View-Aware Pose Analysis: A Robust Pipeline for Multi-Person Joint Injury Prediction from Single Camera

Case control study. To quantify precisely and compare intervertebral segmental contributions to cervical spine flexion-extension during continuous, functional flexion-extension in asymptomatic subjects with patients who underwent single-level anterior arthrodesis. Segmental contributions to cervical flexion-extension have traditionally been determined using single images collected at full flexion and full extension. These calculations neglect midrange motion and assume that percent contributions to motion remain constant throughout the entire flexion-extension range of motion (ROM). Six patients with single-level (C5-C6) anterior arthrodesis and 18 asymptomatic control subjects performed flexion-extension while biplane radiographs were collected at 30 images per second. A previously validated tracking process determined 3-dimensional vertebral position with submillimeter accuracy during continuous flexion-extension. Mixed-effects models of segmental percent contribution to C2-C7 flexion-extension were developed to identify differences in percent contribution within each motion segment, among motion segments, and between controls and patients who underwent arthrodesis over the full ROM. The C2-C3, C3-C4, and C4-C5 motion segments made their maximum contributions during the midrange of motion. The C5-C6 and C6-C7 motion segments, in contrast, made their maximum contributions near the start and end of the ROM. Arthrodesis patients' contribution from the C4-C5 motion segment increased significantly over the range of motion from 30% to 95% of the total flexion-extension ROM (average increased contribution of 5.1%) and arthrodesis patients' contribution from the C6-C7 motion segment increased significantly over the entire flexion-extension ROM (average increased percentage contribution of 8.9%) in comparison to controls. Cervical motion segment contributions to flexion-extension change significantly during the flexion-extension motion. The largest change in percent contribution to motion, relative to controls, occurs at the C6-C7 motion segment, over the entire ROM, suggesting a potential mechanical mechanism for the clinical observation of increased incidence of adjacent segment degeneration at C6-C7 rather than at C4-C5 after C5-C6 arthrodesis.

With the increasing awareness of high-quality life, there is a growing need for health monitoring devices running robust algorithms in home environment. Health monitoring technologies enable real-time analysis of users' health status, offering long-term healthcare support and reducing hospitalization time. The propose of this work is twofold, the software focuses on the analysis of gait, which is widely adopted for joint correction and assessing any lower limb, or spinal problem. On the hardware side, a novel marker-less gait analysis device using a low-cost RGB camera mounted on a mobile tele-robot is designed. As gait analysis with a single camera is much more challenging compared to previous works utilizing multi-cameras, a RGB-D camera or wearable sensors, we propose using vision-based human pose estimation approaches. More specifically, based on the out-put of state-of-the-art human pose estimation models, we devise measurements for four bespoke gait parameters: inversion/eversion, dorsiflexion/plantarflexion, ankle and foot progression angles. We thereby classify walking patterns into normal, supination, pronation and limp. We also illustrate how to run the proposed machine learning models in low-resource environments such as a single entry-level CPU. Experiments show that our single RGB camera method achieves competitive performance compared to multi-camera motion capture systems, at smaller hardware costs.

The etiology of adjacent-segment disease following cervical spine arthrodesis remains controversial. The objective of the current study was to evaluate cervical intervertebral range of motion during dynamic flexion-extension in patients who had undergone a single-level arthrodesis and in asymptomatic control subjects. Ten patients who had undergone a single-level (C5/C6) anterior arthrodesis and twenty asymptomatic control subjects performed continuous full range-of-motion flexion-extension while biplane radiographs were collected at thirty images per second. A previously validated tracking process determined three-dimensional vertebral position on each pair of radiographs with submillimeter accuracy. Six-degrees-of-freedom kinematics between adjacent vertebrae were calculated throughout the entire flexion-extension movement cycle over multiple trials for each participant. Cervical kinematics were also calculated from images collected during static full flexion and static full extension. The C4/C5 motion segment moved through a larger extension range of motion and a smaller flexion range of motion in the subjects with the arthrodesis than in the controls. The extension difference between the arthrodesis and control groups was 3.8° (95% CI [confidence interval], 0.9° to 6.6°; p = 0.011) and the flexion difference was -2.9° (95% CI, -5.3° to -0.5°; p = 0.019). Adjacent-segment posterior translation was greater in the arthrodesis group than in the controls, with a C4/C5 difference of 0.8 mm (95% CI, 0.0 to 1.6 mm) and a C6/C7 difference of 0.4 mm (95% CI, 0.0 to 0.8 mm; p = 0.016). Translation range of motion and rotation range of motion were consistently larger when measured on images collected during dynamic functional movement as opposed to images collected at static full flexion or full extension. The upper 95% CI limit for anterior-posterior translation range of motion was 3.45 mm at C3/C4 and C4/C5, but only 2.3 mm at C6/C7. C5/C6 arthrodesis does not affect the total range of motion in adjacent vertebral segments, but it does alter the distribution of adjacent-segment motion toward more extension and less flexion superior to the arthrodesis and more posterior translation superior and inferior to the arthrodesis during in vivo functional loading. Range of motion measured from static full-flexion and full-extension images underestimates dynamic range of motion. Clinical evaluation of excessive anterior-posterior translation should take into account the cervical vertebral level.

