-
Journal of Orthopaedic Science :... Nov 2023The relationship between anterior pelvic tilt and overall sagittal alignment has been well-described previously. However, the relationship between pelvic tilt, frontal,...
INTRODUCTION
The relationship between anterior pelvic tilt and overall sagittal alignment has been well-described previously. However, the relationship between pelvic tilt, frontal, and axial leg alignment remains unclear. The aim of the study was to analyze the relationship between pelvic tilt and frontal and axial leg alignment in healthy subjects.
MATERIAL AND METHODS
Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope), hip-knee-ankle angle (HKA), femoral antetorsion and tibial torsion were measured using SterEOS (EOS Imaging) software. EOS was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of HKA, femoral antetorsion, tibial torsion and gender on pelvic tilt was analyzed in a univariate correlation and multiple regression model.
RESULTS
Sixteen female subjects and 14 male subjects with a mean age of 27.1 years ± 10 (range 20-67) were included. HKA, femoral antetorsion, and tibial torsion correlated with anterior pelvic tilt in univariate analysis (all p < 0.05). Anterior pelvic tilt increased 1.1° (95% CI: 0.7 to 1.5) per 1° of knee valgus (p < 0.001) and 0.5° (95% CI: 0.3 to 0.7) per 1° of external tibial torsion (p < 0.001). Overall, linear regression model fit explained 39% of variance in pelvic tilt by the HKA, femoral antetorsion and tibial torsion (R = 0.385; p < 0.001).
CONCLUSION
Valgus alignment and increasing tibial torsion demonstrated a weak correlation with an increase in anterior pelvic tilt in healthy subjects when placing their feet anteriorly. The relationship between frontal, axial leg alignment and pelvic tilt needs to be considered in patients with multiple joint disorders at the hip, knee and spine. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the pelvic tilt when the FPA is kept constant.
Topics: Humans; Male; Female; Young Adult; Adult; Middle Aged; Aged; Leg; Healthy Volunteers; Lower Extremity; Femur; Posture; Knee Joint
PubMed: 36336637
DOI: 10.1016/j.jos.2022.10.002 -
Medical & Biological Engineering &... Sep 2023To determine the effect of muscle activation on the dynamic responses of the neck of a pilot during simulated emergency ejections. A complete finite element model of the... (Review)
Review
To determine the effect of muscle activation on the dynamic responses of the neck of a pilot during simulated emergency ejections. A complete finite element model of the pilot's head and neck was developed and dynamically validated. Three muscle activation curves were designed to simulate different activation times and levels of muscles during pilot ejection: A is the unconscious activation curve of the neck muscles, B is the pre-activation curve, and C is the continuous activation curve. The acceleration-time curves obtained during ejection were applied to the model, and the influence of the muscles on the dynamic responses of the neck was investigated by analyzing both angles of rotation of the neck segments and disc stresses. Muscle pre-activation reduced fluctuations in the angle of rotation in each phase of the neck. Continuous muscle activation caused a 20% increase in the angle of rotation compared to pre-activation. Moreover, it resulted in a 35% increase in the load on the intervertebral disc. The maximum stress on the disc occurred in the C4-C5 phase. Continuous muscle activation increased both the axial load on the neck and the posterior extension angle of rotation of the neck. Muscle pre-activation during emergency ejection has a protective effect on the neck. However, continuous muscle activation increases the axial load and rotation angle of the neck. A complete finite element model of the pilot's head and neck was established and three neck muscle activation curves were designed to investigate the effects of muscle activation time and level on the dynamic response of the pilot's neck during ejection. This increased insights into the protection mechanism of neck muscles on the axial impact injury of the pilot's head and neck.
Topics: Finite Element Analysis; Biomechanical Phenomena; Range of Motion, Articular; Stress, Mechanical; Muscles; Cervical Vertebrae
PubMed: 36976416
DOI: 10.1007/s11517-023-02817-y -
PeerJ 2023The functional biomechanics of the lumbar spine have been better understood by finite element method (FEM) simulations. However, there are still areas where the behavior...
