Interspinous Fusion

xray of human ribcage and spinal column, with spine highlighed in red glow

Interspinous fusion procedures are less invasive than standard (open) lumbar fusions. 

That said, the majority of patients who qualify for fusion surgery are not candidates for interspinous fixation. Indications for interspinous fusion, to name a few, are stable spondylolisthesis with radicular symptomatology or claudication, and recurrent disc herniation. Interspinous fusion devices obviate the need for pedicle screws (although may be used in conjunction with pedicle screws) and therefore require less surgical exposure. This translates to a lesser amount of postoperative pain and a shorter inpatient stay.

  • This procedure starts with an incision in the lumbar region.
  • The paraspinal muscles are then elevated exposing the lamina (the bones that form the back of the spinal canal serving both protective and structural roles).
  • The lamina are removed (or a laminotomy made) utilizing a variety of techniques. This exposes the covering of the spinal cord and nerve roots known as the dura.
  • The bony arthritis is removed (or the disc herniation excised).
  • After the decompression has been performed, the spinous processes (palpable bony prominences on the back of the spine) are prepared with a rasp. This creates a denuded (bleeding) bony surface and introduces growth factors into the local area.
  • The interspinous implant (shaped liked a claw) is affixed to adjacent spinous process and crimped tightly. Bone graft placed in the device’s hollow cylinder serves as a fusion scaffold, bridging the gap between spinous processes.
  • Final x-rays are obtained and the wound is closed in anatomical layers.
  • Patients typically are mobilized on the night of surgery in a brace and discharged home the following day.

xray with views of anterior and lateral interspinous fusion

WHAT YOU WANT TO KNOW

“So I won’t need screws put in my back?”

No, the interspinous device affixes adjacent spinous processes together obviating the need for screws. That said, surgical selection is critical. The technique is not to be used in patients with instability (mobile spondylolisthesis or fracture with significant biomechanical compromise for example). Some surgeons (like Dr. Osborn), will perform an adjuvant “facet fusion” to further stabilize the targeted level.

“For how long will I need to wear a brace after surgery?”

Patients typically wear a brace for 6-12 weeks postoperatively.  This reduces pain in the acute period (by limiting movement) and theoretically improves the chances of bony fusion long-term.  

“What are the chances of a successful fusion relative to a standard pedicle screw-based procedure?”

For a single-level fusion, the fusion rates of the two procedures are similar.

“What can I do to better my chances of fusing?”

Smoking dramatically decreases bony fusion rates. It also impairs wound healing and predisposes one to infection. Smoking cessation is paramount therefore. Early weight-bearing activities will stimulate bony remodeling and healing. Vitamin D3, vitamin K and calcium supplementation are also recommended as is a sound diet with limited simple sugars.

“When can I return to the gym in the wake surgery?"

Light exercise is prescribed 2-3 weeks postoperatively (after the incision has been cleared and the staples removed). Return to normal weight training is expected by 3 months postop (as the majority of well-nourished, non-smokers fuse within this time period).

SOURCE:

Ho Jung Kim, et al. Posterior Interspinous Fusion Device for One-Level Fusion in Degenerative Lumbar Spine Disease : Comparison with Pedicle Screw Fixation - Preliminary Report of at Least One Year Follow Up. J Korean Neurosurg Soc. 2012 Oct; 52(4): 359–364.

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