Traumatic Elbow Injuries
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Transcript of Traumatic Elbow Injuries
Traumatic elbow injuries are commonly encountered in the emergency department setting ~ complexity & clinical significance often go unrecognized at the initial evaluation
15% of emergency department visits for upper-extremity musculoskeletal injuries annually
Orthopedic surgeons frequently use a classification system different from those used by their colleagues in radiology : miscommunication or delay in communication of the most clinically relevant findings
Awareness and detection of these injuries may be improved by a better-developed and more intuitive understanding of the mechanisms that underlie the most common injury patterns
Elbow : 3 primary articulations that provide two degrees of freedom of motion Flexion and extension movements are centered at
the ulnotrochlear articulation pronation and supination are centered at the
radiocapitellar and radioulnar articulations The elbow articulations are stabilized by the
Medial Collateral Ligament (MCL) complex anterior, posterior, and transverse bundles
Lateral Collateral Ligament complexes radial collateral ligament (RCL) lateral ulnar collateral ligament (LUCL) annular ligament
CT 3D lateral view LCL Complex LUCL (red) RCL (blue) Annular ligament
(yellow)
• CT 3D oblique view MCL Bundles•Anterior (red)•Posterior (blue)•Transverse (yellow)
ELBOW INSTABILITY
• VALGUS INSTABILITY MOST COMMONLY RESULTS FROM INJURIES TO THE ANTERIOR BUNDLE OF THE MCL
• WHEN THE ANTERIOR MCL IS INJURED, SECONDARY STABILIZATION IS PROVIDED BY THE FLEXOR-PRONATOR MUSCLES AND RADIOCAPITELLAR ARTICULATION
• NORMAL FUNCTIONAL STRESSES ON THE ANTERIOR MCL ARE THOUGHT TO BE HIGHEST WHEN VALGUS LOADING OCCURS WHILE THE FOREARM IS SUPINATED AND EXTENDED OR FLEXED AT AN ANGLE BETWEEN 0° AND 90°
Injury mechanism involves valgus and pronation stresses after a fall onto an outstretched hand (FOOSH)
Ligament damage is best depicted at computed tomographic (CT) arthrography, magnetic resonance (MR) arthrography, or MR imaging
Elbow trauma Early identification of injuries that can lead to elbow
instability is critical to guide decision making about appropriate treatment
An understanding of the most common injury mechanisms will help direct attention toward the most critical injuries
RADIAL HEAD & NECK INJURY ESSEX LOPRESTI FRACTURE
DISLOCATION DISTAL HUMERUS FRACTURE CORONOID PROCESS FRACTURE OLECRANON FRACTURE ELBOW DISLOCATION TERRIBLE TRIAD MONTEGGIA FRACTURE &
DISLOCATION
Most common elbow fractures in adults approximately 33%–50% of elbow fractures 20% of elbow trauma cases
Most often associated with a FOOSH-type injury mechanism results from axial loading during forearm pronation with
extension or relative flexion of 0°–80° causes the radial head to forcefully impact the
capitellum of the humerus
Mason-Johnston system, radial head and neck fractures morphologic characteristics of the fracture presence or absence of associated dislocation
Mason - Johnston type I injury
Mason-Johnston type II fracture
Uncommonly seen but clinically important involves a comminuted fracture of the radial head with dislocation of the distal radioulnar joint and disruption of the interosseous membrane,
producing the oft-cited “floating radius” The mechanism is most likely a variation of that present in a
FOOSH-type injury The radiographic features of distal radioulnar joint dislocation
can be subtle but a radioulnar distance discrepancy of >5 mm
on lateral radiographs of the injured wrist relative to the contralateral uninjured wrist
axial loading along the forearm
distraction forces at the distal radioulnar joint
comminuted radial head fracture
dorsal subluxation of the distal ulna with widening of the radioulnar distance
medial and lateral structural columns that provide primary axial load-bearing stability to the humerus
Potential injury mechanisms include a direct impact on the elbow with resultant axial loading of the humerus during flexion of various degrees, as well as a FOOSH
distal humerus fractures, it is most critical to report the salient radiographic findings that guide treatment: column involvement, the direction and degree of displacement of epicondylar avulsion fractures and single-column fractures, and the presence of comminution or two-column injury
2 bone columns that provide primary load-bearing support to the arm
