shoulder girdle Flashcards
How many bones are there in the shoulder girdle (joint)?
3
What type of bone is each individual one?
Humerus – long, Scapula – flat, clavicle – long
What type of joint is the shoulder joint?
Synovial ball and socket
How many, and what types of movement occur at the shoulder joint?
5 types of bone include: Long, short, flat, irregular and sesamoid
HumerusAnatomy(L Arm, Anterior view)
humeral head
greater tuberosity
lesser tuberosity
anatomical neck
surgical neck
deltoid tuberosity
medial epicondyle
lateral epicondyle
capitulum
trochlea
what is a clavicle
Extends and articulates from manubrium of sternum and acromion of the scapula
Three key functions:
- Attaches the upper limb to the trunk as part of the shoulder/pectoral girdle
- Protects the underlying neurovascular structures supplying the upper limb
- Transmits force from upper limb to axial skeleton
when does the clavicle ossify
Differs from other long bones in two ways: 1) it has no medullary cavity and 2) it is ossified in membrane (Dean and West 1991)
Most commonly fractured bone in the body?
“S- shaped”
Flattened, concave lateral element
Thickened, convex medial two-thirds
Ball and socket joint
Head of the humerus articulates with the glenoid cavity of the scapula
Articular surfaces covered in articular hyaline cartilage
Fibrous capsule forms a loose ‘sleeve’ around joint which allows movement
- Attached to the ‘rim’ of the glenoid cavity and laterally to the anatomical neck of humerus
Ball and socket joint
Hyaline cartilage is atype of connective tissue
Synovial membrane lines the fibrous capsule, which secretes synovial fluid and lubricates joint.
Encloses the tendon of the long head of biceps.
Bursae preventing friction during movement.
Fluid-filled bursa between joint and subscapularis muscle (subscapular bursa)
Fluid-filled bursa between the joint and acromion process (subacromial bursa).
Glenoid Labrum deepens the ‘socket’, increasing surface of the joint.
Ossification centres
Approximate age guess – 1.5-2.5 years two ossification centres seen, no lesser tubercle to be seen, very small.
Proximal Humerus Ossification
Primary or secondary centres?
What ages do the following begin ossification?
Head
Greater Tuberosity
Lesser Tuberosity
Tuberosities fuse to form a single epiphysis
Fuse at shaft
Primary will be the core part of the bone, for example the shaft of the humerus will be the primary ossification.
Secondary centres will be part of the active process of bone growth
Proximal Humerus Ossification
Humerus - 8th intrauterine week
Secondary centre ossification ages:
Head- 6 months
Greater Tuberosity- 1-2 years
Lesser Tuberosity- 4-5 years
Tuberosities fuse – coalesce at 6-7 years and fuse to humeral head 7-13 years
Fuse at shaft- 18-20 years or 14-17 in girls & 16-18 in boys
(Gunn, 2017)
Clavicle Ossification
First bone to ossify, last to complete union (Hill, 2020)
Primary Centres- Intramembranous
Two in shaft at 5th week of intrauterine life- medial and lateral
Fuse to form one centre in first year (~45 days)
Secondary Centre- Endochondral
Site appears at sternal end aged 18-20
Fuses with the shaft age 18-25
Scapula Ossification
Primary Centre
Body (towards glenoid cavity)- 8th intrauterine week
Secondary Centres- 7 centres
Coracoid Process (2 centres) appears are:
Lateral – appears at 1yr fuses with body at 15 yrs
Medial - appears at 17yr fuses with body at 25 yrs
Acromion process, 2-3 centres appear at 14-20 (puberty)
Inferior angle, 14-20 years (puberty)
Medial border, 14-20 years (puberty)
Glenoid Cavity, 10-11 years (varies)
All should fuse by age 20-25
Clavicle- Muscular Attachment
Medial 2/3
Origin of Sternocleidomastoid muscle (in neck)- head of clavicle/manubrium. Flexes neck and rotates
Pectoralis Major- flexion, adduction and internal rotation of shoulder joint
Subclavius- depresses shoulder
Costoclavicular ligament
Lateral 1/3
Trapezius- Movement of scapula and neck
Deltoid- flexion, internal rotation and abduction of arm
Coracoclavicular ligament
Muscular Attachments
17 muscles in total attached to the scapula
11 originate from the scapula
Including the 4 rotator cuff muscles – what are they?
