SPONGIT: Comparison of Two Surgical Approaches in the Treatment of Degenerative Spondylolysthesis

Degenerative spondylolisthesis is defined as the slip of one vertebra onto the other due to degenerative lesions; the L4-L5 intervertebral space is mainly involved. Mean age of symptomatic disease is about 60. Surgery is indicated in the presence of radiculalgia and/or neurological claudication and/or invalidating lombalgia, worsening neurological deficit, presence of sphincterian incontinence.

Surgical treatment of degenerative spondylolisthesis usually consists in neural decompression followed by posterolateral fusion with instrumentation. In the literature, fusion rate is estimated to be 80% with GPLI and seems to be increased by interbody fusion, especially transforaminal lumbar interbody fusion which has the advantage of unilateral disc interspace route, and fusion rate over 90%.

It seems that hypolordosis in the instrumented segments caused increased loading of the posterior column in the adjacent segments. These biomechanical effects may explain the degenerative changes at the junction level that have been observed as long-term consequences of lumbar fusion.

In addition to fusion, segmental lordosis gain seems to be an important long-term prognostic factor. Segmental lordosis recovery (upper than 3° in order to take into account measurement variability), was never assessed after TLIF procedure nor compared to that after posterolateral fusion in controlled randomized clinical trials.

The main objective of the study is the comparison of efficacy between circumferential fusion (TLIF plus GPLI) and GPLI alone as surgical treatment of degenerative spondylolisthesis in term of "Success" rate, defined as fusion and at least 3-degree increase of segmental lordosis angle, 24 months after surgery.

In this trial, included patients will be randomly assigned to undergo either posterolateral fusion with instrumentation (GPLI) or circumferential fusion with transforaminal lumbar interbody fusion (TLIF) combined to GPLI. In both arms, bone autograft will be performed using loose fragments obtained during neurological decompression.

Six visits are planned during the study: pre-inclusion visit within 3 months before surgery, inclusion/randomisation on the day before surgery, 3 follow-up visits (2, 6, and 12 months after surgery) and an end of study visit 24 months after surgery (or at time of withdrawal if relevant). Hospital stay (about one week, on average) is planned after surgery.

Inclusion criteria

• Adults aged less than 75,
• Having been informed about clinical trial objectives and risk,
• Covered by health insurance system,
• Suffering from degenerative spondylolisthesis (whatever the grade and intervertebral disc height) needing one-level surgical fusion due to either invalidating lombalgia/radiculalgia despite 6-month optimal medical treatment and/or motor neurological symptoms.

Exclusion criteria

• Previous lumbar fusion,
• Previous spine traumatism,
• Presence of at least one major contraindication to surgery and/or general anaesthesia (ie, non controlled coagulopathy, active infection, or serious underlying disease, auto-immune affection).
• Presence of at least one contraindication to either TLIF or GPLI,
• Severe radiological osteoporosis.
• Active cancer at time of inclusion into the study.
• Unlikely to comply with the requirements of the study and/or to complete the study for psychological, social, familial or geographical reasons.
• Under any administrative or legal supervision.