Shoulder Motion and Dynamics

Shoulder Motion

• Shoulder has 3 degrees of freedom: flexion-extension, abduction-adduction, internal and external rotation
• Additional movements include horizontal abduction and horizontal adduction
• The shoulder sacrifices stability for mobility

Range of Motion

• Full ROM of the shoulder complex requires motion at three bones: humerus, scapula and clavicle
• Joints involved in shoulder motion include: glenohumeral, sternoclavicular, acromioclavicular and scapulothoracic

Glenohumeral Joint (GHJ)

• Synovial ball-and-socket joint
• Humeral head is convex, glenoid fossa is concave
• Relies heavily on soft tissue structures for stability: glenoid labrum, joint capsule, ligaments and musculature

Glenoid Labrum

• Provides stability to the shoulder
• Increases glenoid depth by 30-50%
• Injury can contribute to limited function, pain and instability

‘Glenohumeral Clock’

• Helps to understand the components of stability in the shoulder
• Describes structures injured or repaired during surgery
• Provides a visual representation of the many components to GHJ stability

Capsular Pattern of Limitation (GHJ)

• External Rotation is the most limited movement
• Abduction is the second most limited movement
• Internal Rotation is the least limited movement

Scapulothoracic Joint

• Not a real joint, but a "functional joint"
• Motions are caused by the independent or combined motions of the sternoclavicular and acromioclavicular joints

Sternoclavicular Joint (SCJ)

• Connects the clavicle to the sternum and cartilage of the 1st rib
• Synovial joint, saddle shaped
• Strong joint capsule supported by: anterior and posterior SC ligament, costoclavicular ligament and interclavicular ligament

SC Joint

• Motion occurs at the clavicle on a fixed sternum
• 3 degrees of freedom: elevation-depression, protraction-retraction, anterior-posterior rotation

Acromioclavicular Joint (ACJ)

• Connects the scapula to the clavicle
• Weak joint capsule supported by: superior and inferior AC ligament, coracoclavicular ligament

AC Joint

• 3 degrees of freedom: upward-downward rotation, horizontal plane adjustments, sagittal plane adjustments

Tests and Measures

• Begin with observation and palpation
• Assess gross ROM, strength, flexibility, sensation bilaterally
• Relate findings to the patient's primary complaint, functional limitations and activity limitations
• Palpate systematically from superficial to deep with purpose
• Understand the anatomy and what you are feeling for

ROM/Goniometry

• Observe posture and starting position
• Perform on the contralateral side first
• Observe active ROM
• Palpate landmarks for goniometry
• Measure active and passive ROM using an appropriate device
• Assess end feel
• Document objective measures, end feel and subjective reports
• Consider quality in addition to quantity
• Repeat all steps on the affected side

Shoulder Strength

• Assess strength of both scapular and "shoulder" muscles
• Isolate and stabilize as necessary
• Trunk/spine position can alter testing

Shoulder Motion

• 3 degrees of freedom: Flexion and Extension, Abduction and Adduction, Internal and External Rotation
• Additional movements: horizontal abduction and horizontal adduction
• Shoulder sacrifices stability for mobility

Range of Motion

• Full range of motion of the shoulder complex requires motion at three bones: Humerus, Scapula and Clavicle
• Joints involved in shoulder motion: Glenohumeral, Sternoclavicular, Acromioclavicular, Scapulothoracic

Glenohumeral Joint (GHJ)

• Synovial ball-and-socket joint
• Humeral head is convex; Glenoid fossa is concave
• Relies heavily on soft tissue for stability: Glenoid labrum, joint capsule, ligaments, musculature

Glenoid Labrum

• Provides stability to the shoulder
• Increases glenoid depth by 30-50%
• Injury can contribute to limited function, pain, and instability

Glenohumeral "Clock"

• Helpful way to understand the components of stability in the shoulder
• Used to describe structures injured and/or repaired during surgical procedures
• Provides a visual of the many components to stability of the GHJ

Capsular Pattern of Limitation (GHJ)

• Describes the order of limitation from most restricted to least restricted
• External Rotation > Abduction > Internal Rotation

Scapulothoracic Joint

• A "functional joint"- not a true joint
• Motions are caused by independent or combined motions of the sternoclavicular and acromioclavicular joints

Sternoclavicular Joint (SCJ)

• Clavicle articulates with the sternum and cartilage of the first rib
• Synovial joint, saddle shaped
• Strong joint capsule: Anterior and posterior SC ligament, costoclavicular ligament (inferior clavicle), interclavicular ligament

SC Joint Motion

• Clavicle moves on a fixed sternum
• 3 degrees of freedom: Elevation and Depression, Protraction and Retraction, Anterior and Posterior Rotation

Acromioclavicular Joint (ACJ)

• Scapula articulates with the clavicle
• Fibrocartilagenous disc surrounded by a weak joint capsule
• Superior and inferior AC ligament, coracoclavicular ligament

AC Joint Motion

• 3 degrees of freedom: Upward and Downward Rotation, Horizontal Plane Adjustments (rotation), Sagittal Plane Adjustments (tipping/tilting)

Tests and Measures

• Start with observation and palpation
• Assess gross ROM and strength, as well as flexibility, sensation, and bilateral comparisons
• Palpate superficially to deeply, understanding the relevant anatomy and its function
• Document objective measures, end feel, and subjective reports

ROM/Goniometry

• Observe posture and starting position
• Perform on the contralateral side first
• Observe active range of motion (AROM)
• Palpate landmarks for goniometry
• Measure AROM and passive range of motion (PROM) using appropriate devices
• Assess end feel
• Document objective measure, end feel, and any subjective reports
• Assess quality of movement

Shoulder Strength Assessment

• Assess both scapular and "shoulder" muscle strength
• Isolate muscles and stabilize as necessary
• Trunk/spine position can alter testing results