The Shoulder Complex

1
Chapter 14

• The Shoulder Complex

2
Overview

• The shoulder is a complex set of articulations
  that work together toward the common goal of
  positioning the hand in space, which allows an
  individual to interact with the environment and
  to perform fine motor functions

3
Anatomy

• Although the entire shoulder complex functions as
  an integrated unit, it is anatomically simpler to
  describe each joint separately. The shoulder
  joint complex consists of
• Three bones (the humerus, the clavicle, and the
  scapula)
• Three joints (the sternoclavicular (S-C), the
  acromioclavicular (A-C), and the glenohumeral
  (G-H) joints)
• One pseudojoint
• One physiological area

4
Anatomy

• Glenohumeral Joint
• The glenohumeral (G-H) joint is a true
  synovial-lined diathrodial joint that connects
  the upper extremity to the trunk, as part of a
  kinetic chain
• The GH joint is formed by the humeral head and
  the glenoid fossa of the scapula

5
Anatomy

• Glenoid fossa
• The glenoid fossa is flat, but is made
  approximately 50 deeper and more concave by a
  ring of fibrocartilage called a labrum
• The labrum, which forms part of the articular
  surface, is attached to the margin of the glenoid
  cavity and the joint capsule, and contributes to
  joint stability

6
Anatomy

• Scapula
• The scapula forms the base of the G-H joint
• It is a flat blade of bone that lies along the
  thoracic cage at 30 to the frontal plane, 3
  superiorly relative to the transverse plane, and
  20 forward in the sagittal plane
• The scapulas wide and thin configuration allows
  for its smooth gliding along the thoracic wall,
  and provides a large surface area for muscle
  attachments both distally and proximally

7
Anatomy

• Scapula
• A prominent feature of the scapula in man is the
  large overhanging acromion, which, along with the
  coracoacromial ligament functionally enlarges the
  glenohumeral socket
• The position of the acromion also places the
  deltoid muscle in a dominant position to provide
  strength during elevation of the arm
• Although the acromion appears to be flat, three
  types of acromion morphology have been described,
  of which the hooked is associated with an
  increase in rotator cuff pathology

8
Anatomy

• Joint capsule
• The voluminous joint capsule of the glenohumeral
  joint allows for large amounts of motion to occur
  at the G-H joint
• The lateral attachment of the glenohumeral joint
  capsule attaches to the anatomical neck.
• Medially, the capsule is attached to the
  periphery of the glenoid and its labrum
• The overall strength of the joint capsule bears
  an inverse relationship to the patients age the
  older the patient, the weaker the joint capsule

9
Anatomy

• The greater and lesser tuberosities
• Located on the lateral aspect of the anatomical
  neck of the humerus
• Serve as attachment sites for the tendons of the
  rotator cuff muscles
• The greater tuberosity serves as the attachment
  for the supraspinatus, infraspinatus and teres
  minor
• The lesser tuberosity serves as the attachment
  for the subscapularis
• The greater and lesser tuberosities are separated
  by the intertubercular groove, through which
  passes the tendon of the long head of the biceps
  on its route to attach on the superior rim of the
  glenoid fossa

10
Anatomy

• The glenohumeral ligaments
• At the anterior portion of the outer fibers of
  the joint capsule, three local reinforcements are
  present the superior, middle and inferior G-H
  ligaments (gtZ ligaments)
• Superior - serves to limit external rotation and
  inferior translation of the humeral head with the
  arm at the side
• Middle - serves to limit external rotation (Table
  14-5) and anterior translation of the humeral
  head with the arm in 0 and 45 of abduction
• Inferior - consists of an anterior band, a
  posterior band, and an axillary pouch with
  varying functions

11
Anatomy

• The coracohumeral ligament
• Covers the superior G-H ligament
  anterior-superiorly, and fills the space between
  the tendons of the supraspinatus and
  subscapularis muscle uniting these tendons to
  complete the rotator cuff in this area

12
Anatomy

• The coracoacromial ligament
• Consists of two bands that join near the acromion
  and is ideally suited, both anatomically and
  morphologically, to prevent separation of the A-C
  joint surfaces

13
Anatomy

• Coracoacromial Arch
• Formed by the anterior-inferior aspect of the
  acromion process, coracoacromial ligament, and
  inferior surface of the A-C joint
• During overhead motion in the plane of the
  scapula, the supraspinatus tendon, the region of
  the cuff most involved in the degenerative
  process, can pass directly underneath the
  coracoacromial arch
• If the arm is elevated while internally rotated,
  the supraspinatus tendon passes under the
  coracoacromial ligament, whereas if the arm is
  externally rotated, the tendon passes under the
  acromion itself

14
Anatomy

• Suprahumeral/subacromial space
• An area located on the superior aspect of the G-H
  joint
• Contents include the long head of biceps tendon,
  supraspinatus and upper margins of subscapularis
  and infraspinatus, subdeltoid-subacromial bursa
• The space is at its narrowest between 60 and
  120 of scaption

