Elbow Flashcards
Which direction is the distal humeral articulation angled in the axial plane?
How much varus/valgus is there at the distal humerus?
How much is the distal humerus rotated in the sagittal plane?
5 (5-7) degrees internally rotated
6 (6-8)degrees valgus. This differs from the actual carrying angle
30 degrees anteriorly tilted (flexed) in sagital plane)-The humerus shows a 30 degrees anterior rotation of the articular condyles with respect to the long axis on the humerus
What is the plane and flexion angle of the capitellum?
The capitellum is actually extended approximately 30 degrees
What is the normal carrying angle in men and women?
Men: 10-15 degrees Women: 15-20 degrees
What angles are the medial and lateral columns of the elbow at?
Medial: 45 degrees
Lateral: 20 degrees
What is the safe zone for radial head fixation?
90 degree arc between Lister’s tubercle & Radial styloid with the arm in neutral rotation Generally, posterolateral forearm
Describe the bowing of the radius.
Apex dorsal bow: 5 degrees (in sagittal plane)
Radial bow: 10 degrees (in coronal plane), concave medially (towards ulna)
How do you measure the radial bow?
Where on the radius is the apex of the bow?
WHat is the average maximum bow?
See diagram below.
The site of bowing is 60% the length of the radius as measured from the proximal end (the radial tuberosity)
The maximal bow (as measured below) is 7% of the total radial length
What is the bare area of the ulna?
Non-articular portion of the ulna between the olecranon articular facet and the coronoid articular facet. Located ~2cm from triceps insertion, between the tendons of FCU/ECU Important because you aim for there when doing olecranon osteotomies
What is the proximal ulnar dorsal angulation (PUDA)?
~5 degrees located ~5 cm distal to the tip of the olecranon Important because it is a landmark for comparing to the contralateral side in patients with comminuted or distorted anatomy
The proximal ulna dorsal angulation: a radiographic study.
Rouleau DM1, Faber KJ, Athwal GS
What are the components of the lateral ligamentous complex of the elbow?
Annular ligament
Radial collateral ligament
Lateral ulnar collateral ligament
Accessory lateral collateral ligament - from the inferior margin of the annular ligament to the supinator crest
What are the components of the annular ligament? Its attachments?
Superior & inferior oblique bands
Annular ligament band itself
Attachments: anterior and posterior portions of the sigmoid notch of the proximal radius
What are the attachments of the lateral radial collateral ligament?
Lateral epicondyle
Distally, inserts into (blends with) the annular ligament above the equator of the radial head
What are the attachments of the lateral ulnar collateral ligament?
Lateral epicondyle
Distally, at the supinator crest of the ulna
What are the components of the medial ligamentous complex of the elbow?
What is the most important?
MCL:
Anterior bundle - most important. Primary stabilizer to valgus stress at 20-120 degrees
Posterior bundle
Transverse bundle
What are the components of the anterior bundle of the MCL of elbow?
Which band is most important?
Anterior band
Posterior band
Central band - most important, isometric bundle. Can maintain normal elbow kinematics and stability throughout the arc of flexion
What is the role of the anterior bundle of MCL?
It is the primary static stabilizer to valgus stress at 20-120 degrees of elbow flexion
What is the primary stabilizer to valgus stress at >120 degrees of elbow flexion?
Ulnohumeral articulation, specifically the intrinsic osseous restraint between the ulna and trochlea
In extension, which part of the ulnar collateral ligament is most susceptible to valgus overload?
Anterior band of the anterior bundle
In flexion, which part of the ulnar collateral ligament is most susceptible to valgus overload?
Posterior band of the anterior bundle
When is the central band tight?
It is isometric throughout the ROM
What is the role of the posterior BUNDLE (not band)?
