The optimal position for the patella (kneecap) is in the middle of the knee. Kneecaps that point inward or outward move unevenly over the femur (thigh bone). The articular cartilage along the under surface of the patella can get scratched and torn when there's maltracking of the patella.
X-rays and MRIs aren't really necessary since the condition is obvious to the naked eye. These tests may help identify the degree of displacement. They may show the presence of any tilt in the patella. But they do not necessarily contribute anything extra to the diagnosis.
A full exam of the individual may be more helpful. Any structural or postural factors contributing to the problem can be identified and addressed. Muscle weakness, lack of coordination, or altered motor control can also be observed and treated.
Your daughter may only need a support in her shoe to change the angle of her knee. This can change the forces that are transmitted through the leg. Or she may need a remedial strengthening program to overcome muscle imbalances. In some cases, neuromuscular control is altered (muscles fire too soon, too late, or not enough). A rehab program can also address this problem.