A solution from the world of computer games can help with the diagnosis of injuries
Motion capture system used in the creation of computer games and movies, can also be used as a solution supporting the diagnosis of knee injuries of dancers and athletes, scientists from the Lodz University of Technology claim after examination of professional dancers.
Motion capture is the solution most often associated with the production of computer games and movies. It allows to capture the actor`s movement (with the help of special cameras and markers placed on the actor`s outfit), save it to a computer drive, and then - assign this movement to a character created in a computer program. A spectacular effect of using this system is the Gollum character from the "Lord of the Rings" movies.
Scientists often find new applications for solutions of this type. Dr. Radosław Bednarski from the Department of Computer Graphics and Multimedia at the Institute of Computer Science, Lodz University of Technology, emphasises that the idea was born from the desire to check how the motion capture system could be useful - apart from applications in computer games or movie production.
Researchers propose using the system to study the movement of dancers and athletes. The idea is to perform a test that on the one hand allows to assess the degree of correctness of the performed movements, on the other - to check whether the patient`s motor performance has returned to the state from before the injury. The motion capture system seems to perfect for such applications - the more so that the dancer or athlete should be active during the motion test.
Experts wanted to find out whether during the study of very specific movements the system could verify, for example, if a person has problems with the motor system (which consists of muscles, ligaments and bones - responsible for movement and maintaining posture). So they created a system that could help doctors diagnose knee injuries. The system was tested on professional dancers, with the participation of orthopaedists and physiotherapists.
The solution is intended for dancers, says co-creator of the solution (and dance instructor) Adrianna Bielak from the Institute of Computer Science, Lodz University of Technology. She adds that dance is a field with a large amount of movement variation. But while there are many known dance techniques, there is also a series of movements with established rules that all professional dancers know.
According to Bielak, dance - just like any other sport or performative art - is difficult to study in static conditions, for example lying down. "In the case of dancers, the study of movement is much better in a dynamic position, when the dancer is active, like an athlete. That is why we wanted to propose a solution that would help physiotherapists - and support diagnosis in the context of knee injuries" - she adds.
Why was the knee joint chosen? Firstly, it is one of the most injury-prone joints; not only among dancers, athletes, or physically very active people; this joint is simply exposed to high stress in every human being.
The solution itself is based on a system that allows to capture motion and map it to computer memory. Before the test, the dancer puts on a special suit, on which several dozen markers are applied. "During the test, dancers perform a series of codified, specific movements, during which we dynamically read data related to biomechanics of their movement" - explains Adrianna Bielak.
Researchers use the theory of the dynamic Q angle, which - according to Bielak - determines the position between a very specific area of the hip joint relative to a precisely defined area of the knee joint.
"Since we can use motion capture system, we are able to determine the relationship of this areas in the hip and knee joint dynamically, during the dancer`s movement" - she adds. The movements selected for the tests are known to cause particular stress on dancers` knee joints because they are not natural. They consist in the rotation of the bones in the hip joint that is so unnatural that it can cause injuries.
Specialists from Lodz University of Technology have also created a special application that allows to dynamically check whether a given movement (and in which phase) is injurious for the dancer.
"It allows the physiotherapist to determine that if a dancer moves in a certain way, then from a certain moment a movement begins that may threaten his or her health. Or - in the case of a dancer who is after a surgery, for example a knee joint ligament reconstruction, this system allows to check whether after this operation, and after all the structures in the knee have joined together, the dancer can do the exercise that caused the injury" - explains the author of the invention.
Researchers at Lodz University of Technology are now working on enhancing the system by combining it with a 3D model of the calf muscle. "The calf is connected to the knee joint, so we will be able to enhance this solution and obtain a much larger spectrum of data and much more accurate information about the condition of the examined dancer" - says Adrianna Bielak.
PAP - Science in Poland, Kamil Szubański
szu/ zan/ kap/