Threaded fusion cage for lumbar spondylolisthesis.

Fifteen patients with Meyerding I spondylolisthesis causing disabling lumbago underwent threaded fusion cage implantation at the unstable segments. Low back pain and intermittent claudication subsided in all patients postoperatively. The preoperative Japan Orthopaedic Association score was 11.5 on average, and improved to 23.5 after surgery. Five patients achieved significant resolution of preoperative symptoms, six improved reasonably, and four required less medication. There was no failure of fixation. No patient required supplemental fixation such as pedicle screws to achieve stable fusion. One patient had an inflammatory course but re-surgery was not necessary. The threaded fusion cage is an effective and promising device for the relief of low back pain when used to promote fusion of the lumbar spine in patients with low-grade spondylolisthesis.