Current Low-Cost Video-Based Motion Analysis Options for Clinical Rehabilitation: A Systematic Review

Automating Video-Based Two-Dimensional Motion Analysis in Sport? Implications for Gait Event Detection, Pose Estimation, and Performance Parameter Analysis

BACKGROUND

Two-dimensional (2D) video is a common tool used during sports training and competition to analyze movement. In these videos, biomechanists determine key events, annotate joint centers, and calculate spatial, temporal, and kinematic parameters to provide performance reports to coaches and athletes. Automatic tools relying on computer vision and artificial intelligence methods hold promise to reduce the need for time-consuming manual methods.

OBJECTIVE

This study systematically analyzed the steps required to automate the video analysis workflow by investigating the applicability of a threshold-based event detection algorithm developed for 3D marker trajectories to 2D video data at four sampling rates; the agreement of 2D keypoints estimated by an off-the-shelf pose estimation model compared with gold-standard 3D marker trajectories projected to camera's field of view; and the influence of an offset in event detection on contact time and the sagittal knee joint angle at the key critical events of touch down and foot flat.

METHODS

Repeated measures limits of agreement were used to compare parameters determined by markerless and marker-based motion capture.

RESULTS

Results highlighted that a minimum video sampling rate of 100 Hz is required to detect key events, and the limited applicability of 3D marker trajectory-based event detection algorithms when using 2D video. Although detected keypoints showed good agreement with the gold-standard, misidentification of key events-such as touch down by 20 ms resulted in knee compression angle differences of up to 20°.

CONCLUSION

These findings emphasize the need for de novo accurate key event detection algorithms to automate 2D video analysis pipelines.

Technological interventions in functional capacity evaluations: An insight into current applications

BACKGROUND

Functional Capacity Evaluation (FCE) is a crucial component within return-to-work decision making. However, clinician-based physical FCE interpretation may introduce variability and biases. The rise of technological applications such as machine learning and artificial intelligence, could ensure consistent and precise results.

OBJECTIVE

This review investigates the application of information and communication technologies (ICT) in physical FCEs specific for return-to-work assessments.

METHODS

Adhering to the PRISMA guidelines, a search was conducted across five databases, extracting study specifics, populations, and technological tools employed, through dual independent reviews.

RESULTS

Nine studies were identified that used ICT in FCEs. These technologies included electromyography, heart rate monitors, cameras, motion detectors, and specific software. Notably, although some devices are commercially available, these technologies were at a technology readiness level of 5-6 within the field of FCE. A prevailing trend was the combined use of diverse technologies rather than a single, unified solution. Moreover, the primary emphasis was on the application of technology within study protocols, rather than a direct evaluation of the technology usability and feasibility.

CONCLUSION

The literature underscores limited ICT integration in FCEs. The current landscape of FCEs, marked by a high dependence on clinician observations, presents challenges regarding consistency and cost-effectiveness. There is an evident need for a standardized technological approach that introduces objective metrics to streamline the FCE process and potentially enhance its outcomes.

Validity and Reliability of Upper Limb Kinematic Assessment Using a Markerless Motion Capture (MMC) System: A Pilot Study

OBJECTIVE

To investigate the validity and test-retest reliability of a customized markerless motion capture (MMC) system that used iPad Pros with a Light Detection And Ranging scanner at two different viewing angles to measure the active range of motion (AROM) and the angular waveform of the upper-limb-joint angles of healthy adults performing functional tasks.

DESIGN

Participants were asked to perform shoulder and elbow actions for the investigator to take AROM measurements, followed by four tasks that simulated daily functioning. Each participant attended 2 experimental sessions, which were held at least 2 days and at most 14 days apart.

SETTING

A Vicon system and 2 iPad Pros installed with our MMC system were placed at 2 different angles to the participants and recorded their movements concurrently during each task.

PARTICIPANTS

Thirty healthy adults (mean age: 28.9, M/F ratio: 40/60).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The AROM and the angular waveform of the upper-limb-joint angles.

