Physiological Range Of Motion Research Articles

Moment arm and torque generating capacity of semitendinosus following tendon harvesting for anterior cruciate ligament reconstruction: A simulation study.

Altered semitendinosus (ST) morphology and distal tendon insertion following anterior cruciate ligament reconstruction (ACLR) may reduce knee flexion torque generating capacity of the hamstrings via impaired ST force generation and/or moment arm. This study used a computational musculoskeletal model to simulate mechanical consequences of tendon harvest for ACLR on ST function by modeling changes in ST muscle tendon insertion point, moment arm, and torque generating capacity across a physiological range of motion. Simulated ST function was then compared between ACLR and uninjured contralateral limbs. Magnetic resonance imaging from 18 individuals with unilateral history of ACLR involving a hamstring autograft was used to analyse bilateral hamstring muscle (ST, semimembranosus, bicep femoris long head and short head) morphology and distal ST tendon insertion. The ACLR cohort was sub-grouped into those with and without ST regeneration. For each participant with ST regeneration (n = 7), a personalized musculoskeletal model was created including postoperative remodeling of ST using OpenSim 4.1. Knee flexion and internal rotation moment arms and torque generating capacities of hamstrings were evaluated. Bilateral differences were calculated with an asymmetry index (%) ([unaffected limb-affected limb]/[unaffected limb + affected limb]*100%). Smaller moment arms or knee torques within injured compared to uninjured contralateral limbs were considered a deficit. Compared to uninjured contralateral limbs, ACLR limbs with tendon regeneration (n = 7) had minor reductions in knee flexion (5.80% [95% confidence interval (CI) = 3.97-7.62]) and internal rotation (4.92% [95% CI = 2.77-7.07]) moment arms. Decoupled from muscle morphology, altered ST moment arms in ACLR limbs with tendon regeneration resulted in negligible deficits in knee flexion (1.20% [95% CI = 0.34-2.06]) and internal rotation (0.24% [95% CI = 0.22-0.26]) torque generating capacity compared to uninjured contralateral limbs. Coupled with muscle morphology, ACLR limbs with tendon regeneration had substantial deficits in knee flexion (19.32% [95% CI = 18.35-20.28]) and internal rotation (15.49% [95% CI = 14.56-16.41]) torques compared to uninjured contralateral limbs. Personalized musculoskeletal models with measures of ST distal insertion and muscle morphology provided unique insights into post-ACLR ST and hamstring function. Deficits in knee flexor and internal rotation moment arms and torque generating capacities were evident in those with ACLR even when tendon regeneration occurred. Future studies may wish to implement this framework in personalized musculoskeletal models following ACLR to better understand individual muscle function for injury prevention and treatment evaluation.

A new method to design energy-conserving surrogate models for the coupled, nonlinear responses of intervertebral discs

The aim of this study was to design physics-preserving and precise surrogate models of the nonlinear elastic behaviour of an intervertebral disc (IVD). Based on artificial force-displacement data sets from detailed finite element (FE) disc models, we used greedy kernel and polynomial approximations of second, third and fourth order to train surrogate models for the scalar force-torque -potential. Doing so, the resulting models of the elastic IVD responses ensured the conservation of mechanical energy through their structure. At the same time, they were capable of predicting disc forces in a physiological range of motion and for the coupling of all six degrees of freedom of an intervertebral joint. The performance of all surrogate models for a subject-specific L4|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\vert$$\\end{document}5 disc geometry was evaluated both on training and test data obtained from uncoupled (one-dimensional), weakly coupled (two-dimensional), and random movement trajectories in the entire six-dimensional (6d) physiological displacement range, as well as on synthetic kinematic data. We observed highest precisions for the kernel surrogate followed by the fourth-order polynomial model. Both clearly outperformed the second-order polynomial model which is equivalent to the commonly used stiffness matrix in neuro-musculoskeletal simulations. Hence, the proposed model architectures have the potential to improve the accuracy and, therewith, validity of load predictions in neuro-musculoskeletal spine models.