The use of multi camera systems to determine 3D object coordinates is a common approach in close range photogrammetry. The paper discusses system configurations based on a single camera and mirror systems to generate a virtual multi camera system. The two main advantages of mirror-based multiple-view vision systems can be seen in the lack of synchronisation requirements and the costs of only one camera. The latter applies especially if high speed cameras are required to capture the dynamics of an application. These advantages have to be weighted against the disadvantages of a reduced active image format per view and the restrictions to the imaging geometry. In the paper we present two different systems used for motion analysis applications: A fixed two mirror system is used to analyse pedestrian protection testing in the context of vehicle safety development, and a flexible four mirror system is used to capture 3D velocity fields of particles visualising gas flows in a wind tunnel. A geometric model for multi-mirror stereoscopic systems has been developed, representing the mirror system by multiple virtual cameras in order to warrant compatibility with existing photogrammetric stereo data processing software solutions. The accuracies achieved in practical tests are almost comparable to those obtained with multi camera systems.

Reconstruction after pan-plexus root avulsions often includes gracilis free functioning muscle transfer. For elbow flexion reconstruction, the free functioning muscle transfer distal tendon is inserted into the biceps tendon or more distally (i.e., flexor digitorum profundus/flexor pollicis longus tendons) for combined elbow and finger flexion; the theoretical drawback of the latter approach is weaker elbow flexion. The authors compared elbow flexion strength with a biceps tendon versus a flexor digitorum profundus/flexor pollicis longus tendon attachment to determine which insertion point resulted in better elbow flexion. Thirty-nine patients underwent free functioning muscle transfer with either a biceps tendon or a distal attachment. Groups were compared on postoperative elbow flexion strength, preoperative and postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire scores, range of motion, and other surgical and demographic characteristics. A biomechanical analysis simulating different tendon attachments determined which reconstruction resulted in optimal elbow flexion mechanics. Distal tendon attachment was associated with M3 or M4 elbow flexion and greater range of motion compared with the biceps tendon attachment (p < 0.05). There were no statistically significant improvements in Disabilities of the Arm, Shoulder, and Hand questionnaire scores. Biomechanical analysis demonstrated that all distal tendon attachments studied generated a 15 to 30 percent greater torque compared with the biceps tendon attachment; this was true for attachments either at the flexor digitorum profundus/flexor pollicis longus tendon, or directly at the radius at 10 cm or 15 cm from the elbow axis of rotation. The flexor digitorum profundus/flexor pollicis longus tendon attachment of the gracilis free functioning muscle transfer distal tendon was superior in achieving elbow flexion strength. Patients with only elbow flexion reconstruction may also benefit from a flexor digitorum profundus/flexor pollicis longus tendon attachment or from a more distal attachment to the radius. Therapeutic, III.

Human motion capture (MoCap) plays a key role in healthcare and human–robot collaboration. Some researchers have combined orientation measurements from inertial measurement units (IMUs) and positional inference from cameras to reconstruct the 3D human motion. Their works utilize multiple cameras or depth sensors to localize the human in three dimensions. Such multiple cameras are not always available in our daily life, but just a single camera attached in a smart IP devices has recently been popular. Therefore, we present a 3D pose estimation approach from IMUs and a single camera. In order to resolve the depth ambiguity of the single camera configuration and localize the global position of the subject, we present a constraint which optimizes the foot-ground contact points. The timing and 3D positions of the ground contact are calculated from the acceleration of IMUs on foot and geometric transformation of foot position detected on image, respectively. Since the results of pose estimation is greatly affected by the failure of the detection, we design the image-based constraints to handle the outliers of positional estimates. We evaluated the performance of our approach on public 3D human pose dataset. The experiments demonstrated that the proposed constraints contributed to improve the accuracy of pose estimation in single and multiple camera setting.

