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  • 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
      • age
        • the mean age is ~ 45 years
        • 85% occur between the ages of 30-60
  • 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
    • Basic
      • 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
      • 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
      • 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
    • CT
      • indications
        • comminuted fractures
          • further delineate fragments
        • complex fracture dislocations
      • findings
        • may be helpful in planning surgical technique/approaches
  • Treatment
    • Nonoperative
      • immobilization for 3-7 days followed by early ROM
        • indications
          • Mason Type I - isolated minimally displaced fractures with no mechanical blocks
        • outcomes
          • good results in 85% to 95% of patients
          • beware elbow stiffness with prolonged immobilization
    • Operative
      • ORIF (open reduction internal fixation)
        • 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
        • 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
        • 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
      • intramedullary nail fixation
        • indications
          • not yet considered mainstream treatment as it is in the pediatric population
        • technique
          • retrograde titanium nail reduction and stabilization
        • 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 (open reduction internal fixation)
      • 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
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