• Journal of Korean Neurosurgical Society
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• v.58 no.5
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• pp.412-418
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• 2015

Objective : To investigate the effects of posterior implant rigidity on spinal kinematics at adjacent levels by utilizing a cadaveric spine model with simulated physiological loading. Methods : Five human lumbar spinal specimens (L3 to S1) were obtained and checked for abnormalities. The fresh specimens were stripped of muscle tissue, with care taken to preserve the spinal ligaments and facet joints. Pedicle screws were implanted in the L4 and L5 vertebrae of each specimen. Specimens were tested under 0 N and 400 N axial loading. Five different posterior rods of various elastic moduli (intact, rubber, low-density polyethylene, aluminum, and titanium) were tested. Segmental range of motion (ROM), center of rotation (COR) and intervertebral disc pressure were investigated. Results : As the rigidity of the posterior rods increased, both the segmental ROM and disc pressure at L4-5 decreased, while those values increased at adjacent levels. Implant stiffness saturation was evident, as the ROM and disc pressure were only marginally increased beyond an implant stiffness of aluminum. Since the disc pressures of adjacent levels were increased by the axial loading, it was shown that the rigidity of the implants influenced the load sharing between the implant and the spinal column. The segmental CORs at the adjacent disc levels translated anteriorly and inferiorly as rigidity of the device increased. Conclusion : These biomechanical findings indicate that the rigidity of the dynamic stabilization implant and physiological loading play significant roles on spinal kinematics at adjacent disc levels, and will aid in further device development.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1495-1496
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• 2013

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.137-144
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• 2010

In general, spinal fusion surgery takes pressure off the pain induced nerves, by restoring the alignment of the spine. Therefore spinal fixation system is used to maintain the alignment of spine. In this study, a biomechanical study was performed comparing the SROM(Spinal Range Of Motion) of three types of system such as Rigid, Dynesys, and Fused system to analyze the behavior of spinal fixation system inserted in vertebra. Dynesys system, a flexible posterior stabilization system that provides an alternative to fusion, is designed to preserve inter-segmental kinematics and alleviate loading at the facet joints. In this study, SROM of inter-vertebra with spinal fixation system installed in the virtual vertebra from L4 to S1 is estimated. To compare with spinal fixation system, a simulation was performed by BRG. LifeMOD 2005.5.0 was used to create the human virtual model of spinal fixation system. Through this, each SROM of flexion, extension, lateral bending, and axial rotation of human virtual model was measured. The result demonstrates that the movement of Dynesys system was similar to normal condition through allowing the movement of lumbar.

• Korean Journal of Applied Biomechanics
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• v.29 no.1
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• pp.23-32
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• 2019

Objective: The aim of this study was to provide kinematic data on the characteristics of spinal disease patients by comparing and analyzing kinematic variables related to foot balance and gait pattern of spinal disease. Method: The subjects of the study included 40 adult men and 60 adult women who visited the hospital in Busan. Patients who were diagnosed with spinal disease by a physician through X-ray examination were selected as subjects for the diagnosis of vertebral disc herniation, spinal stenosis, spinal disease diagnosed with spinal disease and the general public. Left and right foot pressure and contact area were checked by Gaitview pro meter. X-ray photographs were taken with a Zen-2090 mobile fluoroscopy under physicians' direct participation. One-way ANOVA was performed to compare the differences between the kinematic variables and post-hoc was performed by the Duncan method. Results: The difference in contact area between the left foot and the right foot was $115.30{\pm}14.15cm^2$ in the left side and $124.25{\pm}13.65cm^2$ in the left side in the spinal disease patients. The difference in pressure between the left and right side of the spinal disease patients was wider than that of the general people. Especially, the right side of the spinal disease patients showed a larger area of left foot contact than the general population. Conclusion: Spinal disease patients have wider contact area of the left foot than those of the general population. In the case of right spinal disease, the left foot support area is widened due to pain. In the gait, women showed slightly more posterior body center than men, and the upper body muscle imbalance and immobilization due to the spinal disease caused imbalance of the muscles moving to the lower limb, It was analyzed to inhibit movement.