6 insert on the scapula
Attachment Sites
Deltoid Tuberosity
- Deltoid Muscle
Lesser Tuberosity
- Tendon of the subscapularis
Greater Tuberosity
- Supraspinatus tendon
- Infraspinatus tendon
- Teres Minor Tendon
Rotator Cuff
4 tendons connect the deepest layer of muscles that rotator cuff muscles to the humerus before these muscles attach to the upper end of the humerus they join together to form a single tendon
these rotoar cuff muscles help raise arm from the side and rotate the shoulder in many ways
Supraspinatus
Responsible for abduction of shoulder
Innervated by suprascapular nerve
Infraspinatus
Responsible for lateral rotation of shoulder
Innervated by suprascapular nerve
Teres minor
Lateral rotation
Innervated by axillary nerve
Subscapularis
Adduction and medial rotation
Innervated by subscapular nerve
The tendons of the muscles, together called the rotator cuff, encircle the joint except inferiorly.
These muscles work together to keep the keep the head of the humerus in the glenoid cavity - socket
Blood supply
Multiple osteochonromas (known as diaphyseal aclasia) is a rare autosomal disorder characterised by multiple bone exostosis mainly affecting the long bones with resultant deformities. It also involves the ribs and scapula. There is a 5% increase in the risk of malignancy in the cartilaginous cap (chondrosarcoma).
Arterial Supply
Scapula Anastomosis
Branches of the subscapular artery e.g. circumflex scapular artery
Suprascapular Artery
Dorsal Scapular artery
Clavicle Vascular Supply
The clavicle is supplied by a nutrient branch of the suprascapular artery
This is one of the branches of the thyrocervical trunk
Arterial Supply
Axillary Artery
Supplies the axilla, lateral thorax and upper limb with arterial blood
Anterior Circumflex Artery
Supplies glenohumeral joint, teres major and minor and deltoid
Anastomoses (connects to) the PHCA to supply the humeral head
Posterior Circumflex Artery
Supplies glenohumeral joint, teres major and minor and deltoid
Circles around the surgical neck of the humerus
Why is the shoulder anatomy significant
The complexity of the shoulder girdle gives it a greater range of movement than any singular joint in the body
This mobility pre-disposes the shoulder to injury, with many types of pathology possible due to the number of systems involved
Shoulder anatomy includes both radio-lucent and radio-opaque structures, sometimes requiring input from a number of modalities
Additionally radiographic assessment of the shoulder can involve a variety of projections depending on the presenting complaint
Referral and Pathways
Shoulder radiography is used in both non-trauma and trauma radiography
Sources of referrals may include:
GP Requests
Emergency Department Attendances
Orthopaedic/Rheumatology/Oncology Clinics/Neurology
As with any radiographic examination, the request must be justified under IR(ME)R 2017 and be subject to a risk/benefit decision by the referrer.
Referral Criteria – Common Symptoms
Shoulder
Reduced mobility of shoulder
Shoulder instability
Suspected arthritis
Suspected Bony Lesion or Metastases
Trauma
Signs of infection or septic arthritis of shoulder joint
Clavicle
Trauma
Visible Deformity
Bony Tenderness
Previous Fracture Review
Post-operative Review
Referral Criteria – Common Pathologies
Osteoarthritis (OA) of Glenohumeral Joint
Acromial Spurring
Calcific Tendonitis
Proximal Humerus Fracture (Diagnosis and follow-up)
Dislocation of Glenohumeral joint
Clavicle Fracture
Scapular Fracture
Indications for other modalities
Rotator cuff tear – MRI or Ultrasound
Labral Tear - MRI
Adhesive Capsulitis (Frozen Shoulder) – MRI
NB: Often x-ray is used to rule out similar presenting conditions, in these cases there must be valid symptoms or suspected pathology in order to be justified under IR(ME)R 2017.
