Background: Lumbar fusion is a common surgical procedure for treatment of back pain caused by degeneration of lumbar disc. The aim of fusion is to prevent motion in the destabilized segments to decrease the back pain . All types of interbody fusion approaches work with posterior pedicle screw fixation to increase stabilization and fusion rates. It has some disadvantages including paraspinal muscle dissection, screw malposition, neurologic risk , increased the time of operation with blood loss and risk of infection. A modified interspinous device can provide stabilization similar to pedicular screw fixation avoiding its complication when used for interbody fusion as a minimally invasive procedur.
Patient and Methods: The study involved 20 patients with moderate segmental instability in lumbar spine . Transforaminal interbody fusion using the polyethere- therketone( PEEK )cage and rigid interspinous device fixation was performed. Patients were followed up and treatment outcomes were assessed within approximately 24 months after surgery.
Results: according to pain intensity level on the visual analogue scale, the need for painkillers and the quality of life according to the Oswestry Disability Index scale during the early postoperative period demonstrated significantly better outcomes due to a less severe operative trauma to the paravertebral soft tissues. The formation of interbody bone formation was observed after 20—36 months in 94% of patients . Postoperative complications occurred in 2.2% of patient.

Conclusion: The use of transforaminal interbody fusion and rigid interspinous stabilization provides better clinical outcomes and fewer postoperative complications in patients with moderate lumbar segmental instability.