Kinematics of a selectively constrained radiolucent anterior lumbar disc: Comparisons to hybrid and circumferential fusion

Daftari, Tapan K.; Chinthakunta, Suresh; Ingalhalikar, Aditya; Gudipally, Manasa; Hussain, Mir; Khalil, Saif

doi:10.1016/j.clinbiomech.2012.05.010

Cited by 11 publications

(7 citation statements)

References 32 publications

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“…Each spine was fixed to the load frame of a custom-built 6- df spine simulator, and a pure moment was applied to the construct through servomotors. 13 The design of the load frame enables unconstrained motion of the spine in response to an applied load. There was no compressive preload applied to the specimen.…”

Section: Methodsmentioning

confidence: 99%

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Pedicle screw instrumentation of thoracolumbar burst fractures: Biomechanical evaluation of screw configuration with pedicle screws at the level of the fracture

Bolesta¹,

Caron²,

Chinthakunta³

et al. 2012

The International Journal of Spine Surgery

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BackgroundPosterior fixation alone may not be adequate to achieve and maintain burst fracture reduction. Adding screws in the fractured body may improve construct stiffness. This in vitro study evaluates the biomechanical effect of inserting pedicle screws in the fractured body compared with conventional short- and long-segment posterior fixation.MethodsStable and unstable L2 burst fractures were created in 8 calf spines (aged 18 weeks). Constructs were tested at 8 Nm in the intact state and then with instrumentation consisting of long- and short-segment posterior fixation with and without screws in the fractured L2 vertebral body after (1) stable burst fracture and (2) unstable burst fracture. Range of motion was recorded at L1-3 for flexion-extension, lateral bending, and axial rotation. Statistical analysis was performed with repeated-measures analysis of variance, with significance set at P < .05. The data were normalized to the intact state (100%).ResultsBoth long- and short-segment constructs with screws in the fractured body significantly reduced motion compared with the stable and unstable burst fracture in flexion-extension and lateral bending. Fracture screws enhanced construct stability by 68% (on average) relative to conventional short-segment posterior fixation and were comparable to long-segment posterior fixation.ConclusionsScrews at the fracture level improve construct stiffness. Short-segment constructs may suffice for stable burst fractures. More severe injuries may benefit from fracture screws and can be considered as an alternative treatment to long-segment constructs.

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Section: Methodsmentioning

confidence: 99%

“… 15 The 3-dimensional intervertebral rotation was obtained from the motion analysis data files in the form of Euler angles (degrees) about the X, Y, and Z axes, with R x /-R x , R y /-R y , and R z /-R z denoting FE, AR, and LB range of motion (ROM), respectively. 13 …”

Section: Methodsmentioning

confidence: 99%

Pedicle screw instrumentation of thoracolumbar burst fractures: Biomechanical evaluation of screw configuration with pedicle screws at the level of the fracture

Bolesta¹,

Caron²,

Chinthakunta³

et al. 2012

The International Journal of Spine Surgery

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“…Among them, hybrid LTDR in multi-level DDD has been tried clinically and experimentally by many surgeons. Daftari et al 20) reported the results of a kinematic study that both one-level and a two-level LTDR and hybrid constructs did not significantly change adjacent kinematics compared to the intact level, while the two-level fusion construct presented an increase in flexibility at the adjacent level and two-level LTDR construct tended to decrease motion with a stability concern. These results were interpreted that hybrid constructs may be applied to two-level lumbar DDD as a replacement for two-level fusion surgery.…”

Section: The Past and Present Of Ltdr Including Long-term Outcomementioning

confidence: 99%

Total Disc Replacement in Lumbar Degenerative Disc Diseases

Park

2015

J Korean Neurosurg Soc

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More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above.

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“…Previous studies have compared intact IVD and TDR devices [12][13][14][15] but neglected to apply a physiological preload, which is known to significantly affect spinal stiffness. These studies also used FSU or multi-level spinal specimens, and it is possible that the facets and posterior ligaments will have shielded potential differences between the intact disc and the TDR.…”

Section: Principal Stiffness Termsmentioning

confidence: 99%

“…There are a number of studies that have compared spinal specimens with an intact IVD and after a TDR. [12][13][14][15] However, despite the stiffening effect of a physiological preload being well-documented, 10,16,17 there are few biomechanical studies of TDRs that have included the application of a physiological preload [18][19][20] and no studies that have assessed a TDR dynamically, in all six axes, with a physiological axial preload.…”

Section: Introductionmentioning

confidence: 99%

Dynamic, six-axis stiffness matrix characteristics of the intact intervertebral disc and a disc replacement

Holsgrove

Gill

Miles

et al. 2015

Proc Inst Mech Eng H

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Thorough pre-testing is critical in assessing the likely in vivo performance of spinal devices prior to clinical use. However, there is a lack of data available concerning the dynamic testing of lumbar (porcine model) total disc replacements in all six axes under preload conditions. The aim of this study was to provide new data comparing porcine lumbar spinal specimen stiffness between the intact state and after the implantation of an unconstrained total disc replacement, in 6 degrees of freedom. The dynamic, stiffness matrix testing of six porcine lumbar isolated disc specimens was completed using triangle waves at a test frequency of 0.1 Hz. An axial preload of 500 N was applied during all testing. Specimens were tested both in the intact condition and after the implantation of the total disc replacement. Sixteen key stiffness terms were identified for the comparison of the intact and total disc replacement specimens, comprising the 6 principal stiffness terms and 10 key off-axis stiffness terms. The total disc replacement specimens were significantly different to the intact specimens in 12 of these key terms including all six principal stiffness terms. The implantation of the total disc replacement resulted in a mean reduction in the principal stiffness terms of 100%, 91%, and 98% in lateral bending, flexion-extension, and axial rotation, respectively. The novel findings of this study have demonstrated that the unconstrained, low-friction total disc replacement does not replicate the stiffness of the intact specimens. It is likely that other low-friction total disc replacements would produce similar results due to stiffness being actively minimised as part of the design of low-friction devices, without the introduction of stiffening elements or mechanisms to more accurately replicate the mechanical properties of the natural intervertebral disc. This study has demonstrated, for the first time, a method for the quantitative comparative mechanical function testing of total disc replacements and provides baseline data for the development of future devices.

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Kinematics of a selectively constrained radiolucent anterior lumbar disc: Comparisons to hybrid and circumferential fusion

Cited by 11 publications

References 32 publications

Pedicle screw instrumentation of thoracolumbar burst fractures: Biomechanical evaluation of screw configuration with pedicle screws at the level of the fracture

Pedicle screw instrumentation of thoracolumbar burst fractures: Biomechanical evaluation of screw configuration with pedicle screws at the level of the fracture

Total Disc Replacement in Lumbar Degenerative Disc Diseases

Dynamic, six-axis stiffness matrix characteristics of the intact intervertebral disc and a disc replacement

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