RCT on the Efficacy and Safety of Minimally Invasive SAIF Technique vs Spinal Fixation in Unstable Osteoporotic Vertebral Fractures

Osteoporosis is an increasing health problem worldwide with an enormous economic burden for society. Osteoporotic vertebral fractures (OVF) represent a significant cause of morbidity, mortality, decreased level of function and quality of life. Stable fractures with controllable pain can be managed conservatively, and only those that remain painful despite conservative treatment can be treated with minimally-invasive measures of vertebral augmentation (VA). At the other end of the spectrum, the most severe OVFs are unstable. In these cases standard vertebral augmentation techniques are generally considered an under-treatment and surgical stabilization, with various techniques, is considered necessary to restore the physiological loading capacity of the spine, and allow fast and painless mobilization. Unfortunately, this elderly, osteoporotic patient population poses serious challenges to spinal surgery, due to tissue frailty and frequent comorbidities. More specifically, all the surgical stabilization techniques include rigid posterior fixation of multiple spinal segments, but the reduced bone mechanical properties of osteoporotic patients can lead to hardware implant failure, new fractures, complications, and need of re-intervention.

On the other hand, treatment and reinforcement of the anterior spinal column, that should enhance posterior stabilization, requires a more invasive surgical approach, which carries a significant rate of complications and prolonged recovery times in this elderly population.

A recently described minimally-invasive interventional technique, called Stent-screw Assisted Internal Fixation (SAIF), can reconstruct, stabilize and restore axial load capability of the vertebral body affected by severe fractures, potentially obviating the need of a surgical multi-level rigid construct.

The study seeks primarily to determine whether the SAIF intervention is not inferior to surgical stabilization in improving quality of life in subjects with unstable OVFs at one year follow-up.

The principle secondary objective of this study is to evaluate whether the effect of the SAIF intervention on the radiological outcome is not inferior to surgical stabilization in subjects with OVFs.

Other secondary objectives are to compare both treatments in terms of safety, length of operation, blood loss, days of hospitalization postoperatively, pain, the intake of analgesics, disability and cost-effectiveness.

The total expected number of patients to randomized is 140, 70 per group. This ensures 80% power to test the hypothesis that SAIF is not inferior to surgical stabilization in increasing quality of life measured with the QUALEFFO questionnaire, assuming a standard deviation of 16 points, with a non-inferiority margin of 8 points. This also ensures over 90% power to exclude a non-inferiority margin of 4 degrees of kyphosis correction. The alpha for testing is set at 5%.

Estimated duration for the main investigational plan will be 60 months (from start of screening of first subject to last subject processed and finishing the study).

Inclusion criteria

• one to two unstable OVFs* type OF 3-5** as assessed on CT scan, located between T2 and L5, of age <3 months or with persistent edema on STIR, or with pseudarthrosis, at the index level
• patients reporting pain upon mobilization
• a diagnosis of osteoporosis, based on a DEXA T-score ≤ -2.5, or on a spontaneous thoracolumbar vertebral fracture or a vertebral fracture caused by minor trauma
• able to read and speak the official language of the region of the site,
• informed consent

• additional OVF without unstable features (OF 1-2) allowed ** OF-Classification

Exclusion criteria

• compressive neurologic symptoms such as myelopathy or radiculopathy with motor deficit
• acute infection
• spinal malignancy
• comorbid severe psychiatric conditions
• known or suspected non-compliance, drug or alcohol abuse
• known hypersensitivity or allergy to the investigational product
• inability to follow the procedures of the study