Imaging pattern according to the body part of upper extremity

-- Radiography, CT, or MRI imaging findings.

1. Shoulder/upper arm
   1) Clavicle fracture (Fig 1)

   - Mechanism of injury:

     * direct blow on the point of shoulder is the commonest mechanism

     * usually medium to high energy, with falling on to outstretched arm

   2) Proximal humeral fracture (Fig 2)

   - Mechanism of injury:

     * after both high- and low-energy trauma

     * particularly characteristic of falls in elderly women with osteoporosis

    3) Anterior shoulder dislocation (Fig 3)

   - Mechanism of injury 

     * Commonly, a fall on an outstretched hand

    * In contact sports, from forced abduction-external rotation (ABER) or direct posterior blow to the shoulder

    4) Humeral shaft fracture (Fig 4)

    - Mechanism of injury:

     * Fall on outstretched hand

     * Commonly motor vehicle accidents, direct load applied to arm

2. Elbow
   1) Distal humeral fracture

     : Medial and lateral structural columns that provide primary axial load-bearing stability to the humerus

    - Supracondylar fracture (Fig 5)

      Mechanism of injury

     * Hyperextension  type: a fall onto an outstretched hand that puts a hyperextension load on the arm, distal fragment displaces posteriorly (> 95% of cases)

      * Flexion-type: rare, a fall directly onto a flexed elbow

    - Medial or lateral condylar fracture

    - Transcondylar fracture

    - Intercondylar fracture

    - Capitellum fracture: associated with radial head/neck fracture

    - Trochlea fracture

   2) Proximal radial fracture (Fig 6)

    - Mechanism of injury

     * Most often associated with a falling onto outstretched hand

   * Axial loading during forearm pronation with extension or relative flexion of 0°–80°, which causes radial head to forcefully impact capitellum of humerus

    * Essex-Lopresti Fracture-Dislocation: same mechanism and combined diatal radioular joint dislocation

   3) Proximal ulnar fracture

   - Coronoid process fracture (Fig 7)

   * axial loading translating to shear stress, commonly seen in falling on to an outstretched hand type injuries

   - Olecranon fracture (Fig 8)

  * most commonly axial loading of humerus by impact on the elbow during flexion of 90°

   * Forceful contraction of triceps against resistance, typically fall onto a partially flexed elbow

   4) Posterior dislocation with/without coronoid fracture (Fig 9)

  - Mechanism of injury :

   * Most variants of falling onto an outstretched hand type

   * Elbow hyperextension during axial loading, which was thought to lever the distal humerus out of the olecranon

3. Forearm
    - Radial and ulnar shaft fracture

    1) Galeazzi fracture (Fig 10)

      - Fracture of radial shaft at any level with associated dislocation of the distal radioulnar joint (DRUJ)

      - Mechanism of injury:

    * fall on an outstretched hand in hyperpronation, with flexed elbow;

    * hyperpronation and hypersupination, which tend to cause ligamentous disruption in adults, can cause epiphyseal avulsion in children 

    2) Monteggia fracture (Fig 11)

     - Fracture of proximal ulna in association with anterior dislocation at radial head

    - Mechanism of injury:

    * direct blow to the ulna

  * falling onto outstretched hand with the forearm in pronation or hyperextension

4. Wrist
   1) Distal radial fracture

     <Classification>     

     - Colles fracture (Fig 12)

     - Smith fracture (Fig 13) : reverse Colles fracture

     - Barton fracture : shear type fracture, dorsal articular surface

      * Reverse Barton fracture (Fig 14): volar type, by location of fragment

    - Hutchinson (Chauffeur) fracture : intraarticular fracture, within radial styloid +/- scapholunate ligament tear

     <Mechanism of injury>

    - Typically a fall onto an outstretched hand

   - In younger patient, caused by high-energy mechanism such as a motor vehicle accident

   2) TFCC tear (traumatic) (Fig 15)

   - TFCC injury : acute trauma vs. degenerative cause

    * Palmer classification : type 1 (traumatic), type 2 (degenerative)

   - Mechanism of traumatic TFCC injury:

   * Most often forced axial loading on the wrist in extension-pronation position, as a fall on an outstretched hand

   * A distraction force applied to the volar forearm or wrist, frequently encountered in racket sport

5 Hand
   1) Scaphoid fracture (Fig 16)

    - M/C carpal fracture and intercarpal injury

    - Mechanism of injury :

   * Hyperextension of the wrist, from pure compressive force or transverse loading injury

    * A fall on an outstretched hand cause palmar tensile and dorsal compressive force on the scaphoid

   2) Lunate fracture (Fig 17)

    - Mechanism of injury :

     * Generally a fall on an outstretched

     * Compressive force may also be involved

   3) Scapholunate ligament tear (Fig 18, 19)

    - Mechanism of injury :

    * Most commonly due to trauma with wrist extension, ulnar deviation and intercarpal supination

    * Eventually, scapholunate dissociation leads to misalignment of other scaphoid joints and ultimately to osteoarthritis (SLAC wrist)

   4) Lunate and perilunate dislocation (Fig 20)

    - M/C carpal dislocation, young men

    - Two patterns: primarily ligamentous injuries & involves lesser arc

     * With fracture : greater arc injury (transradial styloid, transscaphoid, transcapitate, transtriquetral,transulnar styloid)

     * Without fracture : lesser arc injury

    - Mechanism of injury : typically fall on an outstretched hand in which an axial force is directed on carpus with wrist hyperextension (dorsiflexion), ulnar deviation, supination on a fixed pronated forearm

   5) Pisotriquetral joint subluxation or dislocation (Fig 21)

    - Mechanism of injury :

    * Secondary to direct trauma

   * Traction caused by the FCU tendon either during a fall on a dorsiflexed wrist or while lifting heavy objects