Aspen™ Spinous Process Fixation System*

1. Posterior Interlaminar Fusion with the Aspen Device

Using bone from the direct decompression and the Aspen device for posterior instrumentation, fusion is encouraged between the posterior medial segments including facet joints, laminae and within the central load sharing barrel of the device. Biomechanical testing showed significant restriction of ROM and a stabilizing affect on foraminal height.¹ Posterior interlaminar fusion is a less invasive approach to posterior fusion.

2. Posterolateral Fusion with the Aspen Device

Posterolateral Fusion is a construct that involves the transverse process, unlike the less-invasive Posterior Interlaminar Fusion construct (above). Conservative direct decompression and sparing of the posterior elements permits secure placement of the Aspen device. Bridwell et al, and Fischgrund et al both reported significantly higher fusion rates with adjunctive instrumentation.^2,3 In a long-term study comparing fusion and pseudoarthrosis, Kornblum et al found that successful fusion correlated with an improved functional outcome and less pain in the long-term.⁴ The Aspen device is a posterior, non-pedicle supplemental fixation device which may offer an alternative to pedicle screw instrumentation. Placement of the Aspen device has the advantage of eliminating the risk associated with pedicle screw placement. Biomechanical testing showed significant restriction of ROM and a stabilizing affect on foraminal height.¹

3. ALIF with the Aspen Device

The most reliable constructs employ anterior fusion stabilized posteriorly with instrumentation. Although pedicle screw fixation is currently the most widely used method for creating rigid internal stabilization of the lumbar spine, it is associated with well-know risks, including cerebrospinal fluid leakage, nerve injury, and deep wound infection. Biomechanical testing showed posterior fixation with the Aspen device in an application utilizing an anterior lumbar interbody provided stability that was equivalent to ALIF with bilateral pedicle screws. Utilizing the Aspen device eliminates the risk associated with pedicle screw and facet screw placement.

See the ALIF biomechanical data

4. TLIF with Unilateral Pedicle Screws and the Aspen Device

TLIF enables a circumferential arthrodesis with a single posterior approach through the foramen. Biomechanical testing of the Aspen device with unilateral pedicle screws in a TLIF construct showed comparable restriction of ROM to TLIF with bilateral pedicle screws. Utilizing the Aspen device with unilateral pedicle screws in a TLIF construct may offer equivalent biomechanical stability to bilateral pedicle screws without the need to disrupt the contralateral side. A MIS technique within every surgeon's reach, one small skin incision followed by two facial incisions; 2 cm lateral to midline fascial incision for decompression and pedicle screw placement, and a midline fascial incision for placement of the
Aspen device.

See the TLIF biomechanical data

5. TLIF with the Aspen Device

Biomechanical testing of the Aspen device alone in a TLIF construct showed comparable ROM restriction to unilateral pedicle screws-rods in a TLIF construct. For the least invasive TLIF approach, adjunctive spinous process fixation alone may offer stability comparable to a unilateral pedicle screw construct without the risks of pedicle screw placement, such as intrusion into the spinal canal, pedicles, and/or facet joints.

See the TLIF biomechanical data

6. Hybrid Constructs/Revision Procedures

Hybrid constructs combine two or more fixation devices to achieve optimal segmental and construct stability and desired patient outcomes. The Aspen device may be combined with facet screws, pedicle screws, anterior plates, and lateral plates. Additionally, revision procedures present significant challenges to surgeons. When the anatomy and situation allows, posterior fixation with the Aspen device may address the fixation needs of adjacent level disease and eliminate the need to revise previously placed hardware, reducing the extent of the revision procedure.

See Posterior Fusion biomechanical data

7. Direct Lateral with the Aspen Device

The lateral approach to lumbar interbody fusion circumvents the vascular and neural risks associated with anterior and posterior approaches while offering the patient a minimally disruptive alternative to anterior column access. Biomechanical testing showed posterior fixation with the Aspen device in an application utilizing an anterior lumbar interbody provided stability equivalent to ALIF with bilateral pedicle screws. Utilizing the Aspen device eliminates the risk associated with pedicle screw and facet screw placement. Placement of the Aspen device for posterior fixation may be accomplished with the patient in the lateral position.