285 - Clinical Outcomes of Direct or Indirect Decompression with Silicone or...

#285 Clinical Outcomes of Direct or Indirect Decompression with Silicone or PEEK Interspinous Implants

Lumbar Therapies and Outcomes

Poster Presented by: A.J. Berg


A.J. Berg (1)
C.D. Jensen (1)
C. Nita (1)
M. Hernandez (1)
J.A. Tankel (1)
G.R. Reddy (1)
T. Friesem (1)

(1) North Tees and Hartlepool NHS Foundation Trust, Spinal Unit, Stockton on Tees, United Kingdom


Introduction and Purpose: Foraminal and spinal canal stenosis causes neurogenic claudication. Interspinous devices provide an indirect decompression by distracting the involved vertebrae thereby tightening the buckled flavum and opening the foraminae. They may also aid in off loading the facets and the disc. When used for indirect decompression alone they avoid scar tissue formation in the canal. The DIAM™ (Medtronic, USA) is made of silicone and therefore conforms more to the interspinous space. The InSWing™ (Orthofix, USA) is made of PEEK (Polyether Ether Ketone) and is non-compressible. To provide benefit the distraction needs to be maintained. We feel a balance is required between and implant that has enough rigidity to maintain distraction but is also not too abrasive towards the spinous processes that it causes osteolysis. We report the outcomes between a silicone/non-rigid implant and a PEEK/non-compressible implant. We also report the outcomes between direct and indirect decompressions.

Methods: Retrospective analysis performed for surgery July 2009 - 2011. Paired and unpaired t-test used to assess statistical significance (p< 0.05).

Results: 60 patients (22 females, 38 males). Age 46 (21 - 78) years.Pre-operative duration of symptoms 65 (4-420) months. The numbers in each implant/decompression group and follow up is shown in Table 1. Statistically significant improvement observed in all outcome measures in direct and InSWing™ groups and all outcomes except MCS in DIAM™ group. Indirect group improved in all outcomes but these were only significant in VAS Back/Leg. InSWing™ and direct groups scores improved more than the DIAM™ and indirect groups respectively but these differences were only significant in Oswestry in the decompression group. All five patients requiring revision surgery were in the DIAM™ group.

Conclusion: Statistically significant improvement was seen in all outcome measures in patients undergoing direct decompressions or implantation with InSWing™/non-compressible implants. Improvement in scores was greater in these groups compared to the indirect decompression or DIAM™/non-rigid groups.

Table 1: Group patient numbers and follow-up.