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POTH 225 - Intro to Biomechanics > L8 - Elbow and Wrist > Flashcards

L8 - Elbow and Wrist Flashcards

1
Q

What are the 3 things we are considering?

A
  1. Motion: kinematics
  2. Stability: constraint
  3. Strength: force transmission
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2
Q

Name the elbow movements.

A
  1. Flexion-extension (sagittal)
  2. Pronation-supination (transverse)

See NDC p.6 for illustration

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3
Q

Important Terminology
What is valgus?

A

Lateral deviation of a distal segment with respect
to proximal segment.
–> forearm moves lateral in relation to humerus
** vaLgus = Lateral

See NDC p.7 for illustration

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4
Q

Important Terminology
What is varus?

A

Medial deviation of a distal segment with respect
to proximal segment.
–> forearm moves medial in relation to humerus

See NDC p.7 for illustration

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5
Q

What is the functional AROM of the elbow for most ADLs?

A

The arc of movement required for most ADLs:
- 30° of extension to 130° f flexion
- 50° of pronation and 50°of supination

See NDC p.9-11 for illustration

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6
Q

Elbow Joint Loads During Activities of Daily Living
Which activities produce the biggest elbow joint loads?
- reaching task
- self-care
- push-up: weightbearing through upper extremity
- work task (hammering)
- cyclic task

A
  1. Self-care: 3Nm
  2. Reaching task: 11Nm
  3. Cyclic task: 21Nm
  4. Push-up: 26Nm
  5. Work task: 39Nm

See NDC p.12 for illustration

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7
Q

Name the bones forming the elbow joint.

A
  1. Humerus
  2. Radius
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8
Q

Name the structures of the humerus. (5)
Name the articular surfaces. (2)

A
  1. Epicondyles: medial and lateral
  2. Coronoid fossa (A, medial)
  3. Radial fossa (A, lateral)
  4. Olecranon fossa (P)
  5. Cubital tunnel (medial)

Articular surfaces
1. Trochlea (medial)
2. Capitellum (lateral)

See NDC p

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9
Q

Describe the cubital tunnel.
- location
- what passes
- what occurs in a compression?

A

Medial to the medial epicondyle of humerus.
The radial nerve passes.
Compression = numbness in little and ring fingers

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10
Q

What is the angle of the distal humerus? (2)

A

30° anterior curve.
6° tilt.

See NDC p.15-16 for illustration

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11
Q

Name the structures of the proximal ulna. (2)
Name the articulating structure.

A
  1. Olecranon
  2. Coronoid Process

Articulating structure: Trochlear notch

See NDC p.17 for illustration

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12
Q

Name the structures of the proximal radius. (3)
Name the articulating structure.

A
  1. Radial Head
  2. Radial Neck
  3. Radial tuberosity (biceps distal attachment)

Articulating structure: Fovea (with capitulum)

See NDC p.18 for illustration

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13
Q

Name the joints forming the elbow joint.

A
  1. Humeroulnar
  2. Humeroradial
  3. Proximal radioulnar

See NDC p.19 for illustration

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14
Q

Joints of the Elbow
Describe the humeroulnar joint.
- classification
- movements
- joint space
- bone shape

A
  1. Ginglymus (hinge)
  2. Flexion-extension
  3. Joint space asymmetrical
  4. Bone shape favors flexion

See NDC p.20 for illustration

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15
Q

Joints of the Elbow
Describe the humeradial joint.
- classification
- movements
- joint contact greatest when….

A
  1. Ginglymus Joint (hinge)
  2. Flexion and extension
  3. Greater contact with elbow in flexion

See NDC p.21 for illustration

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16
Q

Joints of the Elbow
Describe the superior radioulnar joint.
- classification
- movements
- support

A
  1. Trochoid joint (pivot)
  2. Pronation and supination
  3. No support from bone structure = soft tissues only: annular ligament

See NDC p.22 for illustration

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17
Q

What is the function of the interosseous membrane?

A

An important static longitudinal stabilizer of the forearm (less contribution to forearm rotation).

See NDC

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18
Q

Elbow Center of Rotation
What is the center of rotation for flexion-extension in the eblow?
Why is it important to know this?

A

Line passing through capitulum and trochlea.
Important for orthotic hinge alignment.

See NDC p.25-26 for illustration

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19
Q

Elbow Center of Rotation
What is the center of rotation for pronation-supination in the eblow?

A

Rotation about a longitudinal axis between the radial head and the ulnar head.

See NDC p.27 for illustration

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20
Q

Describe the joint contact of the elbow joints in static elbow extension?

A

Compressive force and joint contact is greater in humeroradial than humeroulnar.

See NDC p.28 for illustration

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21
Q

Describe the carrying angle of the elbow. (3)
How do we characterize the angle?
Is it different in men VS women?

A
  1. Medial trochlea extends farther distally
  2. Medial aspect trochlear notch of ulna farther distally
  3. Lateral deviation of ulna with respect to humerus

Valgus 10-15 degrees
–> Men=Women

See NDC p.29 for illustration

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22
Q

Elbow Stabilization
Name the 3 primary constraints of the elbow joint.
What is their importance?

