Which direction is the distal humeral articulation angled in the axial plane?
5-7 degrees internally rotated
How much is the distal humerus rotated in the sagittal plane?
30 degrees flexed
How much varus/valgus is there at the distal humerus?
6-8 degrees valgus
What is the normal angle of the articular surface angle at the elbow?
What is the plane and flexion angle of the capitellum?
Plane: 30 degrees anterior Flexion: 60 degrees flexed
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)
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 ~50mm 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
What are the components of the lateral ligamentous complex of the elbow?
Annular ligament Radial collateral ligament Lateral ulnar collateral ligament
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, 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?
Anterior bundle Posterior bundle Transverse bundle
What are the components of the anterior bundle of the MCL of elbow?
Anterior band Posterior band Central band
What is the role of the anterior band of the anterior bundle?
It is the primary static stabilizer to valgus stress at 20-120 degrees of elbow flexion
What is the primary static stabilizer of the elbow to valgus stress from 20-120 degrees of elbow flexion?
Anterior band of the anterior bundle
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
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 innervates the muscles of the deep flexor compartment of the forearm?
What is the innervation of flexor digitorum profundus?
Radial 2: AIN Ulnar 2: ulnar
What is the innervation of FPL?