Preliminary Design and Experimental Studies of a Novel Soft Implant for Correcting Sagittal Plane Instability in the Lumbar Spine

Minns, R.J.; Walsh, W.

doi:10.1097/00007632-199708150-00004

Cited by 92 publications

(53 citation statements)

References 32 publications

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“…With the exception of a few studies, all of the biomechanical and clinical studies address cranial segment degeneration [15,39], because ASD caudal to a fusion is significantly less common [10]. The explanation for this is that in the adjacent segment cephalad to a fusion there is increased mobility compared with the adjacent caudal segment [5].…”

Section: Discussionmentioning

confidence: 99%

“…In this study, the vertebral segment cephalad to instrumented fusion was selected for several documented reasons: (1) this is the most frequent localisation of ASD [3]; (2) lumbosacral instrumented fusion is very rare (\3%) [15]; and (3) with exception of few studies, all clinical and biomechanical studies address cranial segment degeneration following the rigid lumbar/lumbosacral instrumentation [39]. All patients were clinically assessed preoperatively and postoperatively with the SF-36 (physical function domain) and Oswestry Disability Index (ODI) score and the pain magnitude with Visual Analogue Scale (0-10 scale, VAS).…”

Section: Methodsmentioning

confidence: 99%

“…Adjacent segment degeneration describes nearly any abnormal process that develops in the mobile segment next to a spinal fusion and although the exact mechanism remains uncertain, altered biomechanical stresses (hypermobility, olisthesis, disc height (DH) loss, instability) appear to play a key role in its development [4,16,19,30,33,34,39,47]. Although several clinical and radiological criteria have been introduced to define segmental spinal instability there is no consensus as regard its definition.…”

Section: Introductionmentioning

confidence: 99%

“…Although most often the criteria to determine ASD are based solely on radiographic findings [2,7,19,28,30,34,39,41,59] reporting an ASD incidence ranging from 8 to 100%, the symptomatic incidence of ASD is significantly lower ranging from 5.2 to 18.5% [7,28,31], while the rate of re-operation rate for symptomatic ASD ranges from 2.7 to 20% [16,58].…”

Section: Introductionmentioning

confidence: 99%

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Does Wallis implant reduce adjacent segment degeneration above lumbosacral instrumented fusion?

et al. 2009

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Delayed complications following lumbar spine fusion may occur amongst which is adjacent segment degeneration (ASD). Although interspinous implants have been successfully used in spinal stenosis to authors' knowledge such implants have not been previously used to reduce ASD in instrumented lumbar fusion. This prospective controlled study was designed to investigate if the implantation of an interspinous implant cephalad to short lumbar and lumbosacral instrumented fusion could eliminate the incidence of ASD and subsequently the related reoperation rate. Groups W and C enrolled initially each 25 consecutive selected patients. Group W included patients, who received the Wallis interspinous implant in the unfused vertebral segment cephalad to instrumentation and the group C selected age-, diagnosis-, level-, and instrumentationmatched to W group patients without interspinous implant (controls). The inclusion criterion for Wallis implantation was UCLA arthritic grade \II, while the exclusion criteria were previous lumbar surgery, severe osteoporosis or degeneration[UCLA grade II in the adjacent two segments cephalad to instrumentation. All patients suffered from symptomatic spinal stenosis and underwent decompression and 2-4 levels stabilization with rigid pedicle screw fixation and posterolateral fusion by a single surgeon. Lumbar lordosis, disc height (DH), segmental range of motion (ROM), and percent olisthesis in the adjacent two cephalad to instrumentation segments were measured preoperatively, and postoperatively until the final evaluation. VAS, SF-36, and Oswestry Disability Index (ODI) were used. One patient of group W developed pseudarthrosis: two patients of group C deep infection and one patient of group C ASD in the segment below instrumentation and were excluded from the final evaluation. Thus, 24 patients of group W and 21 in group C aged 65? 13 and 64? 11 years, respectively were included in the final analysis. The follow-up averaged 60 ± 6 months. The instrumented levels averaged 2.5 ? 1 vertebra for both groups. All 45 spines showed radiological fusion 8-12 months postoperatively. Lumbar lordosis did not change postoperatively. Postoperatively at the first cephalad adjacent segment: DH increased in the group W (P = 0.042); ROM significantly increased only in group C (ANOVA, P \ 0.02); olisthesis decreased both in flexion (P = 0.0024) and extension (P = 0.012) in group W. The degeneration or deterioration of already existed ASD in the two cephalad segments was shown in 1 (4.1%) and 6 (28.6%) spines in W and C groups, respectively. Physical function (SF-36) and ODI improved postoperatively (P \ 0.001), but in favour of the patients of group W (P \ 0.05) at the final evaluation. Symptomatic ASD required surgical intervention was in 3 (14%) patients of group C and none in group W. ASD remains a significant problem and accounts for a big portion of revision surgery following instrumented lumbar fusion. In this series, the Wallis interspinous implant changed the natural history of ASD and saved th...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Does Wallis implant reduce adjacent segment degeneration above lumbosacral instrumented fusion?

