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Pediatric Radial Neck Fracture

- See:
      - Adult Radial Neck Frx and Radial Head Frx;
      - Pediatric Elbow Injuries

- Discussion:
    - radial neck frx are more common in children, whereas frx of radial head occur primarily in adults;
    - site of frx in childhood is either thru physis w/ metaphyseal fragment (type II physeal injury), or thru neck proper (3-4 mm
          distal to epiphyseal plate);
          - most cases are Salter-Harris type II fractures (90%);
          - in children, proximal radial epiphysis is cartilaginous & is more prone to fracture than hard articular surface of radial head;
          - may have angulation or lateral translation of radial head to a variable degree (Jeffrey type I);
    - this frx occurs on average at age of 10 yrs, after ossification center of the proximal radial epiphysis appears;
          - ossification center of the upper epiphysis of the radius appears at fifth yr & fuses w/ body between ages of 16 and 18 years; 
    - mechanism:
          - results from a hard fall on an extended & supinated outstretched hand;
          - force is transmitted thru shaft of radius, & momentum of body drives capitellum against lateral half of radial head, tilting &
                 displacing it laterally;
          - direction of tilting of displaced head relative to shaft of radius depends upon the rotational attitude of radius at time of injury;
                 - if the forearm is fully supinated, the displacement is lateral;
                 - if the forearm is in neutral mid position, it is posteiror;
          - total displacement, especially in posterior direction, may occur following spontaneous relocation of an elbow dislocation;
    - associated Injuries:
          - capitulum fracture
          - dislocation of distal RU joint;
          - valgus instability (MCL avulsion);
          - rupture of triceps tendon;
          - fracture of olecranon or upper shaft of the ulna;
          - compression force may frx lateral humeral condyle;

- Physical Exam:
    - carefully assess the function of the posterior interosseous nerve

- Radiographic Features:
    - before age 4, normal lateral (valgus) sloping of radial neck may be misinterpreted as representing an injury;
           - up to 15 deg of valgus may be normal;
    - notch at lateral aspect of proximal radial metaphysis may be seen in older children and should not be confused with injury;
    - note that the radial neck may lie in 15 deg of valgus;
    - note that the physis of the proximal radius is widened on the lateral side; 
    - technique:
           - anteriorposterior, lateral (look for fat pad sign)
           - consider radiocapitellar view;
           - forearm in neutral rotation & the x-ray tube angle 45 deg. cephalad
    - type I frx:
           - may be difficult to identify;
           - posterior fat pad sign should suggest further oblique views, including radial head capitellum view;
    - Salter Harris II:
           - type II frx is most common type of radial head & neck frxs in children;
                  - look for positive posterior fat pad signs, but note that this fracture type can be extra-articular, and therefore a fat pad sign
                            may not be seen;
                  - subtle anterior or posterior displacement of the radial head or shaft, as determined by use of radiocapitellar line;

- Accetable Reduction:
    - younger child:
          - < 10 deg of residual neck angulation will correct w/ growth;
          - up to 30 deg of residual angulation can be accepted;
          - angulation is > 30 deg
                - closed manipulative reduction or percutaneous pin to manipulate frx;
    - age > than 10 yrs:
          - poor results w/ angulation > 30 deg, or translocation > 3 mm;
          - inability to reduce angulation < 45 deg, requires ORIF
                - crossed K-wire fixation of the proximal radius is preferred;
          - inability to pronate and supinate the forearm more than 60 deg, is another sign that that the reduction is not adequate;

