Lumbar spinal fusion is commonly performed as a "last resort" in patients with chronic low back pain caused by degenerative changes and instability of the spine. The aim of this study is to compare two fusion devices, which are used in spinal surgery in order to promote the fusion of two lumbar vertebrae.

Lumbar spinal fusion is commonly performed as a "last resort" in patients with chronic low back pain caused by degenerative changes and instability of the spine. The surgical treatment involves the removal of an intervertebral disc, and subsequently the union of the two adjacent intervertebral bodies, such that a bony connection is formed within time after surgery. Lumbar spinal fusion is being performed with increasing frequency. Many interbody fusion methods have been described. In recent years, several types of fusion cages have been developed. These cages are made of various materials: titanium, stainless steel, carbon fiber or polyethylethylketone (Peek). Fusion cages have been quickly integrated into orthopedic practice.

To date, no studies have been conducted that compare the efficacy of nonresorbable and bioresorbable fusion cage devices. In this study the surgical and clinical outcomes are compared of patients with degenerative lumbar spine disorders who undergo lumbar fusion with a nonresorbable versus a bioresorbable fusion cage. Patients with lumbar spinal disorders will be recruited from several European centers and randomly allocated to one of the two intervention groups. In both treatment groups lumbar spinal fusion is performed using a standardized technique.

Patients will be evaluated during two years post-operatively. During this follow up period, the clinical outcome and fusion parameters will be assessed.

Inclusion Criteria:

• Both genders, age between 18 and 70 years
• Chronic low back pain (> 3 months) with or without leg pain but no signs of motor loss
• Based on clinical history, physical examination, and radiographic signs, pain interpreted as emanating from L4-L5 or L5-S1
• Symptoms refractory to conservative treatment for at least 3 months
• Evidence of degenerative changes at L4-L5 or L5-S1 (spondylosis) on plain radiographs and/or CT scan, and/or MRI. The pathology should be predominant on one level.
• Single-level Posterior Lumbar Interbody Fusion surgery (PLIF) is indicated by the spine surgeon
• Additional posterior fixation is mandatory
• Use of autograft of the iliac crest is possible
• Ability to provide informed consent

Exclusion Criteria:

• Previous lumbar spinal fusion
• All other previous spinal surgery except for successful removal of a herniated disc more than 2 years before entering the study
• Symptomatic degenerative disc disorder at more than one lumbar level
• Pregnancy or intention to become pregnant during the two year study
• Ongoing psychiatric illness
• Evidence of alcohol and/or drug abuse
• Inability to complete the questionnaires
• Inability to walk independently
• Other indications than degenerative spinal disorders including a metabolic bone disease, osteoporosis, infection, old fracture, inflammatory process, or neoplasm
• Obvious painful and disabling arthritic hip joints