Session 5

Question 0

Describe the 3 articulations of the elbow joint

Answer 0

1. Humero-ulnar joint between the trochlea of the humerus and the trochlear notch of the ulnar or elbow proper.
2. Humero-radial joint between the capitulum of the humerus and the radial head
3. The proximal radio-ulnar joint between the edge of the head of the radius and the radial notch of the ulna.

All 3 are synovial joints and surrounded by a capsule that is attached near the margins of the articular surfaces and defining a single joint capsule.

The elbow is a hinge type synovial joint. At full extension, the ulna makes an angle of 170 with the humerus.

Note: the forearm is angled further away from the trunk in females.

Question 1

What are the muscles producing the hinge movement of the elbow joint?

Answer 1

Major flexors: biceps brachii, brachialis and brachioradialis

Major extensor: triceps brachii

Question 2

Describe the capsule surrounding the elbow joint

Answer 2

Relatively weak anteriorly and posteriorly

Strengthen by COLLATERAL LIGAMENTS medially and laterally.

The elbow and proximal radio ulnar joint share a capsule (both enveloped within the same capsule).

Synovial membrane lines the fibrous capsule and humerus enclosed by the capsule.

Question 3

What are the 3 major ligaments associated with this joint?

Answer 3

Ulnar collateral

Radial collateral

Annular ligament

Question 4

Describe the ulnar collateral ligament

Answer 4

Triangular between the medial epicondyle and the coronoid process and olecranon of the ulna.

3 bands: Anterior (strongest, tough, cordlike)

Posterior (spreads out into can shape)

Oblique (slender, deepens the socket for trochlea - runs in the trochlea notch of the ulna)

Question 5

Describe the radial collateral ligament

Answer 5

Broad fan like shape

Blends with annular ligament - continuous which helps prevent disruption of the Humero-radial joint.

Attaches between the lateral epicondyle of the humerus and the annular ligament of the radius below

It keeps the head of the radius and the capitulum in close association.

Question 6

Describe the annular ligament

Answer 6

Ligamentous ring just beneath the head of the radius

Attach to the ulna anterior and posterior to its radial notch,

Allows complete freedom of the movement of the elbow joint because the ligamentous collar/ring supports the joint from underneath (inferior, beneath the head of the radius)

Maintains its contact with the radial notch on the ulna.

Question 7

Describe the bursae around the elbow

Answer 7

Number of bursae around the elbow but only 2 have major importance: Subcutaneous olecranon bursa lies in the subcutaneous connective tissue overlying the olecranon. Repeated pressure in this area can cause inflammation (student’s/miner’s elbow) Subtendinous bursa lies between the triceps tendon and the olecranon and can become inflamed due to friction such as can occur in some assembly line jobs. Although not common, the feature of this injury is that it is most severe during flexion of the forearm. In addition to these, a bursa between the triceps tendon and the radius may become inflamed in persons who make repeated pronation/supination movements.

Question 8

Describe the neurovascular supply of elbow

Answer 8

Hilton’s Law: the nerve supplying s joint also supplies both the muscles that move the joint and the skin covering the articular insertion of those muscles (radial and ulnar) Arterial anastomoses, formed by collateral arteries and recurrent branches of ulnar, radial and interrosseus arteries give a prominent, rich blood supply with lots of redundancy.

Question 9

Describe the radioulnar joints

Answer 9

Distal radio-ulnar joint is a pivot joint in which the distal end of the radius moves around the distal end of the ulnar. The articular disc use main structure affording joint integrity - it separates cavity of distal radioulnar joint from wrist cavity. The proximal radio-ulnar joint is also a pivot joint. In addition, the interosseous membrane forms a fibrous joint (does not show up on x-Ray) between the radius and ulna. Attached from the radius above to the ulna below this membrane keeps the bones together during movements of pronation and supination, and also prevents anterior displacement of the radius when a force is applied to the outstretched hand. Fibres run inferio-medially which allows some distribution of force from radius (which receives most of the force when you fall) to ulna. The aim is to prevent fracture of the radius but sometimes force is too great.

Question 10

What does pronation and supination exactly involve?

Answer 10

Movement at the elbow and forearm joints; head of radius pivots on the capitulum (ball and socket joint). During supination: bones are parallel During pronation: bones cross as head of radius pivots on capitulum.

Question 11

Describe the Distal Radioulnar Joint in Pronation/Supination

Answer 11

Articular disc ensures joint integrity is maintained - allows a little bit of twisting to allow the bones to cross each other. Sacciform recess superior extension of synovial capsule allows twisting of the capsule.

