Radial Head Fractures - Trauma

summary
- Radial Head Fractures are common intra-articular elbow fractures that can be associated with an episode of elbow instability, a mechanical block to elbow motion, an injury to the distal radioulnar joint and/or to the interosseous membrane (Essex-Lopresti).
- Diagnosis can be made with plain radiographs of the elbow. CT studies can be helpful for surgical planning.
- Treatment may be nonoperative for non-displaced fractures without a mechanical block to motion but operative management is indicated for displaced fractures, or fractures associated with mechanical block to motion or elbow/forearm instability.

Epidemiology
- Incidence
  - very common fracture
    
    makes up 1-4% of all fractures in adults
    
    makes up 20-30% of all elbow fractures
- Demographics
  - 85% occur between the ages of 30-60
  - mean age is ~ 45 years

Etiology
- Pathophysiology
  - mechanism of injury
    
    fall on an outstretched hand
    
    elbow in extension and forearm in pronation
    
    leads to most force transmitted from wrist to radial head
- Associated conditions
  - incidence
    
    30% have associated soft tissue or skeletal injuries
  - types
    
    ligamentous/ interosseous injuries
    
    lateral collateral ligament (LCL) injury
    
    most common (up to 80% on MRI)
    
    medial collateral ligament (MCL) injury
    
    Essex-Lopresti injury
    
    radial head fracture
    
    distal radioulnar joint (DRUJ) injury
    
    interosseus membrane injury
    
    elbow fractures & dislocations
    
    coronoid fracture
    
    olecranon fracture
    
    Monteggia fracture/dislocation
    
    terrible triad
    
    posterolateral elbow dislocation
    
    radial head fracture
    
    coronoid fracture
    
    carpal fractures
    
    scaphoid fracture

Anatomy
- Osteology
  - proximal radius consists of
    
    radial head
    
    radial neck
    
    radial tuberosity
    
    radial shaft
  - radial head
    
    head-neck osteology
    
    the radial head is 15º offset from the neck (not collinear)
    
    anterolateral third of radial head lacks subchondral bone
    
    easily fractured in this area
    
    articular surface
    
    has 40º oval-shaped concavity that articulates with capitellum
    
    nonarticular portion
    
    90-110º of radial head defined by the projections of the radial styloid and Lister's tubercle
    
    considered a safe zone for hardware placement
- Arthrology
  - radiocapitellar joint
    
    a pivot joint
    
    60% load transfer across elbow joint
    
    fracture or resection of the radial head decreases surface area available for load transfer and decreases stability
  - proximal radial ulnar joint (PRUJ)
    
    ulnar portion of radial head that articulates with the lesser sigmoid notch of the ulna
    
    important for forearm pronation and supination
- Ligaments
  - lateral collateral ligament complex
    
    lateral ulnar collateral ligament (LUCL)
    
    inserts onto supinator crest of ulna.
    
    primary stabilizer to varus and external rotation (hypersupination) stress
    
    more important stabilizer near elbow extension
    
    deficiency results in posterolateral rotatory instability
    
    radial collateral ligament (RCL)
    
    inserts into annular ligament
    
    annular ligament
    
    originates and inserts on the anterior and posterior aspects of the lesser sigmoid notch, respectively
    
    stabilizes the proximal radioulnar joint by maintaining the radial head in contact with the ulna
    
    accessory lateral collateral ligament
  - medial (ulnar) collateral ligament (MCL)
    
    three bundles
    
    anterior bundle
    
    primary stabilizer to valgus stress (radial head is second)
    
    posterior bundle
    
    transverse bundle
- Biomechanics
  - radial head confers two types of stability to the elbow
    
    valgus stability
    
    secondary restraint to valgus load at the elbow, important if MCL deficient
    
    longitudinal stability
    
    restraint to proximal migration of the radius
    
    contributions from interosseous membrane and DRUJ
    
    load-sharing from wrist to radiocapitellar joint is dependent on radiocapitellar surface area
    
    loss of longitudinal stability occurs with Essex-Lopresti injury pattern
    
    radial head fracture + DRUJ injury + interosseous membrane disruption
    
    radial head must be fixed or replaced to restore stability, preventing proximal migration of the radius and ulnocarpal impaction

