Quantifying Cross-scatter Contamination in Biplane Fluoroscopy Motion Analysis Systems

Biplane fluoroscopy is used for dynamic in vivo three-dimensional motion analysis of various joints of the body. Cross-scatter between the two fluoroscopy systems may limit tracking accuracy. This study measured the magnitude and effects of cross-scatter in biplane fluoroscopic images. Four cylindrical phantoms of 4-, 6-, 8-, and 10-in. diameter were imaged at varying kVp levels to determine the cross-scatter fraction and contrast-to-noise ratio (CNR). Monte Carlo simulations quantified the effect of the gantry angle on the cross-scatter fraction. A cadaver foot with implanted beads was also imaged. The effect of cross-scatter on marker-based tracking accuracy was investigated. Results demonstrated that the cross-scatter fraction varied from 0.15 for the 4-in. cylinder to 0.89 for the 10-in. cylinder when averaged across kVp. The average change in CNR due to cross-scatter ranged from 5% to 36% CNR decreases for the 4- and 10-in. cylinders, respectively. In simulations, the cross-scatter fraction increased with the gantry angle for the 8- and 10-in. cylinders. Cross-scatter significantly increased static-tracking error by 15%, 25%, and 38% for the 6-, 8-, and 10-in. phantoms, respectively, with no significant effect for the foot specimen. The results demonstrated submillimeter marker-based tracking for a range of phantom sizes, despite cross-scatter degradation

PEAK VERTICAL GROUND REACTION FORCE PREDICTION FROM KINEMATICS IN MALE RUNNERS USING MACHINE LEARNING ALGORITHMS

The purpose of this study was to examine if peak vertical ground reaction forces during treadmill running can be predicted from kinematic input using machine learning models. Eighteen healthy male runners\u27 hip, knee, and ankle sagittal angles, with subject metadata, were input into random forest, support vector, and multi-layer perceptron regressors. Thirty strides per side at three speeds were pulled for the dataset. Random forest performed the best with a correlation coefficient of 0.950 and a root mean squared error of 0.456, while multi-layer perceptron was the worst with values of 0.948 and 0.462 respectively. The study showed machine learning models can predict peak vertical ground reaction forces

BIOMECHANICAL DIFFERENCES BETWEEN ONE-HANDED AND TWO-HANDED FOLLOW THROUGH TECHNIQUES AMONG PROFESSIONAL BASEBALL HITTERS

The purpose of this study was to compare the lead shoulder joint dynamics between one-handed and two-handed follow through batting techniques. Seventeen professional baseball players underwent motion analysis while hitting a ball off a tee using one- and two-handed follow through techniques. Linear mixed regression models were used to compare the kinematic and kinetic variables between the two techniques. Shoulder horizontal abduction, elbow flexion, and lateral trunk tilt differed between the follow through types. The shoulder kinetics increased greatly during a one-handed follow through compared to a two-handed follow through, with the horizontal adduction torque increasing 23.3 Nm and the proximal force increasing 117.2 N. A one-handed follow through increases the demands on the shoulder compared to a two-handed follow through

DOES A SINGLE PITCHING SESSION INDUCE LOWER EXTREMITY MUSCULAR FATIGUE IN HIGH SCHOOL BASEBALL PITCHERS?

The purpose of this study was to assess hip strength changes and provide a quantifiable measurement to show muscular fatigue after pitching a single pitching session. Fifteen adolescent male baseball pitcher‘s hip external rotator, internal rotator, and extensor strength, along with a functional test were measured before and after a single pitching session. After an average of 19 pitches, all hip strength measures in both legs significantly decreased in post-pitching tests. This study showed pitching increased muscular fatigue of the hip muscles after a small number of pitches thrown. With overall fatigue being a large indicator of injury risk in baseball pitchers, monitoring lower extremity muscular fatigue may be a way to potentially reduce risk of injury

DIFFERENCES IN TEMPORAL VARIABLES AND THEIR EFFECT ON KINETICS IN HIGH SCHOOL PITCHERS WITH HIGH AND LOW PITCH VELOCITIES

The purpose of this study was to compare temporal parameters between high and low velocity high school (HS) pitchers and investigate the influence these parameters have on both pitch speed and upper extremity kinetics. 30 healthy right-handed HS male pitchers with no recent injuries, and clearance to play were included. A 3D motion analysis system was used. Analysis included 15 kinetic and 35 temporal variables. Statistical tests conducted in SPSS. Correlation strength was interpreted as weak, moderate, or strong. High velocity and low velocity throwers showed differences in the timing to progress through the pitching cycle and these temporal variables showed separate relations to pitch speed and kinetics

Biplane Fluoroscopy for Hindfoot Motion Analysis during Gait: A Model-based Evaluation

