Effect of Axial Load on the Flexural Properties of an Elastomeric Total Disc Replacement

Mahomed, Aziza; Moghadas, Parshia; Shepherd, Duncan E.T.; Hukins, D.W.L.; Roome, Amy; Johnson, Scott A.

doi:10.1097/brs.0b013e31824da3ba

Cited by 15 publications

(14 citation statements)

References 20 publications

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“…However, as with the moisture condition, the temperature of spinal devices, such as UHMWPE bearings, or elastomeric devices, may behave in an altogether different manner at room temperature than at body temperature. The testing frequency and preload magnitude has also been shown to affect the sagittal bending properties of the elastomeric Cadisc TDR, 96 highlighting the notion that replicating the in-vivo environment is critical to understanding not only the properties of the natural spine, but also its properties with spinal instrumentation, and ultimately, the effects of the instrumentation.…”

Section: 75mentioning

confidence: 99%

Advanced Multi-Axis Spine Testing: Clinical Relevance and Research Recommendations

et al. 2015

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Back pain and spinal degeneration affect a large proportion of the general population. The economic burden of spinal degeneration is significant, and the treatment of spinal degeneration represents a large proportion of healthcare costs. However, spinal surgery does not always provide improved clinical outcomes compared to non-surgical alternatives, and modern interventions, such as total disc replacement, may not offer clinically relevant improvements over more established procedures. Although psychological and socioeconomic factors play an important role in the development and response to back pain, the variation in clinical success is also related to the complexity of the spine, and the multi-faceted manner by which spinal degeneration often occurs.The successful surgical treatment of degenerative spinal conditions requires collaboration between surgeons, engineers, and scientists in order to provide a multi-disciplinary approach to managing the complete condition. In this review, we provide relevant background from both the clinical and the basic research perspectives, which is synthesized into several examples and recommendations for consideration in increasing translational research between communities with the goal of providing improved knowledge and care.Current clinical imaging, and multi-axis testing machines, offer great promise for future research by combining invivo kinematics and loading with in-vitro testing in six degrees of freedom to offer more accurate predictions of the performance of new spinal instrumentation. Upon synthesis of the literature, it is recommended that in-vitro tests strive to recreate as many aspects of the in-vivo environment as possible, and that a physiological preload is a critical factor in assessing spinal biomechanics in the laboratory. A greater link between surgical procedures, and the outcomes in all three anatomical planes should be considered in both the in-vivo and in-vitro settings, to provide data relevant to quality of motion, and stability.

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Section: 75mentioning

confidence: 99%

Advanced Multi-Axis Spine Testing: Clinical Relevance and Research Recommendations

et al. 2015

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“…5,23 The simulator has six degrees of freedom: four active (flexion/extension, lateral bend, axial rotation and axial The two generic total disc replacement devices (one with a ball radius of 10 mm and the other with a ball radius of 16 mm) were tested with two different lubricants:…”

Section: Frictional Torquementioning

confidence: 99%

Effect of lubricants on friction in laboratory tests of a total disc replacement device

Moghadas

Mahomed

Hukins

et al. 2013

Proc Inst Mech Eng H

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Some designs of total disc replacement devices have articulating bearing surfaces, and these devices are tested in vitro with a lubricant of diluted calf serum. It is believed that the lubricant found in total disc replacement devices in vivo is interstitial fluid that may have properties between that in Ringer's solution and diluted calf serum. To investigate the effect of lubricants, a set of friction tests were performed on a generic model of a metal against metal ball-and-socket total disc replacement device. Two devices were tested: one with a ball radius of 10 mm and other with a ball radius of 16 mm; each device had a radial clearance of 0.015 mm. A spine simulator was used to measure frictional torque for each device in axial rotation, flexion-extension and lateral bending at frequencies of 0.25-2 Hz, under 1200 N axial load. Each device was tested with two different lubricants: a solution of new born calf serum diluted with deionised water and Ringer's solution. The results showed that the frictional torque generated between the bearing surfaces was significantly higher in Ringer's solution than in diluted calf serum. The use of Ringer's solution as a lubricant provides a stringent test condition to detect possible problems. Diluted calf serum is more likely to provide an environment closer to that in vivo. However, the precise properties of the fluid lubricating a total disc replacement device are not known; hence, tests using diluted calf serum may not necessarily give the same results as those obtained in vivo.

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“…More recently, TDR prostheses have been manufactured from flexible polymeric materials to mimic more closely the natural disc. Laboratory studies have shown that the flexibility of a polymeric prosthesis can be comparable to that of a normal human disc 44 with one version predicted to have a fatigue life of about 50 years. 45 It should be noted, however, that such studies cannot reproduce in vivo conditions, and the fixation of a GAGs Active MMPs 6.7 6.5 6.3 Graph showing how a lowered pH level reduces the glycosaminoglycan (GAG) synthesis by disc cells much more than that of matrix metalloproteinase (MMP) production so favouring degradation of the matrix (modified with permission from Razaq MS.…”

Section: Pathology Of Disc Degenerationmentioning

confidence: 99%

The pathogenesis of degeneration of the intervertebral disc and emerging therapies in the management of back pain

Hughes

Freemont

Hukins

et al. 2012

The Journal of Bone and Joint Surgery. British volume

111

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This article reviews the current knowledge of the intervertebral disc (IVD) and its association with low back pain (LBP). The normal IVD is a largely avascular and aneural structure with a high water content, its nutrients mainly diffusing through the end plates. IVD degeneration occurs when its cells die or become dysfunctional, notably in an acidic environment. In the process of degeneration, the IVD becomes dehydrated and vascularised, and there is an ingrowth of nerves. Although not universally the case, the altered physiology of the IVD is believed to precede or be associated with many clinical symptoms or conditions including low back and/or lower limb pain, paraesthesia, spinal stenosis and disc herniation. New treatment options have been developed in recent years. These include biological therapies and novel surgical techniques (such as total disc replacement), although many of these are still in their experimental phase. Central to developing further methods of treatment is the need for effective ways in which to assess patients and measure their outcomes. However, significant difficulties remain and it is therefore an appropriate time to be further investigating the scientific basis of and treatment of LBP.

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Effect of Axial Load on the Flexural Properties of an Elastomeric Total Disc Replacement

Abstract: Effect of axial load on the flexural properties of an elastomeric total disc replacement. Spine 37: E908-E912.

Cited by 15 publications

References 20 publications

Advanced Multi-Axis Spine Testing: Clinical Relevance and Research Recommendations

Advanced Multi-Axis Spine Testing: Clinical Relevance and Research Recommendations

Effect of lubricants on friction in laboratory tests of a total disc replacement device

The pathogenesis of degeneration of the intervertebral disc and emerging therapies in the management of back pain

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