                        Classification
                    
                        Common
                    
                        Mason Classification(Modified by Hotchkiss and Broberg-Morrey)

                        Type I
                    
                        Nondisplaced or minimally displaced (<2mm), no mechanical block to rotation
                    
                        Type II
                    
                        Displaced >2mm or angulated, possible mechanical block to forearm rotation
                    
                        Type III
                    
                        Comminuted and displaced, mechanical block to motion
                    
                        Type IV
                    
                        Radial head fracture with associated elbow dislocation
                    
                        Advanced
                    
                        OTA Classification 
                    
                        2R1A
                    
                        Extra-articular pattern
                    
                        2R1B
                    
                        Partial articular pattern
                    
                        2R1C
                    
                        Complete articular pattern

Presentation
- Symptoms
  - common symptoms
    
    pain
    
    pain and tenderness along lateral aspect of elbow
    
    limited elbow or forearm motion
    
    particularly supination/pronation
- Physical exam
  - inspection
    
    ecchymosis/swelling possible
    
    tenderness over lateral elbow
    
    deformity possible in setting of associated dislocation
  - motion
    
    important to evaluate for mechanical blocks to elbow motion
    
    flexion/extension
    
    normal = 0-150º
    
    pronation/supination
    
    normal pronation = 85º, supination = 75º
    
    aspiration of joint hematoma and injection of local anesthesia aids in evaluation of mechanical block
  - stability testing
    
    elbow
    
    posterolateral drawer test and posterolateral pivot shift test (tests LUCL)
    
    valgus stress test (tests MCL)
    
    DRUJ
    
    palpate wrist for tenderness
    
    translation in sagittal plane > 50% compare to contralateral side is abnormal
    
    if difficult to determine on exam, can get dynamic CT scan in neutral, pronation and supination for subtle injury
    
    interosseous membrane
    
    palpate along interosseous membrane for tenderness
    
    radius pull test (performed at the time of surgery)
    
    >3mm translation concerning for longitudinal forearm instability (Essex-Lopresti)

Imaging
- Radiographs
  - recommended views
    
    AP and lateral elbow
    
    AP and lateral forearm/wrist
  - findings
    
    fracture with or without displacement/intra-articular involvement
    
    may see anterior/posterior fat pad sign indicating occult minimally displaced fracture
    
    demonstrates intra-articular hemarthrosis
    
    posterior fat pad sign more sensitive for fracture
    
    must rule out concomitant involvement of forearm/wrist
  - additional views
    
    radiocapitellar view (Greenspan view)
    
    oblique lateral view of elbow
    
    beam angled 45 degrees cephalad
    
    allows visualization of the radial head without coronoid overlap
    
    helps detect subtle fractures of the radial head
- CT
  - indications
    
    comminuted fractures
    
    further delineate fragments
    
    complex fracture dislocations
  - findings
    
    may be helpful in planning surgical technique/approaches

Treatment
- Nonoperative
  - short period of immobilization (3-7 days) followed by early ROM
    
    indications
    
    isolated minimally displaced fractures with no mechanical blocks (Mason Type I)
    
    outcomes
    
    good results in 85% to 95% of patients
    
    beware elbow stiffness with prolonged immobilization
- Operative
  - open reduction internal fixation (ORIF)
    
    indications
    
    Mason Type II with mechanical block
    
    Mason Type III where ORIF feasible
    
    presence of other complex ipsilateral elbow injuries
    
    techniques
    
    screw(s) only
    
    plate + screw(s)
    
    outcomes
    
    >90% good-excellent outcomes in Mason II fractures, with variable outcomes in Mason III fractures
    
