1.A Biomechanical Comparison of Intralaminar C7 Screw Constructs with and without Offset Connector Used for C6-7 Cervical Spine Immobilization : A Finite Element Study.
Muhammad QASIM ; Jae Taek HONG ; Raghu N NATARAJAN ; Howard S AN
Journal of Korean Neurosurgical Society 2013;53(6):331-336
OBJECTIVE: The offset connector can allow medial and lateral variability and facilitate intralaminar screw incorporation into the construct. The aim of this study was to compare the biomechanical characteristics of C7 intralaminar screw constructs with and without offset connector using a three dimensional finite element model of a C6-7 cervical spine segment. METHODS: Finite element models representing C7 intralaminar screw constructs with and without the offset connector were developed. Range of motion (ROM) and maximum von Mises stresses in the vertebra for the two techniques were compared under pure moments in flexion, extension, lateral bending and axial rotation. RESULTS: ROM for intralaminar screw construct with offset connector was less than the construct without the offset connector in the three principal directions. The maximum von Misses stress was observed in the C7 vertebra around the pedicle in both constructs. Maximum von Mises stress in the construct without offset connector was found to be 12-30% higher than the corresponding stresses in the construct with offset connector in the three principal directions. CONCLUSION: This study demonstrated that the intralaminar screw fixation with offset connector is better than the construct without offset connector in terms of biomechanical stability. Construct with the offset connector reduces the ROM of C6-7 segment more significantly compared to the construct without the offset connector and causes lower stresses around the C7 pedicle-vertebral body complex.
Biomechanics
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Immobilization
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Range of Motion, Articular
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Spine
2.The Effect of Lifting Speed on Cumulative and Peak Biomechanical Loading for Symmetric Lifting Tasks.
Kasey O GREENLAND ; Andrew S MERRYWEATHER ; Donald S BLOSWICK
Safety and Health at Work 2013;4(2):105-110
BACKGROUND: To determine the influence of lifting speed and type on peak and cumulative back compressive force (BCF) and shoulder moment (SM) loads during symmetric lifting. Another aim of the study was to compare static and dynamic lifting models. METHODS: Ten male participants performed a floor-to-shoulder, floor-to-waist, and waist-to-shoulder lift at three different speeds [slow (0.34 m/s), medium (0.44 m/s), and fast (0.64 m/s)], and with two different loads [light (2.25 kg) and heavy (9 kg)]. Two-dimensional kinematics and kinetics were determined. A three-way repeated measures analysis of variance was used to calculate peak and cumulative loading of BCF and SM for light and heavy loads. RESULTS: Peak BCF was significantly different between slow and fast lifting speeds (p < 0.001), with a mean difference of 20% between fast and slow lifts. The cumulative loading of BCF and SM was significantly different between fast and slow lifting speeds (p < 0.001), with mean differences > or =80%. CONCLUSION: Based on peak values, BCF is highest for fast speeds, but the BCF cumulative loading is highest for slow speeds, with the largest difference between fast and slow lifts. This may imply that a slow lifting speed is at least as hazardous as a fast lifting speed. It is important to consider the duration of lift when determining risks for back and shoulder injuries due to lifting and that peak values alone are likely not sufficient.
Biomechanics
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Humans
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Kinetics
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Lifting*
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Male
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Shoulder
3.Biomechanics of the Elbow.
Journal of the Korean Shoulder and Elbow Society 2010;13(1):141-145
PURPOSE: Understanding elbow biomechanics is necessary to understand the pathophysiologic mechanism of elbow injury and to provide a scientific basis for clinical practice. This article provides a summary of key concepts that are relevant to understanding common elbow injuries and their management. MATERIALS AND METHODS: The biomechanics of the elbow joint can be divided into kinematics, stability and force transmission through the elbow joint. Active and passive stabilizers include bony articular geometry; soft tissues provide joint stability, compression force and motion. RESULTS AND CONCLUSION: Knowledge of elbow biomechanics will help (i) advance surgical procedures and trauma management, (ii) develop new elbow prostheses and (iii) stimulate future research.
Biomechanics
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Elbow
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Elbow Joint
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Elbow Prosthesis
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Joints
4.Biomechanical Evaluation of a Novel Posterior Integrated Clamp That Attaches to an Existing Posterior Instrumentation for Use in Thoracolumbar Revision.
