SPONGIT: Comparison of Two Surgical Approaches in the Treatment of Degenerative Spondylolysthesis
Condition: Degenerative Spondylolisthesis
MeSH terms: Spondylolisthesis
Study type: Interventional

Summary: 
      This trial, conducted in adult patients with degenerative spondylolisthesis needing surgical
      treatment at one level, aimed at comparing two approaches of spinal fusion.
    

Detailed description: 
      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.
    

Intervention name(s): Circumferential arthrodesis; Posterolateral fusion with instrumentation
Intervention type(s): Procedure; Procedure
Intervention description(s): Patients are carefully positioned in the proned position and submitted to a posterior surgical approach under general anaesthesia. Surgical levels are viewed laterally by mean of intraoperative radiographs which can be performed at surgeon's demand during the whole surgery time.
The preceding procedure is performed. In case of foraminal stenosis, decompression is performed at the same time as discal approach via the narrowest foramen.
In addition to this, before preparation of bed for bone grafting, nerve roots are retracted and the disc nucleus is removed entirely, then endplate decortication is performed. The disc space is distracted. The most anterior part of the disc space is packed with cancellous bone. A cage packed with bone is inserted into the anterior portion of the interspace. According to cage location, bone graft could be inserted in the posterior portion of the interspace. Cage placement is radiologically checked.
The end of the procedure is the same as for GPLI.; Patients are carefully positioned in pronation and submitted to a posterior surgical approach under general anaesthesia. Surgical levels are viewed laterally by mean of intraoperative radiographs performed at surgeon's demand during the whole surgery time.
Pedicle screw instrumentation is performed, followed by posterior neural decompression depending on the type of stenosis:
Central stenosis: decompression is performed including medial facectomy, laminectomy;
Foraminal stenosis: foraminotomy is performed, while preserving a graft bed as large as possible;
Pure foraminal stenosis: spinal duct is not opened. Local bone is harvested from the lamina and the spinous process and carefully fragmented for autologous graft.
Subperiosteal dissection is performed between the transverse processes and lateral aspects of the facet joints.
Two rods are placed and locked on screws in maximum compression to optimize segmental lordosis.
Bone autograft is placed into this bed.
Other intervention name(s): TLIF+GPLI; GPLI
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Spondylolisthesis; degeneration; spinal fusion