This study was performed to determine the voluntary range of movements for Korean adults at the age between 18 and 60. Three hundred and eighteen males and 260 females participated for this study. Twenty-seven body movements at various joints were conducted to measure the range of movements. Subjects were grouped by age into three to analyze the differences of range of movements due to the aging. The age ranged for the first group was from 18 to 29. The second group ranged from 30 to 39, and the last group ranged from 40 to 60. The data were also analyzed to see the differences of range of movements between sexes. The results show that female subjects have larger range of movements than male subjects in hip movement (hip adduction and abduction), knee movement (knee rotation medial and lateral), neck movement (right flexion, dorsal flexion, right rotation), wrist movement (wrist extension and adduction), elbow flexion and shoulder extension (p&lt;0.05). On the other hand, male subjects have larger range of movements than female subjects in wrist abduction, wrist flexion, forearm supination, shoulder rotation (lateral), shoulder adduction, knee flexion (standing), ankle flexion, hip flexion, and hip rotation medial (sitting). (p&lt;0.05). Generally, the range of movements decrease with ages, however, some range of joint movements such as wrist flexion and extension show increase with ages for both male and female subjects. To apply these data in designing products or workplace, the designers may need serious consideration to the limiting factor of incidence of arthritis due to the aging.

PurposeThe aim of this study was to elucidate segmental range of motion (ROM) before and after common decompression and fusion procedures on the lumbar spine.MethodsROM of fourteen fresh-frozen human cadaver lumbar segments (L1/2: 4, L3/4: 5, L5/S1: 5) was evaluated in six loading directions: flexion/extension (FE), lateral bending (LB), lateral shear (LS), anterior shear (AS), axial rotation (AR), and axial compression/distraction (AC). ROM was tested with and without posterior instrumentation under the following conditions: 1) native 2) after unilateral laminotomy, 3) after midline decompression, and 4) after nucleotomy.ResultsMedian native ROM was FE 6.8°, LB 5.6°, and AR 1.7°, AS 1.8 mm, LS 1.4 mm, AC 0.3 mm. Unilateral laminotomy significantly increased ROM by 6% (FE), 3% (LB), 12% (AR), 11% (AS), and 8% (LS). Midline decompression significantly increased these numbers to 15%, 5%, 21%, 20%, and 19%, respectively. Nucleotomy further increased ROM in all directions, most substantially in AC of 153%. Pedicle screw fixation led to ROM decreases of 82% in FE, 72% in LB, 42% in AR, 31% in AS, and 17% in LS. In instrumented segments, decompression only irrelevantly affected ROM.ConclusionsThe amount of posterior decompression significantly impacts ROM of the lumbar spine. The here performed biomechanical study allows creation of a simplified rule of thumb: Increases in segmental ROM of approximately 10%, 20%, and 50% can be expected after unilateral laminotomy, midline decompression, and nucleotomy, respectively. Instrumentation decreases ROM by approximately 80% in bending moments and accompanied decompression procedures only minorly destabilize the instrumentation construct.

BackgroundSurgical treatments for early onset scoliosis (EOS) correct curvatures and improve respiratory function but involve many complications. A distractible, or ‘growing rod,’ implant construct that is more flexible than current metal rod systems may sufficiently correct curves in small children and reduce complications due to biomechanical factors. The purpose of this pilot study was to determine ranges of motion (ROM) after implantation of simulated growing rod constructs with a range of clinically relevant structural properties. The hypothesis was that ROM of spines instrumented with polymer rods would be greater than conventional metal rods and lower than non-instrumented controls.MethodsBiomechanical tests were conducted on six thoracic spines from skeletally immature domestic swines (35–40 kg). Paired pedicle screws were used as anchors at proximal and distal levels. Specimens were tested under the following conditions: control, then dual rods of polyetheretherketone (PEEK) (diameter 6.25 mm), titanium (4 mm), and cobalt-chrome alloy (CoCr) (5 mm). Lateral bending (LB) and flexion-extension (FE) moments were applied, and vertebral rotations were measured. Differences were determined by two-tailed t-tests and Bonferroni for four primary comparisons: PEEK vs control and PEEK vs CoCr, in LB and FE (α = 0.05/4).ResultsIn LB, ROM of spine segments after instrumenting with PEEK rods was lower than the non-instrumented control condition at each instrumented level. ROM was greater with PEEK rods than with Ti and CoCr rods at every instrumented level. Combining treated levels, in LB, ROM for PEEK rods was 35 % of control (p < 0.0001) and 270 % of CoCr rods (p < 0.01). In FE, ROM with PEEK was 27 % of control (p < 0.001) and 180 % of CoCr (p < 0.01). At proximal and distal adjacent non-instrumented levels in FE, mean ROM was lower for PEEK than for either metal.ConclusionsPEEK rods increased flexibility versus metal rods, and decreased flexibility versus non-instrumented controls, both over the entire instrumented segment and at each individual level. Smaller mean increases in ROM at proximal and distal adjacent motion segments occurred with PEEK compared to metal rods, which may help decrease complications, such as junctional kyphosis. Flexible growing rods may eventually help improve treatment options for young patients with severe deformity.

