-
Experimental Brain Research Mar 2011To better understand normative behavior for quantitative evaluation of motor recovery after injury, we studied arm movements by non-injured rhesus monkeys during a...
To better understand normative behavior for quantitative evaluation of motor recovery after injury, we studied arm movements by non-injured rhesus monkeys during a food-retrieval task. While seated, monkeys reached, grasped, and retrieved food items. We recorded three-dimensional kinematics and muscle activity, and used inverse dynamics to calculate joint moments due to gravity, segmental interactions, and to the muscles and tissues of the arm. Endpoint paths showed curvature in three dimensions, suggesting that maintaining straight paths was not an important constraint. Joint moments were dominated by gravity. Generalized muscle and interaction moments were less than half of the gravitational moments. The relationships between shoulder and elbow resultant moments were linear during both reach and retrieval. Although both reach and retrieval required elbow flexor moments, an elbow extensor (triceps brachii) was active during both phases. Antagonistic muscles of both the elbow and hand were co-activated during reach and retrieval. Joint behavior could be described by lumped-parameter models analogous to torsional springs at the joints. Minor alterations to joint quasi-stiffness properties, aided by interaction moments, result in reciprocal movements that evolve under the influence of gravity. The strategies identified in monkeys to reach, grasp, and retrieve items will allow the quantification of prehension during recovery after a spinal cord injury and the effectiveness of therapeutic interventions.
Topics: Animals; Arm; Biomechanical Phenomena; Elbow Joint; Electromyography; Gravitation; Hand; Hand Strength; Joints; Macaca mulatta; Muscle Contraction; Muscle, Skeletal; Neuropsychological Tests; Orientation; Psychomotor Performance; Range of Motion, Articular; Shoulder Joint; Space Perception; Vision, Ocular
PubMed: 21170707
DOI: 10.1007/s00221-010-2514-x -
Journal of Biomechanics Jun 2020Changes in human balance control can objectively be assessed using system identification techniques in combination with support surface translations. However, large,...
Changes in human balance control can objectively be assessed using system identification techniques in combination with support surface translations. However, large, expensive and complex motion platforms are required, which are not suitable for the clinic. A treadmill could be a simple alternative to apply support surface translations. In this paper we first validated the estimation of the joint stiffness of an inverted pendulum using system identification methods in combination with support surface translations, by comparison with the joint stiffness calculated using a linear regression method. Second, we used the system identification method to investigate the effect of horizontal ground reaction forces on the estimation of the ankle torque and the dynamics of the stabilizing mechanism of 12 healthy participants. Ankle torque and resulting frequency response functions, which describes the dynamics of the stabilizing mechanism, were calculated by both including and excluding horizontal ground reaction forces. Results showed that the joint stiffness of an inverted pendulum estimated using system identification is comparable to the joint stiffness estimated by a regression method. Secondly, within the induced body sway angles, the ankle torque and frequency response function of the joint dynamics calculated by both including and excluding horizontal ground reaction forces are similar. Therefore, the horizontal ground reaction forces play a minor role in calculating the ankle torque and frequency response function of the dynamics of the stabilizing mechanism and can thus be omitted.
Topics: Ankle; Ankle Joint; Biomechanical Phenomena; Humans; Torque
PubMed: 32517986
DOI: 10.1016/j.jbiomech.2020.109813 -
The Journal of Experimental Biology Nov 2010Articular cartilage is the soft tissue that covers contacting surfaces of bones in synovial joints. Cartilage is composed of chondrocytes and an extracellular matrix...
Articular cartilage is the soft tissue that covers contacting surfaces of bones in synovial joints. Cartilage is composed of chondrocytes and an extracellular matrix containing numerous biopolymers, cations and water. Healthy cartilage functions biomechanically to provide smooth and stable joint movement. Degenerative joint diseases such as osteoarthritis involve cartilage deterioration, resulting in painful and cumbersome joint motion. Temperature is a fundamental quantity in mechanics, yet the effects of temperature on cartilage mechanical behavior are unknown. This study addressed the questions of whether cartilage stiffness and stress relaxation change with temperature. Samples of middle-zone bovine calf patellofemoral cartilage were tested in unconfined compression first at 24°C and then again after heating to 60°C. The data reveal that when temperature increases: (1) both peak and equilibrium stiffness increase by 150 and 8%, respectively, and (2) stress relaxation is faster at higher temperature, as shown by a 60% decrease in the time constant. The increases in temperature-dependent stiffness are consistent with polymeric mechanisms of matrix viscoelasticity but not with interstitial fluid flow. The changes in the time constant are consistent with a combination of both fluid flow and matrix viscoelasticity. Furthermore, we discovered a novel phenomenon: at stress-relaxation equilibrium, compressive stress increased with temperature. These data demonstrate a rich area of cartilage mechanics that has previously been unexplored and emphasize the role of polymer dynamics in cartilage viscoelasticity. Further studies of cartilage polymer dynamics may yield additional insight into mechanisms of cartilage material behavior that could improve treatments for cartilage degeneration.