A
  1. Ulnohumeral articulation
  2. Anterior bundle of the medial collateral ligaments
  3. Lateral collateral ligaments

If these are intact = elbow is stable

See NDC p.31 for illustration

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23
Q

Elbow Stabilization
Name the 4 secondary constraints of the elbow joint.

A
  1. Radiocapitellar articulation
  2. Common origin of the flexors
  3. Common origin of the extensors
  4. Capsule
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24
Q

Elbow Stabilization
Name the components of the stabilization of the elbow joint by bones. (4)

A
  1. Congruent articular surfaces
  2. Radial Head stabilizes with stress in valgus direction
  3. Olecranon stabilizes with stress in valgus direction
  4. Coronoid stabilizes with stress in varus direction

See NDC p.32 for illustration

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25
Elbow Stabilization Name the medial collateral ligaments of the elbow joint. What is their function?
1. Anterior bundle 2. Posterior bundle 3. Transverse bundle Important valgus stabilizer (particularly anterior bundle) --> prevents valgus = prevents carrying angle from increasing, prevents forearm from deviating lateral relative to humerus See NDC p.33 for illustration + IDENTIFICATION
26
Elbow Stabilization Name the lateral collateral ligaments of the elbow joint. What is their function?
1. Lateral ulnar collateral 2. Accessory lateral collateral 3. Radial collateral 4. Annular Important varus stabilizer (particularly LUCL) --> prevents varus = prevents carrying angle from decreasing, prevents forearm from deviating medial relative to humerus See NDC p.34 for illustration + IDENTIFICATION
27
What is the link between pitching and elbow injuries? What ligaments are affected?
Overhead throwing activity = high valgus moment = ↑ elbow injuries Result: injury to medial collateral ligaments See NDC p.35 for illustration
28
Name the rehabilitation approaches.
1. MCL deficient elbow 2. LCL deficient elbow
29
Rehabilitation Approaches Describe the MCL deficient elbow approach. - in what position should the elbow be rehabed? - why?
The MCL deficient elbow should be rehabilitated in supination. Reason: supination = the muscles are taut generating greater passive tension enhancing medial sided stability. * Point the thumb in the opposite direction of the injured side!
30
Rehabilitation Approaches Describe the LCL deficient elbow approach. - in what position should the elbow be rehabed? - why?
The LCL deficient elbow should be rehabilitated in pronation. Reason: pronation = the muscles are taut generating greater passive tension enhancing lateral sided stability. * Point the thumb in the opposite direction of the injured side! See NDC p.37 for example of exercise
31
Ligament Stress Tests Describe the varus elbow stress test. - purpose - technique
Assess the integrity of the lateral collateral ligament (LCL) The examiner applies a varus (inward) force to the elbow, while palpating the lateral joint line. 1. Arm supinated 2. Arm slightly out of extension 3. Position yourself medial to arm 4. Put finger over lateral collateral ligament 5. Push elbow out If the person's elbow was unstable, the arm would keep going. See NDC p.38 for the video
32
Ligament Stress Tests Describe the vaLgus elbow stress test. - purpose - technique
Assess the integrity of the medial collateral ligament (MCL) The examiner applies a valgus (outward) force to the elbow, while palpating the medial joint line. 1. Arm supinated 2. Arm slightly out of extension 3. Position yourself lateral to arm 4. Put finger over medial collateral ligament 5. Push elbow in If the person's elbow was unstable, the arm would keep going. See NDC p.38 for the video
33
Your patient has a ruptured elbow medial collateral ligament and a radial head fracture.  They will likely have: vaLgus or varus stress instability?
Valgus stress instability.
34
Name the muscles of the elbow joint.
1. Flexors 2. Extensors 3. Pronators 4. Supinators
35
Name the elbow flexors. (4) When are the biceps more active?
1. Biceps brachii 2. Brachialis 3. Brachioradialis 4. Pronator Teres Biceps less active with arm in full pronation (twisted). See NDC p.40 for illustration + IDENTIFICATION
36
Name the elbow extensors. (4)
1. Triceps brachii 2. Anconeus See NDC p.41 for illustration + IDENTIFICATION
37
Name the pronators of the elbow. (2)
1. Pronator Teres 2. Pronator Quadratus See NDC p.42 for illustration + IDENTIFICATION
38
Name the supinators of the elbow. (2)
1. Supinator 2. Biceps See NDC p.42 for illustration + IDENTIFICATION
39
What is epicondylitis? Name the 2 types. - common name - muscle group affected
Inflammation and microtear at the origins of the muscle attaching at the epicondyle. 1. Lateral epicondylitis (tennis elbow): extensor problem 2. Medial epicondylitis (golfer’s elbow): flexor problem See NDC p.43 for illustration
40
Describe lateral epicondylitis. - overuse of what - what causes it - considerations / activity modifications (4)
Resistance with arm and wrist in extension Activity modification 1. EMG: decreased extensor activity with two handed back hand 2. Bending elbow 3. Increase grip diameter (less force) 4. Decreasing weight #1 thing to do is to perform activities with elbow flexed