15
Anatomy

• The subacromial bursa
• One of the largest bursa in the body
• Provides two smooth serosal layers one of which
  adheres to the overlying deltoid muscle and the
  other to the rotator cuff lying beneath

16
Anatomy

• Neurology
• The shoulder complex is embryologically derived
  from C 5-8, except the A-C joint, which is
  derived from C 4. The sympathetic nerve supply
  to the shoulder originates primarily in the
  thoracic region from T 2 down as far as T 8

17
Anatomy

• Vascularization
• The vascular supply to the rotator cuff muscles
  of the shoulder consists of three main sources
  the thoracoacromial, suprahumeral, and
  subscapular arteries
• The brachial artery provides the dominant
  arterial supply to each of the two heads of the
  biceps

18
Anatomy

• Glenohumeral joint
• Close packed position
• The close packed position for the G-H joint is
  90 of glenohumeral abduction and full external
  rotation or full abduction and external
  rotation, depending on the source
• Open packed position
• Without internal or external rotation occurring,
  the open packed, or rest position of the G-H
  joint has traditionally been cited as 55 of
  semi-abduction and 30 of horizontal adduction

19
Anatomy

• Glenohumeral joint
• Capsular pattern
• According to Cyriax, the capsular pattern for the
  shoulder is external rotation the most limited,
  abduction the next most limited, and internal
  rotation the least limited in a 321 ratio
  respectively

20
Anatomy

• The acromioclavicular joint
• The acromioclavicular (A-C) joint is a
  diarthrodial joint, formed by the acromion and
  the lateral end of the clavicle
• The joint serves as the main articulation
  suspending the upper extremity from the trunk,
  and it is at this joint about which the scapular
  moves

21
Anatomy

• Acromioclavicular joint
• The articulating surface of the lateral end of
  the clavicle can be either convex or concave and
  corresponds with the articulating surface of the
  acromion. Consequently, although the joint is
  described as a planar joint, there is often a
  male-female relationship, with 3 degrees of
  freedom

22
Anatomy

• A-C ligaments
• The coracoclavicular ligaments (conoid and
  trapezoid) are the primary support for the A-C
  joint
• These ligaments provide mainly vertical
  stability, with control of superior and anterior
  translation as well as anterior axial rotation

23
Anatomy

• A-C joint
• Neurology. Innervation to this joint is provided
  by the suprascapular, lateral pectoral, and
  axillary nerves
• Capsular pattern. Lacks a true capsular pattern
• Close and open packed positions. Undetermined

24
Anatomy

• Sternoclavicular (S-C) joint
• Represents the articulation between the medial
  end of the clavicle, the clavicular notch of the
  manubrium of the sternum, and the cartilage of
  the first rib, which forms the floor of the joint
• Has been classified as a ball and socket joint, a
  plane joint, and as a saddle joint
• A meniscus completely divides the joint into two
  cavities

25
Anatomy

• Sternoclavicular (S-C) joint
• Ligaments. A number of ligaments provide support
  to this joint
• Anterior sternoclavicular ligament
• Posterior sternoclavicular ligament
• Interclavicular
• Costoclavicular

26
Anatomy

• Sternoclavicular (S-C) joint
• Close packed position. The close packed position
  for the S-C joint is maximum arm elevation and
  protraction
• Open packed position. The open packed position
  for the S-C joint has yet to be determined, but
  is likely to be when the arm is by the side
• Capsular pattern. Lacks a specific capsular
  pattern

27
Anatomy

• Scapulothoracic Joint
• Functionally a joint but it lacks the anatomic
  characteristics of a true synovial joint
• Plays a significant role in all motions of the
  shoulder complex

28
Anatomy

• Muscles of the Shoulder Complex
• For simplicity, the muscles acting at the
  shoulder may be described in terms of their
  functional roles scapular pivoters, humeral
  propellers, humeral positioners, and shoulder
  protectors

29
Anatomy

• Muscles of the Shoulder Complex
• Scapular pivoters
• Comprise the trapezius, serratus anterior,
  levator scapulae, rhomboid major, and rhomboid
  minor
• As a group, these muscles are involved with
  motions at the scapulothoracic articulation, and
  their proper function is vital to the normal
  biomechanics of the whole shoulder complex

30
Anatomy

• Muscles of the Shoulder Complex
• Humeral propellers
• Comprise the latissimus dorsi, pectoralis major,
  and pectoralis minor

31
Anatomy

• Muscles of the Shoulder Complex
• Humeral positioners. Comprised of the three
  parts of the deltoid muscle

32
Anatomy

• Muscles of the Shoulder Complex
• Shoulder protectors
• Rotator cuff
• Biceps brachii

