Assesment of hip movements with goniometer and Kinect movement analyzer

Range of motion (ROM) is the arch what is made by the joint measured in degrees. Goniometer is a medical tool that measures ROM in the peripheral joints, used for assessment and evaluation. The popularity of Kinect which is sometimes used instead of goniometer can be explained by the easy access and user friendly set-up but the accuracy of the outcome is still questionable. The comparison of these methods can show us the impact of technology in the field of physiotherapy.
The primary aim of the study is to compare the ROM measured with goniometer and Kinect in the hip joint. Literature shows that movement analyser can easier assess the ROM in distal joints, so further aim was to compare the ROM in the knee and the ankle joint as well.
50 healthy participants (46 female and 4 male; age: 20-25 years) from the second year of physiotherapy (PT) students. The dominant side was assessed for all the movements in the hip, knee and ankle. Goniometer assessment was made by following the international movement system assessment protocol, while during Kinect measurements small changing in the positions was required. Statistical analysis was made with MS Excel; mean and standard deviation was calculated, and paired t-test was used for checking significance. Individual comparison was also made to check the usability of the device.
The results show that in hip flexion with bent leg (69.7±11.6° vs. 69±11.4°; p=0.76) and strait leg (107.5±14.2° vs. 103.1±13.6°; p=0.18) and in knee flexion (126.4±7.1° vs.127.4±10.8°; p=0.50) showed not significant difference, so Kinect measurement in these movements can be used for diagnostic purposes. While significant difference was experienced in hip extension (18.9±5.3° vs. 33.3±8.7°; p<0.001), knee extension (0.5±2°vs. 9.2±4.6°; p<0.001), ankle dorsal flexion (20.1±9.2° vs. 11.7±8.3°; p<0.001) and plantar flexion (30.5±16.7° vs. 72.4±8.6°; p<0.001).
According to our findings Kinect can replace the goniometer in the future only in some specific joint movement but it cannot fully replace traditional PT assessment. Furthermore according to the literature Kinect can be used for measuring complex functions like gaiting and posture.