Two-to-three times increase in natural hip and lumbar non-sagittal plane kinematics can lead to anterior cruciate ligament injury and cartilage failure scenarios during single-leg landings

BackgroundAnalyzing sports injuries is essential to mitigate risk for injury, but inherently challenging using in vivo approaches. Computational modeling is a powerful engineering tool used to access biomechanical information on tissue failure that cannot be obtained otherwise using traditional motion capture techniques. MethodsWe extrapolated high-risk kinematics associated with ACL strain and cartilage load and stress from a previous motion analysis of 14 uninjured participants. Computational simulations were used to induce ACL failure strain and cartilage failure load, stress, and contact pressure in two age- and BMI-matched participants, one of each biological sex, during single-leg cross drop and single-leg drop tasks. The high-risk kinematics were exaggerated in 20% intervals, within their physiological range of motion, to determine if injury occurred in the models. Where injury occurred, we reported the kinematic profiles that led to tissue failure. FindingsOur findings revealed ACL strains up to 9.99%, consistent with reported failure values in existing literature. Cartilage failure was observed in all eight analyzed conditions when increasing each high-risk kinematic parameter by 2.61 ± 0.67 times the participants' natural landing values. The kinematics associated with tissue failure included peak hip internal rotation of 22.48 ± 19.04°, peak hip abduction of 22.51 ± 9.09°, and peak lumbar rotation away from the stance limb of 11.56 ± 9.78°. InterpretationOur results support the ability of previously reported high-risk kinematics in the literature to induce injury and add to the literature by reporting extreme motion limits leading to injurious cases. Therefore, training programs able to modify these motions during single-leg landings may reduce the risk of ACL injury and cartilage trauma.

Fixation of Terrible Triad Fracture in Young Adult through Anterior Approach – A Case Report

Introduction: The terrible triad of the elbow is defined as the combination of fractures of the radial head and ulnar coronoid process and dislocation of the elbow joint, and is often associated with collateral ligaments injuries. Objective: The objective is to report the clinical outcomes of an anterior surgical approach for coronoid fracture with plate fixation in the management of a case of terrible triad fracture with undisplaced radial head. Case Details: A 23 years old male presented with complaints of pain and swelling in right wrist and left elbow region since 1 day. He had a history of fall from height 1 day back with no known comorbidities or DNVD. Conclusion: Terrible triad fracture can be treated successfully with plate fixation through an anterior surgical approach in cases of undisplaced radial head with physiological range of motion at elbow which allows for accurate reduction and rigid internal fixation and early functional exercise, resulting in a favourable outcome.

Defining the optimal position of the lipped liner in combination with cup orientation and stem version.

The aim of this study was to identify the optimal lip position for total hip arthroplasties (THAs) using a lipped liner. There is a lack of consensus on the optimal position, with substantial variability in surgeon practice. A model of a THA was developed using a 20° lipped liner. Kinematic analyses included a physiological range of motion (ROM) analysis and a provocative dislocation manoeuvre analysis. ROM prior to impingement was calculated and, in impingement scenarios, the travel distance prior to dislocation was assessed. The combinations analyzed included nine cup positions (inclination 30-40-50°, anteversion 5-15-25°), three stem positions (anteversion 0-15-30°), and five lip orientations (right hip 7 to 11 o'clock). The position of the lip changes the ROM prior to impingement, with certain combinations leading to impingement within the physiological ROM. Inferior lip positions (7 to 8 o'clock) performed best with cup inclinations of 30° and 40°. Superior lip positions performed best with cup inclination of 50°. When impingement occurs in the plane of the lip, the lip increases the travel distance prior to dislocation. Inferior lip positions led to the largest increase in jump distance in a posterior dislocation provocation manoeuvre. The lip orientation that provides optimal physiological ROM depends on the orientation of the cup and stem. For a THA with stem anteversion 15°, cup inclination 40°, and cup anteversion 15°, the optimal lip position was posterior-inferior (8 o'clock). Maximizing jump distance prior to dislocation while preventing impingement in the opposite direction is possible with appropriate lip positioning.