RESULTS

The iPad Pro MMC system underestimated the shoulder joint and elbow joint angles in all four simulated functional tasks. The MMC demonstrated good to excellent test-retest reliability for the shoulder joint AROM measurements in all 4 tasks.

CONCLUSIONS

The maximal AROM measurements calculated by the MMC system had consistently smaller values than those measured by the goniometer. An MMC in iPad Pro system might not be able to replace conventional goniometry for clinical ROM measurements, but it is still suggested for use in home-based and telerehabilitation training for intra-subject measurements because of its good reliability, low cost, and portability. Further development to improve its performance in motion capture and analysis in disease populations is warranted.

Validity of assessing level walking with the 2D motion analysis software TEMPLO and reliability of 3D marker application

In gait analysis, knowledge on validity and reliability of instruments and influences caused by the examiner's performance is of crucial interest. These measurement properties are not yet known for commonly used, low-cost two-dimensional (2D) video-based systems. The purpose of this study was to assess the concurrent validity of a video-based 2D system against a three-dimensional (3D) reference standard, as well as the inter-rater reliability, and test-retest reliability of 3D marker application. Level walking was captured simultaneously by a 2D and a 3D system. Reflective markers were applied independently by three raters and repeated by one rater on a second day. We assessed the agreement between the two systems, as well as reproducibility, and inter-rater agreement of derived spatio-temporal parameters and sagittal kinematics. Nineteen healthy participants completed this study. 2D gait analysis provides a possibility to accurately assess parameters such as stride time, stride length, gait velocity, and knee RoM. Interrater and test-retest reliability of 3D gait analysis are generally acceptable, except for the parameters toe-off and pelvic RoM. This is the first study to publish measurement properties of a commercially available 2D video-based gait analysis system, which can support interpretation of gait pattern near the sagittal plane.

3D Motion Analysis for the Assessment of Dynamic Coupling in Transtibial Prosthetics: A Proof of Concept

Assessment of coupling between transtibial sockets and users is historically based on clinicians' observations and experience, but can be inaccurate and unreliable. Therefore, we present a proof of concept, for five out of six possible degrees of freedom coupling metric system for a socket, using motion analysis calibrated on a 3D printed limb substitute. The method is compatible with any socket suspension method and does not require prior modifications to the socket. Calibration trials were used to locate the axis of rotation of the knee joint referenced against a marker cluster on the thigh; this allowed for the identification of the limb during test trials despite the entire residuum being obscured from view by the socket. The error in the technique was found to be within 0.7 mm in displacement and 0.7 degrees in rotation, based on the control data. Dynamic testing showed the Inter Quartile Range (IQR) of inter time step variance was <0.5 mm/deg for all metrics. The method can form a basis for objective socket evaluation, improve clinical practice and the quality of life for amputees.

Computer-assisted approaches for measuring, segmenting, and analyzing functional upper extremity movement: a narrative review of the current state, limitations, and future directions

The analysis of functional upper extremity (UE) movement kinematics has implications across domains such as rehabilitation and evaluating job-related skills. Using movement kinematics to quantify movement quality and skill is a promising area of research but is currently not being used widely due to issues associated with cost and the need for further methodological validation. Recent developments by computationally-oriented research communities have resulted in potentially useful methods for evaluating UE function that may make kinematic analyses easier to perform, generally more accessible, and provide more objective information about movement quality, the importance of which has been highlighted during the COVID-19 pandemic. This narrative review provides an interdisciplinary perspective on the current state of computer-assisted methods for analyzing UE kinematics with a specific focus on how to make kinematic analyses more accessible to domain experts. We find that a variety of methods exist to more easily measure and segment functional UE movement, with a subset of those methods being validated for specific applications. Future directions include developing more robust methods for measurement and segmentation, validating these methods in conjunction with proposed kinematic outcome measures, and studying how to integrate kinematic analyses into domain expert workflows in a way that improves outcomes.