Topics: Animals; Biomechanical Phenomena; Cartilage, Articular; Cattle; Compressive Strength; Elasticity; Humans; In Vitro Techniques; Osteoarthritis; Stress, Mechanical; Temperature; Viscosity
PubMed: 21037073
DOI: 10.1242/jeb.042960 -
Archives of Oral Biology Apr 2016The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to...
OBJECTIVE
The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs.
DESIGN
Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs.
RESULTS
Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface.
CONCLUSIONS
The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering.
Topics: Age Factors; Animals; Biomechanical Phenomena; Cell Count; Elastic Modulus; Extracellular Matrix; Female; Models, Animal; Swine; Temporomandibular Joint Disc; Temporomandibular Joint Disorders; Tissue Engineering
PubMed: 26774186
DOI: 10.1016/j.archoralbio.2016.01.003 -
Molecules (Basel, Switzerland) Jun 2023Most injectable preparations for the articular cavity are solution-type preparations that are frequently administered because of rapid elimination. In this study,...
Most injectable preparations for the articular cavity are solution-type preparations that are frequently administered because of rapid elimination. In this study, triptolide (TPL), an effective ingredient in the treatment of rheumatoid arthritis (RA), was prepared in the form of a nanoparticle thermosensitive gel (TPL-NS-Gel). The particle size distribution and gel structure were investigated by TEM, laser particle size analysis and laser capture microdissection. The effect of the nanoparticle carrier material PLGA on the phase transition temperature was investigated by H variable temperature NMR and DSC. The tissue distribution, pharmacokinetic behavior, four inflammatory factors and therapeutic effect were determined in a rat RA model. The results suggested that PLGA increased the gel phase transition temperature. The drug concentration of the TPL-NS-Gel group in joint tissues was higher than that in other tissues at different time points, and the retention time was longer than that of the TPL-NS group. After 24 days of administration, TPL-NS-Gel significantly improved the joint swelling and stiffness of the rat models, and the improvement degree was better than that of the TPL-NS group. TPL-NS-Gel significantly decreased the levels of hs-CRP, IL-1, IL-6 and TNF-α in serum and joint fluid. There was a significant difference between the TPL-NS-Gel and TPL-NS groups on Day 24 ( < 0.05). Pathological section results showed that inflammatory cell infiltration was lower in the TPL-NS-Gel group, and no other obvious histological changes were observed. Upon articular injection, the TPL-NS-Gel prolonged drug release, reduced the drug concentration outside the articular tissue and improved the therapeutic effect in a rat RA model. The TPL-NS-Gel can be used as a new type of sustained-release preparation for articular injection.
Topics: Rats; Animals; Joints; Injections, Intra-Articular; Arthritis, Rheumatoid; Nanoparticles
PubMed: 37375214
DOI: 10.3390/molecules28124659 -
Mathematical Biosciences and... Jun 2019Landing is a crucial factor in gymnastics competitions, but the underlying biomechanical and neuromuscular strategies remains unclear. This study aimed to investigate...
Landing is a crucial factor in gymnastics competitions, but the underlying biomechanical and neuromuscular strategies remains unclear. This study aimed to investigate the biomechanical characteristics and neuromuscular strategies of landing for backward somersault. A 19-segment human model was developed and bilateral lower-limb joint loadings were estimated using computer stimulation. Bilateral lower-limb joint angles, vertical ground reaction force (vGRF), impulse, joint reaction force, joint torque, power, work, stiffness and electromyogram (EMG) of the rectus femoris, biceps femoris, tibialis anterior, and lateral gastrocnemius were presented during initial (touchdown to peak vGRF) and terminal impact-phases of landing (peak vGRF to vGRF equaling to body weight). The hip, knee, and ankle joints were rapidly flexed (8º, 20º, and 18º, respectively) during initial impact-phase and maintained at around 90º, 120º, and 60º, respectively terminal impact-phase. Flexor and extensor torques were demonstrated for lower-limb joints during initial and terminal impact-phases, respectively. The stiffness of lower limb joints and the EMGs amplitude of all examined muscles during terminal impact-phase were several times larger than that during initial impact-phase. The absolute symmetry indexes were less than 10% for lower limb joint angles and larger than 10% for the kinetics and muscle activation. The findings demonstrated symmetrical motion for lower limb joints with flexing rapidly at initial impact-phase and maintaining unchanged at terminal impact-phase and asymmetry in joint loading and muscle activation during landing.
