Fusion to the sacrum: results of transileal fixation

Abstract

Mesfin A. Lemma, MD, David B. Cohen, MD, MPH, Lee H. Riley, III, MD, Khaled M. Kebaish, MD, Alfred Faust, MD, John P. Kostuik, MD, Baltimore, MD, USAPurpose: Long spinal fusions to the sacrum have been fraught with difficulties achieving fusion at the lumbar sacral junction. Adequate fixation in the sacrum is often difficult to obtain, and numerous different techniques for obtaining fixation have been described. For the last 5 years we have used a transileal rod placed by means of an inside out technique and locked into bicortical S1 pedicle screws as a method of fixation in long fusions to the sacrum. We report on the long-term outcome and efficacy of this technique.Methods: Between September 1996 and October 1999 93 patients underwent long fusions to the sacrum using a transileal rod locked into bicortical S1 pedicle screws as sacral fixation. The radiographs and clinic and hospital charts of these patients were retrospectively reviewed by an independent observer to determine the rates of fusion at the lumbar sacral level, as well as any complications or complaints associated with the transileal rod.Results: Ninety-three patients who underwent long fusions to the sacrum with a minimum 2-year follow-up were available for review. Patients averaged 57.4 years of age (range, 38 to 82 years) with 5 patients (5.4%) having a primary spinal procedure and 88 patients (94.6%) who underwent a revision spinal procedure. Fifty-six of 93 patients (60.2%) had structural grafting to the L5–S1 disc space in conjunction with the transileal rod. Ninety of 93 patients (96.8%) went on to solid fusion at 2 years. Twenty-three of 93 patients (24.7%) required additional surgeries during their follow-up. Fifteen of the 93 patients (14%) went on to additional procedures at the lumbosacral level. Eleven surgeries were for removal of painful hardware. Three were for repair of pseudarthrosis at the lumbosacral level. One patient went on to require a fusion of the sacroiliac joint secondary to joint degeneration and pain.Discussion: Long fusions to the sacrum have been associated with rates of pseudarthrosis as high as 30%. Most failures are the result of inadequate sacral fixation. In the current series using a transileal bar locked into bicortical S1 pedicle screws to obtain sacral purchase, we had a 3.2% pseudarthrosis rate, which is comparable to recent reports using a combination of ileal and S1 screws in these surgeries. A total of 11.8% of patients require revision surgery for removal of hardware and 1.1% for sacroiliac joint fusion. These are better than 24% hardware removal rates reported with the use of ileal screws. Given these results, we think that the transileal rod locked into bicortical S1 pedicle screws offers an excellent method of achieving long fusions to the sacrum when combined with structural grafting at the L5–S1 level in primary and revision surgeries.