the shoulder complex. a.general structure & function b.structure & function of specific...
TRANSCRIPT
The Shoulder Complex
The Shoulder Complex
A. General Structure & Function
B. Structure & Function of Specific Joints
C. Muscular Considerations
D. Specific Functional Considerations
E. Common Injuries
The Shoulder Complex
A. General Structure & Function
B. Structure & Function of Specific Joints
C. Muscular Considerations
D. Specific Functional Considerations
E. Common Injuries
General Structure
General Function
Provides very mobile, yet strong base for hand to perform its intricate gross and skilled functions
Transmits loads from upper extremity to axial skeleton
Shoulder Girdle
Shoulder Complex Movements Shoulder Girdle
Elevation & depression Protraction & retraction Upward & downward rotation Upward tilt
Shoulder (glenohumeral) FL, EXT, HyperEXT ABD, ADD, HyperADD, HyperABD MR, LR, HorizontalABD, HorizontalADD
Abduction/Lateral Tilt (Protraction)
Adduction/Reduced Lateral Tilt (Retraction)
Linear MovementFrontal PlaneAngular movementTransverse Plane
Depression
Elevation
Linear MovementFrontal Plane
Downward rotation
Upward rotation
Shoulder Complex Movements
Upward tiltReduction of Upward Tilt
Angular movementSagittal plane
Limited by capsular torsion
Limited by bony impingement of greater tubercle on acromion
Large ROM Due To:
Poor bony structure Poor ligamentous restraint Scapulohumeral cooperative action
The Shoulder Complex
A. General Structure & Function
B. Structure & Function of Specific Joints
C. Muscular Considerations
D. Specific Functional Considerations
E. Common Injuries
Structure & Function of Specific Joints
1. Sternoclavicular Joint
2. Acromioclavicular Joint
3. Scapulothoracic Joint
4. Glenolhumeral Joint
5. Coracoacromial Arch
Sternoclavicular Joint: Bony Structure
PoorDiarthrodial Biaxial
Sternoclavicular Joint: Capsule
Very strong
Sternoclavicular Joint: Interclavicular Ligament
Resists superior & anterior (posterior portion) motion
Sternoclavicular Joint: Sternoclavicular Ligament
Resists anterior (PSL), posterior (ASL), & superior motion
Sternoclavicular Joint: Costoclavicular Ligament
Resists upward and posterior motion
Sternoclavicular Joint: Accessory Structures
Resists medial & inferior displacement via articular contact
Sternoclavicular Joint: Articular Surfaces
Medial end of clavice
is convex
Clavicular facet is
reciprocally shaped
Sternoclavicular Joint: Motions
Axial Rotation: 50°EL/DEP: 35°PROT/RET: 35°
Sternoclavicular Joint: Motions
Frontal planeElev/Dep
Sagittal planePost Rot
Horizontal planeProT/ReT
Ant/Post axisVertical axis
Acromioclavicular JointBony Structure
PoorDiarthrodial Nonaxial
Acromioclavicular Joint:Joint Capsule
Very weak
Acromioclavicular JointAcromioclavicular Ligament
Resists axial rotation & posterior motion
Acromioclavicular JointCoracoclavicular Ligament
Resists superior motion
Acromioclavicular JointAccessory Structures
Articular disc
Acromioclavicular Joint: Motion
Little relative motion at AC joint
UR/DR: 60°EL/DEP: 30°PROT/RET: 30-50°
Acromioclavicular Joint: Osteokinematics
Horizontal plane
adjustments
during scapulothoracic
protraction
Sagittal plane adjustment
during scapulothoracic
elevation
Clavicle
Acts a strut connecting upper extremity to thorax
Protects brachial plexus & vascular structures
Serves as attachment site for many shoulder muscles
Scapula
Scapular Plane
Scapulothoracic Joint
No osseous connection
SUBSCAP & SA
Glenohumeral Joint: Humerus
Retroversion angle: 30°
Glenohumeral Joint: Humerus
Inclination angle: 45°
Glenohumeral Joint: Glenoid Fossa
Inclination angle: 5° Retroversion angle: 7°
Glenohumeral Joint: Glenoid Fossa