Center of mass-based posturography for free living environment applications

BACKGROUND

Postural assessment is crucial as risk of falling is a major health problem for the elderly. The most widely used devices are force and balance plates, while center of pressure is the most studied parameter as measure of neuromuscular imbalances of the body sway. In out-of-laboratory conditions, where the use of plates is unattainable, the center of mass can serve as an alternative. This work proposes a center of mass-based posturographic measurement for free living applications.

METHODS

Ten healthy and ten Parkinson's disease individuals (age = 26.1 ± 1.5, 70.4 ± 6.2 years, body mass index = 21.7 ± 2.2, 27.6 ± 2.8 kg/m², respectively) participated in the study. A stereophotogrammetric system and a force plate were used to acquire the center of pressure and the 5th lumbar vertebra displacements during the Romberg test. The center of mass was estimated using anthropometric measures. Posturographic parameters were extracted from center of pressure, center of mass and 5th lumbar vertebra trajectories. Normalized root mean squared difference was used as metric to compare the trajectories; Spearman's correlation coefficient was computed among the posturographic parameters.

FINDINGS

Low values of the metric indicated a good agreement between 5th lumbar vertebra trajectory and both center of pressure and center of mass trajectories. Statistically significant correlations were found among the postural variables.

INTERPRETATION

A method to perform posturography tracking the movement of the 5th lumbar vertebra as an approximation of center of mass has been presented and validated. The method requires the solely kinematic tracking of one anatomical landmark with no need of plates for free living applications.

Enhancing motion tracking accuracy of a low-cost 3D video sensor using a biomechanical model, sensor fusion, and deep learning

Low-cost 3D video sensors equipped with routines for extracting skeleton data facilitate the widespread use of virtual reality (VR) for rehabilitation. However, the accuracy of the extracted skeleton data is often limited. Accuracy can be improved using a motion tracker, e.g., using a recurrent neural network (RNN). Yet, training an RNN requires a considerable amount of relevant and accurate training data. Training databases can be obtained using gold-standard motion tracking sensors. This limits the use of the RNN trackers in environments and tasks that lack accessibility to gold-standard sensors. Digital goniometers are typically cheaper, more portable, and simpler to use than gold-standard motion tracking sensors. The current work suggests a method for generating accurate skeleton data suitable for training an RNN motion tracker based on the offline fusion of a Kinect 3D video sensor and an electronic goniometer. The fusion applies nonlinear constraint optimization, where the constraints are based on an advanced shoulder-centered kinematic model of the arm. The model builds on the representation of the arm as a triangle (the arm triangle). The shoulder-centered representation of the arm triangle motion simplifies constraint representation and consequently the optimization problem. To test the performance of the offline fusion and the RNN trained using the optimized data, arm motion of eight participants was recorded using a Kinect sensor, an electronic goniometer, and, for comparison, a passive-marker-based motion tracker. The data generated by fusing the Kinect and goniometer recordings were used for training two long short-term memory (LSTM) RNNs. The input to one RNN included both the Kinect and the goniometer data, and the input to the second RNN included only Kinect data. The performance of the networks was compared to the performance of a tracker based on a Kalman filter and to the raw Kinect measurements. The accuracy of the fused data was high, and it considerably improved data accuracy. The accuracy for both trackers was high, and both were more accurate than the Kalman filter tracker and the raw Kinect measurements. The developed methods are suitable for integration with immersive VR rehabilitation systems in the clinic and the home environments.

