Prospective Study on Ennovate® Pedicle Screw Fixation in Isthmic Spondylolisthesis Patients

The present study is planned to demonstrate the efficacy and safety of a new pedicle screw system for the specific indication of isthmic spondylolisthesis, as this condition concerns relatively young patients requiring good fixation of the performed reposition to come to satisfactory clinical results.

Adult Isthmic spondylolisthesis, which is associated with "spondylolysis," is defined as an osseous discontinuity of the vertebral arch at the isthmus (the pars interarticularis), which usually occurs in the fifth lumbar vertebra. The prevalence of isthmic spondylosis is proposed to be about 6% to 26% in different studies. The European Spine Tango registry found 15%. It is proposed to affect more men than women. Conservative treatments including braces, physical therapy, and medication are shown to be effective for some patients; however, surgical treatments are mainly the final effective treatment. There are several different options for surgery among which posterolateral fusion (PLF) is considered as the method of choice. It is shown that PLF is more effective than conservative treatments such as exercise. The fusion helps to fix the motion of the affected segment and therefore, might lead to pain reduction. Decompression, supplemental instrumentation, and supplemental anterior column support are also considered for treatment. These treatment strategies can be used separately or in any combination; however, studies trying to compare separate treatments with a combination of them have led to inconsistent results.

Supplementary pedicle screws might be added to fusion methods for fixation and it is proposed that they have the ability to correct the deformity, reduce the listhesis, and increase the fusion rates, although a majority of the studies comparing instrumented PLF and noninstrumented PLF could not show the superiority of instrumented approaches. The literature has been reviewed in 2000 already, and the method has already been proved to be "practical, safe, and effective" for various spinal indications. Other authors found a better result for isthmic spondylolisthesis patients with posterior lumbar interbody Fusion (PLIF), vs. PLF, especially for high grade isthmic spondylolisthesis.

The present study is planned to demonstrate the efficacy and safety of a new pedicle screw system for the specific indication of isthmic spondylolisthesis, as this condition concerns relatively young patients requiring good fixation also in the long-term.

Eligibility Criteria:
Inclusion Criteria:

* Symptomatic single-level IS (L4-S1), (VAS \> 30mm, treated conservatively for a minimum of 6 months)
* Isthmic Spondylolisthesis Meyerding grade I and II
* Signed Informed Consent of the patient regarding the participation in this study

Exclusion Criteria:

* Multilevel IS
* Severe degenerative changes of cranial adjacent level (disc height of \<50% of the next healthy segment,
* Previous lumbar spine surgery except microdiscectomy or micro- decompression of the index level
* Patients psychically or mentally not able to give or refuse consent
* Patients psychically or mentally not able to answer the questions regarding their health status and quality of life
* Pregnancy (current or planned)
* BMI \>35
* Systemic or local infection
* Chemotherapy or radiation ongoing
* Desire of early retirement (running pension request)
* All contraindications as listed in the instructions for use