The functional biomechanics of the lumbar spine have been better understood by finite element method (FEM) simulations. However, there are still areas where the behavior of soft tissues can be better modeled or described in a different way. The purpose of this research is to develop and validate a lumbar spine section intended for biomechanical research. A FE model of the 50th percentile adult male (AM) Total Human Model for Safety (THUMS) v6.1 was used to implement the modifications. The main modifications were to apply orthotropic material properties and nonlinear stress-strain behavior for ligaments, hyperelastic material properties for annulus fibrosus and nucleus pulposus, and the specific content of collagenous fibers in the annulus fibrosus ground substance. Additionally, a separation of the nucleus pulposus from surrounding bones and tissues was implemented. The FE model was subjected to different loading modes, in which intervertebral rotations and disc pressures were calculated. Loading modes contained different forces and moments acting on the lumbar section: axial forces (compression and tension), shear forces, pure moments, and combined loading modes of axial forces and pure moments. The obtained ranges of motion from the modified numerical model agreed with experimental data for all loading modes. Moreover, intradiscal pressure validation for the modified model presented a good agreement with the data available from the literature. This study demonstrated the modifications of the THUMS v6.1 model and validated the obtained numerical results with existing literature in the sub-injurious range. By applying the proposed changes, it is possible to better model the behavior of the human lumbar section under various loads and moments.
Topics: Adult; Male; Humans; Intervertebral Disc; Finite Element Analysis; Lumbar Vertebrae; Annulus Fibrosus; Nucleus Pulposus
PubMed: 37583909
DOI: 10.7717/peerj.15805 -
Pain Practice : the Official Journal of... Jan 2024Pain originating from the lumbar facets can be defined as pain that arises from the innervated structures comprising the joint: the subchondral bone, synovium, synovial... (Review)
Review
INTRODUCTION
Pain originating from the lumbar facets can be defined as pain that arises from the innervated structures comprising the joint: the subchondral bone, synovium, synovial folds, and joint capsule. Reported prevalence rates range from 4.8% to over 50% among patients with mechanical low back pain, with diagnosis heavily dependent on the criteria employed. In well-designed studies, the prevalence is generally between 10% and 20%, increasing with age.
METHODS
The literature on the diagnosis and treatment of lumbar facet joint pain was retrieved and summarized.
RESULTS
There are no pathognomic signs or symptoms of pain originating from the lumbar facet joints. The most common reported symptom is uni- or bilateral (in more advanced cases) axial low back pain, which often radiates into the upper legs in a non-dermatomal distribution. Most patients report an aching type of pain exacerbated by activity, sometimes with morning stiffness. The diagnostic value of abnormal radiologic findings is poor owing to the low specificity. SPECT can accurately identify joint inflammation and has a predictive value for diagnostic lumbar facet injections. After "red flags" are ruled out, conservatives should be considered. In those unresponsive to conservative therapy with symptoms and physical examination suggesting lumbar facet joint pain, a diagnostic/prognostic medial branch block can be performed which remains the most reliable way to select patients for radiofrequency ablation.
CONCLUSIONS
Well-selected individuals with chronic low back originating from the facet joints may benefit from lumbar medial branch radiofrequency ablation.
Topics: Humans; Zygapophyseal Joint; Low Back Pain; Nerve Block; Lumbosacral Region; Prognosis; Lumbar Vertebrae
PubMed: 37640913
DOI: 10.1111/papr.13287 -
Journal of Ultrasound in Medicine :... Feb 2024A new ultrasound-based device is proposed to non-invasively measure the orientation of the scapula in the standing position to consider this parameter for Total Shoulder...
OBJECTIVES
A new ultrasound-based device is proposed to non-invasively measure the orientation of the scapula in the standing position to consider this parameter for Total Shoulder Arthroplasty. The aim of this study was to assess the accuracy and reliability of this device.
METHODS
Accuracy was assessed by comparing measurements made with the ultrasound device to those acquired with a three-dimensional (3D) optical localization system (Northern Digital, Canada) on a dedicated mechanical phantom. Three users performed 10 measurements on three healthy volunteers with different body mass (BMI) indices to analyze the reliability of the device by measuring the intra and interobserver variabilities.
RESULTS
The mean accuracy of the device was 0.9°± 0.7 (0.01-3.03), 1.3°± 0.8 (0.03-4.55), 1.9°± 1.5 (0.05-5.76), respectively, in the axial, coronal, and sagittal planes. The interobserver and intraobserver variabilities were excellent whatever the BMI and the users experience.
CONCLUSIONS
The device is accurate and reliable enough for the measurement of the scapula orientation in the standing position.
Topics: Humans; Reproducibility of Results; Standing Position; Scapula; Observer Variation; Canada; Shoulder Joint; Range of Motion, Articular; Biomechanical Phenomena
PubMed: 37987527
DOI: 10.1002/jum.16370 -
Journal of Biomechanical Engineering Oct 2023The spine is a multi-tissue musculoskeletal system that supports large multi-axial loads and motions during physiological activities. The healthy and pathological...
