Pediatric Radial Neck Fracture : Wheeless' Textbook of Orthopaedics

- 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.