Secondary stabilizer of the elbow at high degrees of flexion
ALSO, Lies posteriorly so acts as a varus stabilizer and resists internal rotation (see below)
Effect of the Posterior Bundle of the Medial Collateral Ligament on Elbow Stability
Pollock et al
These results indicate that isolated sectioning of the posterior bundle of the medial collateral ligament causes a small increase in varus angulation and internal rotation during both passive varus and active vertical flexion. This study suggests that isolated sectioning of the posterior bundle of the medial collateral ligament may not be completely benign and may contribute to varus and rotation instability of the elbow. In patients with insufficiency of the posterior bundle of the medial collateral ligament, appropriate rehabilitation protocols (avoiding forearm pronation and shoulder abduction) should be followed when other injuries permit.
**Classic teaching is that it may be released in a stiff elbow but may not be completely benign
What is the role of the transverse bundle of the ulnar collateral ligament?
Unknown - it doesn’t cross the joint (ulna-ulna) I think it’s a labrum type structure that deepens the joint
Which bundle of the ulnar collateral ligament does not play a significant role in elbow stability? Why not?
Transverse bundle of the ulnar collateral ligament Because it doesn’t cross the elbow joint
How does the radial head affect varus stability?
Indirectly provides varus stability by tensioning the LCL
What are the two origins of FCU
- Humeral head: common flexor origin
- Ulnar head: medial margin of olecranon
What is associated with distal radial shaft fractures occuring within 7.5cm of the radiocarpal joint?
DRUJ injury (Galeazzi fracture)
What is the Kocher interval?
The posterolateral interval: ECU and anconeus
What is the Kaplan interval?
EDC & ECRB
What is the column theory of the distal humerus?
3 columns make up distal humerus
- Medial: diverges from humeral shaft at 45 deg angle
- Lateral: diverges from humeral shaft at 20 deg angle
- Distal: connect 2 columns. The “spool”. Is the articular part
What is the definition of the normal distal humerus angle on an AP xray?
Angle between long axis of humerus and articular surface. 82-84 deg - remember b/c there is 6-8deg valgus at elbow
What is the Baumann angle? What is the normal Baumann angle?
Angle between capitellar growth plate (of lateral condyle) and long axis of humerus 64-81 deg Mean of 72deg
Where should the anterior humeral capitellar line intersect the capitellum?
Central 1/3
What inserts onto the coronoid and where do these soft tissues insert?
Important to note that nothing attached right to the tip
Capsule 6mm from tip
Brachialis 12mm from tip
MCL 18mm from tip
What attaches to the coronoid tip?
Nothing
What type of instability pattern do you get if you have injury of the lateral ligamentous complex of the elbow?
posterolateral rotatory instability (PLRI)
What are the primary stabilizers of the elbow?
Ulnohumeral articulation
MCL
LCL
What are the secondary stabilizers of the elbow?
- Radial head
- Joint capsule
- Common flexor and extensor origins
What is the primary stabilizer of axial forearm stability? (1)
Secondary Stabilizers? (2)
Primary:
Intact radial head
Secondary:
Triangular fibrocartilage complex (TFCC)
Interosseous membrane
Describe the axial force transmittance from wrist to elbow
ie. force distribution through radius and ulna at elbow vs. at wrist, and why
80/20% radius/ulna at wrist
60/40 radius/ulna at elbow
In ulnar neutral variance, radiocarpal joint absorbs 80% of axial load transmitted at wrist - Remaining 20% transmitted to ulna Interosseous membrane redistributes load so that at elbow, radiocapitellar joint sees 60% and ulnohumeral joint sees 40%
What are the components of the interosseous membrane?
5 ligaments:
- Central band
- Accessory band
- Proximal oblique cord
- Distal oblique bundle
- Dorsal oblique accessory cord
How do you differentiate between radial tunnel syndrome, PIN syndrome and lateral epicondylitis?
Radial tunnel syndrome: presents with lateral forearm pain, 3-4cm distal to lateral epicondyle
PIN Syndrome: present with weakness or paralysis as chief complaint
Lateral epicondylitis: Focal tenderness on lateral epicondyle at insertion of ECRB
What are the borders of the cubital tunnel?
Floor: - MCL of elbow - Joint capsule - Olecranon
Roof: - Arcuate ligament of osborne
What is a Gantzer’s accessory FPL muscle?
An accessory long head of FPL - May cause compression of AIN
What are the borders of the cubital fossa? What are its contents?