IN VITRO METHODOLOGY FOR SYSTEMATIC CT INVESTIGATION OF THE PERICLAVICULAR SPACE

The periclavicular space is a conduit for the brachial plexus and subclavian-axillary vascular system. Changes in its shape/form generated by alteration in the anatomy of its bounding structures, e.g. clavicle malunion, cause distortion of the containing structures, particularly during arm motion, leading to syndromes of thoracic outlet stenosis etc., or alterations of scapular posture with potential reduction in shoulder function.Aim of this study was developing an in vitro methodology for systematic and repeatable measurements of the clinically poorly characterized periclavicular space during arm motion using CT-imaging and computer-aided 3D-methodologies.A radiolucent frame, mountable to the CT-table, was constructed to fix an upper torso in an upright position with the shoulder joint lying in the isocentre. The centrally osteotomized humerus is fixed to a semi-circular bracket mounted centrally at the end of the frame. All arm movements (ante-/retroversion, abduction/elevation, in-/external rotation) can be set and scanned in a defined and reproducible manner. Clavicle fractures healed in malposition can be simulated by osteotomy and fixation using a titanium/carbon external fixator.During image processing the first rib served as fixed reference in space. Clavicle, scapula and humerus were registered, segmented, and triangulated. The different positions were displayed as superimposed surface meshes and measurements performed automatically. Initial results of an intact shoulder girdle demonstrated that different arm positions including ante-/retroversion and abduction/elevation resulted solely in a transverse movement of the clavicle along/parallel to the first rib maintaining the periclavicular space.A radiolucent frame enabling systematic and reproducible CT scanning of upper torsos in various arm movements was developed and utilized to characterize the effect on the 3D volume of the periclavicular space. Initial results demonstrated exclusively transverse movement of the clavicle along/parallel to the first rib maintaining the periclavicular space during arm positions within a physiological range of motion.

Joint Coordinate System Using Functional Axes Achieves Clinically Meaningful Kinematics of the Tibiofemoral Joint as Compared to the International Society of Biomechanics Recommendation.

Quantification of clinically meaningful tibiofemoral motions requires a joint coordinate system (JCS) with motions free from kinematic crosstalk errors. The objectives were to use a JCS with literature-backed functional axes (FUNC) and a JCS recommended by the International Society of Biomechanics (ISB) to determine tibiofemoral kinematics of the native (i.e., healthy) knee, determine variability associated with each JCS, and determine whether the FUNC JCS significantly reduced kinematic crosstalk errors compared to the ISB JCS. Based on a kinematic model consisting of a three-cylindric joint chain, the FUNC JCS included functional flexion-extension (F-E) and internal-external (I-E) tibial rotation axes. In contrast, the ISB JCS included F-E and I-E axes defined using anatomic landmarks. Single-plane fluoroscopic images in 13 subjects performing a weighted deep knee bend were analyzed. Tibiofemoral kinematics using the FUNC JCS fell within the physiological range of motion in all six degrees-of-freedom. Internal tibial rotation averaged 13 deg for the FUNC JCS versus 10 deg for the ISB JCS and motions in the other four degrees-of-freedom (collectively termed off-axis motions) were minimal as expected based on biomechanical constraints. Off-axis motions for the ISB JCS were significantly greater; maximum valgus rotation was 4 deg and maximum anterior and distraction translations were 9 mm and 25 mm, respectively, which is not physiologic. Variabilities in off-axis motions were significantly greater with the ISB JCS (p < 0.0002). The FUNC JCS achieved clinically meaningful kinematics by significantly reducing kinematic crosstalk errors and is the more suitable coordinate system for quantifying tibiofemoral motions.

Enhancing the Biofidelity of an Upper Cervical Spine Finite Element Model Within the Physiologic Range of Motion and Its Effect on the Full Ligamentous Neck Model Response.

