SpineShape
System IV

Dynamic stabilisation of the lumbar spine with three selectable flexibilities. Quality of life and zest for life are returned.

SYSTEM IV VIDEO FEEDBACK & RESULTS

Biomechanics

The biomechanical principle of the dynamic stabilisation of the lumbar spine consists in the control of uncoordinated and thus painful relative movements between vertebral bodies. This kind of implant does not replace any tissues. Depending on the chosen rod flexibility, structures with more or less load sharing are added. Consequently, the implantation of such a system is reversible.

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With the insertion of the connecting rods approximately at the location of the facet joints, these facet joints are maximally being discharged. Therefore, pain due to arthrosis or capsular stretching may be eliminated. With this implantation set-up the natural kinematics (instantaneous centers of rotation) is only minimally altered and the loading stimulus of the intervertebral disc is maintained. In addition, the dorsal bulging of the disc may be reduced which might be beneficial in the case of nerve root irritation. Finally the global inclination of the disc may also be reduced what may diminish the danger of disc herniation.

Mimic of anatomy

The connection rods made of polymeric material mimic natural ligaments (collagenous structures) and provide comparable viscoelastic properties. They behave in a similar manner under tension and flexion loads and, in addition, are also capable to carry compression loads. The demanding anchorage, in analogy, is assured with the sophisticated interaction between pedicle screw and clamp screw.

2000+

patients

years as longest follow-up

years of experience

made in switzerland

System IV highlights

Dynamic stabilisation of lumbar vertebrae and intervertebral discs through flexible rods
In most cases permanent pain relief without spinal fusion surgery and without postoperative medication
The mobility of the lower spine is preserved
Protection of adjacent vertebrae and discs from excessive wear and tear
Rods with three levels of flexibility for optimal adaptation to the particular disease pattern
Proven and gentle operation

Design

The SpineShape System IV consists of PCU (polycarbonateurethane) rods having a dedicated cross section with plane parallel sides. Patents are issued for this cross section allowing for a safe and at the same time smooth anchorage of the rod through unique pedicle and clamp screws made of titanium alloy. The rods exist in three different flexibilities (high-flex, mid-flex and low-flex). For the mid-flex and low-flex rods a stepped version (Varistab™) is further available, allowing the connection of an adjacent segment with higher flexibility for cases where a fusion is expected. A great advantage of the Varistab™ includes the use of the same type of clamp screws and pedicle screws for the stepped end, where only a longer version of the clamp screw is required. The implants (rods, pedicle screws and clamp screws) are supplied in sterile condition after gamma irradiation.

Regeneration of the intervertebral disc

Cases are reported where intervertebral discs are re-accommodating water following the implantation of dynamic stabilisation systems. A plausible explanation could read as follows: With the implantation of a dynamic stabilisation system the hydrostatic pressure inside the intervertebral disc may be decreased, thus increasing the oncotic pressure (water content in proteins).

Elastic coupling

With the low-flex connecting rods, a motion segment can be stabilised to a degree, where a spontaneous fusion could occur. The fusion of a motion segment often leads to an excessive loading of the adjacent segment, which, according to recent knowledge, should be protected. Therefore connecting rods capable to achieve fusions should provide transition features allowing an elastic coupling of adjacent segments for the protection from excessive loads.

Tests

Allocation of flexibility

Based on a considerable number of in-vitro tests, SpineSave has developed an envelope allowing the allocation as well as the test load derivation for dynamic stabilisation systems. In the fusion zone titanium- and PEEK rods are allocated whereas in the dynamic zone, mid-flex and high-flex PCU rods are allocated. In between is the transition zone, where Dynesys^® (trademark of Zimmer^®) and the low-flex PCU rod are allocated. The curves shown are taken after 1 million cycles of longitudinal loads.

Fatigue testing

Since dynamic implants, not intended to lead to fusion with a later load-relief, are subject to repetitive loads for many years, they must undergo dedicated fatigue testing. The standard test of SpineSave includes 1 million cycles each at maximum load (worst-case) followed by 9 each million cycles at typical load in a longitudinal as well as in a transversal test set-up. Depending on the hypothesis (“bottom-up” or “top-down”), 1 million cycles at maximum load reflect a period of implantation in the body between 30 and 124 years.

Hypothesis	Cycles	Load-case	Per day	Years
Bottom-up	1 Mio	Max	22 times	124
Top-down	1 Mio 9 Mio	Max Type	91 times 822 times	30 30

Maximal load means forward bending with the finger tips to ground, occurring during putting on socks and shoes or washing feet. Typical load is estimated to be one third of maximal load occurring during sitting down and standing up.

Clinical use

Indications
- Lumbar spinal column from L1 to S1 with all the structural tissues present, but lacking in efficiency and/ or co-ordination.
- Dynamic stenosis
- Degenerative spondylolisthesis (grade 1 according Meyerding)
- Hypermobility with anterolisthesis
- Hypomobility with retrolisthesis
- Recurrent herniated disk
- Post-nucleotomy syndrome
- Early degenerative (non-ridgid) scoliosis
Contraindications
- Lack of or damaged structural tissues (e.g. vertebrae, intervertebral disk, facet joints, etc)
- Marked idiopathic scoliosis
- Spondylolisthesis > Meyerding grade 1
- Isthmic spondylolisthesis
- Bone tumour
- Osteoporosis that could compromise the screw anchorage
- Patient suffering from infections
- Known allergic reactions to single elements contained in the implant materials used or combinations thereof
- Skeletal growth
Operating technique
- The implantation is performed through the classical approaches (see Operative technique for SpineShape System IV). A set of extensive especially developed instruments is available.

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Ordering information

Pedicle screws exist in 17 sizes available in sets packed with two each, including two normal clamp screws. Rods are available as standard version (normal clamp screws) and Varistab™ (long clamp screws).

Art.-No.	Thread length	Thread diameter
21.018.11-540-S	40 mm	5.4 mm
21.018.11-545-S	45 mm	5.4 mm
21.018.11-550-S	50 mm	5.4 mm
21.018.11-640-S	40 mm	6.2 mm
21.018.11-645-S	45 mm	6.2 mm
21.018.11-650-S	50 mm	6.2 mm
21.018.11-655-S	55 mm	6.2 mm
21.018.11-735-S	35 mm	7.0 mm
21.018.11-740-S	40 mm	7.0 mm
21.018.11-745-S	45 mm	7.0 mm
21.018.11-750-S	50 mm	7.0 mm
21.018.11-755-S	55 mm	7.0 mm
21.018.11-835-S	35 mm	7.8 mm
21.018.11-840-S	40 mm	7.8 mm
21.018.11-845-S	45 mm	7.8 mm
21.018.11-850-S	50 mm	7.8 mm
21.018.11-855-S	55 mm	7.8 mm

Rods exist in 5 versions. Straight standard rods are packed with 1 each and Varistab™ rods with 2 each with following article numbers:

Art.-No.	Flexibility	Type
21.012.21-200	high-flex	prismatic (standard rod)
21.012.23-200	mid-flex	prismatic (standard rod)
21.012.25-200	low-flex	prismatic (standard rod)
21.015.23-200	mid-flex	stepped (Varistab™)
21.015.25-200	low-flex	stepped (Varistab™)

Conformity

The implants and instruments are CE marked. According to the medical device directive 93/42/EEC the implants belong to the class IIb and the instruments to the class I

Changes reserved.