S2-Ala-iliac screws for extended pelvic fixation in longer lumbar instrumentations.Description of a freehand technique

Objective. To reduce the rate of implant failures at the lumbosacral junction in polysegmental lumbar fusions. Indications. Spinal fusion with deformity correction including L5/S1, revision surgery for pseudoarthrosis L5/S1, screw pull-out and pedicle fractures in S1, and S1/S2 fractures after polysegmental fusions. Contraindications. Osteosynthesis of complex pelvic ring fractures, tumors of the ilium. Relative contraindication: infection, to avoid contamination of the iliosacral joint. Surgical technique. Conventional posterior approach to the lumbar spine. Positioning of the lumbar and S1 pedicle screws in common technique. Identification of the correct entrance point for one or two S2-Ala-iliac screws for each side and preparation of the drill holes in freehand technique. Connection of the lumbar and S1 pedicle screws and S2-Ala-iliac screws with one stress-free rod on each side without the use of connectors or special plates. Postoperative managenent. Back-friendly mobilization beginning on day 1 after surgery with support of a physiotherapist. No sports for 12 weeks. Results. In all, 25 patients were treated with an extended pelvic fixation using S2-Ala-iliac screws. A primary deformity correction was performed in 11 patients, whereas 14 patients underwent revision surgery. A total of 24 patients were clinically and radiologically followed for a mean of 16 months. Two patients showed a loosening of the S2-Ala-iliac screws on one side, and one patient had broken screw as well only on one side without clinical symptoms. So far, no patient has undergone revision surgery because of S2-Ala-iliac screw-associated complications.