Efficacy of the Aspen Spinous Process System in Anterior Lumbar Interbody Fusion (ALIF)

This is a multi-center, prospective randomized clinical study to evaluate the clinical
outcome of subjects with DDD who are treated with ALIF and supplemental posterior fixation
using Aspen compared to pedicle screw instrumentation. The study will involve up to
approximately 25 investigational sites and enroll up to 156 67 subjects. The randomization
ratio of two Aspen subjects to one pedicle screw subject (2:1) will be utilized.

Subjects with lumbar DDD who are candidates for ALIF at a single level will be screened for
inclusion in the study. If the subject meets all of the eligibility criteria, they will be
enrolled and randomized to either the Aspen or pedicle screw group. Subjects will continue to
be followed by the guidelines set forth in this clinical protocol, which include: a
postoperative discharge exam; six week, three month, six month, and one year post-op visits;
and, concludes with a two year post-op visit. The follow-up is counted from the day of
surgery. The enrollment period is expected to be approximately 12 months and subjects will be
followed for 2 years post-op for the duration of the clinical investigation. The anticipated
duration of the study is approximated to be 3 years.

Inclusion Criteria:

- Age between 18 and 75 years

- Scheduled for an elective single level ALIF with posterior fixation

- Diagnosis of primary symptomatic DDD confirmed with appropriate imaging studies and/or
positive lumbar discography

- Oswestry Disability Index (ODI) v 2.1 score >30%

- Failed at least 6 weeks of conservative care (non-surgical)/clinical signs of
neurological deterioration

- No contraindications for ASPEN spinous process system (at the discretion of the
investigator)

Exclusion Criteria:

- Prior lumbar fusion surgery at any level (prior discectomy and/or laminectomy allowed)

- Spondylolisthesis grade 3 or more

- Lytic spondylolisthesis

- Incompetent or missing posterior arch at the affected level (e.g. laminectomy, pars
defect)

- Currently requires laminectomy at level of surgery

- Facet joints at implant level are absent or fractured

- Post-traumatic vertebral body compromise or acute fracture at implant level

- Body mass Index (BMI) > 40

- Known allergy to titanium

- Osteoporosis: SCORE (Simple Calculated Osteoporosis Risk Estimation) will be used to
screen subjects who require DEXA. Subjects with T-score < -2.5 will be excluded

- Paget's disease, osteomalacia, or any other metabolic bone disease

- Use of medications or any drug known to potentially interfere with bone/soft tissue
healing (e.g. chronic systemic steroids)

- Planned use of Bone Morphogenetic Protein (BMP)

- Unlikely to comply with the follow-up evaluation schedule

- Subject has recent history (less than 3 years) of chemical substance dependency or
significant psychosocial disturbance that may impact the outcome or study
participation

- Participation in a clinical trial of another investigational drug or device within the
past 30 days

- Systemic infection such as AIDS, HIV, and active hepatitis

- Active malignancy defined as history of invasive malignancy, except if the subject has
received treatment and displayed no clinical signs and symptoms for at least five
years

- Pregnant or planning to become pregnant during the length of study participation

- Involvement in active litigation related to back problems at the time of screening

- Direct involvement in the execution of this protocol