The injury that often results in an internally rotated leg is a posterior hip dislocation injury.
A posterior hip dislocation injury is often associated with an internally rotated leg, along with a shortened and adducted or drawn inward leg, which occurs when severe force to a flexed knee and hip is applied.
Posterior hip dislocations are the most common type of hip dislocation and requires immediate medical attention and treatment to prevent damage to the nerves and the blood supply.
The symptoms of a posterior hip dislocation are an internally rotated leg, in which your foot will point inwards towards your body's midline.
A posterior hip dislocation will also cause a shortened leg as the affected leg will often appear shorter than the other and the leg will be drawn inward toward the other leg which is also known as an adducted leg.
The causes of a posterior hip dislocation are a severe force that is applied to the knee while your hip and your knee are flexed.
Immediate treatment is needed when you have a posterior hip dislocation because the bones of the hip are displaced which can lead to damage to the bone, blood supply or even nerves around your hip, which can also cause temporary injury or even permanent injury.
Another similar injury is an anterior hip dislocation which is less common and results in the leg being externally rotated.