Smart Phone-Based Motion Capture and Analysis: Importance of Operating Envelope Definition and Application to Clinical Use

Human movement is vital for life, with active engagement affording function, limiting disease, and improving quality; with loss resulting in disability; and the treatment and training leading to restoration and enhancement. To foster these endeavors a need exists for a simple and reliable method for the quantitation of movement, favorable for widespread user availability. We developed a Mobile Motion Capture system (MO2CA) employing a smart-phone and colored markers (2, 5, 10 mm) and here define its operating envelope in terms of: (1) the functional distance of marker detection (range), (2) the inter-target resolution and discrimination, (3) the mobile target detection, and (4) the impact of ambient illumination intensity. MO2CA was able to detect and discriminate: (1) single targets over a range of 1 to 18 ft, (2) multiple targets from 1 ft to 11 ft, with inter-target discrimination improving with an increasing target size, (3) moving targets, with minimal errors from 2 ft to 8 ft, and (4) targets within 1 to 18 ft, with an illumination of 100–300 lux. We then evaluated the utility of motion capture in quantitating regional-finger abduction/adduction and whole body–lateral flex motion, demonstrating a quantitative discrimination between normal and abnormal motion. Overall, our results demonstrate that MO2CA has a wide operating envelope with utility for the detection of human movements large and small, encompassing the whole body, body region, and extremity and digit movements. The definition of the effective operating envelope and utility of smart phone-based motion capture as described herein will afford accuracy and appropriate use for future application studies and serve as a general approach for defining the operational bounds of future video capture technologies that arise for potential clinical use.

What is the acceptance of video consultations among orthopedic and trauma outpatients? A multi-center survey in 780 outpatients

INTRODUCTION

The purpose of the present study was to assess orthopedic and orthopedic trauma patients' willingness to perform hypothetical remote video consultations, possible advantages as well as concerns.

METHODS

Between June 2019 and November 2019, a survey amongst consecutive regular orthopedic and orthopedic trauma patients at the outpatient clinics from three European level I trauma centers was conducted via paper-based questionnaires, composed of participants` demographics as well as five open and closed questions. Participation was voluntary and anonymity was granted.

RESULTS

In total, 780 participants (female 302, 38.7%, male 478, 61.3%) with a mean age of 43.8 years (SD 17.1, range from 14 years to 94 years) were included. The majority of the participants (57,6%) were eager to use a remote consultation. Participants with an age of more than 55 years were significantly less likely to use a remote consultation than their younger counterparts (OR= 0.18, p=0.003. r²=0.141). Among the whole study population, 86.2% stated, that they had a device compatible with an online video consultation. The highest willingness to conduct a video consultation in respect of the participants` occupation was observed in "part-time"-jobs (70.6%), whereas the lowest disposition was seen in retired patients (37.1%) (p= 0.0001). The most stated reason why to conduct a video consultation was "communication of medical findings" (67.8%). The most stated advantage was the "reduction of physical consultations" (66.4%). "No physical examination" was the most frequently stated disadvantage (75.9%).

CONCLUSION

The majority of orthopedic and orthopedic trauma outpatients would use a video consultation, especially because of commuting and time issues and ideally to communicate medical findings, such as x-ray reports or lab values. Elderly patients appear to be less eager in regard to video consultations. These results may change for even better acceptance in view of a current pandemic situation, as experienced since early 2020. We feel that this assumption may warrant further investigation.

The effect of Covid-19 on the willingness to use video consultations among orthopedic and trauma outpatients: a multi-center survey in 1400 outpatients

Introduction

Due to the Covid-19 pandemic, making more use of remote medical solutions has been advertised. The purpose of this study was to assess the willingness of orthopedic trauma patients to conduct an online video consultation (OVC) during the coronavirus pandemic compared to before.

Methods

A survey amongst orthopedic and trauma outpatients from three European trauma centers was conducted via paper-based questionnaires, composed of participants’ demographics and five open and closed questions between June and November 2019 and between April and July 2020 during Covid-19. The main outcome was the difference between the cohorts regarding the willingness to use an OVC, reasons for and against usage as well as advantages and disadvantages. Sub-analysis was performed for gender, participants’ occupation and three age groups (≤ 30 years; 31–55 years; > 55 years).

