Temporary external pedicular fixation versus definitive bony fusion:: a prospective comparative study on pain relief and function

Temporary external pedicular fixation is used as a prognostic instrument when treating degenerative conditions with spinal fusion. We studied the validity of the method and whether a functional test could improve the prognostic value of such fixation. Twenty-six patients with long-standing lumbar pain had an external temporary fixation. Pain levels were registered before fixation on a visual analogue scale at rest, as a mean for the previous week, and at seven different standardized activities. Walking capacity and walking speed for a standardized distance were also measured. Identical evaluations were then repeated during the external fixation and 1 year after definitive fusion. Based on the outcome of the temporary fixation, 20 patients were recommended for definitive surgical fusion. In six cases, the option of fusion surgery was rejected due to an unfavourable pain response or insufficient pain relief during the test fixation period, and this group was not further followed within the study. One year after surgery, 14 of 20 patients reported a good outcome. Solid bony fusion assessed by conventional radiography was seen in 19 patients. One patient with a poor clinical outcome had a pseudarthrosis. The mean values for pain level at rest, during last week and at the seven different activities in the functional test tended to decrease after fusion compared to the situation with temporary external fixation. In no activity did the external fixator overestimate the mean positive pain-relieving effect after definitive fusion. The walking capacity significantly increased, while the walking speed did not alter at the three different measurements. We conclude that with a good outcome ratio of 14 patients out of 19 having a solid fusion, the external frame improved patient selection and can be used as a valid prognostic instrument. The pain relief and function after definitive fusion can not be quantified by the external fixation, probably due to the fact that the stabilisation with an external frame is partial. The value of the functional test design presented is moderate, and an outcome evaluation comprising pain relief at rest and mean pain level during a week in fixation seems adequate.