SEMIRIGID INSTRUMENTATION IN THE MANAGEMENT OF LUMBAR SPINAL CONDITIONS COMBINED WITH CIRCUMFERENTIAL FUSION - A MULTICENTER STUDY

Study Design. Patients with the diagnosis of degenerative disc conditi ons or spondylolisthesis undergoing circumferential fusion with poster ior pedicle screw fixation using a semirigid rod were reviewed. Object ives. To determine the effective of this approach in achieving a spina l fusion and satisfactory clinical outcome, and to determine the compl ications associated with the procedure. Summary of Background Data. Th e use of instrumentation to stabilize the lumbar motion segments and t hereby enhance the fusion rate has been proposed in a number of studie s. Semirigid fixation was believed to be effective in achieving these objectives without concern for stress-shielding, which was suggested b y some authors using rigid fixation systems. Methods. Patients who req uired spinal fusion with anterior and posterior approaches because of specific lumbar pathology or previous surgeries were selected. The sur gery consisted of an anterior interbody fusion using allograft, follow ed by a posterolateral fusion and pedicle screw fixation. Fusion was d etermined by continuity of trabecular bridging, and outcomes were dete rmined by pain reduction and return to previous levels of activity. Fu sion was considered solid if the two posterolateral areas were fused ( Zones one and two), or if all three zones were fused. Complications we re documented during and after surgery.Results. Sixty-two percent of p atients had previous surgery with 25% of these patients having a diagn osis of pseudarthrosis. Fifty-five percent of patients had two or more levels fused, and 43% were heavy smokers. Ninety-seven percent of pat ients had successful fusion. Pain was significantly reduced on a pain analogue scale from 7.1 to 2.1 in the back and from 5.8 to 1.5 in the leg (P < 0.006 and 0.0001, respectively). Fifty-nine percent of patien ts returned to their previous level of activity, and 18% returned to l ighter work or job retraining, for a total of 77% returning to the sam e or lighter levels of activity. Complications included metal failure, 4.9%; neurologic deficit, 1.2%; deep infection, 1.2%; deep venous thr ombosis, 4.9%; and vascular injury, 2.4%. Fatal pulmonary embolus occu rred in one patient. Conclusion. This technique produces a satisfactor y fusion rate (97%) and a good clinical outcome based on pain reductio n and return to a satisfactory level of activity (77%). It is associat ed with few, but significant, complications that compare well with oth er reported series in a difficult group of patients. This procedure sh ould be reserved for patients who are considered to be a high risk for not achieving spinal fusion.