Tibial Spine Fractures in Children: Information for Families

What is a tibial spine fracture?

The tibial spine is a bony bump in the middle of the top of the shin bone (tibia). The ACL, a strong ligament in the centre of the knee, attaches here.

In adults, a twisting injury usually tears the ACL itself. In children, the bone is still partly soft cartilage and is weaker than the ligament. So the ligament stays intact and pulls a piece of bone off instead. This is why it is sometimes called the childhood ACL injury.

Other names for it are tibial eminence fracture or intercondylar eminence fracture.

How does it happen?

It is uncommon, about 3 in every 100,000 children each year, but becoming more common as more children play sport.

Common causes:

• sport, especially with twisting, sudden stops or landing
• falls from a bike
• skiing, skateboarding and other outdoor sports
• road traffic accidents

The knee is usually twisted with the foot planted, or bent backwards too far. Boys are affected more often after age 10. Girls tend to be affected a little younger (around 11 to 12) than boys (around 13 to 14).

Signs to look for

• sudden pain in the knee
• swelling that comes on quickly, often within a few hours
• difficulty putting weight on the leg
• the knee will not straighten fully
• the knee may feel wobbly

A child with a swollen knee after an injury should see a doctor promptly. These fractures can be missed on a quick look at an X-ray.

How is it diagnosed?

1. Examination. The doctor checks the swelling, movement and stability of the knee.
2. X-ray. This shows the fracture and how far it has moved. Views from the front and side are taken.
3. MRI scan. This shows other damage that X-ray cannot, such as a torn meniscus or a meniscus trapped under the bone fragment. It also checks the ACL. It does not use radiation.
4. CT scan. Sometimes used to look at the bone fragments in more detail.

About 1 in 3 children with this fracture have another injury in the knee, most often to a meniscus. Sometimes part of a meniscus or a small ligament gets trapped under the bone fragment and stops it going back into place.

Types of fracture

Doctors grade the fracture by how far the bone piece has moved.

A newer grading system, based on MRI, also takes into account trapped tissue and whether the fracture reaches the weight-bearing part of the joint. MRI changes the grade in about 1 in 3 children.

Treatment

Without surgery

Used for fractures that have not moved, or that go back into place.

• If the piece has moved a little, the doctor may gently move the knee to push it back into place, under pain relief or sedation. This works best within 48 hours of the injury.
• The leg is then held in a long cast or brace, either straight or slightly bent, for about 4 to 6 weeks.
• X-rays and sometimes an MRI check that the piece stays in place.

Keyhole surgery

Used when the piece has moved and will not go back, when something is trapped under it, or when there is another injury that needs repair.

1. The surgeon looks inside the knee with a small camera.
2. Any trapped meniscus or ligament is freed, and the fracture bed is cleaned.
3. The bone piece is put back in place.
4. It is held with strong stitches or small screws. Both work well.
5. Any meniscus tear is repaired at the same time.

Screws and stitches are placed to avoid the growth plate where possible.

Open surgery, through a larger cut, is sometimes used instead. Results are similar.

Timing matters

If surgery is needed, it is best done within about 3 weeks of the injury. In a large study, a meniscus tear was found at surgery in about 1 in 5 children operated on within 3 weeks, but in about 2 in 5 when surgery was later.

Delays often happen because the injury is not diagnosed or scanned straight away. If your child's knee swells quickly after an injury, ask about an MRI scan within 1 to 2 weeks.

Recovery and getting back to sport

The most important thing after surgery is to get the knee moving early. Children who start moving the knee within 4 weeks of treatment are much less likely to get a stiff knee.

A typical plan after surgery:

If a meniscus was also repaired, the early stages may be slower. An injury prevention programme is recommended before returning to sport.

After treatment in a cast, the knee is usually moved and strengthened with a physiotherapist once the cast comes off.

Risks and outlook

Most children do well, with good knee scores and a return to their previous sport.

Things that raise the risk of stiffness include an ACL tear at the same time, an injury not from sport (such as a road accident), being under 10, and a cast after surgery.