Topics: Adolescent; Ankle Joint; Anthropometry; Biomechanical Phenomena; Computer Simulation; Electromyography; Gymnastics; Hamstring Muscles; Humans; Imaging, Three-Dimensional; Joints; Knee Joint; Male; Models, Anatomic; Movement; Quadriceps Muscle; Stress, Mechanical; Weight-Bearing
PubMed: 31499742
DOI: 10.3934/mbe.2019293 -
Journal of Spinal Disorders & Techniques Apr 2015An in vitro biomechanical study for rabbit lumbar functional spinal units (FSUs) using a robot-based spine testing system.
STUDY DESIGN
An in vitro biomechanical study for rabbit lumbar functional spinal units (FSUs) using a robot-based spine testing system.
OBJECTIVE
To elucidate the effect of annular puncture with a 16 G needle on mechanical properties in flexion/extension, axial rotation, and lateral bending.
SUMMARY OF BACKGROUND DATA
Needle puncture of the intervertebral disk has been shown to alter mechanical properties of the disk in compression, torsion, and bending. The effect of needle puncture in FSUs, where intact spinal ligaments and facet joints may mitigate or amplify these changes in the disk, on spinal motion segment stability subject to physiological rotations remains unknown.
METHODS
Rabbit FSUs were tested using a robot testing system whose force/moment and position precision were assessed to demonstrate system capability. Flexibility testing methods were developed by load-to-failure testing in flexion/extension, axial rotation, and lateral bending. Subsequent testing methods were used to examine a 16 G needle disk puncture and No. 11 blade disk stab (positive control for mechanical disruption). Flexibility testing was used to assess segmental range-of-motion (degrees), neutral zone stiffness (N m/degrees) and width (degrees and N m), and elastic zone stiffness before and after annular injury.
RESULTS
The robot-based system was capable of performing flexibility testing on FSUs-mean precision of force/moment measurements and robot system movements were <3% and 1%, respectively, of moment-rotation target values. Flexibility moment targets were 0.3 N m for flexion and axial rotation and 0.15 N m for extension and lateral bending. Needle puncture caused significant (P<0.05) changes only in flexion/extension range-of-motion and neutral zone stiffness and width (N m) compared with preintervention. No. 11 blade-stab significantly increased range-of-motion in all motions, decreased neutral zone stiffness and width (N m) in flexion/extension, and increased elastic zone stiffness in flexion and lateral bending.
CONCLUSIONS
These findings suggest that disk puncture and stab can destabilize FSUs in primary rotations.
Topics: Animals; Biomechanical Phenomena; Female; In Vitro Techniques; Intervertebral Disc; Lumbar Vertebrae; Needles; Punctures; Rabbits; Range of Motion, Articular; Rotation; Zygapophyseal Joint
PubMed: 25370985
DOI: 10.1097/BSD.0000000000000196 -
Journal of Orthopaedic Surgery and... Feb 2017This study sought to determine whether several metatarsophalangeal (MTP) fusion techniques require complete immobilization or if some level of weight-bearing could be...
BACKGROUND
This study sought to determine whether several metatarsophalangeal (MTP) fusion techniques require complete immobilization or if some level of weight-bearing could be recommended after surgery. A comparison of synthetic composite to actual bone was included in order to examine the validity of the testing conditions.
METHODS
Four MTP fusion modalities were tested in synthetic composite bone models: unlocked plating, locked plating, crossed lag screws, and an unlocked plate with a single lag screw. Stiffness was calculated and then used to find the two most rigid constructs; the load to failure was recorded. Stiffness and load to failure testing for the two more rigid constructs in paired cadaveric bones were followed.
RESULTS
The unlocked plate plus screw and crossed screw constructs were stiffest (p < 0.008). Loads to failure of the unlocked plate plus screw and crossed screws in synthetic bone were 131 and 101 N, respectively and in cadaveric bone were 154 and 94 N, respectively, which are less than the estimated 25% body weight required at the MTP joint. The plate plus screws were statistically more stiff than crossed screws (p = 0.008), but there was no statistical difference between synthetic and cadaveric bone in load to failure (p = 0.296).
CONCLUSIONS
The plate plus screw offered the greatest stiffness; the failure test showed that no construct could withstand weight-bearing as tolerated; and, synthetic composite models of the MTP joint did not provide the consistent results in stiffness and failure.