AO-ASIF type A1 fracture
mildly displaced medial epicondylar fracture
transverse metaphyseal fracture
AO-ASIF type C1 injury
comminuted intraarticular fracture of the distal humerus
AO-ASIF type C3 fracture
Makes up the anterior margin of the ulnohumeral articulation and serves to resist varus stress and prevent posterior elbow subluxation
serves as the site of anterior attachment of the joint capsule, insertion of the MCL, and insertion of the brachialis muscle at its anterior aspect
The mechanism of fracture is thought to relate to axial loading translating to shear stress on the coronoid process ~ commonly seen in FOOSH-type injuries
Fractures of the anteromedial facet are a commonly seen coronoid process fracture pattern, often with associated injuries of the MCL (which inserts on the sublime tubercle of the medial coronoid base) that lead to the development of varus and posteromedial rotatory instability or PLRI (
O’Driscoll fracture classification system, which comprises three fracture types (I, II, and III) defined on the basis of their
location in the 3D anatomy
comminuted fracture (arrow) extending through the anteromedial facet of the coronoid process, a finding of an
O’Driscoll type II fracture
fracture of the anteromedial facet of the ulnar coronoid process
Olecranon, which forms the posteroinferior margin of the ulnohumeral articulation, functions as a buttress preventing anterior dislocation of the elbow
Mechanism : Axial loading of the humerus by an impact on the elbow
during flexion of 90° >>>> Complex forced hyperextension injuries Simultaneously opposing contraction of the brachialis and
triceps, or a fall onto a partially flexed elbow, can cause olecranon fractures and triceps avulsion injuries
Patients with nondisplaced fractures that are les than 2 mm wide, with no increase in displacement over 90° of flexion or during active extension, can usually undergo a trial of conservative therapy
Displacement of fracture fragments (with a gap of >2 mm), increased displacement during elbow flexion or extension, and the presence of comminution are surgical indications.
comminuted fracture of the olecranon avulsion fracture of the olecranon at the site of triceps tendon insertion
Second most common type of joint dislocation in adults, after shoulder dislocation
Classified according to the direction of movement and described as either simple or complex, depending on the absence or presence of an associated fracture
Adult elbow dislocations are most commonly posterior in direction
Anterior dislocations of the elbow are rare and are most often seen in children, in whom they are usually the result of rebound after posterior dislocation
simple posterior elbow dislocations complex posterior elbow dislocations
Computer-generated images of the elbow show the stages of posterior elbow subluxation and
instability
MR arthrography demonstrates disruption of the RCL and LUCL after reduction for posterior dislocation
lateral capitellum and lateral epicondyle, an injury produced by impact of the radial head.
Full-thickness tears of the MCL and LUCL complex
combination of posterior elbow dislocation with radial head fracture coronoid process fractures
associated with extensive ligament damage
chronic instability and severe arthritis
coronoid process fracture fragment (arrowhead).
TERRIBLE TRIAD
comminuted radial head fracture (arrow)
Monteggia injuries are classified within the Bado system Direction of dislocation Angulation of the ulnar fracture fragment Presence or absence of an associated fracture of
the radius
fracture of the proximal ulna in association with anterior dislocation at the radial head
any ulnar fracture with radiocapitellar dislocation
Bado type I Monteggia fracture
transverse fracture of the ulnar diaphysis (arrowhead) with anterior angulation of the apex and predominantly anterior dislocation of the radial head (arrow),
Evaluation of traumatic elbow injuries Radiographic detection of bone abnormalities Inference of potential associated secondary occult bone and soft-
tissue injuries
Understanding of the most common injury mechanisms
Radiologist’s
direct the early imaging evaluation as appropriate to facilitate detection of the most clinically
relevant associated injuries
adopting the clinically most relevant classification systems used by their colleagues in orthopedic
surgery, radiologists can minimize the potential for inappropriate or delayed treatment