Jeonghoon Oh

Microsoft Kinect can distinguish differences in over-ground gait between older persons with and without Parkinson's disease

Gait patterns differ between healthy elders and those with Parkinsons disease (PD). A simple, low-cost clinical tool that can evaluate kinematic differences between these populations would be invaluable diagnostically; since gait analysis in a clinical setting is impractical due to cost and technical expertise. This study investigated the between group differences between the Kinect and a 3D movement analysis system (BTS) and reported validity and reliability of the Kinect v2 sensor for gait analysis. Nineteen subjects participated, eleven without (C) and eight with PD (PD). Outcome measures included spatiotemporal parameters and kinematics. Ankle range of motion for C was significantly less during ankle swing compared to PD (p=0.04) for the Kinect. Both systems showed significant differences for stride length (BTS (C 1.24±0.16, PD=1.01±0.17, p=0.009), Kinect (C=1.24±0.17, PD=1.00±0.18, p=0.009)), gait velocity (BTS (C=1.06±0.14, PD=0.83±0.15, p=0.01), Kinect (C=1.06±0.15, PD=0.83±0.16, p=0.01)), and swing velocity (BTS (C=2.50±0.27, PD=2.12±0.36, p=0.02), Kinect (C=2.32±0.25, PD=1.95±0.31, p=0.01)) between groups. Agreement (RangeICC =0.93-0.99) and consistency (RangeICC =0.94-0.99) were excellent between systems for stride length, stance duration, swing duration, gait velocity, and swing velocity. The Kinect v2 can was sensitive enough to detect between group differences and consistently produced results similar to the BTS system.

Kinect-based assessment of lower limb kinematics and dynamic postural control during the star excursion balance test

Assessments using dynamic postural control tests, like the Star Excursion Balance Test (SEBT), in combination with three-dimensional (3D) motion analysis can yield critical information regarding a subjects lower limb movement patterns. 3D analysis can provide a clear understanding of the mechanisms that lead to specific outcome measures on the SEBT. Currently, the only technology for 3D motion analysis during such tests is expensive marker-based motion analysis systems, which are impractical for use in clinical settings. In this study we validated the use of the Microsoft Kinect as a cost-effective and marker-less alternative to more complex and expensive gold-standard motion analysis systems. Ten healthy subjects performed the SEBT while their lower limb kinematics were measured concurrently using a traditional motion capture system and a single Kinect v2 sensor. Analyses revealed errors in lower limb kinematics of less than 5°, except for the knee frontal-plane angle (5.7°) in the posterior-lateral direction. Ensemble curve analyses supported these findings, showing minimal between-system differences in all directions. Additionally, we found that the Kinect displayed excellent agreement (ICC3,k=0.99) and consistency (ICC2,k=0.99) when assessing reach distances in all directions. These results indicate that this low-cost and easy to implement technology may provide to clinicians a simple tool to simultaneously assess reach distances while developing a clearer understanding of the lower extremity movement patterns associated with SEBT performance in healthy and injured populations.

Prediction of ground reaction forces for Parkinson's disease patients using a kinect-driven musculoskeletal gait analysis model

Kinetic gait abnormalities result in reduced mobility among individuals with Parkinsons disease (PD). Currently, the assessment of gait kinetics can only be achieved using costly force plates, which makes it difficult to implement in most clinical settings. The Microsoft Kinect v2 has been shown to be a feasible clinic-based alternative to more sophisticated three-dimensional motion analysis systems in producing acceptable spatiotemporal and kinematic gait parameters. In this study, we aimed to validate a Kinect-driven musculoskeletal model using the AnyBody modeling system to predict three-dimensional ground reaction forces (GRFs) during gait in patients with PD. Nine patients with PD performed over-ground walking trials as their kinematics and ground reaction forces were measured using a Kinect v2 and force plates, respectively. Kinect v2 model-based and force-plate measured peak vertical and horizontal ground reaction forces and impulses produced during the braking and propulsive phases of the gait cycle were compared. Additionally, comparison of ensemble curves and associated 90% confidence intervals (CI90) of the three-dimensional GRFs were constructed to investigate if the Kinect sensor could provide consistent and accurate GRF predictions throughout the gait cycle. Results showed that the Kinect v2 sensor has the potential to be an effective clinical assessment tool for predicting GRFs produced during gait for patients with PD. However, the observed findings should be replicated and model reliability established prior to integration into the clinical setting.