Contemporary finite element (FE) neck models are developed in a neutral posture; however, evaluation of injury risk for out-of-position impacts requires neck model repositioning to non-neutral postures, with much of the motion occurring in the upper cervical spine (UCS). Current neck models demonstrate a limitation in predicting the intervertebral motions within the UCS within the range of motion, while recent studies have highlighted the importance of including the tissue strains resulting from repositioning FE neck models to predict injury risk. In the current study, the ligamentous cervical spine from a contemporary neck model (GHBMC M50 v4.5) was evaluated in flexion, extension, and axial rotation by applying moments from 0 to 1.5 N·m in 0.5 N·m increments, as reported in experimental studies and corresponding to the physiologic loading of the UCS. Enhancements to the UCS model were identified, including the C0-C1 joint-space and alar ligament orientation. Following geometric enhancements, an analysis was undertaken to determine the UCS ligament laxities, using a sensitivity study followed by an optimization study. The ligament laxities were optimized to UCS-level experimental data from the literature. The mean percent difference between UCS model response and experimental data improved from 55% to 23% with enhancements. The enhanced UCS model was integrated with a ligamentous cervical spine (LS) model and assessed with independent experimental data. The mean percent difference between the LS model and the experimental data improved from 46% to 35% with the integration of the enhanced UCS model.

A case of heterotopic ossification of the elbow joint

Patients who have undergone severe elbow trauma often develop various complications. Heterotopic ossification is considered to be the most severe complication, which leads to severe impairment of upper limb function due to the formation of severe contractures and ankylosis in the elbow joint. The paper presents the results of surgical treatment of the elbow joint in a patient with «immature» ossification against the background of aged dislocation of the forearm, non-unionized fracture of the radial head, and stage II osteoarthritis. Analysis of the outpatient follow-up of the patient after injury revealed gross diagnostic and treatment errors. As a result of medical errors, inadequate treatment of injuries in the early stages after injury was prescribed, which contributed to the formation of heterotopic ossification and resulted in functional failure of the joint. During surgery, the ossification located in the ulnar fossa was removed via a small posterior access to the elbow joint, the remaining tissues of the joint were not affected, thorough hemostasis was performed, and a Volkov-Oganesian joint-distraction device was applied to provide a physiological range of motion in the elbow joint. Postoperative long-term rehabilitation ensured restoration of the elbow joint function with the patient's return to professional activities.

Operative management of gouty tophi in the region of the olecranon: a case series.

BackgroundTophaceous gout affecting the olecranon region can result in local discomfort, skin ulceration, secondary infection, and considerable disability if left untreated. However, there are limited reports of outcomes, including postoperative complications and recurrence after surgical excision of tophaceous gout deposits at the elbow. The aim of this study is to present our surgical technique and minimum one-year outcomes after surgical excision of tophaceous gout involving the elbow.MethodsA retrospective chart review was performed on all patients from a single surgeon's practice who underwent surgical excision of gouty tophi of the elbow between January 2016 and December 2019. The indications for surgical excision of tophi included failure of medical management, presence of skin ulceration, and/or large gouty tophi. The relevant data pertaining to patient demographics, preoperative findings, intraoperative findings, surgical pathology reports, and short-term postoperative complications were collected through retrospective chart review. Patients were subsequently contacted for a follow-up telehealth visit to assess recurrence of gouty tophi, functional outcomes, and range of motion (ROM) measurements.ResultsSix male patients underwent 7 total procedures (1 bilateral elbow) during the study period. The mean age of the cohort at the time of surgery was 56.0 ± 7.1 years (range: 45.3-63.5). The mean size of the swelling in 2 maximum dimensions was 5.8 × 3.4 cm. There were no intraoperative or immediate postoperative wound complications. There was no recurrence of gouty tophi at a mean follow-up time of 30.8 months (range: 14.0-43.5). Patients reported physiologic ROM (mean flexion-extension arc of 2°-134°) with no pain at final follow-up.ConclusionSurgical treatment of tophaceous gout of the elbow is associated with a low risk of wound complication and recurrence.

Optimized Joint Coordinate System Achieves Clinically Meaningful Kinematics of the Tibiofemoral Joint as Compared to the International Society of Biomechanics (ISB) Recommendation.