    # fragments
    
    ORIF shown to have worse outcome when more than 3 fragments present compared to ORIF with 3 or less fragments
    
    >50% rate of unsatisfactory outcomes after ORIF with > 3 fragments
    
    isolated vs. complex
    
    ORIF isolated radial head fractures versus complex radial head fractures (other associated fracture/dislocation) show no significant difference in outcomes at 4 years
    
    isolated fractures trended towards better Patient-Rated Elbow Evaluation score, lower complication rate and lower rate of secondary capsular release
  - fragment excision (partial excision)
    
    indications
    
    older, lower demand adults with complex fractures but no associated instability
    
    fragments less than 25% of the surface area of the radial head or 25%-33% of capitellar surface area
    
    outcomes
    
    even small fragment excision may lead to instability
  - radial head resection (complete excision)
    
    indications
    
    low demand, sedentary patients
    
    in a delayed setting for continued pain of an isolated radial head fracture
    
    contraindications
    
    presence of destabilizing injuries
    
    forearm interosseous ligament injury (>3mm translation with radius pull test)
    
    coronoid fracture
    
    MCL deficiency
    
    outcomes
    
    worse outcomes with regards to strength, function and motion compared to ORIF
    
    higher percentage of arthritis (73%) compared to contralateral uninjured elbow after excision
  - radial head arthroplasty
    
    indications
    
    comminuted fractures (Mason Type III) with more than 3 fragments
    
    severe plastic deformity of radial head
    
    nonunion/malunion
    
    elbow fracture-dislocations
    
    terrible triad or Monteggia variants
    
    with involvement of >30% of articular surface of radial head
    
    Essex-Lopresti lesions
    
    radial head excision will exacerbate elbow/wrist instability and may result in proximal radial migration and ulnocarpal impingement
    
    outcomes
    
    radial head fractures requiring replacement have shown good clinical outcomes with metallic implants
    
    compared to ORIF for fracture-dislocations and Mason Type III fractures, arthroplasty results in greater stability, lower complication rate and higher patient satisfaction
  - retrograde titanium nail reduction and stabilization
    
    indications
    
    not yet considered mainstream treatment as it is in the pediatric population
    
    outcomes
    
    small powered case studies show good outcomes

Techniques
- Nonoperative management
  - Sling (preferred) or posterior long arm splint
    
    3-7 days only to prevent stiffness
- ORIF
  - approaches
    
    Kocher approach
    
    interval
    
    between ECU (PIN) and anconeus (radial n.)
    
    key steps
    
    incise posterior fibers of the supinator
    
    incise capsule in mid-radiocapitellar plane
    
    anterior to crista supinatoris to avoid damaging LUCL
    
    pros
    
    less risk of PIN injury than Kaplan approach (more posterior)
    
    PIN crosses the proximal radius from anterior to posterior within the supinator muscle 4 cm distal to radial head
    
    in both Kocher and Kaplan approaches, the forearm should be pronated to protect PIN
    
    PIN originates approximately 1.2mm from radiocapitellar joint
    
    pronation pulls the nerve anterior and away from the surgical field
    
    more extensile
    
    cons
    
    risk of destabilizing elbow if capsule incision is too posterior and LUCL is violated, which lies below the equator of the capitellum
    
    recommended when LCL is already disrupted (i.e., associated dislocation)
    
    Kaplan approach
    
    interval
    
    between EDC (PIN) and ECRB (radial n.)
    