Time-to-boundary analysis of postural control following acute lateral ankle sprain

BACKGROUND Acute lateral ankle sprain (ALAS) impairs unipedal balance both with the injured and uninjured limb, suggesting that balance during bipedal stance may also be compromised. However, a previous study failed to find such impairment because of poorly sensitive balance outcomes. Time-to-boundary (TTB) analysis may be sensitive enough for detecting latent deficits in bipedal balance following ALAS. RESEARCH QUESTION We aimed to examine postural stability during bipedal stance in patients with ALAS using TTB outcomes, and to determine bilateral deficits in unipedal balance. METHODS Twenty-seven patients with ALAS and 26 persons without a history of ALAS participated. ALAS was operationally defined as a traumatic injury to the lateral ligaments of the ankle joint occurring within 24-72 h. Both limbs of the control group were side-matched to those of the patients as either injured or uninjured limbs. All participants performed 3 trials of bipedal stance with eyes open and closed. Next, they completed 3 trials of unipedal stance on both the injured and uninjured limbs in both visual conditions. Order of limb and visual condition for each limb was randomly selected. Means and standard deviations of TTB minima in the anteroposterior and mediolateral directions were computed to assess balance, with lower values indicating poorer balance. RESULTS Independent t-tests revealed significant group differences for almost all measures (p=<0.001 to 0.021), indicating that the ALAS group presented poorer bipedal balance. For unipedal balance, there were no significant group-by-limb interactions for all measures (p > 0.05), indicating no side-to-side differences in the ALAS group. However, group main effects were found for all measures (p=<0.001 to 0.048), showing poorer unipedal balance in the ALAS group. SIGNIFICANCE TTB analysis revealed impaired balance during both unipedal and bipedal stance conditions following ALAS. These results support the emerging hypothesis that centrally mediated changes in postural control may occur following ALAS.

Validity of the Microsoft Kinect™ in assessing spatiotemporal and lower extremity kinematics during stair ascent and descent in healthy young individuals

Stair negotiation is one of the most challenging, yet frequently encountered, locomotor tasks in daily life. This study is the first attempt to investigate the capacity of the Kinect™ sensor to assess stair negotiation spatiotemporal and sagittal plane kinematic variables. The goal of this study was to examine the validity of the Kinect™ v2 sensor in assessing lower extremity kinematics and spatiotemporal parameters in healthy young individuals; and to demonstrate its potential as a low-cost stair gait analysis tool. Twelve healthy participants ascended and descended a 3-step custom-built staircase at their preferred speed, as spatiotemporal parameters and kinematics were extracted simultaneously using the Kinect™ and a three-dimensional motion analysis. Spatiotemporal measures included gait speed, swing phase time, and double stance time. Kinematic outcomes included hip, knee, and ankle joint angles in the sagittal plane. Consistency (ICC2,1) and absolute agreement (ICC3,1) between the two systems were assessed using separate interclass correlations coefficients. In addition, ensemble curves and associated 90% confidence intervals (CI90) were generated for the hip, knee, and ankle kinematics to enable between system comparisons throughout the gait cycle. Results showed that the Kinect™ has the potential to be an effective clinical assessment device for sagittal plane hip and knee joint kinematics and for some spatiotemporal parameters during the stair gait negotiation.

Concurrent Validity of Depth Sensing Cameras for Non-Contact ACL Injury Screening During Side-Cut Maneuvers in Adolescent Athletes: A Preliminary Study

Anterior cruciate ligament (ACL) injury is one of the most common knee injuries among adolescent athletes. Majority of the ACL injuries occur due to pivoting, sudden deceleration, and direction change without contact with any player. Preventive interventions can reduce risks of the ACL injury, thus developing a clinician friendly biomechanical assessment tool to identify athletes with such risk factors is crucial. In this study, the authors investigated the concurrent validity of a commercially available depth sensor, Microsoft Kinect, as a cost-effective alternative to the gold-standard 3-dimensional motion analysis systems in noncontact ACL screening for adolescent athletes during side-cut maneuvers. Study participants performed 45° side-cut maneuvers while collecting data from both systems concurrently. The sagittal and frontal plane kinematics were analyzed during the full stance phase and the first 20% of the stance (early deceleration). Absolute agreement (range: ICC = .767-.989) and consistency (range: ICC = .799-.992) were excellent for all measures except early deceleration frontal plane hip angle, which displayed good absolute agreement (ICC = .643) and consistency (ICC = .625). Findings showed that the Kinect has the potential to be an effective clinical assessment tool for sagittal and frontal plane trunk, hip, and knee kinematics during the side-cut maneuvers.