33
Biomechanics

• Complete movement at the shoulder girdle involves
  a complex interaction between the glenohumeral,
  acromioclavicular, sternoclavicular,
  scapulothoracic, upper thoracic, costal and
  sternomanubrial joints, and the lower cervical
  spine
• During these motions, the scapula invariably acts
  as a platform upon which shoulder rotation and
  arm activities are based

34
Biomechanics

• The Scapulohumeral Rhythm
• The combination and synchronization of the
  motions that occur between the scapula and the
  humerus during arm elevation
• An early study by Inman determined that a 21
  ratio existed between the motion occurring at the
  G-H joint and scapula respectively
• This ratio is not consistent throughout the range
  of motion

35
Biomechanics

• Force couples
• During the first 30 of upward rotation of the
  scapula, the serratus anterior muscle and the
  upper and lower divisions of the trapezius muscle
  are considered the principal upward rotators of
  the scapula
• Together these muscles form two force couples
  one formed by the upper trapezius, and the upper
  serratus anterior muscles, the other formed by
  the lower trapezius, and lower serratus anterior
  muscles

36
Examination

• In the presence of shoulder girdle dysfunction
  (assuming systemic or orthopedic causes have been
  ruled out), there are three possible causes for
  shoulder girdle dysfunction
• Compromise of the passive restraint components of
  the shoulder girdle
• Compromise of the neuromuscular systems
  production or control of shoulder girdle motion
• Compromise to one or more of the of the
  neighboring joints that contribute to shoulder
  girdle

37
Examination

• History
• A good history is the cornerstone of proper
  diagnosis, especially since shoulder pain has a
  broad spectrum of patterns and characteristics
• It is important to establish the patients chief
  presenting complaint (which is not always pain)
  as well as defining their other symptoms. The
  most common complaints associated with shoulder
  pathology include pain, instability, stiffness,
  deformity, locking, and swelling

38
Examination

• Systems review
• Symptoms that are not associated with movement
  should alert the clinician to a more serious
  condition
• Scenarios related to the shoulder that warrant
  further investigation by the clinician include an
  insidious onset of symptoms, and complaints of
  numbness or paresthesia in the upper extremity

39
Examination

• Observation
• The clinician observes how the patient holds the
  arm, the overall position of the upper extremity,
  and the willingness of the patient to move the
  arm
• Deformity is a common complaint with injuries of
  the A-C joint and fractures of the clavicle
• A number of static tests for the scapular
  position exist

40
Examination

• Palpation
• The optimal methods of palpating the shoulder
  tendons occur in regions where there is the least
  amount of overlying soft tissue
• It is best to divide the shoulder complex into
  compartments for palpation
• Symptoms reproduced by palpation in these
  compartments are frequently associated with a
  specific underlying pathology

41
Examination

• AROM, PROM with overpressure
• McClure and Flowers classify limited shoulder
  motion into two categories
• Decreased ROM secondary to changes in the
  periarticular structures, including shortening of
  the capsule, ligaments, or muscles as well as
  adhesion formation. Clinical findings for this
  category include a history of trauma,
  immobilization, presence of a capsular pattern,
  capsular end-feel, and no pain with the isometric
  testing
• Decreased ROM due to nonstructural problems,
  including the presence of pain, protective muscle
  spasm, or a loose body within the joint space.
  Clinical findings for this patient include a
  history of trauma or overuse, and the presence of
  a non-capsular pattern

42
Examination

• Examination of the Dynamic Scapula
• Given the importance of the scapulothoracic joint
  to overall shoulder function, it is important to
  examine the scapulothoracic joint
  arthrokinematics, and muscle power

43
Examination

• Strength testing
• Localized, individual isometric muscle tests
  around the shoulder girdle can give the clinician
  information about patterns of weakness other than
  from spinal nerve root or peripheral nerve
  palsies e.g., instabilities, postural
  dysfunction, and also help to isolate the pain
  generators

44
Examination

• Examination of Movement Patterns
• These tests are concerned with the coordination,
  timing, or sequence of activation of the muscles
  during movement

45
Examination

• Functional Testing
• The assessment of shoulder function is an
  integral part of the examination of the shoulder
  complex
• The term shoulder function can include tests for
  biomechanical dysfunction and tests assessing the
  patients ability to perform the basic functions
  of activities of daily living

46
Examination

• Other test for the shoulder complex include
• Muscle Length Tests
• Examination of the passive restraint system and
  neighboring joints
• Special Tests
• Diagnostic and imaging studies

47
Intervention

• Acute phase goals
• Protection of the injury site
• Restoration of pain-free range of motion in the
  entire kinetic chain
• Improve patient comfort by decreasing pain and
  inflammation
• Retard muscle atrophy
• Minimize detrimental effects of immobilization
  and activity restriction
• Maintain general fitness
• Patient to be independent with home exercise
  program

48
Intervention

• Functional phase goals
• Attain full range of pain free motion
• Restore normal joint kinematics
• Improve muscle strength to within normal limits
• Improve neuromuscular control
• Restore normal muscle force couples