Question 12

Distinguish between dislocation and subluxation

Answer 12

Dislocation: complete loss of contact of the joint surfaces

Subluxation: partial dislocation of a joint, so that the bone ends are misaligned but still in contact (e.g. Some contact between radius and ulna but radius and capitulum have lost touch)

Question 13

Describe the facilitation of supination and pronation function:

Answer 13

Head of radius and capitulum of humerus

Annular ligament

Sacciform recesses (extensions of the synovial membrane on neck of radium and at distal radius and ulna (superiorly from articular disc))

Question 14

Describe the wrist joint

Answer 14

Radiocarpal joint: Condyloid type of synovial joint formed between the distal end of the radius, and the scaphoid, lunate and triquetrum (proximal carpal bones).

Ulnar makes no contribution to the wrist joint.

Stabilised by collateral palmar and dorsal ligaments

Question 15

Describe the ligaments associated with the wrist joint

Answer 15

Radial collateral ligament extends between the radial styloid process and the scaphoid and triquetrum.

Ulnar collateral ligament attaches to the ulnar styloid process and the triquetrum and pisiform.

Palmar ulna-carpal ligament connects the ulnar styloid process to the lunate and triquetrum.

Palmar radio carpal ligament connects the radius to the scaphoid, lunate and triquetrum.

This ensures the hand follows the radius during supination.

The dorsal radio carpal ligament connects the radius with the scaphoid, lunate and triquetrum. This ensures the hand follows radius during pronation

Question 16

Why is abduction of the wrist limited?

Answer 16

By the radial styloid process

Question 17

What happens in 40% of Colle’s fractures?

Answer 17

Avulsion of the ulnar styloid process

Question 18

What are the function of joints?

Answer 18

Absorb motion

Absorb shock

Allow growth (epiphyseal growth plates at ends of long bones near joints in children)

Question 19

In the young, what could fractures of the distal radius result in?

Answer 19

Fractures of the distal radius may extend through the distal epiphyseal plate.

During healing there may be mal-alignment of the epiphyseal plate and radial growth may be impaired.

Question 20

When taking a history, what should you consider?

Answer 20

Mechanism of injury

If UL injury, dominant hand

Occupation (fractures are rarely lethal - need to consider more about impairment of function)

Social circumstances (e.g. can they get about at home, care plan etc)

Pre-injury mobility

Relevant previous medical history (IHD/COPD/Diabetes/AF/heart valves/Rheumatoid Arthritis)/Previous injuries/Joint replacement/malignancy(+metastasis?)/Previous DVT

Drug history - anti-clotting agents; steroids/insulin

Allergies

Question 21

What are three principles to keep in mind during examination?

Answer 21

Look

Feel

Move

Question 22

What are some possible examination findings?

Answer 22

Swelling

Bruising

Obvious deformity

Puncture or skin wounds: puncture wounds indicate bone could have gone through the skin and then gone back inside

Joint fluids e.g. Effusion in the knee could be caused by a ligament injury causing a bleed into the knee. Lots of effusion indicates a severe injury.

Painful anatomical sites

Laxity

Crepitus - crunching sound

Range of movement

Pulses difficult to feel - assess neurovascular status, check for nerves and distal pulses

Question 23

What are some common associations?

Answer 23

Distal radius injury (Colles) - Median nerve

Distal 1/3rd humerus - Radial nerve

Shoulder dislocation - Axillary nerve

Hip (or THR) dislocation - Sciatic nerve

Knee dislocation - Popliteal Artery, Common Peroneal Nerve

Question 24

What investigations do you need to consider ordering?

Answer 24

X-Rays: 2 shots at 90 degrees to each other (AP and LATERAL views) otherwise you might miss a fracture

Stress views

MRI

CT

Aspiration: a bleed indicates a serious injury

Question 25

What is the Polo Mint Analogy?

Answer 25

Some bones are paired e.g. Pelvis, radius and ulna, tibia and fibula

It is very hard to fracture one side of the bone alone so always assess both bones.

Question 26

What is the rule of 2’s?

Answer 26

2 bones

2 joints (above and below)

2 sides

2 views (for X-Rays)

Question 27

Define a Fracture

Answer 27

It is a soft tissue injury with an underlying break in the bony cortex.

Includes damage to nerve and vascular structures

Question 28

What are the possible causes of a Fracture?

Answer 28

Trauma

Pathological (infection/malignancy)

Stress (from continuous low level repetitive injury - usually causes a small bone fracture, common in marathon runners and soldiers. Very subtle evidence - callous formation. Stress fractures always heal but painful initially)

Insufficiency (osteoporosis/osteopenia - bone marrow density is lower than normal)

Question 29

What does fracture stability determine?

