APA 4118 Elbow

What type of joint complex is the elbow joint?

Two-degree-of-freedom joint complex

What movements do the humeroulnar and humeroradial joints allow?

Flexion and extension

What movement does the radioulnar joint allow?

Pronation and supination

What is the carrying angle?

Angle between the anatomic axis of the ulnar and humerus in the AP plane in extension

How does the carrying angle differ between children and adults?

Smaller in children than adults

Which gender typically has a greater carrying angle?

Females (13-16 degrees) compared to males (11-14 degrees)

What anatomical feature provides stability in full extension of the elbow?

30 degrees posterior rotation of articular surfaces of the proximal ulna

What is the arc of cartilage in the elbow joint?

Greater than 180 degrees, with a 'bare area' in 90% of people

What type of tissue composes the elbow joint cartilage?

Fatty, fibrous tissue

Where do fractures often occur in the elbow joint?

In the sigmoid notch area, which is not supported by subchondral bone

What is the angulation of the proximal radius from the long axis in the AP plane?

15 degrees away from the bicipital tuberosity

What is the circumference of the radial head covered by hyaline cartilage?

240-280 degrees

What part of the radius is more prone to fracture?

Anterolateral 80-120 degrees without cartilage

What can be used as a 'safe zone' for screw fixation in fractures of the elbow?

The proximal radius

What are the two main articulations involved in elbow flexion/extension?

Humeroulnar and humeroradial articulations

What is the normal range of motion for elbow flexion/extension?

-1.5 to 150 degrees; functional range is 30 to 130 degrees

How does flexion affect the maximum supination and pronation angles?

Max supination angle increases with flexion; max pronation decreases

What is the primary restraint to valgus forces in the elbow?

Medial collateral ligament (MCL)

What percentage of stability does the MCL provide during elbow extension?

30% from MCL, 40% from capsule, 30% from articulation

What is the primary valgus stabilizer of the elbow?

Anterior bundle of the ulnar collateral ligament

What is 'Tommy John' surgery?

UCL reconstruction using tendon grafts to repair the ulnar collateral ligament

What is the most common injury associated with baseball pitching?

Ulnar collateral ligament injury

What is the role of the coronoid process in elbow stability?

Prevents posterior displacement of the ulna

What is the 'terrible triad' in elbow injuries?

Elbow dislocation with lateral ulnar collateral ligament disruption and coronoid fractures

What muscles are primarily responsible for elbow flexion?

Brachialis (primary), biceps long and short head, brachioradialis

Which muscle is primarily responsible for elbow extension?

Long, medial, and lateral heads of triceps (primary), anconeus

What is lateral epicondylitis commonly known as?

Tennis elbow

What is the primary cause of lateral epicondylitis?

Overuse of extensor carpi radialis brevis leading to microtrauma

What are common signs and symptoms of lateral epicondylitis?

Pain around lateral elbow, reduced extension and grasp strength, painful resistance to wrist dorsiflexion

What is the recommended treatment goal for lateral epicondylitis?

Reduce pain and increase strength

What is the impact of elbow flexion on joint forces?

Elbow joint force can be up to 3 times body weight for various activities

How does the stability of the elbow change with flexion and extension?

Different stabilizers are engaged: ulnohumeral articulation is main stabilizer in extension, while articulation is primary in flexion

What is the role of the interosseous membrane in forearm stability?

Provides stability and transmits axial load from arm to elbow

What is the effect of forearm rotation on biceps brachii activity?

Minimally active when forearm is pronated

What is the typical recovery rate for patients with lateral epicondylitis?

Spontaneous recovery occurs in 80-90% of patients within 1-2 years

What is the significance of the brachioradialis during forearm rotation?

Enhanced activity for pronated/neutral forearm

What happens to the mean contact pressure in the radiocapitellar joint during pronation?

It is lower in pronation

What is the impact of elbow flexion on the mechanical advantage of elbow flexors?

Flexion strength increases due to a longer moment arm

What is the typical range of valgus torques experienced during pitching?

10-95 Nm

What is the role of physiotherapy in the rehabilitation of UCL reconstruction?

Includes ultrasound, electrical stimulation, manipulation, and strengthening exercises