Circumferential fusion using a custom-made screw in the management of high-grade spondylolisthesis

Management of high-grade spondylolisthesis is challenging and to date no therapeutic consensus is available. Various surgical procedures have been described using unique or double approach. The aim of the study is to describe an original technique using a posterior-only approach to achieve a circumferential lumbosacral fusion with a custom-made screw.

In our experience, eight patients (mean age 15 years old) were treated for grade III or IV slipping without instrumental reduction. Surgical technique included a laminectomy from L5 to S2, then after mobilization of neural elements a guide wire was inserted from the posterior side of S2 to the antero-superior corner of L5. A specific drill was used and the 10-mm screw was then inserted under fluoroscopic guidance. Further steps included a discectomy, lumbosacral interbody graft and posterolateral graft to obtain a circumferential fusion. Clinical and radiological evaluations were obtained.

On the whole series, solid fusion was achieved after 6 months on average. Sagittal realignment was observed with a regression of pelvic retroversion and hip flessum, a lumbarization of the lumbar lordosis and an improvement of the thoracic kyphosis. For one patient, a postoperative S1 deficit was observed.

This technique provides satisfactory results in the management of high-grade spondylolisthesis. This concept is based on a double spine instability considering viscoelastic properties of the disc and postoperative sagittal reciprocal changes as prerequisite. This posterior-only approach represents a valuable alternative to other procedures.