Prior to imaging/ Patient preparation
- Get patient changed as necessary
- Check previous imaging
- Ensure request form is justified
- Confirm the patient’s ID via 3 point check
- Confirm history with the patient
- Confirm location and side of imaging
- Patient should be risk assessed with regard to mobility in order to determine which projections are safe and appropriate to perform
Shoulder Girdle Imaging Series
Non-Trauma Projections
AP Shoulder
- Standard external rotation of the patient, approx. 15 degrees
Axial
Trauma Projections
AP Shoulder
- (Grashey view) Modified approach can include 45 degrees patient rotation to visualise the gleno-humeral joint
Axial or;
Lateral scapula
- Also referred to as, but not formally:
Y-View
PA Shoulder
AP Projection Positioning
Patient is positioned with their back against the image receptor
The median sagittal plane is perpendicular to the image receptor
The patient is then rotated approximately 10-15 degrees towards the affected side, bringing the scapula parallel to the image receptor
The patient’s affected arm should be externally rotated and abducted (SLIGHTLY) with the posterior humerus in contact with the receptor
AP Projection Positioning
The tube is positioned horizontally and perpendicular to the image receptor
If using AEC, centering over the chamber should be maintained and positioning achieved by moving the patient
The centering point is 2.5cm inferior to the palpable coracoid process
Collimation should include:
- Superiorly: The skin border superior to the clavicle/AC joint
- Inferiorly: The inferior angle of scapula and proximal 1/3 of Humerus
- Medially: The sternoclavicular joint
- Laterally: The skin border lateral to the humerus
AP Projection Positioning
The use of a grid is usually not required
An AEC (usually central chamber) can be used with DR systems
SID = 110cm
Focal Spot Size = Fine
Estimated collimation size = 24 X 30 cm
- Image Receptor = Landscape orientation
Given Exposure Factors:
- 60 kV & 5 mAs
Turned AP Projection (Grashey view)
The centering point is 2.5cm inferior to the palpable coracoid process
Patient is rotated 40-45 degrees towards the affected side
Collimation:
- Superiorly/Inferiorly/Laterally as per AP projection and;
- Medially collimation to midshaft of clavicle as projection foreshortens clavicle if this is a supplementary view
Given Exposure Factors:
60 kV & 5 mAs
Comparison of AP Shoulder positions
True AP Shoulder
MSP is perpendicular to the image receptor (IR)
Standard AP Shoulder
MSP is 10-15 degrees towards affected side with respect to the IR
Truned AP Shoulder (Grashey view)
MSP is 45 degrees towards affected side with respect to the IR
Lateral Scapula Projection Positioning
Patient’s elbow is flexed to 90 degrees
The hand is then rested against the back or abdomen depending on patient comfort
The patient is rotated from a neutral PA until the lateral aspect of the shoulder is touching the receptor
- Warning – Avoid having the patient lean forwards as this will foreshorten the scapula
- If required, a small gap between the AC joint and the IR is acceptable
Lateral Scapula Projection Positioning
The tube is positioned horizontally and perpendicular to the image receptor
Hint - Rotate the ‘box’ of the x-ray tube to align with the humerus
AECs are difficult to use due to narrow and difficult to visualise bony anatomy
The centering point is on the medial border of the scapula, at the height of the humeral head
Collimation should include:
- Superiorly: 2cm above acromion
- Inferiorly: 2cm below inferior angle of scapula
- Medially: The palpable coracoid process
- Laterally: The lateral skin border of humerus
Lateral Scapula Projection Positioning
The use of a grid is recommended but not mandatory
An AEC (usually central chamber) can be used with DR systems
SID = 110cm
Focal Spot Size = Fine
Estimated collimation size = 24 X 30 cm
Image Receptor = Portrait orientation
Given Exposure Factors:
70 kV & 6.3 mAs (Increase mAs if using a grid)
Axial Projection Positioning
Patient is usually seated
Image receptor is placed on table
Table is lowered to waist height (ALWAYS ensure that the patients knees/legs are NOT under the table when adjusting table height, to prevent serious injury)
The patient abducts their arm and leans as far over the table as possible
The elbow should be flexed to 90 degrees
- This is helpful for support/balance
The head should be titled forwards to bring posterior-lateral cranium away from region of interest
Axial Positioning
A grid is not usually required
Manual exposures are usually used as it is unlikely to be able to center directly over a chamber
SID = 110cm or more if needed
- Note the OID (object image distance)
Focal Spot Size = Fine
Estimated collimation size = 18 X 24 cm
- Image Receptor = Portrait orientation (in relation to humerus)
Given Exposure Factors:
65 kV & 5 mAs
AP Clavicle Projection Positioning
True AP position - Patient is positioned with their back against the image receptor