    key steps
    
    incise mid-fibers of supinator
    
    incise capsule anterior to mid-radiocapitellar plane (have access)
    
    pros
    
    less risk of disrupting LUCL and destabilizing elbow than Kocher approach (more anterior)
    
    improved exposure of anterior fractured fragments when screw fixation is performed
    
    cons
    
    greater risk of PIN and radial nerve injury
    
    less extensile
    
    extensor digitorum communis (EDC) split
    
    interval
    
    incision made longitudinally through middle of EDC to origin on lateral epicondyle
    
    pros
    
    improved access to anterior half of radial head
    
    reduced risk of iatrogenic injury to lateral collateral ligament complex
    
    posterior approach
    
    interval
    
    no true intermuscular interval
    
    raising a large lateral skin flap
    
    indications
    
    associated olecranon or Monteggia fracture
    
    pros
    
    access to both medial and lateral sides of elbow
    
    utilitarian approach when the medial aspect of the elbow is planned to be exposed using the same posterior midline skin incision
    
    cons
    
    less popular currently due to skin flap related complications
  - technique
    
    screw(s)
    
    best utilized alone in simple partial articular patterns
    
    headless compression screws (Hebert) if placed in articular surface
    
    better elbow range of motion and functional outcome scores at 1 year compared to plate fixation
    
    plate(s) + screws
    
    fractures involving head and neck
    
    mini-fragment (1.5 - 2.0 mm) plates and screws utilized
    
    posterolateral plate placement
    
    safe zone (non-articular area) consists of 90-110º arc defined by the projections of the radial styloid and Lister's tubercle
    
    this zone is straight lateral with arm in neutral rotation to avoid impingement of ulna with forearm rotation
    
    bicipital tuberosity is the distal limit of plate placement
    
    anything distal to that will endanger PIN
    
    countersink implants on articular surface
    
    plate removal relatively common in order to restore forearm rotation
  - complications
    
    PIN injury
    
    destabilization of lateral ligament complex
    
    articular surface penetration with screws
    
    mechanical block to motion by hardware
- Fragment Excision
  - approach
    
    Kocher or Kaplan approach as described
  - technique
    
    if fracture is <25% of surface area of radial head and does not compromise elbow stability, fragment can be excised
  - complications
    
    elbow instability if fragment excised is too large
- Radial Head Resection
  - approach
    
    Kocher or Kaplan approach
  - technique
    
    remove enough head to fully remove comminuted aspects of radial head
    
    attempt to keep annular ligament intact
  - complications
    
    muscle weakness
    
    wrist pain
    
    valgus elbow instability
    
    heterotopic ossification
    
    elbow arthritis
    
    proximal radial migration
    
    decreased strength
    
    cubitus valgus
- Radial head arthroplasty
  - approach
    
    Kocher
    
    Kaplan
    
    EDC split
  - technique
    
    metal prostheses
    
    loose stemmed prosthesis
    
    acts as a stiff spacer
    
    thought to "settle in" to anatomic position throughout arc of motion
    
    press-fit prosthesis
    
    depend on osteointegration and tight canal fit
    
    may be more prone to incorrect intramedullary positioning given tight fit
    
    bipolar prosthesis
    
    has an articulation in the head-neck junction
    
    thought to allow better articulation of radial head to capitellum throughout arc of motion
    
    may facilitate elbow instability when the radial head angles in reference to the radial stem
    
    pyrocarbon prostheses
    
    pyrocarbon implant thought to better approximate modulus of cartilage and decrease risk of capitellar wear from metallic radial head implant
    
    currently still under investigation
    
    silicon replacements (Sylastic)
    
    no longer used
    
    independent risk factor for revision surgery
    
    implant fracture
    
    reactive synovitis
  - implant design
    
    monoblock
    
    head and stem are a single connected piece implanted together
    
    modular
    
    head and stem are 2 distinct pieces that are attached upon implantation
  - complications
    
    overstuffing of joint that leads to capitellar wear problems and malalignment instability
    
    excessive length produces abnormal loads through the capitellum and is associated with pain, stiffness and progressive capitellar erosion
    
    incorrect diameter radial head prosthesis has cam effect which produces abnormal loads through the lateral aspect of the trochlea and the lesser sigmoid notch
    
    best assessed by direct visualization and fluoroscopy
    
    proximal implant should align with proximal lesser sigmoid notch
    
    deepest point of the radial head dish should be at same height as lateral coronoid facet
    
    range of motion should be assessed in flexion and extension and should be smooth
    
    the radial head should remain properly aligned with the capitellum with elbow flexion and extension as well as with forearm pronation and supination
    
    loosening
    
    higher likelihood in press-fit prosthesis, with potential need for revision surgery
    
    any implant may be fixed with bone cement if needed
    
    implant dissociation
    
    bipolar prosthesis
    
    modular prosthesis with defective locking mechanism of the head on the stem, leading to metalosis and pain