- Treatment Algorithm Based on Displacement:
    - minimally displaced frx:
         - immobilize elbow (in 90 deg of flexion & neutral forearm rotation) in posterior splint for 1-2 weeks, then active ROM;
         - child > 10 years: correct tilting of radial head to less than 15 deg by closed reduction;
    - moderately displaced Frx:
         - w/ frx tilting of between 30 & 60 deg perform closed reduction under GEA;
         - 45 deg of angulation is acceptable, if passive supination and pronation is 60-70 deg in both directions;
         - reduction maneuver;
                 - elbow is completely extended & forearm is then fully supinated;
                 - determine direction of displacement of radial head;
                 - firm digital pressure is applied to acheive reduction;
    - displaced frx:
         - may require open reduction;
         - closed manipulative reduction is attempted under GET
                 - manipulation should achieve < 30 deg of angulation to be acceptable;
                 - attempt reduction by applying a valgus stress and simultaneous direct manipulation w/ the surgeon's thumbs;
                 - percutaneous K-wire manipulation may be attempted before resorting to open reduction;
                       - pronating the forearm moves the posterior interosseous nerve away from the radial head; 
         - note that the residual intact periosteum / capsule will provide some intrinsic fracture stability once the fracture is reduced;
         - oblique K-wires offer the best fixation in this age group;
         - w/ residual angulation > 45 deg after reduction, consider ORIF;
         - when frx is diagnosed late, deformity of radial head tilting can be corrected by open up wedge osteotomy with a bone grafting; 
         - references:
               - Percutaneous reduction of displaced radial neck fractures in children.  
               - Reduction and fixation of displaced radial neck fractures by closed intramedullary pinning.  
               - New reduction technique for severely displaced pediatric radial neck fractures.
               - Elastic stable intramedullary nail fixation for severely displaced fractures of the neck of the radius in children.
               - Centromedullary Pinning of Radial Neck Fractures: Length Matters! 
               - Evaluation of Severely Displaced Radial Neck Fractures in Children Treated With Elastic Stable Intramedullary Nailing
               - Angulated radial neck fractures in children. A prospective study of percutaneous reduction 
               - Displaced Radial Neck Fractures in Children: Association of the Métaizeau and Böhler Surgical Techniques 
               - Radial neck fractures in children treated with the centromedullary Métaizeau technique

- Complications:

     - malunion results from failure either to achieve adequate reduction or to maintain reduction;
           - malunion may also result from premature fusion of upper radial epiphysis occurs frequently displaced fractures;
                  - will cause shortening of the radius and increased cubitus valgus, depending on pt's age & degree of cartilagenous damage;
    - non union:
           - in the study by Waters PM, et al, the authors conducted a retrospective review of 9 cases of radial neck nonunion in an effort to
                  identify risk factors for nonunion and to evaluate treatment options;
                  - 9 patients, average age 8.2 years, sustained displaced Salter-Harris type II fractures of the radial neck, with average
                           angulation of 83 deg and average displacement of 83%, and elbow dislocation or additional fracture in 8/9 patients;
                  - initial treatment with open reduction achieved anatomical alignment of the fracture fragments in 7 of the 9 patients;
                  - initial reduction was lost and radial neck nonunion developed in all patients;
                  - nonunion was treated with observation, radial head and neck excision, or ORIF with bone graft, depending on the level
                           of pain, deformity, and functional deficit;
                  - healing of the nonunion did not necessarily lead to improvement of clinical symptoms;
                  - severity of initial fracture displacement and inadequate fixation technique contributed to radial neck nonunion;
                  - ref: Radial Neck Fracture Nonunion in Children
    - avascular necrosis:
           - may occur in up to 10 %, and is more common with operative intervention; 
    - radial head excision in children:
           - in children radial head should not be excised because of resulting growth disturbance & deformity of wrist & elbow;
           - excision of radial head in children is disastrous, w/ uniformly poor results due to cubitus valgus, proximal migration of
                     radius, & synostosis.
           - ref: Radial growth and function of the forearm after excision of the radial head. A study of growing macaque monkeys.

Percutaneous Leverage Reduction for Severely Displaced Radial Neck Fractures in Children

Fractures of the radial head and neck in children.

Fracture-separation of the distal humeral epiphysis in young children.

Management of radial neck fractures in children: a retrospective analysis of one hundred patients.

Observations concerning radial neck fractures in children

Surgical Management of Pediatric Radial Neck Fractures

Management of displaced radial neck fractures in children: percutaneous pinning vs. elastic stable intramedullary nailing.