Traumatic Elbow Injuries
Summarized by: Akshay Wadera, M.D.
Reviewed by: Prasaanthan Gopee-Ramanan, M.D.
Original publication details
Authors: Scott E. Sheehan, George S. Dyer, Aaron D. Sodickson, Ketankumar I. Patel, Bharti Khurana
DOI: https://doi.org/10.1148/rg.333125176
Reference: Sheehan, S. E., Dyer, G. S., Sodickson, A. D., Patel, K. I., & Khurana, B. (2013). Traumatic elbow injuries: what the orthopedic surgeon wants to know. Radiographics, 33(3), 869-888.
Commonly encountered in the emergency setting
Understand:
Injury mechanism
Elbow biomechanics
Common injury patterns
Anatomy
Radiocapitellar joint → pronation/supination
Ulnotrochlear joint → flexion and extension
Elbow joint: stabilized by the medial collateral ligament (MCL) and lateral collateral ligament (LCL) complexes
MCL complex = anterior, posterior, and transverse bundles.
LCL complex = lateral ulnar collateral ligament (LUCL, radial collateral ligament (RCL), annular ligament and accessory collateral ligament.
Primary stabilization of the elbow → ulnotrochlear joint, anterior bundle of MCL, and LUCL
Secondary stabilization of the elbow → radiocapitellar joint, common flexor-pronator tendon, and common extensor tendon, and joint capsule
Instability
Valgus instability from injury to anterior bundle of MCL, either from chronic repetitive stress (i.e. overhand throwing) or trauma (i.e. FOOSH)
Varus instability and posterolateral rotatory instability (PRLI) from injury to the LCL complex. Fractures of the coronoid process and radial head also contribute to varus and posterolateral rotatory instability.
Anterior elbow instability is rare and most commonly occurs in the setting of olecranon fractures.
Common injury patterns
Radial Head and Neck Fractures
Commonly from FOOSH type mechanism where radial head forcefully contacts capitellum
Biomechanics: Axial loading during forearm pronation with extension or relative flexion of 0-80 degrees
Mason-Johnson Classification System (Type I to IV) is based on degree of displacement, amount of articular surface involvement, and presence of comminuition/dislocation
Type 1
No or minimal (<2mm) displacement
Type 2
Displacement of 2mm or more, articular surface involvement <30%
Type 3
Comminuted radial head fracture
Type 4
Associated proximal radial dislocation
Type 1 and Type 2 Injuries with satisfactory range-of-motion are treated conservatively.
Type 2 with poor range-of-motion, Type 3 and 4 are indicated for surgery.
Essex Lopresti Fracture Dislocation
Comminuted radial head fracture with distal radioulnar joint dislocation. Suspect radioulnar joint dislocation if more than 5mm of radioulnar distance discrepancy on lateral radiograph on the injured wrist relative to the contralateral wrist.
Radiography is usually sufficient for diagnosis except in cases of subtle radial head fractures. CT or MR is not usually indicated, but MR is effective in identifying fractures in adults with radiographic findings of joint effusion
AO-ASIF classification system guides orthopaedic management.
Important to describe column involvement, direction and degree of displacement of epicondylar avulsion and single-column fractures, and presence of comminution or two-column injury.
Distal Humerus Fracture
Distal humerus has medial and lateral columns which include their respective epicondyles and ligamentous complexes.
Biomechanics: Commonly results from direct impact on elbow from axial loading of humerus during flexion.
Type A
Extra-articular fractures
Type A1
Epicondylar avulsion fractures with minimal (<1cm) displacement
Type A2
Simple metaphyseal fracture
Type A3
Comminuted metaphyseal fracture
Type A1 is treated conservatively.
Type B
Partial articular fracture with or without single column involvement.
Type B1
Lateral condylar fracture in sagittal plane
Type B2
Medial condylar fracture in sagittal plane
Type B3
Frontal articular fracture in coronal plane
Type B fractures can be treated conservatively initially but will likely require surgery.
Type C
Articular fracture with disruption of both columns
Type C1
Simple articular and metaphyseal fractures
Type C2
Simple articular fracture with comminuted metaphyseal fracture
Type C3
Comminuted articular and metaphyseal fractures
Type C requires surgery.
Radiography is sufficient for detection. CT is performed for accurate fracture classification. MR is not usually indicated due to relatively low incidence of postoperative instability.
Coronoid Process Fracture
Coronoid process provides static and axial instability to the extended elbow. 50% of coronoid process surface area is needed to maintain posterior and varus instability.
Serves as attachment site for joint capsule, MCL, and brachialis muscle. MCL inserts on sublime tubercle of the medial coronoid base.
