Wallis® Dynamic Posterior Stabilization System

Treat the Pain

Surgery for degenerative lumbar lesions is undergoing a metamorphosis with the emergence of the non fusion concept to treat chronic intractable lumbar pain when conservative treatment fails.

Mechanical supplementation with non-rigid fixation clearly appears to be a useful technique in the management of initial forms of degenerative intervertebral lumbar disc disease.

This method should rapidly assume a specific role along with total disc prostheses in the new step-by-step surgical strategy to obviate definitive fusion of degenerative intervertebral segments.

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We began studying and developing non-rigid stabilization of lumbar segments in 1984. The clinical trials of the first-generation implant provided evidence that the interspinous system of non-rigid stabilization effectively treats low-back pain due to degenerative instability and is free of serious complications.

Today the second generation has been developed after careful analysis of the points that could be improved on the first-generation implant.

This new implant, called Wallis Stabilization System, treats the pain due to degenerative instability, preserves mobility, anatomy and stability while being fully reversible, therefore leaving all subsequent options open.

Preserve Anatomy, Keep Options Open

Resulting in the preservation of anatomy, Wallis System keeps all options open in terms of potential future operations for low back disorders.

Design and Materials

The design and materials minimize need for bony resection and permit an even distribution of stresses on the bone:

natomical design: grooves that fit the physiological shape of the spinous processes,

  • optimization of the surface of contact: flat polyester band for improved stress pattern on the bone,
  • elasticity: spacer and clips made of PEEK for mechanical properties close to those of bone and openings in the spacer for maximum reduction of the implant rigidity. 
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Structure-Sparing Surgical Technique

  • no bony purchase, no bony fixation

Preserve Mobility

Biomechanical effect of the Wallis Implant:

Load-Sharing Effect

The Wallis Implant has a load-sharing effect.

During flexion movements, the bands limit the amplitude of the movement without eliminating it, controlling the mobility of the affected segment. Wallis Wallis

During extension movements, the spacer limits the amplitude of the movement without eliminating it, controlling the mobility of the affected segment. Wallis Wallis

Strength of each component of the system has been validated during mechanical testing.

Flexion and Extension

The Wallis Implant limits the amplitude of movement in flexion and extension1Reduction of 35% of the flexion-extension mobility when implanted in a damaged segment (study performed on 6 cadaveric specimens).

The Wallis Implant increases the rigidity of the segment in flexion and extension1

Inflexion and extension the implantation of a Wallis System increases the rigidity by a factor of 1.9 and 1.5 times, respectively*.

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Intradiscal Pressure

The Wallis Implant reduces the intradiscal pressure1

In an in vitro Finite Element model, the Wallis Implant reduces the intradiscal stresses in a damaged disc both in flexion and extension.

The Wallis Implant does not alter the mechanical behavior of the adjacent segment.

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Related Articles

Indications
Instrumentation/Range
 References
Request Product Brochure and Surgical Technique
 Operative Technique 

Availability

Availability is subject to confirmation: if you have any questions concerning availability please contact Zimmer Spine Europe, Africa, Middle East office found on the Contact Us page.

References

*Study performed on 6 cadaveric specimens.


1. In vitro study performed at the Biomechanical Laboratory of the Ecole Nationale Supérieure des Arts & Métiers (ENSAM, France).