Introduction

Radial head and neck fractures are the most common elbow fractures (33%) with an incidence of 2.5 to 2.9 per 10,000 people per year. Most radial head fractures are minimally displaced, isolated injuries that can be treated nonoperatively with a good functional outcome. Fractures can be associated with lateral collateral ligament (LCL), sometimes medial collateral ligament (MCL) injury, proximal ulna fracture, or a “terrible triad.” A “terrible triad” includes radial head and coronoid process fractures and posterior elbow dislocation. The LCL is usually detached from its humeral origin. Axial load can cause interosseous membrane and distal radioulnar joint ligament injury resulting in axial forearm instability, known as an Essex–Lopresti injury. This chapter will discuss indications for nonoperative versus operative management as well as fixation options.

I. Preoperative

1. 
   

   History and physical exam

   
   
   
   
   1. 
      

      Most common mechanism is a fall onto an outstretched hand.

      
      
   2. 
      

      Elbow swelling, pain, stiffness, and ecchymosis may be present.

      
      
   3. 
      

      Lateral elbow tenderness suggests radial head and/or LCL injury.

      
      
   4. 
      

      Medial elbow tenderness suggests MCL or sublime tubercle injury.

      
      
   5. 
      

      Deformity suggests elbow subluxation or dislocation.

      
      
   6. 
      

      The shoulder and wrist, especially the distal radioulnar joint, should be examined for associated injuries.

      
      
   7. 
      

      It is important to evaluate for instability and mechanical block to elbow motion.

      
      
   8. 
      

      An intra-articular elbow joint injection of local anesthetic is helpful in reducing pain and guarding for an accurate motion exam.

      
      
      
      
      1. 
         

         Injection is usually performed from a lateral approach between the tip of the olecranon and the lateral epicondyle (▶ Fig. 26.1 ).

         

         
         
      2. 
         

         After injection, forearm rotation and elbow flexion/extension are evaluated.

         
         
         
         
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           i. A hard block to forearm rotation with a displaced fracture is a strong indication for surgery.

           
           
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           ii. Complete elbow extension may not be possible due to hemarthrosis.

           
           
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           iii. Document any crepitus or clicking.

         
         
      3. 
         

         Evaluate for significant ulnohumeral instability with elbow extension.

         
         
      4. 
         

         Consider fluoroscopy to detect more subtle instability.

      
      
   9. 
      

      Perform neurovascular exam.

   
   
2. 
   

   Anatomy

   
   
   
   
   1. 
      

      The radial head has a concave, elliptical dish shape at the radiocapitellar articulation with a flattened outer border that articulates with the ulna at the lesser sigmoid notch (radial notch).

      
      
   2. 
      

      The proximal radius “safe zone” for internal fixation is a 110-degree arc centered directly lateral with the forearm supinated 10 degree from neutral (▶ Fig. 26.2 ).

      

      
      
   3. 
      

      The radiocapitellar articulation is a strong stabilizer against valgus forces as is the MCL.

      
      
   4. 
      

      Posterolateral rotatory instability is the most common type of elbow instability that occurs secondary to disruption of the LCL.

      
      
      
      
      1. 
         

         LCL origin: lateral epicondyle of the humerus.

         
         
      2. 
         

         LCL insertion: crista supinatoris of the proximal ulna.

      
      
   5. 
      

      A “terrible triad” injury usually occurs as the result of an elbow fracture-dislocation associated with posterolateral rotatory elbow instability. LCL repair is required to restore rotational stability in a “terrible triad.”

      
      
   6. 
      

      Longitudinal stability of the elbow is provided by the radial head articulation with the capitellum and the interosseous membrane, which transmits longitudinal forces from the distal radius to the ulna.

      
      
      
      
      1. 
         

         The distal radius bears 80% of the load at the wrist.

         
         
      2. 
         

         Force transmission varies with rotational position of the elbow, but generally 60% of longitudinal forces pass through the radiocapitellar articulation.

         
         
      3. 
         

         Fractures of the radial head or neck disrupt longitudinal load sharing causing all forces to be concentrated in the ulnohumeral articulation.

   
   
3. 
   

   Imaging

   
   
   
   
   1. 
      

      Anteroposterior and lateral X-rays should be obtained and are usually sufficient to diagnose displaced radial head fractures.

      
      
   2. 
      

      Radiocapitellar or “Greenspan” view may help identifying less displaced fractures This modified lateral X-ray is obtained in neutral forearm rotation and 90 degree of elbow flexion by angling the X-ray beam 45 degree to eliminate coronoid process overlap.

      
      
   3. 
      

      Nondisplaced radial head fractures can be difficult to diagnose, but are suspected when hemarthrosis causes anterior and posterior fat pad signs (▶ Fig. 26.3 ). An anterior fat pad sign alone is common in the normal population and is not a reliable marker of injury.

      

      
      
   4. 
      

      When wrist pain is noted bilateral wrist X-rays should be obtained to evaluate for axial instability (Essex–Lopresti injury).

      
      
   5. 
      

      Computed tomography (CT) scan may be required for surgical planning or if X-rays are not sufficient to visualize the location of fracture fragments. CT is especially helpful for evaluating osteochondral fragments, radial head fragment number and position, and associated fractures of the capitellum, coronoid, and proximal ulna.

      
      
   6. 
      

      Magnetic resonance imaging is rarely necessary for isolated radial head fractures.

   
   
4. 
   

   Classification

   
   
   
   
   1. 
      

      Modified Mason classification is most commonly used as shown in ▶ Table 26.1 .

      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      

      Table 26.1 Modified Mason classification of radial head fractures

      Mason classification modified by Hotchkiss and Broberg–Morrey
      Type I	Nondisplaced or minimally displaced (< 2 mm), no mechanical block to rotation
      Type II	Angulated or displaced > 2 mm, may have mechanical block to forearm rotation
      Type III	Comminuted and displaced, mechanical block to motion
      Type IV	Radial head fracture with associated dislocation