Articular cartilage thicker on periphery
Shallow fossa 1/3 diameter of humeral head
Glenohumeral Joint: Bony Structure
Pure rotation Bony restraint poor Head 4-5X larger than
fossa Close-packed position
ABD with LR
Glenohumeral Joint: Joint Capsule
Inherently lax Surface area 2X
head Provides restraint for
ABD, ADD, LR, MR
Glenohumeral Joint:Superior GH Ligament
Resists inferior translation in rest or adducted arm
Well-developed in 50%
Glenohumeral Joint: Coracohumeral Ligament
Resists inferior translation in shoulders with less-developed SGH
Glenohumeral Joint:Middle GH Ligament
Great variability in proximal attachment & morphology
Absent in 30% Resists inferior
translation in ABD & ER
Restrains anterior translation (45° ABD)
Glenohumeral Joint:Inferior GH Ligament
3 components (A,P,Ax)
Resists inferior, anterior, & posterior translation
Glenohumeral Joint: Bursae
Subcoracoid Subacromial Subscapular
Glenohumeral Joint: Accessory Structures
50% of depth Increases tangential stability 20%
Labrum
Glenohumeral Joint: Intra-articular Pressure
Synovial fluid causes adhesion
Provides ~50% restraint
Coracoacromial Arch
Glenohumeral Joint: ROM
Flexion (167° W; 171° M) 30° in max LR
Extension (60°) Abduction (180°)
60° in max IR Hyperadduction (75°)
Glenohumeral Joint: ROM
Medial rotation (90°) Lateral rotation (90°)
Horizontal abduction (45°) Horizontal adduction (135°)
Total rotation 180°
Total ROT 90° in 90° ABD
Role of multiarticular muscles???
Soft Tissue Restraint Summary Anterior
Capsule Labrum Glenohumeral lig Coracohumeral lig Subscapularis Pectoralis major
Inferior Capsule Triceps brachii (L)
Posterior Capsule Labrum Teres minor Infraspinatus
Superior Labrum Coracohumeral lig Suprapinatus Biceps brachii (L) Coracoacromial arch Subacromial bursa
The Shoulder Complex
A. General Structure & Function
B. Structure & Function of Specific Joints
C. Muscular Considerations
D. Specific Functional Considerations
E. Common Injuries
Shoulder girdle has its own set of muscles.
Retraction of the Scapulothoracic Joint
Levator scapula
Protraction of the Scapulothoracic Joint
Pectoralis minor
Pathomechanics of a weak serratus anterior muscleDeltoid force causes scapula to downwardly rotate.
Unstable and cannot resist deltoid force
GH Flexion
Prime flexors: Anterior deltoid Pectoralis major: clavicular portion
Assistant flexors: Coracobrachialis Biceps brachii: short head
GH Extension
Gravitational force Posterior deltoid Latissimus dorsi Pectoralis major (sternal) Teres major (with resistance)
Abduction at Glenohumeral Joint Major abductors of humerus:
Supraspinatus Initiates abduction Active for first 110 degrees of abduction
Middle deltoid Active 90-180 degrees of abduction Superior dislocating component neutralized
by infraspinatus, subscapularis, and teres minor
Adduction of Glenohumeral Joint Primary adductors:
Latissimus dorsi Teres major Sternocostal pectoralis
Minor assistance: Biceps brachii: short head Triceps brachii: long head Above 90 degrees- coracobrachialis and
subscapularis
GH Medial Rotation
Subscapularis Latissimus dorsi Pectoralis major Teres major (with resistance)
Decreased activity with ABD
GH Lateral Rotation
Primary Infraspinatus
Assistant: Teres minor Posterior deltoid
Horizontal Adduction and Abduction
Anterior to joint: Pectoralis major (both heads), anterior
deltoid, coracobrachialis Assisted by short head of biceps brachi
Posterior to joint: Middle and posterior deltoid, infraspinatus,
teres minor Assisted by teres major, latissimus dorsi
Muscle Strength
Adduction (2X ABD) Extension Flexion Abduction Internal rotation (max in neutral) External rotation (max at 90° FL)
Role of multiarticular muscles???
