What is Tibial Tubercle Avulsion?
Tibial tubercle fractures, which occur in the bony bump on the shinbone (tibia), are quite rare among children, making up less than 1% of injuries to the ends of their bones. In fact, only about 3% of all fractures to the upper part of the shinbone result in such injuries. There are four stages that the tibial tubercle goes through as it develops: a cartilage stage, an apophyseal stage, an epiphyseal stage, and a bony union stage.
In the cartilage stage, which happens before a new bone-forming center develops, the area exists as cartilage. In the apophyseal stage, which happens roughly between the ages of 8 and 14, a secondary center for bone formation appears. This secondary center merges with the top end of the shinbone during the epiphyseal stage. Finally, the last stage, bony union, takes place when the growth plate closes. This typically happens between the ages of 10 and 15 for girls and 11 to 17 for boys.
What Causes Tibial Tubercle Avulsion?
Fractures to the tibial tubercle, a part of the lower leg bone, often happen in sports that require a lot of jumping. These injuries can be caused by the tightening of the quadriceps muscle in your thigh during a movement like starting a jump. Additionally, injury can occur when landing from a jump. In this scenario, the thigh muscle contracts and the knee bends to absorb the landing’s impact.
The patellar ligament, a strong band of tissue that connects your kneecap to your shinbone, attaches in an area that makes the tibial tubercle susceptible to an avulsion injury. An avulsion injury happens when a muscle or ligament pulls away a piece of the bone where it attaches, usually due to a sudden force or impact.
Risk Factors and Frequency for Tibial Tubercle Avulsion
Tibial tubercle avulsion fractures are common in teenagers, with the average age of 14.6 years old at the time of injury. These types of fractures happen almost entirely in boys and are thought to be caused by an increase in quadriceps strength. Other factors, such as increased sports participation and a later age of bony fusion, are also thought to contribute to the occurrence of these fractures in male teens. The tibial tubercle apophysis (part of the bone’s growth plate) closes in a specific pattern, starting from the back and moving towards the front and moving from the inside to the outside and from the top down.
- The average age of patients with tibial tubercle avulsion fractures is 14.6 years old.
- These fractures typically happen in girls between the ages of 10 and 15, and in boys between the ages of 11 and 17.
- This fracture is most common in boys, possibly due to an increase in quadriceps strength.
- Other contributing factors may include increased sports participation and a later age at bony fusion.
- The tibial tubercle apophysis (a part of the bone’s growth plate) closes from back to front, inside to outside, and top to bottom.
Signs and Symptoms of Tibial Tubercle Avulsion
Patients with fractures in the tibial tubercle, a part of the leg bone, usually come to the doctor with pain in the front area of their knee. They may also have swelling and bleeding within the knee joint. Depending on the extent of the fracture, some patients may still be able to straighten their leg due to the remaining intact structures around the knee. However, patients with more severe fractures may struggle with this movement. It’s important to thoroughly examine young patients because their accounts of symptoms might not be as reliable as adults. It’s also necessary to carry out a detailed examination of the nerve and blood supply of the leg as these fractures put patients at risk of developing compartment syndrome, a serious condition that involves increased pressure in a muscle compartment which can lead to nerve damage and muscle death.
Testing for Tibial Tubercle Avulsion
If your doctor suspects a knee injury, known as a tibial tubercle avulsion fracture, they’ll typically take two types of X-rays of your knee. One will be a front-to-back view (known as an “anteroposterior” or AP view), and the other will be a side view (known as a “lateral” view).
The tibial tubercle, a bump on your shinbone (tibia), isn’t located in the direct center of the bone. So, to make sure they get the best image of your injury, your doctor may ask you to slightly turn your shinbone inwards. This positions the tubercle directly opposite the X-ray film or sensor, giving a clearer picture of the injury.
Your doctor can also use the side view X-ray to check for a condition called “patella alta.” This is where your kneecap (patella) is positioned higher than normal on your knee.