• Journal of Biomedical Engineering Research
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• v.27 no.5
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• pp.210-217
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• 2006

Many types of interspinous distraction devices (IDDs) have been recently developed as an alternative surgical treatment to laminectomy and fusion with pedicle screws for the treatment of the lumbar spinal stenosis (LSS). They are intended to keep the lumbar spine in a slightly flexed posture to relieve pain caused by narrowing of the spinal canal and vertebral foramen. However, their biomechanical efficacies are not well known. In this study, we evaluated the kinematic behaviors and changes in intradiscal pressure (IDP) of the porcine lumbar spine implanted with IDD. For kinematics analysis, five porcine lumbar spines (L2-L6) were used and the IDD was inserted at L4-L5. Three markers (${\phi}{\le}0.8mm$) were attached on each vertebra to define a rigid body motion for stereophotogrammetric assessment of the spinal motion in 3-D. A moment of 7.5Nm in flexion-extension, lateral bending, and axial rotation were imparted with a compressive force of 700N. Then, IDD was implanted at L3-L4. IDPs were measured using pressure transducer under compression (700N) and additional extension moment (700N+7.5Nm). In kinematic behaviors, insertion of IDD resulted in statistically significant decrease 42.8% at the implanted level in extension. There were considerable changes in ROM at the adjacent levels, but statistically insignificant. In other motions, there were no significant changes in ROM as well regardless of levels. IDPs at the surgical level (L3-L4) under compression and extension moment decreased by 12.9% and 18.8% respectively after surgery (p<0.05). At the superiorly adjacent levels, IDPs increased by 19.4% and 12.9% under compression and extension, respectively (p<0.05). Corresponding changes at the inferiorly adjacent levels were 29.4% and 6.9%, but they were statistically insignificant (p>0.05). The magnitude of pressure changes due to IDD, both at the operated and adjacent levels, were far less than the previously reported values with conventional fusion techniques. Our experimental results demonstrated the IDDs can be very effective in limiting the extension motion that may cause narrowing of the spinal canal and vertebral foramens while maintaining kinematic behaviors and disc pressures at the adjacent levels.

• Physical Therapy Rehabilitation Science
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• v.10 no.4
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• pp.450-456
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• 2021

Objective: Studies confirming the lumber spine kinematics of direct or indirect segmental mobility under the application of joint mobilization, which induces passive force on the spine, are insufficient.Therefore, this study aims to obtain the underlying clinical data by identifying direct or indirect segmental mobility produced by Maitland's PA mobilization technique. Design: Randomized controlled trial design. Methods: Thirty subjects with no back pain participated in this study. X-ray testing equipment (SIG-40-525, Ecoray Inc., Korea) was used to verify the segmented movement of their lumbar. Joint mobilization was performed by physiotherapists with more than 10 years of experience in prescription therapy, and radiography was performed once without PA joint mobilization and once without the mobilization for comparing the lumbar vertebrae before and after the mobilization. The radiographs taken were analyzed using the picture archiving and communication system (PACS) program to measure the spinal displacement, intervertebral height, intervertebral angle, and lumbar lordosis angle. Results: Significant differences were observed in the lumbar displacement, intervertebral angle, and lumbar lordosis angle in all lumbar vertebrae before and after the mobilization. The intervertebral height indicated significant differences in all ventral vertebrae and only in L3-L4 and L4-L5 in dorsal vertebrae. Conclusions: This study suggests that the segmental mobility produced through indirect approaches plays an important role in inducing therapeutic effects in patients with back pain.

• Journal of Korean Physical Therapy Science
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• v.9 no.1
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• pp.81-88
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• 2002

This paper presents a design and a control of a New Reciprocating Gait Orthosis and dynamic walking simulation for this system. The New Reciprocating Gait Orthosis is distinguished from other one by which has a very light-weight and a new RGO type with servo motors. The gait of a New Reciprocating Gait Orthosis depends on the constrains of mechanical kinematics and initial posture. The stability of dynamic walking is investigated by ZMP(Zero Moment Point) of the New Reciprocating Gait Orthosis. It is designed according to a human wear type and is able to accomodate itself to human environments. The joints of each leg are adopted with a good kinematic characteristics. To test of the analysis of joint kinematic properties, we did the strain stress analysis of dynamic PLS and the study of FEM with a dynamic PLS. It will be expect that the spinal card injury patients are able to train effectively with a Reciprocating Gait Orthosis. The New Reciprocating Gait Orthosis was able to keep smooth walling by the orthotic servo motors and hybrid system, make a sequence of flexion and extension of the joint during the walking. Also, the New Reciprocating Gait Orthosis turned out to be a satisfactory orthosis for walling training, for the spinal cord injury patient.

