The purpose of this study is to assess the radiographic and clinical outcomes of spinal fusion following use of Allosync Expand and autograft bone graft.

This is a single site, prospective study with patients selected as study subjects from the Investigator's standard patient population who fulfill the Inclusion/Exclusion Criteria and agree to participate in the study. The study surgery is standard of care, with patients identified as requiring surgery prior to enrollment. The study surgery is lumbar posterior fixation with supplemental posterolateral fusion at from 1 to 3 levels. One side of the posterolateral fusion will be Allosync Expand (utilizing the BMA Angel kit to hydrate) and the other side to autograft bone (control).

Inclusion Criteria:

1. At least 22years of age at the time of consent

2. Subject must have a documented diagnosis of spondylolisthesis up to Grade I. and have confirmed back and/or radicular pain with associated spinal stenosis as documented by conditions such as:

   1. Instability as defined by >3mm translation or >5 degree angulation
   2. Osteophyte formation of facet joints or vertebral endplates

3. Subject presents with one or more of the following:

   1. Radiculopathy
   2. Sensory deficit
   3. Motor weakness
   4. Reflex changes

4. Subject requires lumbar posterolateral arthrodesis at 1-3 contiguous levels (L1-S1).

5. The number of levels decompressed must equal the number of levels fused.

6. Subject must have been unresponsive to conservative care for at least 3 months prior to fusion surgery.

7. Subject must be willing and able to sign an informed consent document.

8. Subject must be willing and able to return for all follow-up visits, agree to participate in postoperative clinical and radiographic evaluations and comply with the required study regimen.

Exclusion Criteria:

1. Subject has had prior lumbar spine fusion surgery at any level.
2. Subject has greater than grade 1 spondylolisthesis of the lumbar spine.
3. Subject is pregnant or nursing or planning to become pregnant during the two years (24 months) following arthrodesis
4. Subject has an active local or systemic infection.
5. Subject is a prisoner
6. Patient has any condition (including malignancy), that in the opinion of the Investigator, would prohibit the patient from complying with and/or completing the protocol

A patient who meets all inclusion criteria and none exclusion criteria will be enrolled in the study. A patient is considered enrolled upon placement of the Allosync Expand during the surgical procedure. If the surgeon decides intra-operatively not to utilize Allosync Expand, the patient will be considered a screen failure.