Quantification of clinically meaningful tibiofemoral motions requires a coordinate system where motions are free from kinematic crosstalk errors. The objectives were to 1) develop an algorithm for assigning an optimized joint coordinate system (OPT JCS) that minimizes kinematic crosstalk errors based on a kinematic model of the tibiofemoral joint, 2) determine tibiofemoral kinematics of the native (i.e. healthy) knee during deep knee bend using OPT JCS and a coordinate system recommended by the International Society of Biomechanics (ISB JCS), and 3) determine whether OPT JCS significantly reduces kinematic crosstalk errors compared to ISB JCS. A novel algorithm was developed for assigning a patient-specific, OPT JCS based on a two rotational degree-of-freedom kinematic model, which included flexion-extension and internal-external tibial rotation axes. Single-plane fluoroscopic images of native knees of 13 subjects performing deep knee bend were analyzed to show that tibiofemoral kinematics using OPT-JCS fell within the physiological range of motion in all six degrees of freedom. Internal rotation of the tibia with respect to the femur averaged 11 deg and off-axis motions were minimal as expected based on biomechanical constraints. In contrast, off-axis motions for ISB JCS were non-physiologic; maximum valgus rotation was 12 deg, maximum posterior translation was 12 mm, and maximum distraction translation was 28 mm. Hence, an optimized JCS achieved clinically meaningful kinematics by significantly reducing kinematic crosstalk errors compared to the ISB recommendation and is the more suitable coordinate system for evaluating tibiofemoral joint function.

Neck Braces and Driving Posture Affect Neck Mobility on Powered Two-Wheelers

Cervical spine injuries are a major concern for motorcyclists in traffic accidents and racing competitions. Neck braces aim to prevent cervical spine injuries during accidents by reducing the neck range of motion, and keeping it under physiological limits. This work aims to evaluate the ability of neck braces to reduce neck mobility for two driving postures associated with PTW configurations. The neck mobility of twelve volunteer subjects testing four neck braces on two powered two-wheelers (scooter and racing motorbike) is measured using an optoelectronic motion capture system. With the tested neck braces worn, neck mobility is significantly reduced as compared to the physiological range of motion in all degrees of freedom. However, only flexion/extension is reduced by all neck braces tested. This suggests that these brace designs do not provide protection against all the cervical spine loading directions that may occur in a trauma. Furthermore, specific type of each powered two-wheeler considered significantly affects the neck mobility in axial rotation, as well as the postero-anterior and caudo-cranial translations, thus underscoring the need to consider the driving posture when evaluating neck brace devices.

Biomechanical analysis of different fixation methods of acromioclavicular joint dislocations on acromioclavicular and sternoclavicular joints motions

The injury of acromioclavicular joint is one of the causes limitation function of the shoulder joint. Choice of fixation methods of acromioclavicular joint dislocation is actual topic to research. Objective: to study by a biomechanical experiment and to substantiate influence of different fixation methods of acromioclavicular joint dislocation on range of motion of acromioclavicular and sternoclavicular joints during the upper extremity elevation. Methods: 6 prototypes of a natural skeleton 3D technology from ADS plastic were used. The capsuloligamentous components, dynamic and static stabilizations of acromioclavicular and sternoclavicular joint were modeled from artificial materials. Each model of acromioclavicular dislocation was fixed by 6 different fixations methods: «intact joint», «fixation by Weber», «Bosworth screw», «Hook-plate», «DogBone», «External fixation». During the experimental study, the range of motions was fixed in acromioclavicular and sternoclavicular joints in 90 and 180 degrees of arm elevation, each experiment was repeated 5 times. Results: range of motion in acromioclavicular and sternoclavicular joints in position of 90 degree of arm elevation, with fixation of acromioclavicular joint dislocation by Hook-plate and system of 2 mini plates and suture material (DogBone), in position of 180 degree of arm elevation with fixation of «DogBone» was physiological. Other methods of fixation — «Bosworth screw», «Weber fixation», «External fixation», «Hook plate» limited the range of motion in the acromioclavicular joint and increase motion in the sternoclavicular joint at maximal arm elevation. Conclusions: fixation of acromioclavicular joint dislocation by 2 mini plates and suture material (DogBone) gives physiological range of motion in acromioclavicular and sternoclavicular joints during arm elevation.

