THE GRAF FLEXIBLE STABILIZATION SYSTEM IN THE TREATMENT OF LUMBAR SPINAL STENOSIS - A RETROSPECTIVE STUDY OF 26 PATIENTS

Purpose of the study The aim was to determine the usefulness of a flex ible stabilization system associated with neural decompression in the treatment of lumbar spinal stenosis. 2 points were especially studied: low back pain at follow up and Graf system ability to prevent postope rative instability. Patients and methods 26 patients were screened ret rospectively with an average follow up of 29 months. Clinical results were appreciated on the functional Beaujon's score. Preoperatively all of the patients had static and dynamic standard X-rays. The evaluatio n of sagital olisthesis was done by using displacement of the posterio r border of the vertebral body (Wiltse and Winter method's). On the dy namic X-Rays we accepted as criteria of instability an olisthesis of 2 mm or more, an angular displacement equal or superior to 14,3 degrees in L2 L3, 15,5 degrees in L3 L4 and 18 degrees in L4 L5 according to the Dvorak's criteria, or a rotatory dislocation. Neurological compres sion was studied from CT scan and dynamic and static myelogram. Result s According to our classification results were excellent in 8 cases, g ood in 6 cases, fair in 9 cases and poor in 3 cases. Generally results were good on the neurological symptoms (neurological claudication, ra diculalgia at rest or at exertion) and lair on the low back pain. Only one half of our patients had improvement of back pain and 15 per cent were worsened. A postoperative destabilization occurred in 27 per cen t of our patients (7 levels, 7 patients). The dynamic preoperative X-r ays of these destabilized levels detected always 2 or 3 criteria of in stability: hypermobility, olisthesis of 2 mm or more on the flexion X- rays or rotatory subluxation. For the remaining cases only one criteri a of instability was found (hypermobility or olisthesis on flexion X-r ays). Conclusions Concerning the postoperative low back pain using of a flexible system associated with a neural decompression did not impro ve the results. Concerning the prevention of postoperative instability the Graf system did not avoid the slipping of the most instable level s.