Osigraft Study.

1.Diagnosis of Degenerative and/or Isthmic Spondylolisthesis and/or Degenerative Disc Disease (DDD) at the levels of L3-S1 with;

a. Lumbar instability of at least 2 to 3 mm translation in standing standard radiographs;

b. at least 2 to 3 mm translation in flexion extension radiograms29,30 and/or angulation motion defined as >15° at L3-L4 level, >18° at L4-L5 level, and >17° at L5-S1 spine level;

2. Leg and/or back pain with one or more of the following phenomena: radiculopathy, sensory deficit, motor weakness, reflex pathology, neurogenic claudication;

3. The subject has been non-responsive to at least 6 months of non-operative treatment prior to study enrollment;

4. The subject has a preoperative Oswestry Disability Index of 30-100;

5. Fusion of only one lumbar level in the L-3 to S-1 region is indicated;

6. The subject has no history of previous fusion attempt(s) to the affected spinal level;

7. The subject is willing and able to understand, sign and date the study specific Patient Informed Consent, which has been approved by the Institutional Review Board;

8. The subject agrees to comply with post-operative clinical and radiographic evaluations and required rehabilitation regimen;

9. Age: the subject is skeletally mature between 18 and 80 years of age;

10. Gender: both males and females can be included in the study.

1. The subject has gross instability as a result of Degenerative and/or Isthmic Spondylolisthesis and/or DDD that requires multiple levels fusion (an example would be exclusion of Grade IV Spondylolisthesis);

2. The subject is severely osteoporotic/osteopenic as manifested by the presence of a history of osteoporotic spine fractures and/or medical treatment for osteoporosis and/or such changes on the AP/lateral radiographs that will make the surgeon decide to exclude this patient from any form of pedicle fixation;

3. The subject has an active spinal and/or systemic infection;

4. The subject has a systemic disease or condition, which would affect his/her ability to participate in the study requirements or the ability to evaluate the efficacy of the investigational product (i.e., active malignancy, neuropathy);

5. The subject is a prisoner, a transient or has been treated for alcohol and/or drug abuse in an inpatient substance abuse program within six months prior to proposed study enrollment;

6. The subject has participated in clinical trials evaluating investigational devices, pharmaceuticals or biologics within 3 months of enrollment in the study;

7. The subject is a woman who intends to bear children within 1 year of enrolling in the study (e.g. is not post-menopausal, has not had a hysterectomy, is not on long term oral contraception);

8. The subject is morbidly obese (defined as weight >60 percent over the recommended ideal weight as described in the 1996 Metropolitan Height and Weight Tables for Men and Women, Appendix B);

9. The subject has a known sensitivity to any component of Osigraft®;

10. The subject is known to require at the time of treatment, additional surgery to the lumbar spinal region within the next six months;

11. Patients who have in the last year been prescribed systemic corticosteroids.