- Proximal: horizontal line connecting med/lat epicondyles
- Ulnar: Lateral border of pronator teres
- Radial: medial border of brachioradialis
Contents:
- Biceps brachii tendon
- Brachial artery and branches
- Median nerve
At the elbow, where do you find the:
- Brachial artery
- Radial artery
- Ulnar artery
- Brachial artery: - Deep to bicipital aponeurosis (lacertus fibrosis)
- Radial artery: - Over pronator teres, under brachioradialis (basically in the Henry interval)
- Ulnar artery: - Deep to pronator teres between FDS and FDP muscles
Distally, what and where does the ulnar artery travel with?
With ulnar nerve, between FDP/FDS and FCU
Where is the medial antebrachial cutaneous nerve found for nerve grafting?
The anterior branch is found 2 finger breadths distal and anterior to the medial epicondyle. 3.5cm distal to the medial Epicondyle
Where can you find the posterior branch of the median antebrachial cutaneous nerve?
1.5cm distal to the medial Epicondyle
what are the major superficial veins of the arm and forearm?
cephalic v (lateral)
basilic v (medial)
each give off branch at proximal forearm that joins together forming median interbrachial v
In biceps rupture where does the tendon sit? Medial or lateral? Due to what tethering structure?
sits medially due to tethering by the lacerates fibrosis (bicipetal aponeurosis)
What is the last bone to ossify at the elbow?
CRITOE (age 1,3,5,7,9,11) (1,5,7,10,10,11 is more accurate)
therefore it is the lateral epocondyle
It is really important to make sure that there is no Trochlea before the I (medial epicondyle). If there is a T but no I they you need to go looking for the avulsed ossification centre of the medial epicondyle
Pt with elbow dislocation, has instability and apprehension with pushups with hand supinated. What pattern of instability is this and what ligament (be specific) is injured?
What other tests would be positive?
posterolateral rotatory instability with injury to LUCL
Physical exam:
1) varus instability
2) tenderness over LUCL
3) lateral pivot-shift test -patient lies supine with affected arm overhead; forearm is supinated and valgus stress is applied while flexing the elbow often more reliable on anesthetized patient
4) apprehension test - patient lies supine with affected arm extended overhead; forearm is supinated and valgus stress is applied while flexing the elbow
5) chair rise test
6) table-top relocation test
7) floor push-up test as above
What position do you hold the elbow to test the MCL?
LCL?
What position do you immobilize the elbow if you have an MCL injury?
LCL?
if LCL is disrupted than usually more stable in pronation
if MCL is disrupted than usually more stable in supination
What is the Horii circle?
begins on the lateral side of the elbow & progresses to the medial side in three stages
Stage 1 (PLRI)Lateral collateral ligament is partially or completely disrupted
Rupture of LUCL
Results in posterolateral rotatory subluxation of the elbow which can reduce spontaneously (see below)
Stage 2 (perched ulna)
Additional disruption anterior & posterior capsule
Incomplete posterolateral dislocation with subluxation/ dislocation of radial head & the medial edge of ulna resting on the trochlear (AP film) & coranoid perched on the trochlear (lateral film)
Dislocation reduced with minimal force
Stage 3 (dislocated)
Elbow dislocates & coranoid lies posterior to trochlear
3A - AMCL intact
All soft tissue sleeve including posterior part of medial collateral ligament disrupted (anterior medial collateral ligament intact)
Elbow pivots on intact AMCL
Reduction performed by recreating deformity with supination & valgus stress, followed by application of traction, varus stress, & pronation simultaneously
- often seen with radial head and coronoid fracture
AMCL provides stability if forearm remains pronated
3B - no ligaments
Entire MCL (including AMCL) disrupted
Varus, valgus & rotatory instability all present following reduction
Immobilise in cast 90 flexion
Need to be flexed > 30 - 40o to be stable
3C - no ligaments, no flex/pronator mass
Soft tissues stripped off entire distal humerus (including the flexor-pronator & common extensor origins)
Grossly unstable even in flexion (need to flex > 90)
