The tibial tubercle exists in an anterolateral location on the proximal tibia just distal to the physis and develops in four recognized stages⁵ that are important to understanding potential pathology.¹⁴

Closure of the proximal tibial physis and the tubercle apophysis occurs in a predictable pattern.¹⁴ The proximal tibial physis closes in a posteromedial to anterolateral direction toward the tubercle apophysis, which is simultaneously closing in a proximal to distal direction.

The patellar ligament (tendon) inserts into the apophysis with a large periosteal insertion distally.

It is important to remember the native anterolateral position of the tubercle and therefore the fracture fragment when preoperatively planning the approach for intra-articular visualization.

The anterior tibial recurrent artery is at risk to rupture with a displaced fracture. Bleeding from its proximal branches as it retracts into the anterolateral compartment could cause a compartment syndrome.

The injury occurs with a forceful quadriceps contraction while the foot is fixed. There is a significant eccentric force of the quadriceps mechanism that overcomes the strength of the apophysis and the surrounding periosteum.¹⁰ A second possible mechanism of injury is sudden passive knee flexion while the quadriceps is contracted.

It has been hypothesized that individuals with this fracture may have quadriceps strength that is greater than their peers.⁸ Thus, the conditions for the fracture are present during jumping and in strong individuals.

Many children may have preexisting Osgood-Schlatter syndrome.^{1, 12, 13}

The injury usually occurs at a time when the tuberosity is undergoing normal closure,¹⁴ and the pattern of normal skeletal maturity results in specific fracture patterns.

There have also been reports of associated injuries such as quadriceps tendon injury, cruciate ligament tears, and meniscal injury.^{3, 6, 7, 9}

Patients usually present acutely with significant pain and an inability to bear weight on the affected leg after sustaining an injury during physical activity. They are usually tender, with significant swelling over the anterior proximal tibia. An effusion may be present, and active straight-leg raise against gravity is often not possible.

Neurovascular examination should always be performed, as there is distinct risk of injury with tibia tubercle fractures.

There should also be an evaluation for the presence of leg compartment syndrome.

Osgood-Schlatter syndrome has a more insidious onset and usually will not have an effusion or result in extensor lag, even though it may be significantly tender over the tubercle.

Good anteroposterior (AP) and lateral radiographs are often able to make the diagnosis, but they may be limited in the assessing the extent of injury.¹⁴

The displacement is most obvious on the lateral radiograph.

Ogden et al¹³ described three types of tubercle fractures using only the lateral x-ray:

A multiplanar imaging classification scheme has also been described that takes the skeletal development and risk for associated injuries into consideration.¹⁴