Patrick SENATUS ; Suresh Reddy CHINTHAKUNTA ; Pedram VAZIFEH ; Saif KHALIL
Asian Spine Journal 2013;7(1):1-7
STUDY DESIGN: An in vitro biomechanical study. PURPOSE: To evaluate the biomechanics of a novel posterior integrated clamp (IC) that extends on an already implanted construct in comparison to single long continuous bilateral pedicle screw (BPS) and rod stabilization system. OVERVIEW OF LITERATURE: Revision surgery in the thoracolumbar spine often necessitates further instrumentation following a failed previous back surgery. Stability of these reconstructed constructs is not known. METHODS: Six osteoligamentous T12-L5 calf spines were tested on a spine motion simulator in the following configurations: intact, four level constructs (T13-L4), three level constructs (L1-L4), and two level constructs (L2-L4), by varying the ratio between BPS and IC. A load control protocol of 8 Nm moments was applied at a rate of 1degrees/sec to establish the range of motion value for each construct in flexion-extension, lateral bending, and axial rotation. Statistical analysis was performed on raw data using repeated measures analysis of variance and significance was set at p<0.05. RESULTS: On an average, the reduction in motion for the four level continuous pedicle screw and rod construct (67%) was similar to those extended with integrated clamps (64%). Furthermore, for three level and two level constructs, no significant difference was observed between continuous pedicle screw constructs and those revised with the integrated clamps (regardless of the ratio between BPS and IC). CONCLUSIONS: The novel posterior IC showed equivalent biomechanical rigidity to continuous pedicle screw rod constructs in revision scenarios. Clinical studies on posterior rod adjunct systems are necessary to confirm these results.
Biomechanics
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Bone Screws
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Range of Motion, Articular
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Reoperation
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Spine
5.Morphometric Measurements of Cadaveric Thoracic Spine in Indian Population and Its Clinical Applications.
Roop SINGH ; Sunil Kumar SRIVASTVA ; Chittode Sachudanandam Vishnu PRASATH ; Rajesh Kumar ROHILLA ; Ramchander SIWACH ; Narender Kumar MAGU
Asian Spine Journal 2011;5(1):20-34
STUDY DESIGN: Analysis of morphometric data obtained from direct measurements of 100 cadaveric thoracic spines in Indian population. PURPOSE: To collect a base line morphometric data and analyze it in reference to the musculoskeletal anatomy and biomechanics of the spine; implants and instrumentations; and to suggest the requisite modification in spinal surgery instrumentations. OVERVIEW OF LITERATURE: Most of the previous studies in the world literature have focused primarily on the parameters of the pedicle and to the authors' knowledge; no study has been published from the Indian subcontinent reporting a detailed morphometry of the thoracic spine. METHODS: One thousand and two hundred thoracic vertebrae were studied by direct measurements for linear and angular dimensions of the vertebral body, spinal canal, pedicle, and spinous and transverse processes in 100 human cadavers. RESULTS: Thirty-five point five percent of all the pedicles; 71% of T5 pedicles; 54.6% of all the female pedicles; and 94.4% of the T5 pedicles in females were smaller than 5 mm in mid-pedicle width dimension. Transverse pedicle angle was more at all levels and pedicles were sagittaly angulated in cephalad direction in comparison to other studies. Minimum value of interpedicular distance was at T5 (15.48 +/- 1.24). Vertebral body width showed slight decrease from T1 to T4. The transverse process length was relatively constant between T2 to T10. The spinous process angle showed increasing trend from T1 to T6 and then gradually decreased to T12. CONCLUSIONS: Most of the trends in changes of the parameters from T1 to T12 can be explained on the basis of local musculoskeletal anatomy and biomechanical stresses. The smallest diameter screw and shortest available screw for adults may not be safe in majority of the Indian population in mid-thoracic region. The results of the present study can help in designing implants and instrumentations; understanding spine pathologies; and management of spinal disorders in this part of the world.
Adult
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Biomechanics
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Cadaver
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Female
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Humans
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Spinal Canal
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Spine
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Thoracic Vertebrae
6.The Accuracy of the Swallowing Kinematic Analysis at Various Movement Velocities of the Hyoid and Epiglottis.
Seung Hak LEE ; Byung Mo OH ; Seong Min CHUN ; Jung Chan LEE ; Yusun MIN ; Sang Heum BANG ; Hee Chan KIM ; Tai Ryoon HAN
Annals of Rehabilitation Medicine 2013;37(3):320-327
OBJECTIVE: To evaluate the accuracy of the swallowing kinematic analysis. METHODS: To evaluate the accuracy at various velocities of movement, we developed an instrumental model of linear and rotational movement, representing the physiologic movement of the hyoid and epiglottis, respectively. A still image of 8 objects was also used for measuring the length of the objects as a basic screening, and 18 movie files of the instrumental model, taken from videofluoroscopy with different velocities. The images and movie files were digitized and analyzed by an experienced examiner, who was blinded to the study. RESULTS: The Pearson correlation coefficients between the measured and instrumental reference values were over 0.99 (p<0.001) for all of the analyses. Bland-Altman plots showed narrow ranges of the 95% confidence interval of agreement between the measured and reference values as follows: 0.14 to 0.94 mm for distances in a still image, -0.14 to 1.09 mm/s for linear velocities, and -1.02 to 3.81 degree/s for angular velocities. CONCLUSION: Our findings demonstrate that the distance and velocity measurements obtained by swallowing kinematic analysis are highly valid in a wide range of movement velocity.
Biomechanics
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Deglutition
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Epiglottis
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Mass Screening
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Reference Values
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Reproducibility of Results
7.Tendon Transfer for Irreparable Massive Rotator Cuff Tear.
