Biomechanics of Posterior Dynamic Stabilization Systems

Erbulut, Deniz Ufuk; Zafarparandeh, Iman; Özer, Ali Fahir; Goel, Vijay K.

doi:10.1155/2013/451956

Cited by 25 publications

(17 citation statements)

References 30 publications

(43 reference statements)

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“…8 Many in vitro and biomechanical studies have shown that this system can restrain the amount of flexibility through polyethylene terephthalate cords and polycarbonate urethane spacers. 9 10 11 Contrary to PLIF, which may lead to a rigid connection of the operative level, this system is designed to stabilize the operated segment while allowing some mobility, therefore, it may preserve a better of lumbar mobility than PLIF. 12 …”

Section: Introductionmentioning

confidence: 99%

Short term outcome of posterior dynamic stabilization system in degenerative lumbar diseases

Yang

Chen

et al. 2014

IJOO

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Background:Decompression and fusion is considered as the ‘gold standard’ for the treatment of degenerative lumbar diseases, however, many disadvantages have been reported in several studies, recently like donor site pain, pseudoarthrosis, nonunion, screw loosening, instrumentation failure, infection, adjacent segment disease (ASDis) and degeneration. Dynamic neutralization system (Dynesys) avoids many of these disadvantages. This system is made up of pedicle screws, polyethylene terephthalate cords, and polycarbonate urethane spacers to stabilize the functional spinal unit and preserve the adjacent motion after surgeries. This was a retrospective cohort study to compare the effect of Dynesys for treating degenerative lumbar diseases with posterior lumbar interbody fusion (PLIF) based on short term followup.Materials and Methods:Seventy five consecutive patients of lumbar degenerative disease operated between October 2010 and November 2012 were studied with a minimum followup of 2 years. Patients were divided into two groups according to the different surgeries. 30 patients underwent decompression and implantation of Dynesys in two levels (n = 29) or three levels (n = 1) and 45 patients underwent PLIF in two levels (n = 39) or three levels (n = 6). Clinical and radiographic outcomes between two groups were reviewed.Results:Thirty patients (male:17, female:13) with a mean age of 55.96 ± 7.68 years were included in Dynesys group and the PLIF group included 45 patients (male:21, female:24) with a mean age of 54.69 ± 3.26 years. The average followup in Dynesys group and PLIF group was 2.22 ± 0.43 year (range 2-3.5 year) and 2.17 ± 0.76 year (range 2-3 year), respectively. Dynesys group showed a shorter operation time (141.06 ± 11.36 min vs. 176.98 ± 6.72 min, P < 0.001) and less intraoperative blood loss (386.76 ± 19.44 ml vs. 430.11 ± 24.72 ml, P < 0.001). For Dynesys group, visual analogue scale (VAS) for back and leg pain improved from 6.87 ± 0.80 to 2.92 ± 0.18 and 6.99 ± 0.81 to 3.25 ± 0.37, (both P < 0.001) and for PLIF, VAS for back and leg pain also improved significantly (6.97 ± 0.84–3.19 ± 0.19 and 7.26 ± 0.76–3.56 ± 0.38, both P < 0.001). Significant improvement was found at final followup in both groups in Oswestry disability index (ODI) score (both P < 0.001). Besides, Dynesys group showed a greater improvement in ODI and VAS back and leg pain scores compared with the PLIF group (P < 0.001, P = 0.009 and P = 0.031, respectively). For radiological, height of the operated level was found increased in both groups (both P < 0.001), but there was no difference between two groups (P = 0.93). For range of motion (ROM) of operated level, significant decrease was found in both groups (P < 0.001), but Dynesys showed a higher preservation of motion at the operative levels (P < 0.001). However, no significant difference was found in the percentage change of ROM of adjacent levels between Dynesys and PLIF (0.74 ± 8.92% vs. 0.92 ± 4.52%, P = 0.91). Some patients suffered from degeneration of adjacent intervertebral dis...

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Section: Introductionmentioning

confidence: 99%

Short term outcome of posterior dynamic stabilization system in degenerative lumbar diseases

Yang

Chen

et al. 2014

IJOO

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“…1,4,26 The main design goal of such devices is to apply a distraction force to the processes and prevent further extension of the segment. As a result, ISP devices help to relieve the symptoms of neurogenic intermittent claudication associated with spinal stenosis.…”

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confidence: 99%

“…They are also designed to allow motion during flexion, lateral bending, and axial rotation at the treated segment because they reduce adjacent-level effects. 4,6 Of all ISP devices, the X-Stop device (Saint Francis Medical Technologies Inc.) has been documented most extensively in the literature. 20 It has 2 lateral wings to prevent unnecessary displacements.…”

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confidence: 99%

Determination of the biomechanical effect of an interspinous process device on implanted and adjacent lumbar spinal segments using a hybrid testing protocol: a finite-element study

Erbulut

Zafarparandeh²,

Hassan³

et al. 2015

SPI

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OBJECT The authors evaluated the biomechanical effects of an interspinous process (ISP) device on kinematics and load sharing at the implanted and adjacent segments. METHODS A 3D finite-element (FE) model of the lumbar spine (L1–5) was developed and validated through comparison with published in vitro study data. Specifically, validation was achieved by a flexible (load-control) approach in 3 main planes under a pure moment of 10 Nm and a compressive follower load of 400 N. The ISP device was inserted between the L-3 and L-4 processes. Intact and implanted cases were simulated using the hybrid protocol in all motion directions. The resultant motion, facet load, and intradiscal pressure after implantation were investigated at the index and adjacent levels. In addition, stress at the bone-implant interface was predicted. RESULTS The hybrid approach, shown to be appropriate for adjacent-level investigations, predicted that the ISP device would decrease the range of motion, facet load, and intradiscal pressure at the index level relative to the corresponding values for the intact spine in extension. Specifically, the intradiscal pressure induced after implantation at adjacent segments increased by 39.7% and by 6.6% at L2–3 and L4–5, respectively. Similarly, facet loads at adjacent segments after implantation increased up to 60% relative to the loads in the intact case. Further, the stress at the bone-implant interface increased significantly. The influence of the ISP device on load sharing parameters in motion directions other than extension was negligible. CONCLUSIONS Although ISP devices apply a distraction force on the processes and prevent further extension of the index segment, their implantation may cause changes in biomechanical parameters such as facet load, intradiscal pressure, and range of motion at adjacent levels in extension.

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“…Posterior dynamic stabilization has become a widely spread surgical intervention that can be performed using various types of implants [5,15]. Most of these implants are, however, mechanically complex and not always biomimetic.…”

Section: Discussionmentioning

confidence: 99%

Monolithic superelastic rods with variable flexural stiffness for spinal fusion: Modeling of the processing–properties relationship

Facchinello

Braïlovski

Petit

et al. 2014

Medical Engineering & Physics

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Biomechanics of Posterior Dynamic Stabilization Systems

Cited by 25 publications

References 30 publications

Short term outcome of posterior dynamic stabilization system in degenerative lumbar diseases

Short term outcome of posterior dynamic stabilization system in degenerative lumbar diseases

Determination of the biomechanical effect of an interspinous process device on implanted and adjacent lumbar spinal segments using a hybrid testing protocol: a finite-element study

Monolithic superelastic rods with variable flexural stiffness for spinal fusion: Modeling of the processing–properties relationship

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