Copyright ©The Author(s) 2021.
World J Orthop. Jul 18, 2021; 12(7): 467-484
Published online Jul 18, 2021. doi: 10.5312/wjo.v12.i7.467
Table 1 Studies investigating the reliability of inertial measurement unit sensors
Comparison system
Qiu et al[29], 20163 magnetic angular rate and gravity/thigh, shank, and footViconPosition accuracy of 0.3%, the ΔXY radial distance error of 0.82% and the distance error of 0.27%, position error of 0.4%The combination of distributed wearable sensors with the Denavit–Hartenberg convention resulted in a promising tool for tracking lower limb movements
Sprager et al[30], 20151 multi-sensor platform integrated into a smart garment/kneeNPGood activity discrimination can be achieved based RMSE and SD from flexible sensor, acceleration and gyroscope dataPreliminary results show that walking, running, stairs climbing can be discriminated based on the data collected
Cresswell et al[33], 20174 Shimmer3 sensor nodes/all sides of the shankNPThe results of the fixed effects models highlighted the discrepancies between front–back mounting versus inner–outer mountingFor y-axis gyroscope data, the variation is mostly influenced by mounting location. Mounting location should not vary but if it has to vary, it is better for it to vary between inner and outer leg mounting locations
Fusca et al[35], 20181 IMU/posterior CoMElite (BTS)Mean absolute percentage error of: Stride time is 5.7%; Cadence is 4.9%; Step's length is 5.6%; Step's speed is 13.5%The use of IMU at CoM presents a good reliability for carrying out ambulatory, long-term, and ecologic kinematic of gait analysis
Saggio et al[36], 20207 IMU/pelvis, thighs, shanks and feetViconJoints ROMs RMSE and ICC PCC > 0.75, Reliability all the ICC > 0.975IMUs sensors showed a high reliability on joints' movement and walking test
Table 2 Main features of motion analysis systems
Motion analysis systems
Capture system
Anatomical landmark
Recording system
Optoeletronic measurement systemStereoscopic 3DPassive or active markers placedMulti-IR cameras with stroboscopic LED
Microsoft KinectToF methodMarkeless1 RGB - IR Camera
IMU9 DOFSensor placed with elastic bandMicroprocessor processing raw data
Table 3 Studies investigating the reliability of rasterstereography to evaluate the spine
Mohokum et al[84], 2010To determine reproducibility of rasterstereography for kyphotic and lordotic angles, trunk length, and trunk inclination51 healthy volunteersCronbach-α for the intratester-reliability of the kyphotic angle ICT-ITL (max.) between 0.921 and 0.992. The intertester-reliability for the same parameter is 0.979 (95%CI)The reliability revealed good results, both for intratester and for intertester reliability of rasterstereography in kyphotic and lordotic parameters trunk length and trunk inclination
Guidetti et al[85], 2013To determine intra- and interday reliability of spine rasterstereographic system Formetric 4D with and without reflective markers.26 healthy volunteers with markers (M), 26 healthy volunteers without markers (NM)In M group, for intra- and interday reliability coefficients were 0.971, 0.963, and 0.958 (ICC) and 0.987, 0.983, and 0.985 (Cα) for trunk length, kyphotic angle, and lordotic apex, respectively. In NM group, they were 0.978, 0.982, and 0.972 and 0.989, 0.991, and 0.991 for trunk lengthThe presence of the markers is not necessary for the intraday evaluations and can play a disturbing role for the interday evaluations, because of the repositioning process
Michalik et al[86], 2020To study the spinal and pelvic position under dynamic conditions and compare it to static measurements using a rasterstereographic system.121 healthy volunteers (56 females; 65 males)Trunk inclination (5.31° vs 6.74°), vertebral kyphotic angle (42.53° vs 39.59°), and surface rotation (3.35° vs 3.81°) increase under dynamic conditions (P < 0.001). Trunk shows significant changes during walking compared to static conditions (P < 0.001)The spinal posture differs between females and males during standing and during walking. Rasterstereography is a valuable tool for the dynamic evaluation of spinal posture and pelvic position
Albertsen et al[91], 2018To investigate whether the clinical Matthiass test can be objectified by means ofdynamic rasterstereography in children.101 healthy childrenCluster analysis identified two groups with different postural performance levels during the modified Matthiass Test. Low performers showed a higher increase in backward lean, kyphosis and lordosis (4°–5°, respectively) compared to high performersModified Matthiass Test applied with Rasterstereography can discriminate between low and high posture profile among children
Table 4 Application outline of each mentioned system

Microsoft Kinect
Coach’s Eye
Field of applicationClinicalHighMediumLowMediumHighLowNANA
System potentialAccuracyHighHighMediumHighMediumMediumMedium/LowMedium/Low
Other characteristicsOutdoorNAAvailableAvailableNANAAvailableAvailableAvailable
Time requiredHighLowMediumMediumLowLowLowLow