The Shoulder Complex
A. General Structure & Function
B. Structure & Function of Specific Joints
C. Muscular Considerations
D. Specific Functional Considerations
E. Common Injuries
Specific Functional Considerations
Stability Functions of Shoulder Girdle Mobility Functions of Shoulder Girdle Rotator Cuff Function
Stability Functions of Shoulder Girdle
Provides stable base from which shoulder muscles can generate force Shoulder girdle muscles as stabilizers Maintain appropriate force-length
relationship Maintain maximum congruence of shoulder
joint
Specific Functional Considerations
Stability Functions of Shoulder Girdle Mobility Functions of Shoulder Girdle Rotator Cuff Function
Mobility Functions of Shoulder Girdle
Permits largest ROM of any complex in the body Shoulder girdle increases ROM with less
compromise of stability (scapulohumeral rhythm) (4 joints vs. 1 joint)
Facilitate movements of the upper extremity by positioning GH favorably
Dynamic Stabilization Mechanisms
Passive muscle tension Compressive forces from muscle
contraction Joint motion that results in tightening of
passive structures Redirection of joint force toward center
of GH joint
Muscular Considerations
Force-length relationships quite variable due to multiple joints
Tension development in agonist frequently requires tension development in antagonist to prevent dislocation of the humeral head
Force couple – 2 forces equal in magnitude but opposite in direction
Movements in the Frontal PlaneGH Joint - Abduction
Shoulder Girdle: UR Totals
Upward rotation - 60° GH Abduction - 120°
2:1 (.66) ratio 1.25:1 after 30° 0.5-0.75 across
individuals
ABD
30°
ABD - 30°
UR - 40°
ABD - 60°
UR - 20°
Movements in the Frontal PlaneGH Joint - Adduction
Shoulder Girdle: DR
Fig 5.17
Movements in the Sagittal PlaneGH Joint – Flexion & Extension
Shoulder Girdle: UR ELEV (>90°) PROT ( to 90°) RET (>90°)
Fig 5.18
Movements in the Sagittal PlaneGH Joint - Hyperextension Shoulder Girdle: Upward tilt of scapula
Fig 5.20
Movements in the Transverse PlaneGH Joint – MR & LR
Fig 5.22a
Spinal Contribution to GH Motion
Movements in the Transverse PlaneGH HAdd & HAbd
Large ROM Due To:
Poor bony structure Poor ligamentous restraint Scapulohumeral coordination
Normal movement dependent on interrelationships of 4 joints
Restriction in any of these four can impair normal function
Specific Functional Considerations
Stability Functions of Shoulder Girdle Mobility Functions of Shoulder Girdle Rotator Cuff Function
Subscapularis
Teres minorSupraspinatus
Infraspinatus
Function of Rotator Cuff
Large external muscles (e.g., lats, delts) create shear forces
Rotator cuff provides Joint compression Tangential restraint
(Ant, Post, Sup)
Destabilizing Action of Deltoid
Deltoid produces superior shear force at GH joint.
