Paediatric Radius-Ulna Shaft Fracture
The incidence rate of radius-ulna shaft diaphysis fracture is approximately 1 in 100 children per year.
The peak age of incidence is 12-14 years.
They are the most common open fracture in the upper extremity for the paediatric population.
Forearm shaft fractures can be classified by the following:
Fracture location: proximal, middle or distal third.
Fracture pattern: Plastic deformation: bowing without disruption of cortex; Greenstick fracture (incomplete fracture): an incomplete fracture, in which only the convex side of the cortex is broken with bending of the bone; and complete fracture.
Bone involvement: single bone or both bones.
The most common mechanism is a fall onto an outstretched hand.
Rotational forces through the forearm can cause the fractures of the radius and ulna to be at different levels.
Direct impacts can cause an isolated fracture of one bone, more commonly the ulna.
There may be only subtle findings with plastic deformation and greenstick fractures.
In displaced fractures, there is usually deformity, pain, and tenderness directly over the fracture site and limited range of forearm rotation (supination and pronation).
All fractures should be assessed using the Advanced Trauma Life Support (ATLS) principles to ensure associated and potentially significant injuries are identified.
True anteroposterior(AP) and lateral views to include the wrist and elbow joint (whole forearm) should be ordered.
If the elbow and wrist are not adequately visualized, AP and lateral views of these joints should be obtained to eliminate Monteggia fracture-dislocation, supracondylar humeral fracture, lateral condyle fracture, and Galeazzi fracture-dislocation.
Plastic deformation is often unrecognized. Radiographic findings may be subtle. It is most commonly seen in the ulna.
In single bone fractures, the proximal and distal radioulnar joints should be carefully inspected on x-ray. An isolated ulna fracture may be associated with the dislocation of the radial head (Monteggia fracture-dislocation). An isolated radius fracture may be associated with dislocation of the distal radioulnar joint (Galeazzi fracture-dislocation or Galeazzi equivalent).
Management is based on the amount of angulation, level of fracture, type of fracture, age of the child, and displacement of the fracture.
The acceptable angulation for mid & distal shaft fractures of the radius –
<5 years: up to degrees of angulation
<10 years: <15 degrees of angulation
>10 years: <10 degrees of angulation
The acceptable angulation for the proximal third shaft fracture –
< 10 years: <10 degrees of angulation
>10 years: anatomic reduction is recommended
Up to 45 degrees of rotation is acceptable. However, as rotation is very difficult/impossible to quantify on x-rays.
If the forearm looks deformed clinically, the fracture will usually need a reduction. If the deformity can only be seen on x-ray, it may need a reduction.
Most of the children less than 10 years of age are managed with closed manipulation and above elbow cast immobilization.
Operative treatment is indicated:
Children more than 10 years of age
Neurovascular injury with fracture
Extreme swelling/compartment syndrome
Unable to achieve or maintain reduction
Forearm fractures with elbow or wrist dislocation
Ipsilateral upper extremity fracture
Emphasis should be placed on the elevation of the limb (elbow above the heart) for the first 48 hours and active finger mobilization.
Back slab and sling should be worn under clothing and not through the sleeve.
For displaced fractures, the need for close follow-up should be emphasized due to the risk of loss of reduction.
With proper treatment, most displaced fractures of the radius and ulna have an excellent outcome. Loss of forearm rotation can occur if the fracture does not heal within acceptable ranges of angulation. There is a very low risk of growth arrest in this injury.
A missed injury, especially in single bone fractures is a common complication. With an isolated ulna fracture, check for injury to the radiocapitellar joint (Monteggia fracture-dislocation). With an isolated radius fracture, check for injury at the wrist (Galeazzi fracture-dislocation).
Loss of reduction – For displaced fractures of the diaphysis, up to one in four will lose position and will need a re-reduction. This risk is higher incomplete fractures of both bones. Loss of position and the opportunity for re-reduction can only happen with appropriately timed follow-up.
Poor cast technique and residual angulation/displacement after the initial reduction are two major factors that can cause subsequent loss of alignment.
Compartment syndrome – It is due to restriction by the cast and by the increase in the swelling. The arm should be elevated post-casting and watched closely to assure that the cast is not too tight. Patients may need overnight observation.
Refracture – Approximately one in twenty (5%) will have a refracture within 6 months of injury. The risk is higher immediately after cast removal.
Malunion occurs after closed treatment. Consider the patient’s age and remodelling potential, as most will resolve with remodelling or be minimal.
Forearm stiffness is the most common complication with the closed treatment of shaft fractures is the loss of forearm rotation, with pronation being more affected. Rates are reported at up to 15% with a mild loss of motion (<25 degrees) and up to 8% with a severe loss of motion (>45 degrees).
Delayed union or non-union is rare. Rate is reported to be 0.5% for the delayed union. Non-union is also rare but is at higher risk with an open fracture. The average healing time of a radial shaft fracture is 5.5 weeks (range 2-8 weeks).
Cross-union/synostosis is rare. Usually is associated with high-energy injuries, radial neck fractures, and surgically treated forearm fractures.
Infection rates reported at 0.2% for deep infection and 3% for superficial infection with pinning/flexible nailing of these fractures. Open fractures are at higher risk, rates reported at 1.2% for deep infection.
Neuropraxia is an uncommon complication. The median nerve is the most commonly injured nerve with this fracture, but any nerve can be affected. Most injuries are neuropraxia. The superficial branch of the radial nerve is at risk with the starting point of flexible nail insertion in radius.
Muscle entrapment/tendon rupture can occur with severely displaced fractures. It usually requires open reduction to remove interposed tissue from the fracture site. There is an iatrogenic risk of tendon rupture with flexible nail insertion and removal from the radius.
Complex regional pain syndromes are uncommon. Often seen with less severe trauma. The most reliable physical exam finding is allodynia.