The spine is a multi-tissue musculoskeletal system that supports large multi-axial loads and motions during physiological activities. The healthy and pathological biomechanical function of the spine and its subtissues are generally studied using cadaveric specimens that often require multi-axis biomechanical test systems to mimic the complex loading environment of the spine. Unfortunately, an off-the-shelf device can easily exceed 200,000 USD, while a custom device requires extensive time and experience in mechatronics. Our goal was to develop a cost-appropriate compression and bending (flexion-extension and lateral bending) spine testing system that requires little time and minimal technical knowledge. Our solution was an off-axis loading fixture (OLaF) that mounts to an existing uni-axial test frame and requires no additional actuators. OLaF requires little machining, with most components purchased off-the-shelf, and costs less than 10,000 USD. The only external transducer required is a six-axis load cell. Furthermore, OLaF is controlled using the existing uni-axial test frame's software, while the load data is collected using the software included with the six-axis load cell. Here we provide the design rationale for how OLaF develops primary motions and loads and minimizes off-axis secondary constraints, verify the primary kinematics using motion capture, and demonstrate that the system is capable of applying physiologically relevant, noninjurious, axial compression and bending. While OLaF is limited to compression and bending studies it produces repeatable physiologically relevant biomechanics, with high quality data, and minimal startup costs.
Topics: Humans; Biomechanical Phenomena; Spine; Motion; Weight-Bearing; Pressure; Range of Motion, Articular
PubMed: 37338241
DOI: 10.1115/1.4062780 -
Knee Surgery, Sports Traumatology,... Dec 2023The aim of this study was to assess the biomechanical effects of subtalar ligament injury and reconstruction on stability of the subtalar joint in all three spatial...
PURPOSE
The aim of this study was to assess the biomechanical effects of subtalar ligament injury and reconstruction on stability of the subtalar joint in all three spatial planes.
METHODS
Fifteen fresh frozen cadaveric legs were used, with transfixed tibiotalar joints to isolate motion to the subtalar joint. An arthrometer fixed to the lateral aspect of the calcaneus measured angular displacement in all three spatial planes on the inversion and eversion stress tests. Stress manoeuvres were tested with the intact joint, and then repeated after sequentially sectioning the inferior extensor retinaculum (IER), cervical ligament (CL), interosseous talocalcaneal ligament (ITCL), arthroscopic graft reconstruction of the ITCL, and sectioning of the calcaneo-fibular ligament (CFL).
RESULTS
Sectioning the ITCL significantly increased angular displacement upon inversion and eversion in the coronal and sagittal planes. Reconstruction of the ITCL significantly improved angular stability against eversion in the axial and sagittal planes, and against inversion in the axial and coronal planes, at the zero time point after reconstruction. After sectioning the CFL, resistance to eversion decreased significantly in all three planes.
CONCLUSION
Progressive injury of ligamentous stabilisers, particularly the ITCL, led to increasing angular displacement of the subtalar joint measured with the inversion and eversion stress tests, used in clinical practice. Reconstruction of the ITCL using tendon graft significantly stabilised the subtalar joint in the axial and sagittal planes against eversion and in the axial and coronal planes against inversion, immediately after surgery.
Topics: Humans; Subtalar Joint; Biomechanical Phenomena; Cadaver; Ankle Joint; Ligaments, Articular; Joint Instability; Allografts
PubMed: 37955675
DOI: 10.1007/s00167-023-07622-6 -
BMC Musculoskeletal Disorders Oct 2023To develop and evaluate the performance of radiomics-based computed tomography (CT) combined with machine learning algorithms in detecting occult vertebral fractures...
PURPOSE
To develop and evaluate the performance of radiomics-based computed tomography (CT) combined with machine learning algorithms in detecting occult vertebral fractures (OVFs).
MATERIALS AND METHODS
128 vertebrae including 64 with OVF confirmed by magnetic resonance imaging and 64 corresponding control vertebrae from 57 patients who underwent chest/abdominal CT scans, were included. The CT radiomics features on mid-axial and mid-sagittal plane of each vertebra were extracted. The fractured and normal vertebrae were randomly divided into training set and validation set at a ratio of 8:2. Pearson correlation analyses and least absolute shrinkage and selection operator were used for selecting sagittal and axial features, respectively. Three machine-learning algorithms were used to construct the radiomics models based on the residual features. Receiver operating characteristic (ROC) analysis was used to verify the performance of model.