Treatment Options for Tibial Tubercle Avulsion
The Ogden classification is a system often used to categorize different types of fractures to the tibial tubercle, a bony protrusion on the tibia (the larger bone in your lower leg). This system has two main categories: “A” for fractures where the bone pieces haven’t moved out of place (non-displaced), and “B” for fractures where the bone pieces have moved (displaced). There are also five types of fractures within these categories:
- Type I – the fracture happens in the area of bone growth known as the secondary ossification center
- Type II – the break extends between the secondary and primary areas of bone growth
- Type III – the break runs through both the secondary and primary areas of bone growth
- Type IV – the fracture is in the proximal tibial physis, which is the growth region at the top of the tibia
- Type V – a tear or rupture in the muscles and tendons that straighten the knee, which is known as the extensor mechanism
The ultimate goal in treating these fractures is to restore functionality and structure to the knee joint.
If the fracture is small and the bone hasn’t moved out of place, or if the break isn’t inside the knee joint (extra-articular), a doctor can manipulate the bone fragments back to their proper position through the skin (closed reduction) and then immobilize the leg to allow it to heal. This immobilization often involves a long leg cast, which keeps the knee straight and has a section molded to help keep the knee extension muscles still.
However, certain circumstances may prevent successful closed reduction, such as if the surrounding tissue is damaged. In these cases, the doctor may need to operate to properly reposition the bone fragments (open reduction).
If the bone fragments have moved out of place (displaced) or the fracture is within the structure of the knee joint (intra-articular), the chosen method of treatment is generally open reduction internal fixation. This procedure involves surgery to reposition the bone fragments and using special metal hardware to hold them in place as they heal.
What else can Tibial Tubercle Avulsion be?
When a doctor is trying to diagnose a tibial tubercle avulsion fracture, which is a type of knee injury, it’s crucial to distinguish between this and another condition called Osgood-Schlatter disease. While both affect the same area, Osgood-Schlatter disease is a long-term condition and a tibial tubercle avulsion fracture occurs suddenly. Right now, doctors aren’t sure if having Osgood-Schlatter disease makes you more likely to suffer a tibial tubercle avulsion fracture.
What to expect with Tibial Tubercle Avulsion
A comprehensive survey of existing studies done by Pretell-Mazzini and colleagues shows that patients who suffer from tibial tubercle avulsion fractures, which are breaks at the bony bump located beneath the kneecap, usually have an excellent prognosis, no matter the particular type of fracture the patient has. This simply means that most patients recover well and their normal functionality is regained, resulting in a generally satisfactory outcome.
Possible Complications When Diagnosed with Tibial Tubercle Avulsion
: The major complication of tibial tubercle avulsion fractures is compartment syndrome, which occurs due to damage to the anterior tibial recurrent artery. When this artery is damaged, blood fills up the front compartment of the leg. Common symptoms of compartment syndrome include pain, pale skin, numbness or tingling, pain when stretching, and weakness.
In children, the signs of this syndrome might be different from adults. It can be indicated by a growing need for pain relief medication, heightened anxiety, or increased restlessness or agitation.
Recurvatum, a deformity, is another common outcome following tibial tubercle avulsion fractures, particularly in younger patients. This usually happens when growth is prematurely closed off at the front growth plate while still continuing from the back growth plate.
Lastly, complications like bursitis, caused by painful or protruding orthopedic hardware, often follow after surgically repairing tibial tubercle avulsion fractures.
Complications to Look Out for:
- Compartment syndrome
- Different signs in children like need for more pain relief, anxiety, restlessness
- Recurvatum deformity
- Bursitis after surgical repair
Preventing Tibial Tubercle Avulsion
It’s important for patients and their parents to understand that staying at a healthy weight and eating a balanced diet full of calcium and vitamin D is crucial for the health of your bones. They should also know the significance of staying in touch with their healthcare provider and following any recommended exercise therapy program.
