INTRAOPERATIVE CLINICAL TEST FOR KINEMATIC ASSESSMENT OF ACl GRAFT BEHAVIOUR WITH COMPUTER ASSISTED PROCEDURE

This paper describes a protocol for an accurate and extensive computer-assisted in vivo evaluation of joint laxities durinQl reconstructions of anterior cruciate ,ligament (ACL). The operating technique is a double bundle with over the top graft. Kinematic tests are performed, intraoperatively, before the ACL reconstruction, with ACL deficient knees, and after the ACL reconstruction. Results of first four in vivo cases, highlight that the reconstruction gives a complete restore of stability, in the antero-posterior direction, at 30° and 90° degrees giving and increased stability up to 73%, confirming the role of the ACL in the control of AP dislocation. Internal and external rotations were also satisfactorily restored after the graft fixation; in particular at 30° of tlexion, the reconstruction gives a good control of the joint, reducing laxity up to 43%

Fractional order hereditariness of knee human ligament and tendon

Anterior Cruciate Ligament (ACL) is one of the four major ligaments in the knee, playing a critical role in stabilizing the joint. ACL is highly susceptible to injury, overall during sport activities, often precipitating catastrophic long-term joint outcomes. The ideal replacement graft for a torn ACL would restore native anatomy and function to the knee. Most commonly used autograft and allograft, including patellar tendon (P) and hamstring tendon (H) graft, or bioengineered synthetic grafts, may substantially alter the biomechanics of the knee, permitting a return to only moderate physical activities [1]. Main issues are the sub-optimal graft properties [2] and a still incomplete biomechanics characterization [1]. The goal of the present work is to fully characterize and compare the viscoelastic behavior of the ACL and natural/artificial grafts in order to highlight the differences that should be overcome to achieve a successful biomechanical performance and an ideal graft design

Smart Brace for Static and Dynamic Knee Laxity Measurement

Every year in Europe more than 500 thousand injuries that involve the anterior cruciate ligament (ACL) are diagnosed. The ACL is one of the main restraints within the human knee, focused on stabilizing the joint and controlling the relative movement between the tibia and femur under mechanical stress (i.e., laxity). Ligament laxity measurement is clinically valuable for diagnosing ACL injury and comparing possible outcomes of surgical procedures. In general, knee laxity assessment is manually performed and provides information to clinicians which is mainly subjective. Only recently quantitative assessment of knee laxity through instrumental approaches has been introduced and become a fundamental asset in clinical practice. However, the current solutions provide only partial information about either static or dynamic laxity. To support a multiparametric approach using a single device, an innovative smart knee brace for knee laxity evaluation was developed. Equipped with stretchable strain sensors and inertial measurement units (IMUs), the wearable system was designed to provide quantitative information concerning the drawer, Lachman, and pivot shift tests. We specifically characterized IMUs by using a reference sensor. Applying the Bland–Altman method, the limit of agreement was found to be less than 0.06 m/s2 for the accelerometer, 0.06 rad/s for the gyroscope and 0.08 μT for the magnetometer. By using an appropriate characterizing setup, the average gauge factor of the three strain sensors was 2.169. Finally, we realized a pilot study to compare the outcomes with a marker-based optoelectronic stereophotogrammetric system to verify the validity of the designed system. The preliminary findings for the capability of the system to discriminate possible ACL lesions are encouraging; in fact, the smart brace could be an effective support for an objective and quantitative diagnosis of ACL tear by supporting the simultaneous assessment of both rotational and translational laxity. To obtain reliable information about the real effectiveness of the system, further clinical validation is necessary

Validation of a modular and wearable system for tracking fingers movements

Supervising manual operations performed by workers in industrial environments is crucial in a smart factory. Indeed, the production of products with superior quality at higher throughput rates and reduced costs with the support of Industry 4.0-enabling technologies is based on the strict control of all resources inside the factory, including workers. This paper shows a protocol for validating a new wearable system for tracking finger movements. The wearable system consists of two measuring modules worn on the thumb and index finger that measure flexion and extension of the proximal interphalangeal (PIP) joint by a stretch sensor and rotation of the proximal phalanx (PP) by an inertial measurement unit. A marker-based opto-electronic system is used to validate the proposed device by capturing specific finger movements. Four movements that simulate typical tasks and gestures, such as grasp and pinch, were specifically performed. The maximum root-mean-square error is 3.7 deg for the roll angle of PP. The resistance changes of the stretch sensors with respect to flexion and extension of the PIP joint is 0.47 Ω/deg. The results are useful for data interpretation when the system is adopted to monitor finger movements and gestures

Pinch Grip per SE Is Not an Occupational Risk Factor for the Musculoskeletal System: An Experimental Study on Field