Imaging of Carpal Instabilities.

The term "carpal instability" describes different debilitating wrist conditions, in which the carpus is unable to maintain its physiological range of motion and load transfer. Depending on the cause and location of the dysfunction, four groups can be defined: dissociative, non-dissociative, complex, and adaptive carpal instability. As the most common form by far, dissociative carpal instability can further be categorized as dorsal or palmar intercalated segment instability, contingent on the afflicted interosseous ligament. This review article outlines the different entities of carpal instability, their pathophysiology, and their clinical presentation. It further discusses the diagnostic significance of different imaging methods as well as the established treatment options for each form of instability in context with the current literature. Early detection and treatment of carpal instability are essential for preventing carpal osteoarthritis. Traumatic lesions of the scapholunate interosseous ligament are the most frequent cause of instability. They can occur in an isolated fashion or in context with other carpal injuries. While stress imaging and fluoroscopy facilitate the differentiation between dynamic and static forms of carpal instability, only MRI and CT/MR arthrography can directly reveal the extent of ligament discontinuity. · Carpal instability can manifest only in motion (dynamic) or at rest (static).. · Dissociative forms must be distinguished from non-dissociative, adaptive, or complex entities.. · Most instabilities are related to traumatic injuries or CPPD arthropathy.. · Fluoroscopy, stress imaging, and MR and CT arthrography are helpful for diagnosis.. · Grunz JP, Gietzen CH, Grunz K et al. Imaging of Carpal Instabilities. Fortschr Röntgenstr 2021; 193: 139 - 150.

MRI-based static and functional assessment of complex hip deformities in comparison with CT: a validation study

ObjectiveThis study aimed at investigating the agreement between predefined quantitative parameters of hip morphology derived from magnetic resonance imaging (MRI) and virtual range of motion (ROM) analysis using computed tomography (CT) as standard of reference.MethodsTwenty patients (13 females, 7 males, 16–59 years) with hip deformities underwent MRI prior to surgery. Clockwise alpha angle, femoral head and neck diameter, collum caput diaphysis angle, femoral torsion, center-edge angles, acetabular coverage of the femoral head, sourcil angle, and acetabular anteversion were measured. Additionally, tern single and combined movements were simulated using a motion analysis program. The MRI findings were compared with the corresponding results obtained by CT. Correlation of MRI with CT was assessed using different statistical methods (intraclass correlation coefficient, Bland–Altmann plot, two one-sided t test), and linear regression analysis was performed.ResultsThe results showed near-perfect intraclass correlation coefficients (ICCs) for anteversion (0.95), acetabular sector angles (0.98–0.99), sourcil angle (0.95), and acetabular coverage (anterior 0.96, posterior 0.99). Intermethod correlation for femoral parameters showed almost perfect agreement except for the alpha angle (0.73–0.97). No significant proportional bias was detected for traditional acetabular and femoral parameters. ROM analysis was performed for 370 movements in 37 hips. For 78.4% (290/370) of the movements analysed, neither CT nor MRI detected impingement across the physiological ROM. For 18.6% (69/370) of the movements, impingement was detected by both CT and MRI, while 2.2% (8/370) of the movements with impingement in CT showed no impingement in MRI, and 0.8% (3/370) of the movements with impingement in MRI had no corresponding result in CT.ConclusionFinally, it was concluded that MRI-based assessment of hip morphology and virtual ROM analysis is feasible and can be performed with good intermethod agreement in comparison to the gold standard (CT). Therefore, MRI appears to be substantially equivalent to CT for use in virtual ROM analysis and so may reasonably be used in place of CT for this purpose.

A three-dimensional printed patient-specific scaphoid replacement: a cadaveric study.

We present our first cadaveric test results of a three-dimensional printed patient-specific scaphoid replacement with tendon suspension, which showed normal motion behaviour and preservation of a stable scapholunate interval during physiological range of motion.

