Abstract
Introduction/Aim
Numerous lumbo-pelvic reconstruction methods based on posterior construct and anterior cages have been proposed for cases involving total sacrectomy and lumbar vertebrectomy. These constructs create long lever arms and generate high cantilever forces across the lumbo-sacral junction resulting in implant failure or breakage. Biomechanical studies have shown that placing implants anterior to lumbo-sacral pivot point provide a more effective moment arm to resist flexion force and improve the ultimate strength of the construct. As a result more emphasis is placed on screws in the pelvis.
We report a new and novel technique that allows for the placement of a pelvic ring construct to augment the posterior construct in a lumbo-pelvic reconstruction.
Method
In the prone position, two contoured hard rods are passed along the inner table of the pelvis under the iliac muscle from a minor posterior approach. The rods are connected to the posterior lumbo-pelvic construct with T-junction clamps. The patient is turned supine and the anterior ends of the rods are connected to a sub-cutaneously placed hard rod along the anterior abdominal wall with T-junction clamps. This in turn is fixed to the AIIS (anterior inferior iliac spine) with two poly axial screws. The whole construct resembles an oblong ring.
Results
At six months she is mobilising independently with a frame and X-rays show no failure of construct or implant.
Conclusion
The construct is technically less morbid and bio-mechanically sound to effectively neutralise the flexion to a greater degree than previous constructs described in the literature. It shares and tolerates the flexion moments at the lumbo-pelvic junction by its anterior placement to the sacral pivot point.
