Posterior dynamic lumbar stabilization

Posterior dynamic lumbar stabilization is an alternative instrumented method to rigid spinal fusion aiming to improve segmental stability. Purported advantages of this technique include reduced posterior element and intervertebral disc loading reducing symptoms and potentially allowing for disc regeneration ^1,3. 

Indications

• stabilization after decompression surgery ¹
• adjacent segment disease ²
• lumbar spinal stenosis
• degenerative disc disease
• spondylolisthesis ³

Procedure

The procedure will vary as there are numerous posterior dynamic stabilization systems available or previously available. However, they are most commonly pedicle fixation-based ^3,4:

• dynamic rods
  • soft stabilization (e.g. Graf ligamentoplasty system, FASS)
  • semi-rigid rods
    • metallic (e.g. AccuFlex, Isobar TTL, Bioflex Spring Rod)
    • PEEK (e.g. CD-Horizon Legacy PEEK Rod)
  • polyethene cord/polycarbonate spacer device (e.g. Dynesys)
• dynamic screws (e.g. Cosmic Posterior Dynamic System, Saphinas System)
• dynamic rods and dynamic screws in combination (e.g. BalanC)
• facet function replacing
  • ball-and-socket joint (e.g. Stabilimax NZ)
  • connecting springs (e.g. Dynamic Stabilization System)
• total facet joint replacement (e.g. TOPS, TFAS)
• facet augmentation (e.g. PercuDyn)
• interspinous device (e.g. Wallis Implant, X-Stop)

Complications

Complications of posterior dynamic lumbar stabilization include complications of spinal surgery and in particular the following ^5,6:

• adjacent segment disease
• failed back surgery
• implant malposition
• implant breakage
• implant loosening/implant migration
• pseudarthrosis
• dural tear
• spinal infection

Outcomes

The outcome of different posterior dynamic stabilization systems seems to be heterogeneous and dependent on the exact indication, the implant and procedure ⁵.

The main advantage of posterior dynamic stabilization systems and dynamic stabilization adjacent to fusion seems to be a decreased rate of radiological and clinical adjacent segment pathologies cranial or proximal to the fused segment and decreased amounts of estimated blood loss during surgery ^2,6. The main disadvantage is apparently a high rate of hardware failure and implant loosening ^3-7. Therefore dynamic stabilization systems tend to be used in younger patients.