RESULTS
For mid-axial CT imaging, 6 radiomics parameters were obtained and used for building the models. The logistic regression (LR) algorithm showed the best performance with area under the ROC curves (AUC) of training and validation sets of 0.682 and 0.775. For mid-sagittal CT imaging, 5 parameters were selected, and LR algorithms showed the best performance with AUC of training and validation sets of 0.832 and 0.882. The LR model based on sagittal CT yielded the best performance, with an accuracy of 0.846, sensitivity of 0.846, and specificity of 0.846.
CONCLUSION
Machine learning based on CT radiomics features allows for the detection of OVFs, especially the LR model based on the radiomics of sagittal imaging, which indicates it is promising to further combine with deep learning to achieve automatic recognition of OVFs to reduce the associated secondary injury.
Topics: Humans; Spinal Fractures; Spine; Fractures, Closed; Tomography, X-Ray Computed; Machine Learning; Retrospective Studies
PubMed: 37848859
DOI: 10.1186/s12891-023-06939-0 -
Spine Nov 2023Prospective Cohort.
STUDY DESIGN
Prospective Cohort.
OBJECTIVE
Quantify and compare the effectiveness of cervical orthoses in restricting intervertebral kinematics during multiplanar motions.
SUMMARY OF BACKGROUND DATA
Previous studies evaluating the efficacy of cervical orthoses measured global head motion and did not evaluate individual cervical motion segment mobility. Prior studies focused only on the flexion/extension motion.
METHODS
Twenty adults without neck pain participated. Vertebral motion from the occiput through T1 was imaged using dynamic biplane radiography. Intervertebral motion was measured using an automated registration process with validated accuracy better than 1 degree. Participants performed independent trials of maximal flexion/extension, axial rotation, and lateral bending in a randomized order of unbraced, soft collar (foam), hard collar (Aspen), and cervical thoracic orthosis (CTO) (Aspen) conditions. Repeated-measures ANOVA was used to identify differences in the range of motion (ROM) among brace conditions for each motion.
RESULTS
Compared with no collar, the soft collar reduced flexion/extension ROM from occiput/C1 through C4/C5, and reduced axial rotation ROM at C1/C2 and from C3/C4 through C5/C6. The soft collar did not reduce motion at any motion segment during lateral bending. Compared with the soft collar, the hard collar reduced intervertebral motion at every motion segment during all motions, except for occiput/C1 during axial rotation and C1/C2 during lateral bending. The CTO reduced motion compared with the hard collar only at C6/C7 during flexion/extension and lateral bending.
CONCLUSIONS
The soft collar was ineffective as a restraint to intervertebral motion during lateral bending, but it did reduce intervertebral motion during flexion/extension and axial rotation. The hard collar reduced intervertebral motion compared with the soft collar across all motion directions. The CTO provided a minimal reduction in intervertebral motion compared with the hard collar. The utility in using a CTO rather than a hard collar is questionable, given the cost and little or no additional motion restriction.
Topics: Adult; Humans; Prospective Studies; Cervical Vertebrae; Orthotic Devices; Rotation; Biomechanical Phenomena; Range of Motion, Articular
PubMed: 37339257
DOI: 10.1097/BRS.0000000000004755 -
Medical & Biological Engineering &... Nov 2023Humeral motion can be challenging to measure and analyze. Typically, Euler/Cardan sequences are used for humeral angle decomposition, but choice of rotation sequence has...
Humeral motion can be challenging to measure and analyze. Typically, Euler/Cardan sequences are used for humeral angle decomposition, but choice of rotation sequence has substantial effects on outcomes. A new method called True axial rotation calculation may be more precise. The objective of this study is to compare humeral axial rotation measured from two systems (optical motion capture and inertial measurement units (IMUs)) and calculated with two methods (Euler angles and True axial). Motion of torso and dominant humerus of thirty participants free from any upper limb impairments was tracked using both systems. Each participant performed a functional tasks protocol. Humeral axial rotation was calculated with Euler decomposition and the True axial method. Waveforms were compared with two-way ANOVA statistical parametric mapping. A consistent pattern emerged: axial rotation was not different between motion capture systems when using the True axial method (p > .05), but motion capture systems showed relatively large magnitude differences (~ 20-30°) when using Euler angle calculation. Between-calculation method differences were large for both motion capture systems. Findings suggest that the True axial rotation method may result in more consistent findings that will allow for precise measurements and comparison between motion capture systems. Two methods for calculating humeral axial rotation measured from optical motion capture and inertial measurement units were compared.
Topics: Humans; Rotation; Shoulder Joint; Motion Capture; Range of Motion, Articular; Biomechanical Phenomena; Humerus
PubMed: 37535299
DOI: 10.1007/s11517-023-02894-z