Closed reduction; K-wire fixation

This is a rare injury.

If there is diagnostic doubt, screening by image intensification can be useful.

For fractures that are unstable after reduction, a single K-wire usually provides sufficient stability.

This procedure is normally performed with the patient in a supine position.

A thorough knowledge of the anatomy of the wrist is essential.

The additional material gives a short introduction.

Reduction maneuver is by forearm rotation and direct pressure over the distal ulna.

Posteriorly displaced fractures are reduced by forearm pronation.

Anteriorly displaced fractures are reduced by forearm supination.

Closed reduction is usually successful and if stable will not require fixation.

For irreducible fractures, a K-wire can be inserted into the fracture site (through a stab incision) and used as a lever to facilitate reduction of the ulna.

Note: This technique applies pressure to the already compromised growth plate and should be used only exceptionally and with great care.

A small skin incision is made.

Care should be taken to avoid the dorsal sensory branch of the ulnar nerve.

The incision is deepened to the bone using a blunt artery forceps and a protective sleeve is inserted.

The fracture is stabilized using a single smooth 1.6 mm K-wire through the ulnar styloid, across the physis, engaging the lateral cortex of the ulnar diaphysis.

Continued care should be taken to avoid the dorsal sensory branch of the ulnar nerve during insertion of the K-wire.

The wire should be inserted with an oscillating drill, cooled with saline solution to prevent thermal injury, or by hand using a T-handle.

Ideally, wire insertion is done using image intensification control, in order to check the trajectory of the wire and to ensure engagement of the far diaphyseal cortex without penetration of soft tissues.

The K-wire is left protruding through the skin, bent and cut. The skin is protected with sterile padding prior to application of a cast.

The illustration demonstrates the use of a small section of plastic tubing over the cut end of the protruding wire. This adds further protection for the skin.

Note: Excessive pressure between dressing and skin should be avoided to prevent skin necrosis.

Once the fracture displacement has been reduced and fixed with a K-wire, the arm is splinted in a reduced position with a long arm cast to control forearm rotation.

The purpose of the cast is to maintain reduction by preventing forearm rotation and protect the fixation.

The long arm cast is applied according to standard procedure:

• Long arm cast

If a complete cast is applied in the acute phase after injury, it should be split over the full length of the cast. The split of the cast must be full thickness and expose the underlying skin.

Further swelling in a restricting cast can cause pain, venous congestion in the fingers and occasionally a compartment syndrome.

For this reason any complete cast applied in acute phase should be split down to skin.

Parents/carers should be instructed how to detect circulatory problems by pressing and releasing the fingertips and watching if the blood flow/color returns to normal (capillary refill), compared to the opposite hand.

Compartment syndrome is an unusual but serious complication after the application of a complete cast and can be difficult to diagnose, especially in younger children. Neurological signs appear late and the main sign is excessive pain on passive extension of the fingers.

It is important to make sure that the parents/carers are aware of the risk of compartment syndrome.

The parents/carers and patient should be informed to take note of increased pain and/or unresponsiveness to normal painkillers.

They should know that this may indicate serious complications. It is important for them to detect these signs as early as possible and report them urgently to the surgeon/nurse by telephone, or to attend the Emergency Room (ER) without delay.

Nerve compression is an occasional complication and the signs include:

• Sensory deficits (numbness)
• Weakness of active finger movement
• Paresthesia

See also the additional material on postoperative infections.

If a normal plaster of Paris cast is used, it is important to keep the cast clean and dry in order to maintain the reduction.

When the swelling has reduced, the cast can become loose. The loss of support can result in loss of reduction.

In this circumstance, the parents/carers are advised to return to the healthcare provider.

Depending on the fracture pattern, the age of the child and the method of treatment, the patient has to return for follow-up x-rays to monitor the fracture position.

X-rays taken for fracture position can be taken with cast in place. Any x-rays to assess the state of bone healing must be taken without the cast and correlated with clinical examination.

In most cases, it is conventional to obtain follow-up x-rays after reduction to ensure that the position is maintained.

In general, in the child below 5 years of age, the follow-up is usually about 4-5 days after reduction. In the older child with a potentially unstable fracture, an x-ray would normally be taken at 7-10 days.

Further follow-up x-ray is a matter of clinical judgement, the responsibility of the treating surgeon, and tends to be longer in older children (see also Healing times).

For complete fractures of the metaphysis, redisplacement after reduction is not uncommon. It is therefore, important to take early follow-up x-rays in order to detect a possible redisplacement.

See also the additional material on posttraumatic growth disturbances.

The K-wires can be removed without sedation in the clinic after approximately 3 weeks (depending on the age of the child).