Anatomy of the Elbow

Bones of the Elbow Humerus Radius Ulna

Joints of the elbow Humeral-Ulnar joint – main hinge action of joint Proximal Radio-ulnar joint – Pronation & Supination of forearm Humeral-Radial joint – part of hinge action

Functional Anatomy Elbow ROM = flexion, extension, pronation and supination 145 degrees of flexion 90 degrees of supination and pronation Stable joint: protection from overuse and traumatic injuries Bony limitations, ligamentous support, and muscular stability at the elbow help to Carrying angle due to distal projection of humerus Normal in females is 10-15 degrees, males 5 degrees Critical link in kinetic chain of upper extremity

Elbow X-ray Basic views: AP & lateral Fat pad sign or “sail sign” In kids, be aware of the apophyses

Elbow X-ray - AP

Elbow X-ray - Lateral

Elbow Fat Pads Fat is normally present within the joint capsule of the elbow, but outside the synovium Typically "hidden" in the concavity of the olecranon and coronoid fossae Injuries that produce intra-articular hemorrhage cause distension of the synovium forcing the fat out of the fossa producing triangular radiolucent shadows anterior and posterior to the distal end of the humerus – the FAT PAD SIGNS Synovial membrane then outside that is fibrous joint capsule (fat btwn the 2) (synovial membrane – fat – fibrous joint capsule)

Fat Pad Sign

Fat Pad Sign Normal The Sail Sign

Fat Pad Sign Posterior fat pad sign – ALWAYS abnormal

Fat Pad Sign Pearls X-rays Think occult fracture No visible fracture Positive fat pad sign Think occult fracture Kids: supracondylar fracture Adults: radial head fracture

Ossification Centers There are 6 ossification centers around the elbow Always appear in same order: C-R-I-T-O-E Capitellum Radius Internal or medial epicondyle Trochlea Olecranon External or lateral epicondyle Age of appearance is highly variable but as general guide remember 1-3-5-7-9-11 years

Elbow Anatomy - Ossification C = capitelum 1 y R = radial head 3 y I = medial epicondyle 5 y T = trochlea 7 y O = olecranon 9 y E = lateral epicondyle 11 y This is only a rough guide. Girls may develop ossification centres earlier than boys.

Elbow Anatomy - Ossification

Ossification Centers

Ossification Centers Radial & Lateral epi usually last to close; so if have closure of lat & radial but see a widened area along the medial epicon then most likely an avulsion of the apophysis & not a normal unfused growth plate

Ossification Centers Age of closure is between ages 14-16 Radial & the lateral epicondyle are generally last to close

Anterior Humeral line Should bisect the capitellum If capitellum displaced posteriorly: Extension supracondylar # If capitellum displaced anteriorly: Flexion supracondylar #

Radio-capitellar line Should bisect the capitellum Can be used on any view Disruption represents radial head #/dislocation

Fracture Types: Supracondylar: Type 1 Type 2 Type 3 Type 1 non displaced may be occult. Splint with back slab at 90 degrees

Fracture Types: Supracondylar: Type 1 Type 2 Type 3 Type 2 is hinged. Posterior cortex is intact. Closed reduction plus immob

Fracture Types: Supracondylar: Type 1 Type 2 Type 3 Displaced. Closed reduction and then ORIF with ORTHO. Can have neurovascular issues because fragment can displace in 3 different directions

Case 11 y.o. RH year round baseball player Concerns? pitches on 3 different teams medial sided Rt elbow pain no acute injury Concerns?

Little League Elbow Medial epicondyle apophysitis Overuse injury Common cause of medial sided elbow pain in throwing athletes X-rays: normal or widening of the apophysis Need comparison views No lateral epicon apophysis yet so widening could just be normal unfused growth plate so need hx, PE, x-rays including of the other elbow

Case Fracture dislocation Olecranon fracture

Case 5yo F FOOSH. Type 2 supracondylar #

Case Fat pads. Occult fracture Abnormal anterior humeral line. Extension supracondylar