et al. 2009

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“…Interspinous implants are used for motion-preserving stabilization of primarily posterior lumbar spinal pathologies like spinal stenosis or facet joint arthritis [8]. The aims are to unload the facet joints, to restore foraminal height and to provide sufficient stability especially in extension but still allow motion in the treated segment.…”

Section: Introductionmentioning

confidence: 99%

Biomechanical effect of different lumbar interspinous implants on flexibility and intradiscal pressure

et al. 2008

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Interspinous implants are used to treat lumbar spinal stenosis or facet joint arthritis. The aims of implanting interspinous devices are to unload the facet joints, restore foraminal height and provide stability especially in extension but still allow motion. The aim of this in vitro study was to compare four different interspinous implants--Colfex, Wallis, Diam and X-Stop--in terms of their three-dimensional flexibility and the intradiscal pressure. Twenty-four human lumbar spine specimens were divided into four equal groups and tested with pure moments in flexion/extension, lateral bending and axial rotation: (1) intact, (2) defect, (3) after implantation. Range of motion and the intradiscal pressure were determined.In each implant-group the defect caused an increase in range of motion by about 8% in lateral bending to 18% in axial rotation. Implantation had similar effects with all four implants. In extension, Coflex, Wallis, Diam, and X-Stop all overcompensated the instability caused by the defect and allowed about 50% of the range of motion of the intact state. In contrast, in flexion, lateral bending and axial rotation the values of the range of motion stayed about the values of the defect state. Similarly the intradiscal pressure after implantation was similar to that of the intact specimens in flexion, lateral bending and axial rotation but much smaller during extension. All tested interspinous implants had a similar effect on the flexibility: they strongly stabilized and reduced the intradiscal pressure in extension, but had almost no effect in flexion, lateral bending and axial rotation.

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Preliminary results of a soft novel lumbar intervertebral prothesis (DIAM) in the degenerative spinal pathology

Mariottini

Pieri

Giachi

et al.

Acta Neurochirurgica

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Preliminary Design and Experimental Studies of a Novel Soft Implant for Correcting Sagittal Plane Instability in the Lumbar Spine

Abstract: A circular silicone spacer placed between the spinous processes appears to contribute to the stability of the cadaveric lumbar spine. There are many attractions to using a simple, soft implant that can be placed with minimal surgery between the spinous processes.

Cited by 92 publications

References 32 publications

Does Wallis implant reduce adjacent segment degeneration above lumbosacral instrumented fusion?

Does Wallis implant reduce adjacent segment degeneration above lumbosacral instrumented fusion?

Biomechanical effect of different lumbar interspinous implants on flexibility and intradiscal pressure

Preliminary results of a soft novel lumbar intervertebral prothesis (DIAM) in the degenerative spinal pathology

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