structures in the subacromial space that may be loaded, compressed, irritated, or contribute to SAPS symptoms during arm elevation

surpspinatus tendon, labrum, bursa, long head of biceps

what are the joints that contribute to shoulder elevation and their motions?

• glenohumeral: shoulder abduction via superior roll and inferior glide of the humeral head on the glenoid fossa

• scapulothoracic: scapular upward rotation, protraction, and posterior tilt via the acromion gliding upward on the thorax

• acromioclavicular: slight scapular rotation via a superior glide of the acromion on the clavicle

• sternosclavicular: slight clavicular elevation via elevation and slight posterior rotation of the clavicle via facet joint gliding

what are the muscles contributing to shoulder elevation and their motions?

• deltoid: flexion of the humerus

• teres minor: stabalization of GHJ

• infraspinatus: stabalization of GHJ

• supraspinatus: initiate abduction of the shoulder, stabalize GHJ

• pec major: flexion of humerus

• biceps brachii: flexion of humerus

• coracobrachialis: flexion of humerus

• subscapularis: stabalization of GHJ

• serratus anterior: scapular protraction and upward rotatio

• upper trap: scapular elevation and upward rotation

what are shoulder red flags?

tumor, infection, fracture, neurologic region, visceral pathology

what should our shoulder examination sequency be for SAPS?

1. history (includes ROS and red/yellow flags)

2. observation

3. active motion (goniometry and accessory glides)

4. strength testing (MMT, resisted isometrics, functional testing)

5. special tests: only do if we need more definitive answers and give us more info if needed

6. impairment identification

what are key positive and negative findings to rule in our out subacromial pain syndrome?

positive to rule in: impingement signs (Neer, Hawkins), painful arc, pain with isometric resistance testing, atrophy

negative to rule out: significant loss of motion, instability signs

what are the cluster of special tests we can do in our SAPS examination to rule in if positive?

• painful arc: positive if pain between the joint angles of 60-120 degrees during abduction

• neer (infraspinatus test): full flexion and then IR and ER; positive if pain with testing

• hawkins kennedy: arm flexed to 90 degrees, slight horizontal adduction, maximum IR; positive if reproduction of pain

what are other special tests we can do to test for posterior impingement?

• posterior internal impingement test: pt supine and max ER; positive if pain in the posterior shoulder

• horizontal adduction test: literally overpressure with horizontal adduction; positive if painful

• internal rotation resistance strength test (IRRST): 90 degrees abduction with resistance to IR and ER. positive if good strength with ER and weak with IR. positive for external impingement if strength with IR is good and weak with ER

what are important questions we can ask our patient to help with prognosis, frequency/duration, and education?

• tell me back what i’ve told you about what is going on

• on a scale of 0-10, what are your stres levels at home, work, or in general

• what do you think of the plan we just discussed or do you think PT will help you?

• do you think that this condition can get better or do you think you will be able to get back to doing what you love?

what are common impairments that could lead to SAPS?

rotator cuff weakness, scapular dyskinesis

posterior capsul tightness

thoracic mobility deficits

poor movement coordination

how would we treat pain associated with local tissue injury in someone with high, moderate, and low irritability?

high: activity modification, manual therapy, and modalities

moderate: activity modification, manual therapy, and modalities

low: no modalities

how would we treat limited passive mobility in someone with high, moderate, and low irritability?

high: ROM, stretching, manual therapy in pain free ranges

moderate: ROM, stretching, manual therapy in comfortable end range that is typically intermittent

high: ROM, stretching, manual therapy at end range with longer duration and frequency

how would we treat excessive passive mobility in someone with high, moderate, and low irritability?

high: protect the joint or tissue from end range

moderate: develop active control in mid range while avoiding end range in basic activity. address hypomobility of adjacent joints or tissues

low: develop active control during full range, high level functional activity. adress hypomobility of adjacent joints or tissues

how would we treat neuromscular weakness associated w atrophy, disuse, and deconditioning in someone with high, moderate, and low irritability?

high: AROM within pain free ranges

moderate: light or moderate resistance to fatigue in mid ranges

low: moderate or high resistance to fatigue including end ranges

how would we treat neuromuscular weakness associated with poor motor control or neural activation in someone with high, moderate, and low irritability?

high: AROM within pain free ranges, consider using modalities

moderate: basic movement training with emphasis on quality/precision rather than resistance according to motor learning principles

low: high demand movement training with empahsis on quality rather than resistance according to motor learning principles

what are the do’s when treating SAPS?

• non-operative management first

• exercise therapy is the primary treatment as it is the foundation of care

• combine strengthening and scapulaar control

• address contributing impairments— treat the impairments first

• educate the patient on activity modification