Validation of joint angle measurements: comparison of a novel low-cost marker-less system with an industry standard marker-based system

Human motion tracking is widely used for the assessment of movement dysfunction in orthopaedic patients. Currently, most clinical motion analysis centres use marker-based three-dimensional (3D) systems as they are deemed to be the most accurate method. However, due to space, costs and logistics they are not available in many clinical settings. This study compared joint angles measured in functional tests using the novel low-cost Microsoft Kinect Perfect Phorm system with the established marker-based Nexus VICON system. When measuring right and left knee flexion, the average difference between the VICON and Kinect Perfect Phorm measurement was 13.2%, with a SD of 19.6. Both overestimation and underestimation of the joint angle was recorded in different participants. Although the average percentage difference during hip abduction tests was lower at ?3.9%, the range of error was far greater (SD?=?75). From this, it can be concluded that the level of accuracy presented in the new low-cost Kinect Perfect Phorm system is not yet suitable for clinical assessments. However, for general tests of performance, and for tracking cases where absolute accuracy is less critical, future versions of this software may have a place.     

Functional gait analysis in a spinal contusion rat model

Evaluating functional performance of spinal cord injury (SCI) rat models is essential for the development of novel treatments and breakthroughs. However, due to the variety of functional analysis methods available – each with its own strengths and weaknesses – it can be challenging to choose the most appropriate functional analysis test for the animal model. Therefore, we analyzed the strengths and weaknesses of five methods in order to determine which test is not only accurate and easily reproducible, but also relatively inexpensive so that it can be adopted universally. When comparing the Basso, Beattie, and Bresnahan (BBB) test, Ladder walking test, CatWalk test, Rotating Rod test, Microsoft Kinect system and VICON, we used the criteria of sensitivity, quality of data generated, statistical analysis of data, and rate of human error. These specific tests were chosen in order to compare the advantages and disadvantages of simple yet effective methods (BBB, Ladder test, and Rotating Rod test) to more complex and computerized methods (Catwalk, Microsoft Kinect and VICON).     

The effect of backpack heaviness on trunk-lower extremity muscle activities and trunk posture

The purpose of the present study is to analyze trunk-lower extremity muscle activities and trunk postural changes during the carriage of different backpacks. Nineteen male university students (21+/-3 years) participated in the experiment's four standing modes: (1) unloaded standing, (2) 10% body weight (BW) load (in the form of a backpack), (3) 15% BW load and (4) 20% BW load. Bilateral rectus abdominis, erector spinae, vastus medialis and biceps femoris muscle activities were recorded using surface electromyography (SEMG), while trunk inclination, side flexion and rotation were measured by using VICON 250 during all standing modes. The results showed that rectus abdominis muscle activities increased progressively and disproportionably as the backpack load increased. As for the trunk posture, almost the same backward inclination was adapted even with increasing backpack heaviness. Twenty percent BW backpack causes the most significant muscular and postural changes so it should be avoided. However, it is recommended to study other backpack factors such as frequency of usage, usage time, type of the backpack and age to come up with a complete usage recommendation.