Answer 29

Type of fractue healing.

Mechanical stability governs the mechanical strain.

Primary healing (no callus formation): depends on stability of the bone ends to allow the cells to enter and stem cells to different to form a callus)

Question 30

What are the systemic factors affecting fracture healing?

Answer 30

Age

Nutrition

General health e.g. Diabetes

Generalised atherosclerosis

Drugs e.g. NSAIDs, steroids, EtOH

Smoking (high risk of non-union)

Question 31

What are the local factors affecting fracture healing?

Answer 31

Degree of local trauma/bone loss: a comminuted fracture with soft tissue injury is slower to heal.

Area of bone affected: metaphyseal fractures heal faster than diaphyseal.

Abnormal bone (infection, tumour, irradiated): slower to heal

Degree of immobilization of fracture: motions at site delays healing

Disruption of vascular supply: delays healing

Question 32

Describe Fractures using…

Answer 32

OLD ACID

O: open (bone penetrated through skin and is exposed to air) vs closed,

L: location (which bone, anatomic orientation + landmarks)

D: degree (complex - complete cortical circumference involved, fragments are completely separated; incomplete: not fractured all the way through e.g. Greenstick fracture)

A: articular extension/involvement (intra-articular fractures, dislocation - loss of joint surface/articular congruity)

C: comminution, pattern (transverse, oblique, spiral, linear/longitudinal, segmented, comminuted, compression/impacted, distraction/avulsion)

I: intrinsic bone quality (normal or osteopenia - decreased density)

D: displacement, angulation, rotation

Question 33

What are the goals of fracture treatment?

Answer 33

Restore the patient to optimal functional state

Prevent fracture and soft-tissue complications

Get the fracture to heal and in a position which will produce optimal functional recovery

Rehabilitate the patient as early as possible.

Question 34

What are early fracture complications?

Answer 34

Local: nerve injury, vascular injury, compartment syndrome, avascular necrosis, infection, surgical

Systemic: hypovolaemia/shock, fat embolism, thromboembolism, acute respiratory distress syndrome, disseminate Intravascular coagulation

Question 35

What are late fracture complications?

Answer 35

Local: delayed union, non-union, malunion, myosotis ossificans, re-fracture

Regional: osteoporosis, joint stiffness, chronic regional pain syndrome, abnormal biomechanics, osteoarthrosis, infection

Question 36

What is Myositis Ossificans?

Answer 36

Bone formation in soft tissue which is difficult to treat

Question 37

What is a sprain?

Answer 37

Damage to a ligament

Mechanism of injury: forces which stress the ligaments (I.e. Lengthen)

Initial management: RICE

Can take up to several weeks to heal

Complete (Grade 3); partial (Grade 2); Damaged fibres with continuity intact (Grade 1)

May present like a fracture with swelling, pain, bruising

Question 38

What is a Dislocation?

Answer 38

Complete loss of continuity of the articulating surfaces of the joint.

Question 39

What is Subluxation?

Answer 39

A partial loss of continuity of the articulating surfaces of the joint

Question 40

What are the consequences of injury to a joint?

Answer 40

Pain

Stiffness

Deformity

Loss of function

Cosmetically poor

Loss of limb

Question 41

What do OA and RA commonly affect and what do they result in?

Answer 41

Osteoarthritis commonly affects weight-bearing joints e.g. Vertebral column, hips and knees

Rheumatoid arthritis usually affects small joints of the hand (although other joints in the limbs e.g. Wrist, elbow and shoulder) and vertebral column (cervical spine) may also be affected.

Both of them result in pain, deficient movement (disability) and deformity

Question 42

What is the function of Articular Cartilage and what is its functional integrity dependent on?

Answer 42

Protective shock absorber for the underlying bone.

Functional integrity of articular cartilage in a healthy joint is dependent upon organised synthesis of appropriate amounts of cartilage matrix components by the chondrocytes.

As cartilage is avascular, the survival and the synthetic activity of the chondrocytes depends on the diffusion and transport of nutrients and metabolites through the cartilage matrix

Thus in a healthy tissue, there is a fine balance between synthesis and tissue breakdown with ongoing tissue turnover. When the balance is upset, there is loss of articular cartilage followed by a degenerative process.

Question 43

Define OA and RA

Answer 43

OA: the articular cartilage and subchondral bone undergo destruction.

RA: systemic connective tissue disorder affecting the joint synovium which shows chronic inflammatory changes (synovitis) which eventually leads to invasion and erosion of underlying cartilage and subchondral bone.