41
Describe medial epicondylitis. - overuse of what - what causes it (2) - considerations / activity modifications (4)
Overuse of flexor and pronator musculature 1. Excess valgus force on elbow 2. Excess medial tension Considerations: 1. Appropriate technique 2. Lightweight equipment 3. Repetition
42
Which moment arm is largest among the primary flexors?
Brachioradialis has the longest moment arm. See NDC p.46 for illustration
43
How do the moments arms of the primary flexors change during elbow flexion?
The moment arms peak in the midrange of flexion, between 100-120° flexion. See NDC p.47 for graph
44
When is isometric elbow flexion force the greatest?
Elbow flexion force peaks in midrange between 75°-90° of flexion. See NDC p.48 for illustration
45
What is active insufficiency? When does it occur?
At shortest length, muscle is at weakest length. When a muscle crosses more than one joint, it will influence each joint. Called active insufficiency for multi-joint muscle Bicep: shoulder flexion, elbow flexion, supination
46
Name the movements of the wrist.
1. Flexion-extension 2. Ulnar deviation - Radial deviation 3. Circumduction See NDC p.52 for illustration
47
What is the functional axis of movement of the wrist?
Dart-throw motion combines all movement of wrist. Holding dart = extension and radial deviation Throwing dart = flexion and ulnar deviation See NDC p.53 for illustration
48
Why is the “dart throw motion” important?
Less movement of the scaphoid and lunate compared to pure flexion/extension or ulnar/radial deviation. --> for people with instability, these movements diminish the amount of movement cause Common path of motion in many daily activities. See NDC p.54-55 for graphs See NDC p.56 for Xray of limited movement of lunate
49
What is the functional AROM necessary for the wrist?
40° flexion and 40° extension 10°-15° of ulnar and radial deviation See NDC p.57-58 for AROM and functional wrist ROM tables.
50
What are the biomechanical requirements for distal upper extremity function?
1. Adequate flexion and extension 2. Adequate radial and ulnar deviation 3. Adequate forearm rotation 4. Functional oblique movement (DTM) 5. Adequate ligamentous constraint (translation, rotation, distraction, compression) 6. Independent wrist and finger movement
51
Name the wrist flexor muscles. (2)
1. Flexor carpi radialis 2. Flexor carpi ulnaris See NDC p.60 for illustration + IDENTIFICATION
52
Name the wrist extensor muscles. (3)
1. Extensor carpi radialis brevis 2. Extensor carpi radialis longus 3. Extensor carpi ulnaris See NDC p.60 for illustration + IDENTIFICATION
53
Describe the structure of the bones of the wrist.
1. Variable bone geometry accommodates movement 2. Multifaceted articulations accommodate movement and stability
54
Describe the inclination of the distal radius
Inclined 15° palmar and 15°-20° ulnarly. See NDC p.62 for illustration
55
What can be palpated on the distal radius? Describe the location of these landmarks.
1. Radial styloid: lateral prominence 2. Lister’s tubercle: dorsal prominence
56
What is the mechanism of most distal radius fractures? How common are they?
Mechanism: Fall on outstretched hand (bending and compressive force. Most common upper extremity fracture in people over 50. See NDC p.64 for an Xray example.
57
Name the structures of the distal ulna. (2) (including 1 articular surface)
Styloid process Articulating surface: Head of ulna See NDC p.65 for illustration + IDENTIFICATION
58
Describe the radioulnar kinematics in pronation and supination.
Pronation: Radius crosses over ulna with anterior roll Supination: Radius uncrosses from ulna with posterior roll See NDC p.66 for illustration
59
When is the forearm supinated and pronated maximally? What is the effect of elbow extension on the DRUJ and PRUJ?
The forearm is supinated maximally with the elbow flexed. The forearm is pronated maximally with the elbow extended. Elbow extension also increased transmitted forces across the DRUJ and PRUJ
60
What is ulnar variance?
The distance between distal radius and distal ulna. See NDC p.68 for illustration
61
What is the normal ulnar variance? What is normal load transmission?
Normal ulnar variance = 1mm Normally: 80% load via distal radius and 20% load via distal ulna See NDC p.68 for illustration
62
What is negative ulnar variance? - relative location - load transmission - risk
2-5mm of ulnar variance: the ulna is much more inferior than the radius 95% of load transmission via radius and 5% through ulna. Increased risk for lunate. See NDC p.69 for illustration
63
What is positive ulnar variance? - relative location - load transmission - risk
Ulna is sitting much more superior than radius. 60% of load transmission via radius and 40% via ulna Increase risk of ligamentous (triangular fibrocartilage complex, TFCC) tears. See NDC p.70 for illustration
64
Is it good to promote squeezing a ball while in a cast for a fractured wrist?
Beware of excessive hand squeezing and forceful ROM if distal radius fracture does not have solid fixation. If the radius is higher or lower than it should be relative to ulna, it could be excessive force on one of them.

POTH 225 - Intro to Biomechanics (14 decks)

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