• Journal of Biomedical Engineering Research
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• v.26 no.3
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• pp.151-155
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• 2005

Interspinous spacers have been developed as an alternative surgical treatment for laminectomy or fusion with pedicle screws and rods for the treatment of lumbar spinal stenosis. However, its biomedical efficacies are well not known. In this study, we evaluated kinematic behaviors of the surgical and the adjacent levels before and after inserting interspinous spacers. Three porcine lumbar spines were prepared. On each specimen, an interspinous spacer was inserted at the L4-L5. Flexion-extension moments (0, 2.5, 5.0, 7.5, 10Nm) were applied. A stereophotogrammetric set-up with DLT algorithm was used to assess the three-dimensional motions of the specimen where three markers $({\square}0.8mm)$ were attached to each vertebra. Results showed that extension motion decreased by $15-24\%$ at the surgical level (L4-L5) after insertion of interspinous spacer. At the adjacent levels, the range of motion remained unchanged. In flexion, no significant changes in motion were observed regardless of levels. Therefore, our experimental results demonstrated the interspinous spacer is very effective in limiting the extension motion that may cause narrowing of the spinal canal and vertebral foramen while maintaining kinematic behaviors at the adjacent levels. Further, these results suggested that the use of interspinous spacer may be able to prevent lower back pain at the surgical level and to lower the incidence of degenerative changes at the adjacent levels.

• Journal of Biomedical Engineering Research
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• v.29 no.2
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• pp.139-145
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• 2008

Many recent studies suggest that the posterior dynamic stabilization(PDS) can be a more physiologically-relevant alternative to the rigid fixation for the patients suffering from low back pain. However, its biomechanical effects or clinically proven efficacies still remain unknown. In this study, we evaluated kinematic behaviors of the lower lumbar spine with the PDS system and then compared to those of the rigid fixation system using finite element (FE) analysis. A validated FE model of intact lumbar spine(L2-L5) was developed. The implanted model was then constructed after modification from the intact to simulate two kinds of pedicle screw systems (PDS and the rigid fixation). Hybrid protocol was used to flex, extend, laterally bend and axially rotate the FE model. Results showed that the PDS systems are more flexible than rigid fixation systems, yet not flexible enough to preserve motion. PDS system allowed $16.2{\sim}42.2%$ more intersegmental rotation than the rigid fixation at the implanted level. One the other hand, at the adjacent level it allowed more range of motion ($2.0%{\sim}8.3%$) than the rigid fixation. The center of rotation of the PDS model remained closer to that of the intact spine. These results suggest that the PDS system could be able to prevent excessive motion at the adjacent levels and restore the spinal kinematics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.752-759
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• 2002

This paper presented a design and a control of a biped walking RGO and walking simulation by this system. The biped walking RGO was distinguished from the other one by which had a very light-weight and a new RGO type with 12-servo motors. The vibration evaluation of the dynamic PLS on the biped walking RGO was used to access by the 3-axis accelerometer with a low frequency vibration for the spinal cord injuries. The gait of a biped walking RGO depended on the constrains of mechanical kinematics and the initial posture. The stability of dynamic walking was investigated by a ZMP (Zero Moment Point) of the biped walking RGO. It was designed according to a human wear type and was able to accomodate itself to a human environments. The joints of each leg were adopted with a good kinematic characteristics. To test of the analysis of joint kinematic properties, we did the strain stress analysis of the dynamic PLS and the analysis study of FEM with a dynamic PLS. It will be expect that the spinal cord injury patients are able to recover effectively with a biped walking RGO.