Dowel fibular strut grafts for high-grade dysplastic isthmic spondylolisthesis

This is a clinical study that examines the results of partial reduction and fibular dowel graft placement for high-grade isthmic spondylolisthesis.

To demonstrate the efficacy of partial reduction and fibular dowel graft placement in the treatment of high-grade isthmic spondylolisthesis.

Previous literature has demonstrated difficulty in treating high-grade isthmic spondylolisthesis both with high rates of pseudarthrosis as well as neurologic complications if a complete reduction is attempted. There are no published data examining partial reduction with dowel graft placement.

Seventeen consecutive patients (mean age 20.3 years) with high-grade isthmic spondylolisthesis who were treated with posterior fusion and fibular strut grafts were studied (mean follow-up 4.6 years). Radiographs were reviewed at preoperative, immediate (within 3 months) postoperative, and ultimate (>2 years) follow-up. Parameters measured included lumbar lordosis, slip angle, Meyerding-Newman scores, and pelvic incidence. The anterior and posterior fusions were graded on a I-IV scale, and the implants (if used) were examined for failure. Clinical outcomes were measured with Oswestry and Scoliosis Research Society outcomes tools.

There were 17 patients treated: 10 primary and 7 revision patients. All patients had posterior fusion with fibular dowel grafts (11 allograft, 6 autograft). Meyerding grade improved 1.3 grades and slip angle improved 14 degrees with no loss of correction at ultimate follow-up. Sixteen of 17 patients had solid fusions on ultimate follow-up. Clinical evaluation with Scoliosis Research Society and Oswestry tools showed high patient function and satisfaction. Complications included one case of a broken strut in a revision patient; this was then revised to an instrumented circumferential fusion. There were no cases of deep or superficial infection. There were no neurologic deficits at ultimate follow-up.

Fibular strut grafting is a useful surgical adjunct in high-grade spondylolisthesis that is partially reduced. Clinical and radiographic outcomes were satisfactory. Our experience shows that there is no significant difference between allograft and autograft. All struts healed and remodeled by the ultimate follow-up, and there was only one instance of fibula fracture.