Complications
- Surgical Site Infection
  - treatment
    
    incision and drainage
    
    consider radial head excision if osteomyelitis present
    
    consider hardware/implant removal when infection complicates ORIF or radial head replacement
    
    six weeks of intravenous antibiotics, possibly followed by oral antibiotics if hardware/prosthesis retained
- Secondary displacement of fracture
  - incidence
    
    occurs in < 5% of fractures initially treated nonoperatively
  - treatment
    
    fixation may be necessary
    
    serial radiographs do not change management
- Posterior interosseous nerve injury (with operative management)
  - risk factors
    
    dissection distal to biceps tuberosity in ORIF
    
    overaggressive retraction at radial neck
  - treatment
    
    if neuropraxia suspected, begin conservatively
    
    cock-up wrist splint, therapy
    
    may order EMG after several months of conservative management if not improving
    
    may need tendon transfer if permanent
- Elbow stiffness & loss of forearm rotation
  - incidence
    
    3-20%
  - risk factors
    
    prolonged immobilization
    
    intra-articular fracture involvement
    
    malunion/nonunion
    
    heterotopic ossification
  - treatment
    
    nonoperative
    
    first-line management includes supervised exercise therapy with static or dynamic progressive elbow splinting over a 6 month period
    
    primary goal is to achieve "functional" elbow range of motion
    
    100º flexion arc (30º-130º) and 100º of rotation (50º pronation & 50º supination)
    
    operative
    
    contracture release with or without radial head removal or replacement
    
    anconeus or Achilles allograft interposition arthroplasty
- Radiocapitellar joint arthritis
  - risk factors
    
    fracture with intra-articular displacement
    
    use of metallic radial head replacement
    
    worse with overstuffing
  - treatment
    
    nonoperative
    
    activity modification
    
    anti-inflammatories
    
    injections
    
    operative
    
    radial head resection
    
    anconeus or Achilles allograft interposition arthroplasty
    
    radiocapitellar hemiarthroplasty
    
    limited outcome data present
    
    no implants currently available
- Heterotopic ossification (HO)
  - risk factors
    
    CNS injury
    
    burns
    
    elbow fracture/dislocation with significant soft tissue injury
  - treatment
    
    prevention
    
    consider 6-week course of indomethacin to minimize risk after fracture/dislocation
    
    post-operative radiation
    
    controversial
    
    operative removal
    
    ensure HO is mature before resection
    
    most have satisfactory outcome despite residual flexion contracture
    
    ~10% have recurrence
- Loss of hardware fixation
  - treatment
    
    revision fixation
    
    radial head replacement
    
    radial head removal

Action	Numeric Key	Letter Key	Function Key
Show Bullets		S	Enter (frontside only)
20%	1	N
40%	2	H
60%	3	F	Enter (backside only)
80%	4	E
100%	5	M
Toss	0	T

Mason Classification (Modified by Hotchkiss and Broberg-Morrey)
Type I	Nondisplaced or minimally displaced (<2mm), no mechanical block to rotation
Type II	Displaced >2mm or angulated, possible mechanical block to forearm rotation
Type III	Comminuted and displaced, mechanical block to motion
Type IV	Radial head fracture with associated elbow dislocation

OTA Classification
2R1A	Extra-articular pattern
2R1B	Partial articular pattern
2R1C	Complete articular pattern