Abstract
Introduction Dynamic stabilisation is a new technology with origins in France. Interspinous spacers are placed in the lumbar spine to offload the facet joints and posterior disc annulus. Three devices are presently available in Australia. Finite element analysis suggests that such devices can restore or ‘normalise’ the biomechanics of a degenerate motion segment without effecting adjacent motion segments. This study reports an evaluation of the safety of these devices, their potential applications, the technique for implantation and complications experienced by a single surgeon over two years.
Methods 120 patients were selected and had either Wallis or DIAM dynamic stabilisation implants placed in the lumbar spine during surgery for disc prolapse, degenerative stenosis or ‘discogenic’ back pain.
Results 55% of patients had implants placed after discectomy, 30% of patients after stenotic decompression, 10% for ‘discogenic’ pain and 5% above an instrumented fusion. 58% of patients had a single level procedure, 38% had a two level procedure and 4% a three level procedure. No device related or other significant complications were encountered. Three patients required removal of devices, two to remove an L45 Wallis implant and place L45 and L5S1 DIAM implants and one to remove DIAM implants for recurrent disc prolapse before performing a fusion procedure. Patient bed stay has averaged less than 4 days.
Discussion Dynamic stabilisation is a safe and simple procedure for several common lumbar spinal conditions. The DIAM implant is a simpler device to insert compared to the Wallis implant and can almost always be fitted to the L5S1 level. The Wallis implant appears to be better suited to degenerative spondylolithesis as it is of more robust design and may better limit flexion instability. Patient outcomes and satisfaction are satisfactory to date. Surgical technique must be modified to preserve the spinous process and lamina.
The abstracts were prepared by Assoc Prof Bruce McPhee. Correspondence should be addressed to him at the Division of Orthopaedics, The University of Queensland, Clinical Sciences Building, Royal Brisbane Hospital, Herston, Brisbane, 4029, Australia.