Jae K YUM ; Hee Sung LEE ; Sung Bum PARK
Journal of the Korean Shoulder and Elbow Society 2010;13(1):161-166
PURPOSE: Irreparable massive rotator cuff tears pose a distinct clinical challenge for the orthopaedist and non-surgical treatment has had inconsistent results and proven unsuccessful for chronic symptoms, while surgery, including debridement and partial and complete repairs have had varying degrees of success. MATERIALS AND METHODS: For rotator cuff tears that are deemed irreparable, treatment options are limited. RESULTS AND CONCLUSION: The use of tendon transfers (latissimus dorsi for posterosuperior type cuff defects and pectoralis major for subscapularis defects) in younger patients to reconstruct rotator cuffs and re-establish function and restore shoulder kinematics can be useful in solving this difficult problem.
Biomechanics
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Debridement
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Humans
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Rotator Cuff
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Shoulder
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Tendon Transfer
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Tendons
8.Effect of microthreads on removal torque and bone-to-implant contact: an experimental study in miniature pigs.
Yee Seo KWON ; Hee NAMGOONG ; Jung Hoon KIM ; In Hee CHO ; Myung Duk KIM ; Tae Gwan EOM ; Ki Tae KOO
Journal of Periodontal & Implant Science 2013;43(1):41-46
PURPOSE: The objective of this study was to evaluate the effect of microthreads on removal torque and bone-to-implant contact (BIC). METHODS: Twelve miniature pigs for each experiment, a total of 24 animals, were used. In the removal torque analysis, each animal received 2 types of implants in each tibia, which were treated with sandblasting and acid etching but with or without microthreads at the marginal portion. The animals were sacrificed after 4, 8, or 12 weeks of healing. Each subgroup consisted of 4 animals, and the tibias were extracted and removal torque was measured. In the BIC analysis, each animal received 3 types of implants. Two types of implants were used for the removal torque test and another type of implant served as the control. The BIC experiment was conducted in the mandible of the animals. The P1-M1 teeth were extracted, and after a 4-month healing period, 3 each of the 2 types of implants were placed, with one type on each side of the mandible, for a total of 6 implants per animal. The animals were sacrificed after a 2-, 4-, or 8-week healing period. Each subgroup consisted of 4 animals. The mandibles were extracted, specimens were processed, and BIC was analyzed. RESULTS: No significant difference in removal torque value or BIC was found between implants with and without microthreads. The removal torque value increased between 4 and 8 weeks of healing for both types of implants, but there was no significant difference between 8 and 12 weeks. The percentage of BIC increased between 2 and 4 weeks for all types of implants, but there was no significant difference between 4 and 8 weeks. CONCLUSIONS: The existence of microthreads was not a significant factor in mechanical and histological stability.
Animals
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Biomechanics
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Dental Implants
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Mandible
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Osseointegration
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Swine
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Tibia
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Tooth
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Torque
9.In Vivo Biomechanics Using Dual Orthogonal Fluoroscopy after Posterior Stabilized Total Knee Arthroplasty.
Sang Eun PARK ; Jin Young YANG ; Moo Joon LIM
Journal of Korean Orthopaedic Research Society 2009;12(2):76-85
This study investigated the six degrees of freedom (DOF) kinematics and three-dimensional (3D) contact during kneeling after total knee replacement arthroplasty. A total of 16 South Korean female patients (22 knees) after posteriorly stabilized (PS) TKA (LPS-Flex) performed by a single surgeon were randomly recruited. The patients were imaged using a dual fluoroscopic technique while they were kneeling from initial to maximum flexion. The acquired images and 3D models were then used to recreate the in vivo pose of the components Patients flexed their knee, on average, from 107.3degrees to 128.0degrees during the kneeling activity. Changes in kinematics included proximal, medial, posterior translation and varus rotation. Articular contact moved posteriorly by 5.9 mm and 6.4 mm in the medial and lateral compartments, respectively. Contact also moved medially by 3.2 mm and 5.8 mm in the medial and lateral compartments. A decrease in articular contact was observed in both condyles, and lateral condylar lift-off increased with flexion (P=0.0001). The tibiofemoral and cam/post articular contact data acquired in this study further suggest that kneeling may be performed by patients after clinically successful PS TKA who feel comfortable with activity and are free of
Arthroplasty
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Arthroplasty, Replacement, Knee
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Biomechanics
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Female
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Fluoroscopy
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Freedom
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Humans
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Knee
10.Correction of dental Class III with posterior open bite by simple biomechanics using an anterior C-tube miniplate.
Hyo Won AHN ; Kyu Rhim CHUNG ; Suk Man KANG ; Lu LIN ; Gerald NELSON ; Seong Hun KIM
The Korean Journal of Orthodontics 2012;42(5):270-278
In the correction of dental Class III molar relationship in skeletal Class II patients, uprighting of the mandibular posterior segments without opening the mandible is an important treatment objective. In the case reported herein, a C-tube miniplate fixed to the lower labial symphysis and connected with a nickel-titanium reverse-curved archwire provided effective uprighting of the lower molars, without the need of orthodontic appliances on the mandibular anteriors. Using this approach, an appropriate magnitude of force is exerted on the molars while avoiding any negative effect on the mandibular anteriors.
Biomechanics
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Humans
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Mandible
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Molar
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Open Bite
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Orthodontic Appliances
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Recurrence