Contribution of the Ligamentum Teres to Hip Stability in the Presence of an Intact Capsule: A Cadaveric Study

To determine the contribution of the ligamentum teres (LT) to hip stability in the presence of an intact capsule with special attention to the change in range of motion and femoral head translation. Seven fresh-frozen cadaveric pelvises were used. Following visual inspection of the LT at different hip positions, internal rotation angles were measured at 10° of extension and at 0° of flexion, while external rotation was measured at 60°, 90°, and 110° of flexion with different hip abduction angles using electromagnetic motion tracking sensor. Femoral head translations were measured simultaneously. The tests were repeated after resection of the LT. The capsule was left intact for all test conditions. The results were compared between intact and LT resected conditions when torque of 2 and 4Nm was applied. Compared with the intact hip, the LT resected hip showed no significant difference when 2Nm torque was applied in all scenarios. With 4 Nm torque application, significant increase in external rotation was found at 60° and at 90° of flexion (1.7° ± 0.8° and 2.1° ± 1.0°, respectively). Significant difference was also noted at 60°, 90°, and 110° of flexion when the hip was in the adducted position while at 90° in the abducted hip. However, LT resection did not show significant change in internal rotation. There was no significant difference in the translation distance of the femoral head in the intact hip compared with the LT resected hip (0.77-1.11mm vs 0.79-1.29mm). Our results indicate that within the physiologic range of motion, LT can minimally limit external rotation when the hip is in the flexed position but does not contribute to translation stability. In the hip with intact capsule, LT deficiency can result in a slight increase in range of motion, but its contribution to stability is questionable.

ANALYSIS OF RESULTS OF THE INTERVERTEBRAL TOTAL DISK ARTHROPLASTY OF THE LUMBAR SPINE BY M6-L PROSTHESIS: A MULTICENTER STUDY

Background: Pain in the lower back is an urgent health issue in industrialized countries. The dominant cause of pain in the lumbosacral spine is the degeneration of the inter vertebral discs (I VD). The total prosthetics I VD is a modern method of surgical treatment of I VD degenerative diseases, an alternative method of rigid stabilization.Aim: To analyze the results of surgical inter vention (I VD prosthesis M6-L implantation) in patients with I VD degeneration of lumbar spine at the 6, 12, 24, and 36 months after the surger y.Materials and methods: The study included 156 patients (92 men, 64 women) aged 23 to 45 years who under went a single-level discectomy with implantation of an artificial IVD prosthesis M6-L at the bases of three neurosurgical centers. For dynamic assessment, clinical parameters (pain intensity from the visual analogue pain scale (VAS), quality of life according to the Oswestry index, subjective satisfaction with the result of surgical treatment on the Macnab scale) and instrumental data (amplitude of movements in the operated spinal-motor segment, degree of heterotopic ossification according to McAfeeSuchomel classification) were applied at 6, 12, 24, and 36 months after surger y.Results: The mean value of the quality of life for the Oswestr y index before surger y was 40.2±6.9%, after ― 12.3±6.1% (t-test, p0.001). The mean value of the level of pain according to VAS before surger y was 6.9±1.6 cm; after surger y ― 1.3±1.2 cm (t-test, p0.001). The average range of motion in the operated segment at baseline was 36.8±2.6°, within 36 months after the operation increased up to 41.2±2.9°. During the entire period of obser vation the initial (13.4%) or moderate (10.2%) signs of heterotopic ossification were revealed. Conclusions: The use of prosthetic I VD M6-L can significantly reduce the level of pain, improve the life quality, and maintain the physiological range of motion in the operated spinal motion segment with a low level of adverse outcomes.