Topics: Aged; Aged, 80 and over; Arthrodesis; Biomechanical Phenomena; Bone Plates; Bone Screws; Female; Humans; Male; Metatarsophalangeal Joint; Middle Aged; Weight-Bearing
PubMed: 28166805
DOI: 10.1186/s13018-017-0525-z -
Journal of Neurophysiology Jul 2019Humans have an astonishing ability to extract hidden information from the movements of others. For example, even with limited kinematic information, humans can...
Humans have an astonishing ability to extract hidden information from the movements of others. For example, even with limited kinematic information, humans can distinguish between biological and nonbiological motion, identify the age and gender of a human demonstrator, and recognize what action a human demonstrator is performing. It is unknown, however, whether they can also estimate hidden mechanical properties of another's limbs simply by observing their motions. Strictly speaking, identifying an object's mechanical properties, such as stiffness, requires contact. With only motion information, unambiguous measurements of stiffness are fundamentally impossible, since the same limb motion can be generated with an infinite number of stiffness values. However, we show that humans can readily estimate the stiffness of a simulated limb from its motion. In three experiments, we found that participants linearly increased their rating of arm stiffness as joint stiffness parameters in the arm controller increased. This was remarkable since there was no physical contact with the simulated limb. Moreover, participants had no explicit knowledge of how the simulated arm was controlled. To successfully map nontrivial changes in multijoint motion to changes in arm stiffness, participants likely drew on prior knowledge of human neuromotor control. Having an internal representation consistent with the behavior of the controller used to drive the simulated arm implies that this control policy competently captures key features of veridical biological control. Finding that humans can extract latent features of neuromotor control from kinematics also provides new insight into how humans interpret the motor actions of others. Humans can visually perceive another's overt motion, but it is unknown whether they can also perceive the hidden dynamic properties of another's limbs from their motions. Here, we show that humans can correctly infer changes in limb stiffness from nontrivial changes in multijoint limb motion without force information or explicit knowledge of the underlying limb controller. Our findings suggest that humans presume others control motor behavior in such a way that limb stiffness influences motion.
Topics: Adult; Female; Humans; Joints; Male; Motion Perception; Pattern Recognition, Visual; Range of Motion, Articular
PubMed: 31017844
DOI: 10.1152/jn.00514.2018 -
Bone Dec 2015Reduced functional loads cause adaptations in organs. In this study, temporal adaptations of bone-ligament-tooth fibrous joints to reduced functional loads were mapped...
Reduced functional loads cause adaptations in organs. In this study, temporal adaptations of bone-ligament-tooth fibrous joints to reduced functional loads were mapped using a holistic approach. Systematic studies were performed to evaluate organ-level and tissue-level adaptations in specimens harvested periodically from rats (N=60) given powder food for 6 months over 8,12,16,20, and 24 weeks. Bone-periodontal ligament (PDL)-tooth fibrous joint adaptation was evaluated by comparing changes in joint stiffness with changes in functional space between the tooth and alveolar bony socket. Adaptations in tissues included mapping changes in the PDL and bone architecture as observed from collagen birefringence, bone hardness and volume fraction in rats fed soft foods (soft diet, SD) compared to those fed hard pellets as a routine diet (hard diet, HD). In situ biomechanical testing on harvested fibrous joints revealed increased stiffness in SD groups (SD:239-605 N/mm) (p<0.05) at 8 and 12 weeks. Increased joint stiffness in early development phase was due to decreased functional space (at 8 weeks change in functional space was -33 μm, at 12 weeks change in functional space was -30 μm) and shifts in tissue quality as highlighted by birefringence, architecture and hardness. These physical changes were not observed in joints that were well into function, that is, in rodents older than 12 weeks of age. Significant adaptations in older groups were highlighted by shifts in bone growth (bone volume fraction 24 weeks: Δ-0.06) and bone hardness (8 weeks: Δ-0.04 GPa, 16 weeks: Δ-0.07 GPa, 24 weeks: Δ-0.06 GPa). The response rate (N/s) of joints to mechanical loads decreased in SD groups. Results from the study showed that joint adaptation depended on age. The initial form-related adaptation (observed change in functional space) can challenge strain-adaptive nature of tissues to meet functional demands with increasing age into adulthood. The coupled effect between functional space in the bone-PDL-tooth complex and strain-adaptive nature of tissues is necessary to accommodate functional demands, and is temporally sensitive despite joint malfunction. From an applied science perspective, we propose that adaptations are registered as functional history in tissues and joints.
Topics: Animals; Biomechanical Phenomena; Dental Cementum; Joints; Male; Mastication; Periodontal Ligament; Rats; Rats, Sprague-Dawley; Tooth
PubMed: 26151121
DOI: 10.1016/j.bone.2015.07.004