Commonly seen in FOOSH-type injuries, or associated with other injuries such as elbow dislocation, proximal ulna or radial head fractures.
Biomechanics: Axial loading resulting in shear stress on the coronoid process
Classification System: O’Driscoll
Type I
Transverse coronoid tip fractures involving ⅓ or less of the coronoid process. Commonly associated with occult soft tissue injury which should prompt further cross-sectional CT or MR imaging. Can be treated conservatively
Type II
Fracture involving anteromedial facet which is associated with MCL injury and instability. Greater medial involvement represents more severe injury subtype. Treated surgically in most cases
Type III
Fracture involving at least half of the coronoid process. Treated surgically in most cases.
CT evaluation with 3D reconstruction is recommended for evaluation of coronoid process fractures.
MR indicated for ambitious cases and to evaluate for soft tissue injury.
Olecranon Fracture
Olecranon forms postero-inferior margin of ulnohumeral articulation and prevents anterior dislocation of the elbow.
Serves as attachment site for triceps tendon. Olecranon merges with the coronoid to form the semilunar notch.
Biomechanics: Most commonly during axial loading of humerus by impact of elbow in 90 degree flexion.
Mechanisms for injury include: complex forced hyperextension, simultaneous opposing contracting of brachialis and triceps, and fall onto partially flexed elbow
Classification System: Multiple proposed systems.
Degree of displacement and presence of comminution are important orthopaedic considerations.
Nondisplaced or minimally (<2mm) displaced fractures with no increase in displacement during flexion or active extension can be treated conservatively.
Displaced (>2mm) fractures, increased displacement during flexion and extension, or presence of comminuition are surgical indications.
Radiography is sufficient for diagnosis. CT often performed for when surgical repair is indicated. MR indicated for ambiguous cases, when stress fractures are suspected, and suspected triceps tendon avulsion injury.
Divergent dislocation involve the distal humerus interpositioned between the proximal radius and ulna
Biomechanics: traditionally axial loading during elbow hyperextension. Recent literature suggests combination of axial compression, supination and valgus stress
Classification System: Based on stages of severity
Dislocation
Can be simple or complex with or without associated fracture. Commonly seen in the setting of FOOSH-type mechanisms
Posterior dislocations more common in adults
Anterior dislocations more common in children, and usually the result of rebound posterior dislocation
Stage I
Mild rotatory instability
Stage II
Near complete dislocation with trochlea perched on coronoid process
Stage III
Frank dislocation with tip of coronoid process positioned behind humerus
Damage to soft tissue structures follows a lateral to medial pattern.
LCL complex is initially damaged → stage I PRLI.
Perching of trochlea on coronoid in severe posterior dislocation can damage lateral soft tissue structures and joint capsule.
Full posterior dislocation can damage lateral as well as medial soft tissue structures such as MCL complex.
Simple dislocations are often treated conservatively with early mobilization.
Complex dislocations often require surgery with stabilization.
Radiography is sufficient for diagnosis. CT scan can be performed for occult fracture suspicion or for more detailed evaluation. MR/MR arthrography are best for evaluating soft tissue/ligament complexes.
Terrible Triad
Posterior elbow dislocation, radial head, and coronoid process fracture.
Associated with extensive ligament damage.
CT should be considered in cases of posterior dislocation with radial head fractures for evaluation of coronoid process due to correlation with severe instability.
Monteggia Fracture Dislocation
Ulnar fracture with radiocapitellar dislocation.
Usually occurs due to direct blow to ulna or FOOSH-type mechanism with forearm in pronation or hyperextension. Recent literature emphasizes early surgical repair.
Classification System: Bado system based on direction of dislocation, angulation of ulnar fracture fragment, and presence/absence of radius fracture.
Type I
Fracture of proximal or middle third of ulna with anterior apex angulation and associated anterior dislocation of radial head
Type II
Fracture of proximal or middle third of ulna with posterior apex angulation and associated posterior dislocation of radial head
Type III
Fracture of proximal or middle third of ulna with associated lateral dislocation of radial head
Type IV
Fracture of proximal or middle third of ulna and radius with anterior dislocation of radial head
Radiography is sufficient for diagnosis of ulna fracture component. Radiocapitellar dislocation can be missed in cases of spontaneous reduction. CT is recommended for detecting additional fractures if Monteggia-type mechanism is suspected.
Citation
Sheehan, S. E., Dyer, G. S., Sodickson, A. D., Patel, K. I., & Khurana, B. (2013). Traumatic elbow injuries: what the orthopedic surgeon wants to know. Radiographics, 33(3), 869-888.