Incorporating ligament laxity in a finite element model for the upper cervical spine

Background ContextPredicting physiological range of motion (ROM) using a finite element (FE) model of the upper cervical spine requires the incorporation of ligament laxity. The effect of ligament laxity can be observed only on a macro level of joint motion and is lost once ligaments have been dissected and preconditioned for experimental testing. As a result, although ligament laxity values are recognized to exist, specific values are not directly available in the literature for use in FE models. PurposeThe purpose of the current study is to propose an optimization process that can be used to determine a set of ligament laxity values for upper cervical spine FE models. Furthermore, an FE model that includes ligament laxity is applied, and the resulting ROM values are compared with experimental data for physiological ROM, as well as experimental data for the increase in ROM when a Type II odontoid fracture is introduced. Design/SettingThe upper cervical spine FE model was adapted from a 50th percentile male full-body model developed with the Global Human Body Models Consortium (GHBMC). FE modeling was performed in LS-DYNA and LS-OPT (Livermore Software Technology Group) was used for ligament laxity optimization. MethodsOrdinate-based curve matching was used to minimize the mean squared error (MSE) between computed load-rotation curves and experimental load-rotation curves under flexion, extension, and axial rotation with pure moment loads from 0 to 3.5 Nm. Lateral bending was excluded from the optimization because the upper cervical spine was considered to be primarily responsible for flexion, extension, and axial rotation. Based on recommendations from the literature, four varying inputs representing laxity in select ligaments were optimized to minimize the MSE. Funding was provided by the Natural Sciences and Engineering Research Council of Canada as well as GHMBC. The present study was funded by the Natural Sciences and Engineering Research Council of Canada to support the work of one graduate student. There are no conflicts of interest to be reported. ResultsThe MSE was reduced to 0.28 in the FE model with optimized ligament laxity compared with an MSE 0f 4.16 in the FE model without laxity. In all load cases, incorporating ligament laxity improved the agreement between the ROM of the FE model and the ROM of the experimental data. The ROM for axial rotation and extension was within one standard deviation of the experimental data. The ROM for flexion and lateral bending was outside one standard deviation of the experimental data, but a compromise was required to use one set of ligament laxity values to achieve a best fit to all load cases. Atlanto-occipital motion was compared as a ratio to overall ROM, and only in extension did the inclusion of ligament laxity not improve the agreement. After a Type II odontoid fracture was incorporated into the model, the increase in ROM was consistent with experimental data from the literature. ConclusionsThe optimization approach used in this study provided values for ligament laxities that, when incorporated into the FE model, generally improved the ROM response when compared with experimental data. Successfully modeling a Type II odontoid fracture showcased the robustness of the FE model, which can now be used in future biomechanics studies.

Force Depression in Plantar Flexors Exists Equally in Plantar Flexed and Dorsiflexed Regions.

Isometric muscle force attained during isometric contractions decreases after active shortening compared to that attained during purely isometric contractions. This phenomenon is called residual force depression. The aim of this study was to examine whether residual force depression occurs in human plantar flexors in both plantar flexed and dorsiflexed region. In addition, the magnitude of fascicle shortening was evaluated because not only muscle force but also fascicle shortening during active shortening are considered to affect force depression. Eleven male subjects were recruited. All muscle contractions were evoked by muscle belly-electrical stimulation. In the reference trials, isometric plantar flexion (PF) was performed at 0° and 15° of PF. In the residual force depression trials, the following two contractions were conducted: (1) muscles were activated isometrically at 15° of dorsiflexion, then actively shortened to 0° of PF (long condition) and (2) muscles were activated isometrically at 0° of PF, then actively shortened to 15° of PF (short condition). Isometric joint torque obtained 4.9 s after the onset of contraction was compared between the reference and residual force depression trials at the same joint angle to calculate the magnitude of residual force depression. At the same time point, fascicle length and pennation angle were obtained from ultrasonographic images to examine whether the muscle architecture affected residual force depression. As a result, residual force depression was confirmed in both the long and short length conditions (long: 87.1 ± 9.1%, short: 92.1 ± 7.8%) while the magnitude was not different (p = 0.182). The fascicle length and pennation angle were not different between the reference and residual force depression trials (p = 0.291–0.906). These results indicate that residual force depression occurs in the physiological range of motion in the human plantar flexors, and this phenomenon is not related to muscle architecture. In addition, joint angle dependence of the residual force depression was not observed between long and short muscle length conditions.