- The median sagittal plane is perpendicular to the image receptor
The patient’s arms should be in a neutral and relaxed position, external rotation is not necessary
The tube is positioned horizontally and perpendicular to the image receptor
The centering point is midway between the distal and proximal ends of the clavicle
Collimation should include:
- Superiorly: The skin border superior to the clavicle/AC joint
- Inferiorly: The inferior most aspect of the clavicle
- Medially: The sternoclavicular joint
- Laterally: The acromio-clavicular joint/ soft tissues laterally
AP Clavicle Projection Positioning
A grid is not required
Manual exposures are recommended, AEC can be used however
SID = 110cm
Focal Spot Size = Fine
Estimated collimation size = 24 X 30 cm
Image Receptor = Landscape orientation
Given Exposure Factors:
60 kV & 4 mAs
Axial (infero-superior) Clavicle Projection Positioning
The patient’s position is as for the AP Clavicle projection
- True AP position - The patient’s arms should be in a neutral and relaxed position
The tube is positioned horizontally, with 30* degrees cranial angulation and perpendicular to the image receptor
The centering point is midway between the distal and proximal ends of the clavicle
Collimation as AP Clavicle projection
Exposure factors are the same as AP Clavicle:
- No grid required, AEC can be used if wanted
- SID = 110cm, Focal Spot Size = Fine
- Estimated collimation size = 24 X 30 cm (landscape)
- 60 kV & 4 mAs
Pathology - Anterior Glenohumeral Dislocation
The glenohumeral joint is the most commonly dislocated joint in the human body
Over 95% of these are classified as anterior dislocations
These injuries are particularly prevalent in younger people and males
Common mechanisms of injury involve direct trauma or a fall onto outstretched hand
Patients may present with further dislocations following the initial injury
Usual management is closed reduction in the emergency department under sedation
Hill-Sachs v Bankart
Hill-Sachs - Posterolateral humeral head compression
Bankart - Injury to antero-inferior aspect of the glenoid labrum. Can be soft-tissue or bony fragment
11 x more likely to occur together than separately (Raby et al., 2014)
Posterior Glenohumeral Dislocation
1-4% of glenohumeral dislocations are posterior
These injuries are usually the result of seizures or electrocution
The classic radiographic appearance is the “lightbulb sign”
- Not externally rotating the shoulder can simulate this appearance
This pathology can be difficult to detect on plain film and its innocuous appearance on the AP projection, highlights the importance of taking multiple projections at orthogonal views
Usual management is closed reduction in the emergency department under sedation
Proximal Humerus Fractures
These are most common in the elderly population, especially those with osteoporosis
Most common mechanisms of injuries:
- Fall Onto Out-Stretched Hand (FOOSH)
- Falls from height
- High impact trauma (Sports/ Motorcycle accident)
Fractures could be subtle avulsions from rotator cuff injuries
Care must be taken when positioning for the second projection, a modified axial view may be required.
Management will depend on the age and general health of the patient, treatments could be
- ORIF/ K-wires
- Arthroplasty
- Conservative management
Proximal Humerus Fracture Management
Open Reduction and Internal Fixation (ORIF)
Inter-Medullary (IM) Nail
Kirschner Wire (k-wire)
Proximal Humerus Fracture Management
Open Reduction and Internal Fixation (ORIF)
Inter-Medullary (IM) Nail
Kirschner Wire (k-wire)
Salter-Harris Classification
S – Slipped (Separated): The fracture involves only the growth plate, giving the appearance of a wider physis
A – Above: The fracture is above the growth plate. It involves the metaphysis
L – Lower: The fracture is below the growth plate. It involves the epiphysis
T – Through: The fracture passes through the growth plate affecting both epiphysis and metaphysis
R – Rammed: The growth plate is impacted
Salter-Harris fractures
type 1 - is a fracture restricted to the growth plate.
type 2-4 - represent various patterns of fractures involving the growth plate and the adjacent metaphysis and/or epiphysis
Clavicle Fractures
Clavicle fractures are most common among younger patients and children
Common mechanisms of injury include:
- RTCs
- Falls
- Sports-related injuries
Most injuries involve the middle and distal sections of the bone, medial clavicle fractures are rare
Clavicle fractures can be managed surgically or conservatively
Acromio-Clavicular Joint Dislocation
ACJ injuries can be classified using the “Rockwood Classification”
Rib fractures
Review the full radiograph
Follow the cortex and alignment of the ribs to exclude easy to miss fractures
These maybe pathological and therefore isolated
Rib fractures
Review the full radiograph
Follow the cortex and alignment of the ribs to exclude easy to miss fractures
These maybe pathological and therefore isolated
