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