X-Box and Kinect in Physiotherapy
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Features of the motion sensing input device that may provide benefits in physical therapy practice:
- Contains an RGB video camera and a camera that senses depth. The depth camera has two components, an infrared laser that projects a cloud of dots and an infrared camera that records the dot projection pattern.
- Interprets 3D scene information from continuous data collection. This requires accurate positioning and motion for the subject to sucessfully peform a movement.
- Provides a farily accurate measurement of joint positioning including range of motion, torsion, and angular velocity.
- Hands-free gaming allows for task specific functional training with increasing levels of difficulty, which allows for a variety of custom exercise programs.
- Provides immediate feedback to both the physical therapist and the patient, which may help develop correct movement patterns.
Accuracy in Clinical Practice
From the following blog article that compares motion analysis of running between the Dartfish and Kinect.
The Kinect is not as accurate as the Dartfish. However, it is much more affordable and does not require the patient to wear special clothing.
Real-Time Human Pose Recognition in Parts from Single Depth Images, Shotton et al, 2011
Shotton et al proposed and tested a new method to quickly and accurately predict 3D positions of body joints from a single depth image, using a per-pixel classification system. The system runs at 200 frames per second, which allows for real-time interaction. The kinect was able to identify joints reguardless of body posistion with 98.4% accuracy with over 1,000,000 real images. The kinect can detect depth within 1cm and length and width within 3 mm.
Since June 2010, the kinect has been available commercially as a plug-in tool for the X-Box system. There are many fitness, sports, and other games that can assist physiotherapy clients in performing functional movement, cardiovascular exercise, and therapeutic exercise. Also, because these games are engaging and entertaining, clients will likely have greater motivation to complete their therapeutic exercises daily. Patients could receive a download token for their Xbox and the custom therapy game would help patients do exercises on the days between actual physical therapy visits.
In July of 2011, Microsoft Research released Kinect Beta SDK for windows. This noncommercial software development tool with allow software engineers to develop programs that serve as an interface between windows and the Kinect. The possibilities for this tool in physiotherapy are greatly enhanced by the ability to use the Kinect with a PC. For instance, therapists could use this tool to create individualized home exercise programs that the patient could follow at home. Data about the quality and quantity of each exercise performed would be recorded so that the therapist could review the patient's progress.
The video below shows the output of a program designed with Kinect Beta SDK for Windows.
The points displayed are 3 dimensional representations of joints.The program continuously displays the angle of each joint in relation to two neighboring joints as the subject moves in front of the Kinect.
Advantages in Physiotherapy
- Inexpensive tool - retails at $149.00 (USD)
- Can download free beta version of Kinect for Windows software to create programs to be used on a PC (http://research.microsoft.com/en-us/um/redmond/projects/kinectsdk/download.aspx)
- Provides instant feedback to both patients and therapists
- Does not require the use of any devices attached to the body or held onto by hand (i.e. motion sensors, hand-held remotes, standing on an object, etc.)
- Difficult to “cheat” when performing activities due to the camera’s ability to detect and sense whole body position
- Can increase motivation levels to complete home exercise programs since they can be viewed as a fun activity (Chang 2011)
- Can be used for gross motor upper extremity exercises for individuals in a wheelchair (Chang 2011)
Disadvantages in Physiotherapy
- Software is still in development
- Accuracy is questionable (see accuracy section above)
- More research needs to be done to realize the full potential of the Kinect with respect to biomechanics
- Not all patients will own or be able to afford to purchase a Kinect
- Therapists will need training to learn how to use the Kinect (specifically how to develop a patient’s home exercise program through the Kinect)
- Not all clinics will have a Kinect available for use (clinic’s will be required to purchase one)
- Is not able to detect fine motor movements
Shotton J, Fitzgibbon A, Cook M, Blake A et al. Real-time Human Pose Recognition in Parts from Single Depth Images. CVPR. 2011.
Chang Y, Chen S, Huang J. A kinect based system for physical rehabilitation: A pilot study for young adults with motor disabilities. Res Dev Disabil. 2011; 32: 2566-2570