Biomechanical evaluation of sacroiliac joint fixation with decortication

87. Development of a machine learning algorithm for neck motion classification in patients after anterior cervical discectomy and fusion (ACDF)

Subcoracoid acromioclavicular joint dislocation (Rockwood type VI) sustained in motorcycle crash: A case report

Avaliação da flexão do cotovelo após transferência muscular livre do gastrocnêmio medial ou transferência do latíssimo do dorso na lesão traumática do plexo braquial

BackgroundLumbar spinal stenosis is a common disease in the aging population. Decompression surgery represents the treatment standard, however, a risk of segmental destabilization depending on the approach and extent of decompression is discussed. So far, biomechanical studies on techniques were mainly conducted on non-degenerated specimens. This biomechanical in vitro study aimed to investigate the increase in segmental range of motion (ROM) depending on the extent of decompression in degenerated segments.MethodsTen fresh frozen lumbar specimens were embedded in polymethyl methacrylate (PMMA) and loaded in a spine tester with pure moments of ± 7.5 Nm. The specimens were tested in their intact state for lateral bending (LB), flexion/extension (FE) and axial rotation (AR). Subsequently, four different decompression techniques were performed: unilateral interlaminar decompression (DC1), unilateral with "over the top" decompression (DC2), bilateral interlaminar decompression (DC3) and laminectomy (DC4). The ROM of the index segment was reported as percent (%) of the native state.ResultsSpecimens were measured in their intact state prior to decompression. The mean ROM was defined as 100% (FE:6.3 ± 2.3°; LB:5.4 ± 2.8°; AR:3.0 ± 1.6°). Interventions showed a continuous ROM increase: FE (DC1: + 4% ± 4.3; DC2: + 4% ± 4.5; DC3: + 8% ± 8.3;DC4: + 20% ± 15.9), LB(DC1: + 4% ± 6.0; DC2: + 5% ± 7.3; DC3: + 8% ± 8.3; DC4: + 11% ± 9.9), AR (DC1: + 7% ± 6.0; DC2: + 9% ± 7.9; DC3: + 15% ± 11.5; DC4: + 19% ± 10.5). Significant increases in ROM for all motion directions (p < 0.05) were only obtained after complete laminectomy (DC4).ConclusionUnilateral and/or bilateral decompressive surgery resulted in a statistically insignificant ROM increase, whereas complete laminectomy showed statistically significant ROM increase. If this ROM increase also has an impact on the clinical outcome and how to identify segments at risk for secondary lumbar instability should be evaluated in further studies.

Emergent linkages between musculoskeletal injury and the nervous system have increased interest to evaluate brain activity during functional movements associated with injury risk. Functional magnetic resonance imaging (fMRI) is a sophisticated modality that can be used to study brain activity during functional sensorimotor control tasks. However, technical limitations have precluded the precise quantification of lower-extremity joint kinematics during active brain scanning. The purpose of this study was to determine the validity of a new, MRI-compatible motion tracking system relative to a traditional multi-camera 3D motion capture system for measuring lower extremity joint kinematics. Fifteen subjects (9 females, 6 males) performed knee flexion-extension and leg press movements against guided resistance while laying supine. Motion tracking data were collected simultaneously using the MRI-compatible and traditional multi-camera 3D motion systems. Participants' sagittal and frontal plane knee angles were calculated from data acquired by both multi-camera systems. Resultant range of angular movement in both measurement planes were compared between both systems. Instrument agreement was assessed using Bland-Altman plots and intraclass correlation coefficients (ICC). The system demonstrated excellent validity in the sagittal plane (ICCs>0.99) and good to excellent validity in the frontal plane (0.84 < ICCs < 0.92). Mean differences between corresponding range of angular movement measurements ranged from 0.186 ° to 0.295 °. The present data indicate that this new, MRI-compatible system is valid for measuring lower extremity movements when compared to the gold standard 3D motion analysis system. As there is growing interest regarding the neural substrates of lower extremity movement, particularly in relation to injury and pathology, this system can now be integrated into neuroimaging paradigms to investigate movement biomechanics and its relation to brain activity. 3.