Introduction: Some ergonomic evaluation methods define pinch grip as a risk factor independent of the exerted force. The present experimental study was performed with the main aim of objectively measuring the muscle engagement during the execution of pinch grip. Methods: the participants of the study were healthy workers occupationally involved in a high-intensity repetitive job related to the sorting of letters and small packages. Surface electromyography (sEMG) was used to study the activity of the abductor pollicis brevis and first dorsal interosseous fibers related to the execution of the required working tasks, while the force exerted during voluntary muscle contraction for pinch grip was measured by a portable acquisition system. The subjects were specifically asked to exert the maximum voluntary isometric contraction (MVIC) and further voluntary isometric contractions with a spontaneous force (SF) equal to 10%,20% and 50% of the MVIC; finally, the workers were asked to hold in pinch grip two types of envelopes, weighing 100 g and 500 g, respectively. Results: The force required to pinch 100 and 500 g envelopes by the fifteen subjects of the study corresponded to 4 and 5% MVIC, respectively. The corresponding sEMG average rectified values (ARV) were approximately 6% of that at MVIC for first dorsal interosseus (FDI) fibers and approximately 20-25% of MVIC for abductor pollicis brevis (ABP) fibers. Bivariate correlation analysis showed significant relationships between force at MVIC and FDI ARV at MCV. Conclusions: The obtained results demonstrate that muscle recruitment during pinch grip varies as a function of the SF: not only the position but also the exerted force should be considered when assessing the pinch grip as risk factor for biomechanical overload of the upper limb

Quantifying the contribution of single joint kinematics to the overall ergonomic discomfort

Work-related musculoskeletal disorders (WMSDs) represent one of the major issues concerning the occupational safety and health of workers. Thus, a reliable evaluation of workers’ exposure to the risk factors that may contribute to WMSDs development is mandatory, above all, within an industrial context. At present, standard synthetic indices are widely used in this frame, presenting – however - several limitations due to poor reliability and time efficiency. The aim of this work was to investigate the contribution of the displacement quantified for each single joint during the execution of simple reaching tasks, to the overall discomfort of the worker evaluated by means of standard observational methods. Forty-five healthy volunteers were included in the analysis; each subject was asked to reach and rotate 2 spheres placed on a custom-made rack in standardized positions, i.e., above the head and one at floor level at centre side. Whole-body kinematics was acquired via a system based on wearable inertial measurement units. Standard ergonomic scales including RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment), and MMGA (Method for Movement and Gesture Assessment), were assessed for each subject and each sphere position. Moreover, a quantitative index based on actual joint kinematics, i.e., W1 index, was computed for each joint angle involved in the task. Correlation analysis was performed for W1 relative to each joint with respect to RULA, REBA, and MMGA scores. Considering REBA and MMGA scores, the most comfortable reaching areas were the ones in which the sphere was positioned at the top; in contrast, the lowest positions evidenced the most increased discomfort indexes. The RULA did not result sensitive to the different positions, while REBA and MMGA seemed to be more influenced by the range of motion of the lower limb joint angles than the upper limb ones. This study underlines the necessity to focus on multiple potential contributors to WMSDs and underlines the importance of subject-specific approaches toward risk assessment by exploiting quantitative measurements and wearable technologies, which indeed represent key enabling approaches even in consideration of the novel “Industry 5.0” perspective

Comparison between clinical grading and navigation data of knee laxity in ACL-deficient knees

<p>Abstract</p> <p>Background</p> <p>The latest version of the navigation system for anterior cruciate ligament (ACL) reconstruction has the supplementary ability to assess knee stability before and after ACL reconstruction. In this study, we compared navigation data between clinical grades in ACL-deficient knees and also analyzed correlation between clinical grading and navigation data.</p> <p>Methods</p> <p>150 ACL deficient knees that received primary ACL reconstruction using an image-free navigation system were included. For clinical evaluation, the Lachman, anterior drawer, and pivot shift tests were performed under general anesthesia and were graded by an examiner. For the assessment of knee stability using the navigation system, manual tests were performed again before ACL reconstruction. Navigation data were recorded as anteroposterior (AP) displacement of the tibia for the Lachman and anterior drawer tests, and both AP displacement and tibial rotation for the pivot shift test.</p> <p>Results</p> <p>Navigation data of each clinical grade were as follows; Lachman test grade 1+: 10.0 mm, grade 2+: 13.2 ± 3.1 mm, grade 3+: 14.5 ± 3.3 mm, anterior drawer test grade 1+: 6.8 ± 1.4 mm, grade 2+: 7.4 ± 1.8 mm, grade 3+: 9.1 ± 2.3 mm, pivot shift test grade 1+: 3.9 ± 1.8 mm/21.5° ± 7.8°, grade 2+: 4.8 ± 2.1 mm/21.8° ± 7.1°, and grade 3+: 6.0 ± 3.2 mm/21.1° ± 7.1°. There were positive correlations between clinical grading and AP displacement in the Lachman, and anterior drawer tests. Although positive correlations between clinical grading and AP displacement in pivot shift test were found, there were no correlations between clinical grading and tibial rotation in pivot shift test.</p> <p>Conclusions</p> <p>In response to AP force, the navigation system can provide the surgeon with correct objective data for knee laxity in ACL deficient knees. During the pivot shift test, physicians may grade according to the displacement of the tibia, rather than rotation.</p