Accumulated signal noise will cause the integrated values to drift from the true value when measuring orientation angles of wearable sensors. This work proposes a novel method to reduce the effect of this drift to accurately measure human gait using wearable sensors. Firstly, an infinite impulse response (IIR) digital 4th order Butterworth filter was implemented to remove the noise from the raw gyro sensor data. Secondly, the mode value of the static state gyro sensor data was subtracted from the measured data to remove offset values. Thirdly, a robust double derivative and integration method was introduced to remove any remaining drift error from the data. Lastly, sensor attachment errors were minimized by establishing the gravitational acceleration vector from the acceleration data at standing upright and sitting posture. These improvements proposed allowed for removing the drift effect, and showed an average of 2.1°, 33.3°, 15.6° difference for the hip knee and ankle joint flexion/extension angle, when compared to without implementation. Kinematic and spatio-temporal gait parameters were also calculated from the heel-contact and toe-off timing of the foot. The data provided in this work showed potential of using wearable sensors in clinical evaluation of patients with gait-related diseases.

Background: In the autogenous tendon for anterior cruciate ligament reconstruction, intrinsic fibroblasts are necrotized immediately after surgery, and repopulation and revascularization occur. Vascular endothelial growth factor is considered to be a potent mediator of angiogenesis. Hypothesis: An application of vascular endothelial growth factor significantly enhances angiogenesis in the in situ frozen anterior cruciate ligament, and the application significantly affects mechanical properties of the in situ frozen anterior cruciate ligament. Study Design: Controlled laboratory study. Methods: Right anterior cruciate ligaments from 66 rabbits underwent the freeze-thaw treatment, and animals were then divided into 3 groups. Group I served as a freeze-thaw but otherwise untreated control. In group II, 0.2 mL phosphate-buffered saline alone was applied. In group III, 30 µ g vascular endothelial growth factor was applied. The groups were compared on the basis of histologic revascularization examinations using the Chalkley score, an indicator of the microvessel density, and mechanical evaluations, which included the anterior-posterior translation of the tibia relative to the femur during ± 10 N of anterior-posterior load and the mechanical properties of the anteromedial bundle of the anterior cruciate ligament. Results: Group III's Chalkley score was significantly greater than that of groups I and II. The tensile strength and the tangent modulus of anterior cruciate ligaments in groups I, II, and III were significantly lower than those of a normal anterior cruciate ligament, although there were no significant differences among groups I, II, and III. Conclusion: Vascular endothelial growth factor, as administered in this study, significantly promoted angiogenesis in the devitalized anterior cruciate ligament with in situ freeze-thaw treatment, but it did not affect the mechanical properties of the in situ frozen-thawed anterior cruciate ligament in the rabbit model. Clinical Relevance: An application of the recombinant anterior cruciate ligament is a potential future strategy to enhance revascularization of the autograft in anterior cruciate ligament reconstruction.

Accuracy validation of gait analysis using pose estimation with artificial intelligence (AI) remains inadequate, particularly in objective assessments of absolute error and similarity of waveform patterns. This study aimed to clarify objective measures for absolute error and waveform pattern similarity in gait analysis using pose estimation AI (OpenPose). Additionally, we investigated the feasibility of simultaneous measuring both lower limbs using a single camera from one side. We compared motion analysis data from pose estimation AI using video footage that was synchronized with a three-dimensional motion analysis device. The comparisons involved mean absolute error (MAE) and the coefficient of multiple correlation (CMC) to compare the waveform pattern similarity. The MAE ranged from 2.3 to 3.1° on the camera side and from 3.1 to 4.1° on the opposite side, with slightly higher accuracy on the camera side. Moreover, the CMC ranged from 0.936 to 0.994 on the camera side and from 0.890 to 0.988 on the opposite side, indicating a “very good to excellent” waveform similarity. Gait analysis using a single camera revealed that the precision on both sides was sufficiently robust for clinical evaluation, while measurement accuracy was slightly superior on the camera side.

OpenPose-based motion analysis (OpenPose-MA), utilizing deep learning methods, has emerged as a compelling technique for estimating human motion. It addresses the drawbacks associated with conventional three-dimensional motion analysis (3D-MA) and human visual detection-based motion analysis (Human-MA), including costly equipment, time-consuming analysis, and restricted experimental settings. This study aims to assess the precision of OpenPose-MA in comparison to Human-MA, using 3D-MA as the reference standard. The study involved a cohort of 21 young and healthy adults. OpenPose-MA employed the OpenPose algorithm, a deep learning-based open-source two-dimensional (2D) pose estimation method. Human-MA was conducted by a skilled physiotherapist. The knee valgus angle during a drop vertical jump task was computed by OpenPose-MA and Human-MA using the same frontal-plane video image, with 3D-MA serving as the reference standard. Various metrics were utilized to assess the reproducibility, accuracy and similarity of the knee valgus angle between the different methods, including the intraclass correlation coefficient (ICC) (1, 3), mean absolute error (MAE), coefficient of multiple correlation (CMC) for waveform pattern similarity, and Pearson’s correlation coefficients (OpenPose-MA vs. 3D-MA, Human-MA vs. 3D-MA). Unpaired t-tests were conducted to compare MAEs and CMCs between OpenPose-MA and Human-MA. The ICCs (1,3) for OpenPose-MA, Human-MA, and 3D-MA demonstrated excellent reproducibility in the DVJ trial. No significant difference between OpenPose-MA and Human-MA was observed in terms of the MAEs (OpenPose: 2.4° [95%CI: 1.9-3.0°], Human: 3.2° [95%CI: 2.1-4.4°]) or CMCs (OpenPose: 0.83 [range: 0.99-0.53], Human: 0.87 [range: 0.24-0.98]) of knee valgus angles. The Pearson’s correlation coefficients of OpenPose-MA and Human-MA relative to that of 3D-MA were 0.97 and 0.98, respectively. This study demonstrated that OpenPose-MA achieved satisfactory reproducibility, accuracy and exhibited waveform similarity comparable to 3D-MA, similar to Human-MA. Both OpenPose-MA and Human-MA showed a strong correlation with 3D-MA in terms of knee valgus angle excursion.

Background: Although previous studies suggested that female patients are predisposed to increase graft laxity compared with male patients after single-bundle anterior cruciate ligament reconstruction using autogenous hamstring tendons, there have been no studies specifically examining gender-based differences in outcome after anatomic double-bundle anterior cruciate ligament reconstruction with hamstring tendon autografts.