Development of a Robust, Simple, and Affordable Human Gait Analysis System Using Bottom-Up Pose Estimation With a Smartphone Camera.

Gait analysis is used in many fields such as Medical Diagnostics, Osteopathic medicine, Comparative and Sports-related biomechanics, etc. The most commonly used system for capturing gait is the advanced video camera-based passive marker system such as VICON. However, such systems are expensive, and reflective markers on subjects can be intrusive and time-consuming. Moreover, the setup of markers for certain rehabilitation patients, such as people with stroke or spinal cord injuries, could be difficult. Recently, some markerless systems were introduced to overcome the challenges of marker-based systems. However, current markerless systems have low accuracy and pose other challenges in gait analysis with people in long clothing, hiding the gait kinematics. The present work attempts to make an affordable, easy-to-use, accurate gait analysis system while addressing all the mentioned issues. The system in this study uses images from a video taken with a smartphone camera (800 × 600 pixels at an average rate of 30 frames per second). The system uses OpenPose, a 2D real-time multi-person keypoint detection technique. The system learns to associate body parts with individuals in the image using Convolutional Neural Networks (CNNs). This bottom-up system achieves high accuracy and real-time performance, regardless of the number of people in the image. The proposed system is called the "OpenPose based Markerless Gait Analysis System" (OMGait). Ankle, knee, and hip flexion/extension angle values were measured using OMGait in 16 healthy volunteers under different lighting and clothing conditions. The measured kinematic values were compared with a standard video camera based normative dataset and data from a markerless MS Kinect system. The mean absolute error value of the joint angles from the proposed system was less than 90 for different lighting conditions and less than 110 for different clothing conditions compared to the normative dataset. The proposed system is adequate in measuring the kinematic values of the ankle, knee, and hip. It also performs better than the markerless systems like MS Kinect that fail to measure the kinematics of ankle, knee, and hip joints under dark and bright light conditions and in subjects with long robe clothing.

The effect of positive sagittal spine balance and reconstruction surgery on standing balance.

BACKGROUND: Positive sagittal spine balance (PSSB) may adversely influence standing balance in individuals with degenerative spine diseases. PSSB is often corrected with the help of spinal reconstructive surgeries involving multiple vertebral units. RESEARCH QUESTION: This study investigated the effect of PSSB and reconstructive surgery on postural sway as a measure of standing balance. The secondary goal of this study was to investigate the effect of reconstructive surgery on lower limb kinematics. METHODS: Subjects who underwent spinal reconstructive surgery for correction of PSSB greater than or equal to 7 cm participated in this study. Postural sway data while standing quietly for 20 s on a force platform were analyzed pre-operatively, 6-12 months and 24 months post-operatively. RESULTS: Reconstructive surgery was successful in correcting PSSB in all individuals. There was a moderate correlation between PSSB and postural sway in the anterior-posterior (AP) direction before surgery (r = 0.58) and at 6-12 months post-surgery (r = 0.63). Reconstructive surgery had a significant main effect on postural sway in both the anterior-posterior (p < 0.009, F = 7.01) and medial-lateral directions (p < 0, F = 12.30). Reconstructive surgery also had a significant main effect on standing hip (p < 0, F = 17.01) and knee flexion (p < 0, F = 32.23). SIGNIFICANCE: These results reveal that PSSB in persons with degenerative spinal conditions compromised postural balance, which improved after reconstructive surgery. Additionally, persons with PSSB adopted a crouch posture, which resolved after reconstructive surgery.

Pelvic and Spinal Motion During Walking in Persons With Transfemoral Amputation With and Without Low Back Pain.

OBJECTIVE: Low back pain (LBP) is prevalent in people with transfemoral amputation (TFA), imposing significant disability. Yet, limited data exist describing spine kinematics in people with and without LBP despite the suggestion that gait adaptations required to walk with a prosthesis may be associated or causative of LBP. Hence, the purpose of this study was to determine if there were any differences in pelvic and spinal kinematics in persons with TFA with and without LBP. DESIGN: With the use of a lower body model combined with a regional spine model, pelvic, lumbar, and thoracic kinematics were recorded while walking and compared for participants with TFA with (n = 12) and without (n = 11) self-reported LBP. RESULTS: Opposite patterns of motion were observed between groups in sagittal and transverse lumbar kinematics but inferential analysis using the χ test was unable to confirm that these differing patterns were independently related to LBP. CONCLUSIONS: For community ambulators with TFA who report low levels of LBP, differences in lumbar and thoracic motion do not seem to be independently related to LBP. Results may not generalize to those with higher levels of LBP and associated disability.

Crouch gait in persons with positive sagittal spine alignment resolves with surgery.

OBJECTIVE: Degenerative spinal conditions often result in positive sagittal alignment which may be corrected using multi-segment spinal reconstructive surgeries. The purpose of this study was to investigate gait kinematics before and after spinal reconstructive surgery in persons with positive sagittal alignment. METHODS: Subjects presenting with positive sagittal alignment of greater than or equal to 7 cm who were treated with spinal reconstructive surgery were included in this study. Gait analyses were conducted pre- and 6 months post-operatively. Data were collected while subjects stood quietly for 20s and walked at their normal self-selected walking speed. RESULTS: For 12 subjects, sagittal spine alignment during standing and walking was significantly decreased post-operatively (p<0.0001 for standing and p<0.0005 for walking). Prior to surgery, the subjects appeared to adopt a crouch gait with the knee flexion angle at mid terminal stance decreasing significantly after surgery (p<0.0 for the dominant lower limb and p<0.0 for the non-dominant lower limb). Additionally, dominant step length (p<0.003) and non-dominant step length (p<0.001) increased significantly after surgery. CONCLUSIONS: Positive sagittal alignment resulted in crouch gait, which was resolved after multi-segment reconstructive spinal surgery that improved sagittal spinal alignment. Step and stride lengths also improved after surgical correction of the sagittal alignment.