Results

1400 participants (780 preCovid-19 and 620 Covid-19) were included. There was no difference in willingness to conduct an OVC between the cohorts (57.6% versus 63.9%; p = 0.053). The highest disposition towards an OVC in both cohorts was seen in patients below 30 years of age, followed by 31–55 years and over 55 years. Women were significantly more likely in the Covid-19-group than in the preCovid-19-group to conduct an OVC (p = 0.032). Use of the OVC for “personal questions to the physician” was more often stated in the Covid-19-cohort (p = 0.007). “No danger of an infection” (p = 0.001) and “availability from anywhere” (p = 0.032) as advantages of an OVC were more often stated in the Covid-19-cohort. “No direct contact with the doctor” (p = 0.001) and “relationship to the doctor could change” (p = 0.024) as disadvantages of the OVC were less often stated in the Covid-19-cohort.

Conclusion

The majority of the assessed outpatients would use an OVC. Fear of infections have increased, and direct physical contact is less important since the Covid-19 pandemic, but have not increased the disposition for an OVC significantly.

Evaluating the validity and reliability of inertial measurement units for determining knee and trunk kinematics during athletic landing and cutting movements

Inertial Measurement Units (IMUs) are promising alternatives to laboratory-based motion capture methods in biomechanical assessment of athletic movements. The aim of this study was to investigate the validity of an IMU system for determining knee and trunk kinematics during landing and cutting tasks for clinical and research applications in sporting populations. Twenty-seven participants performed five cutting and landing tasks while being recorded using a gold-standard optoelectronic motion capture system and an IMU system. Intra-class coefficients, Pearson's r, root-mean-square error (RMSE), bias, and Bland-Altman limits of agreements between the motion capture and IMU systems were quantified for knee and trunk sagittal- and frontal-plane range-of-motion (ROM) and peak angles. Our results indicate that IMU validity was task-, joint-, and plane-dependent. Based on good-to-excellent (ICC) correlation, reasonable accuracy (RMSE < 5°), bias within 2°, and limits of agreements within 10°, we recommend the use of this IMU system for knee sagittal-plane ROM estimations during cutting, trunk sagittal-plane peak angle estimation during the double-leg landing task, trunk sagittal-plane ROM estimation for almost all tasks, and trunk frontal-plane peak angle estimation for the right single-leg landing task. Due to poor comparisons with the optoelectronic system, we do not recommend this IMU system for knee frontal-plane kinematic estimations.

Patterns of video-based motion analysis use among sports physical therapists

OBJECTIVE

Examine video-based motion analysis (VBMA) use among sports physical therapists.

DESIGN

Cross-sectional observation.

SETTING

Survey, online-platform.

PARTICIPANTS

American Academy of Sports Physical Therapy members (n = 261).

MAIN OUTCOME MEASURES

VBMA use frequency, reasons for use, facilitators/barriers, tools used, factors associated with use.

RESULTS

194 (74.3%) used VBMA but 163 (84%) use it for ≤ 25% of their caseload. Most (57.7%) used their personal device to capture VBMA. Commonly cited reasons for use were movement analysis (93.8%) and patient education (87.6%). Barriers to use included time (30.7%), unfamiliarity with device/equipment (19.2%), and lack of device/equipment (18.4%). Younger age, advanced training, and greater time spent with return patients were each associated with use. For every 5-year increase of age, there was a 12% reduced likelihood of VBMA use (OR = 0.88; 95% CI = 0.77-1.00). Board-certified sports clinical specialists were more likely to use vs. those without additional certifications/degrees (OR = 3.27; 95% CI = 1.33-8.02). Spending 30-59 (vs. <30) minutes with return patients increased the odds of use (ORs range: 2.71 to 3.85).

CONCLUSION

Most respondents used VBMA, albeit infrequently. Those younger, with advanced training, and spending ≥30 min with return patients were more likely to use VBMA. Future research should investigate whether VBMA use enhances patient outcomes.