The purpose of this study was to quantify the accuracy and precision of a biplane fluoroscopy system for model-based tracking of in vivo hindfoot motion during over-ground gait. Gait was simulated by manually manipulating a cadaver foot specimen through a biplane fluoroscopy system attached to a walkway. Three 1.6-mm diameter steel beads were implanted into the specimen to provide marker-based tracking measurements for comparison to model-based tracking. A CT scan was acquired to define a gold standard of implanted bead positions and to create 3D models for model-based tracking. Static and dynamic trials manipulating the specimen through the capture volume were performed. Marker-based tracking error was calculated relative to the gold standard implanted bead positions. The bias, precision, and root-mean-squared (RMS) error of model-based tracking was calculated relative to the marker-based measurements. The overall RMS error of the model-based tracking method averaged 0.43 ± 0.22 mm and 0.66 ± 0.43° for static and 0.59 ± 0.10 mm and 0.71 ± 0.12° for dynamic trials. The model-based tracking approach represents a non-invasive technique for accurately measuring dynamic hindfoot joint motion during in vivo, weight bearing conditions. The model-based tracking method is recommended for application on the basis of the study results

Sagittal Subtalar and Talocrural Joint Assessment During Ambulation With Controlled Ankle Movement (CAM) Boots

Background: The purpose of the current study was to determine sagittal plane talocrural and subtalar kinematic differences between barefoot and controlled ankle movement (CAM) boot walking. This study used fluoroscopic images to determine talar motion relative to tibia and calcaneal motion relative to talus. Methods: Fourteen male subjects (mean age 24.1 ± 3.5 years) screened for normal gait were tested. A fluoroscopy unit was used to collect images at 200 Hz during stance. Sagittal motion of the talocrural and subtalar joints were analyzed barefoot and within short and tall CAM boots. Results: Barefoot talocrural mean maximum plantar and dorsiflexion were 9.2 ± 5.4 degrees and −7.5 ± 7.4 degrees, respectively; short CAM boot mean maximum plantar and dorsiflexion were 3.2 ± 4.0 degrees and −4.8 ± 10.2 degrees, respectively; and tall CAM boot mean maximum plantar and dorsiflexion were −0.2 ± 3.5 degrees and −2.4 ± 5.1 degrees, respectively. Talocrural mean range of motion (ROM) decreased from barefoot (16.7 ± 5.1 degrees) to short CAM boot (8.0 ± 4.9 degrees) to tall CAM boot (2.2 ± 2.5 degrees). Subtalar mean maximum plantarflexion angles were 5.3 ± 5.6 degrees for barefoot walking, 4.1 ± 5.9 degrees for short CAM boot walking, and 3.0 ± 4.7 degrees for tall CAM boot walking. Mean minimum subtalar plantarflexion angles were 0.7 ± 3.2 degrees for barefoot walking, 0.7 ± 2.9 degrees for short CAM boot walking, and 0.1 ± 4.8 degrees for tall CAM boot walking. Subtalar mean ROM decreased from barefoot (4.6 ± 3.9 degrees) to short CAM boot (3.4 ± 3.8 degrees) to tall CAM boot (2.9 ± 2.6 degrees). Conclusion: Tall and short CAM boot intervention was shown to limit both talocrural and subtalar motion in the sagittal plane during ambulation. The greatest reductions were seen with the tall CAM boot, which limited talocrural motion by 86.8% and subtalar motion by 37.0% compared to barefoot. Short CAM boot intervention reduced talocrural motion by 52.1% and subtalar motion by 26.1% compared to barefoot. Clinical Relevance: Both short and tall CAM boots reduced talocrural and subtalar motion during gait. The short CAM boot was more convenient to use, whereas the tall CAM boot more effectively reduced motion. In treatments requiring greater immobilization of the talocrural and subtalar joints, the tall CAM boot should be considered

RUNNING TO THE BEAT: DOES LISTENING TO MUSIC AFFECT RUNNING CADENCE AND LOWER EXTREMITY BIOMECHANICS?

This aimed to determine if music with specific target beats per minute (bpm) could be used for treadmill running cadence training to alter lower extremity biomechanics and, thus, reduce injury risk. Motion analysis and a synchronized triaxial accelerometer collected data from eighteen runners during treadmill running. Participants ran at a self-selected speed (SS) to determine their baseline cadence. They also ran to music where the bpm of the songs was increased by 5% and 10% over SS cadence. Post hoc tests showed significant differences in heart rate from SS. There were no significant differences between cadence or peak acceleration. In the current study, music was not shown to be a viable method for cadence training in runners. Our findings led to methodology recommendations for future work in using music to effectively improve running cadence