Subscapularis
Resists superior shear
Produces simultaneous internal rotation
Infraspinatus & Teres Minor
Resists superior shear
Neutralizes SUBSCAP internal rotation
Supraspinatus
Summary of Active Arthrokinematics Resisting Shear
Destabilizing Action of Latissimus Dorsi
LD pulls humerus INF
SSP resists INF force
INF & SUBSCAP create compressive force
The Shoulder Complex
A. General Structure & Function
B. Structure & Function of Specific Joints
C. Muscular Considerations
D. Specific Functional Considerations
E. Common Injuries
Common Shoulder Injuries
Joint dislocations Clavicular fracture Rotator cuff injuries Other rotational injuries Subscapular neuropathy
Impingement
Possible mechanisms Weak or inflexible rotator cuff Small anatomical space Hyperabduction of GH joint GH ABD + ROT
Impingement: Roll-Slide Kinematics
“Roll” created by abduction not countered with “Slide” action
During ABD SSP tendon pushed into
acromion process & CA ligament
During ROT SSP tendon dragged along the
inferior surface of the acromion process
Wind-Up Phase
Kinesiological breakdown of overhand throwing
First Motion Maximum knee lift of leg
•Shoulder ABD (DELT & SSP) •RC maintain proper humeral head position
Kinesiological breakdown of overhand throwing
Stride
Lead leg begins to moveArms separate
Lead foot contacts the ground
• ER in ABD position; ER 150-180°• ECC action of SUBSCAP (decelerates ER
humerus)• RC stabilization
Kinesiological breakdown of overhand throwing
Arm Cocking
Lead foot contact Maximum shoulder external rotation
• Concentric IR (PMJR & LD ) • IR velocity (> 1000 °/s)• RC stabilization
Kinesiological breakdown of overhand throwing
Arm Acceleration
Maximum shoulder ER Ball release
• Decelerating IR & ADD • ECC action of TMin• RC stabilization
Kinesiological breakdown of overhand throwing
Arm Deceleration
Ball release Maximum shoulder IR
• Decelerating IR• ECC action of TMin• RC stabilization
Kinesiological breakdown of overhand throwing
Follow Through
Maximum shoulder IR Ends in balanced position
Rotator Cuff Injuries: Solution
Alter technique during problem phases to avoid impingement Arm cocking Arm acceleration
Strengthen rotator cuff Surgical repair
Video techniques
Intrinsic Risk Factors
Age and gender Physical fitness Overtraining Skeletal abnormalities Technique Warm-up Psychological factors
Technique
Technique refers to the movement pattern of an individual during a particular movement or sequence of movements. Good technique is a movement pattern not only effective in performance, but also one that minimizes risk of injury by appropriately distributing the overall load throughout the kinetic chain. Poor technique is characterized by inappropriate utilization and summation of muscular effort and abnormal joint movements, both of which result in localized overload and, therefore, increased risk of injury.
Swimming
Mechanism: ABD + IR
Solutions: Lead with hand to ↓ IR Increase body roll to ↓ ABD
Supraspinatus Tear
Other Rotational Injuries
Tears of labrum Mostly in anterior-superior region
Tears of biceps brachii tendon Due to forceful rotational movements
Also: calcification of soft tissues, degenerative changes in articular surfaces, bursitis
Biceps Tendon Tear
Subscapular Neuropathy
Denervation of INF with ↓ strength GH ER
Mechanism: Repeated stretching of nerve
Injury Potential in the Shoulder Complex - Impacts
Sternoclavicular Joint not commonly injured may sprain anteriorly if fall on
top of shoulder or middle delt - pain in horizontal abd
children may dislocate anteriorly during throwing because of increased joint mobility as compared to adults
posterior dislocation may occur when force is applied to sternal end of clavicle; serious because of trachea, esophagus, and blood vessels located posteriorly
Clavicular Injuries fx to any part due to direct trauma fx to middle 1/3 can occur by
falling on shoulder, outstretched arm, or direct trauma to shoulder that transmits force down shaft of clavicle
AC Injuries dislocation from fall on shoulder,
fall on elbow or outstretched arm overuse injuries from overhand
pattern (throwing, tennis, swimming) or sports that repeatedly load in the overhead position (wrestling, wt lifting)
Glenohumeral Injuries
Most common dislocation in anterior (anterior-inferior 95%)
most commonly dislocated when abducted and ER overhead
recurrence rate 33-50% (66-90% <20 yrs)