[Digitalization in orthopedics and trauma surgery: current status of clinical and practical aspects 2020]

Der vorliegende Beitrag behandelt aus Sicht von Orthopädie und Unfallchirurgie den aktuellen Stand Mitte 2020 im klinischen sowie im Praxisumfeld. Es wird auf Risiken, Schwierigkeiten ebenso wie Potenziale und Chancen im Detail eingegangen. Spezifisch werden die folgenden Themenbereiche erörtert: Telematikinfrastruktur, Apps und „mobile health“, Onlinevideosprechstunde, elektronische Patientenakte sowie Datenschutz. Es wird auf die Vor- und Nachteile und den jeweils aktuellen Stand im Spezialfall der Orthopädie und Unfallchirurgie eingegangen. Zudem werden 7 sinnvolle Beispiele aus dem Bereich der digitalen Anwendung genannt. Eine Mitgliederbefragung des Berufsverbandes der Orthopäden und Unfallchirurgen, BVOU, wird beschrieben und analysiert. Im abschließenden Ausblick werden die aktuellen Hürden und künftig zu klärende Themenbereiche adressiert.

Video-Based Motion Analysis Use: A National Survey of Orthopedic Physical Therapists

OBJECTIVES

Motion analysis is performed by physical therapists to assess and improve movement. Two-dimensional video-based motion analysis (VBMA) is available for smartphones/tablets and requires little to no equipment or cost. Research on VBMA use in clinical practice is limited. The purpose of this study was to examine the current use of VBMA in orthopedic physical therapist practice.

METHODS

Members of the Academy of Orthopaedic Physical Therapy completed an online survey. Questions examined frequency of VBMA use, reasons for use, facilitators/barriers, device/apps used, practice patterns, other certificates/degrees, and demographic information.

RESULTS

Among the final analysis sample of 477 respondents, 228 (47.8%) use VBMA. Of 228 VBMA users, 91.2% reported using it for ≤25% of their caseload, and 57.9% reported using their personal device to capture movement. Reasons for using VBMA included visual feedback for patient education (91.7%), analysis of movement (91.2%), and assessment of progress (51.8%). Barriers to use included lack of device/equipment (48.8%), lack of space (48.6%), and time restraint (32.1%). Those with ≤20 years of clinical experience (odds ratio [OR] = 1.83, 95% CI = 1.21-2.76), residency training (OR = 2.49, 95% CI = 1.14-5.43), and fellowship training (OR = 2.97, 95% CI = 1.32-6.66), and those from the West region of the United States (OR = 1.66, 95% CI = 1.07-2.56) were more likely to use VBMA.

CONCLUSIONS

More than 50% of surveyed orthopedic physical therapists do not use VBMA in clinical practice. Future research should be directed toward assessing reliability and validity of VBMA use by smartphones, tablets, and apps and examining whether VBMA use enhances treatment outcomes. Data security, patient confidentiality, and integration into the electronic medical record should be addressed.

IMPACT

This study is the first to our knowledge to describe the use of VBMA in orthopedic physical therapist practice in the United States. It is the first step in understanding how VBMA is used and might be used to enhance clinical assessment and treatment outcomes.

Monitoring Improvement in Infantile Cerebral Palsy Patients Using the 4DBODY System-A Preliminary Study

Monitoring the patient's condition during rehabilitation is the key to success in this form of treatment. This is especially important in patients with infantile cerebral palsy (ICP). Objective assessment can be achieved through modern optical measurement techniques. The 4DBODY system allows to capture dynamic movement with high accuracy. Eight patients with ICP participated in the study. The group underwent therapy lasting seven days using neurodevelopmental treatment (NDT) and functional training (FT). The patients' condition was monitored by the 4DBODY system. The measurements were taken three times: before the therapy, after, and then again after one week. We have developed the Trunk Mobility in the Frontal Plane Index (TMFPI) for its assessment. The results were compared with a score obtained using the Gross Motor Function Measure scale (GMFM 88). An improvement of the TMFPI parameter was observed in five patients, inconsistent results in two and deterioration in one. The reference GMFM score was higher in all patients relative to pre-treatment values. We found that surface scanning with the 4DBODY system allows to precisely track body movement in ICP patients. The decrease in the TMFPI parameter reflects the improvement in the dysfunction of body alignment, balance and symmetry of movement on the L and R body side.