[Assessment of the use of the Graf ligamentoplasty in the surgical treatment of lumbar spinal stenosis. Apropos of a series of 26 patients].

PURPOSE OF THE STUDY

The aim was to determine the usefulness of a flexible 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 postoperative instability.

PATIENTS AND METHODS

26 patients were screened retrospectively 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 evaluation of sagital olisthesis was done by using displacement of the posterior border of the vertebral body (Wiltse and Winter method's). On the dynamic 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 compression was studied from CT scan and dynamic and static myelogram.

RESULTS

According to our classification results were excellent in 8 cases, good in 6 cases, fair in 9 cases and poor in 3 cases. Generally results were good on the neurological symptoms (neurological claudication, radiculalgia at rest or at exertion) and fair 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 cent of our patients (7 levels, 7 patients). The dynamic preoperative X-rays of these destabilized levels detected always 2 or 3 criteria of instability: hypermobility, olisthesis of 2 mm or more on the flexion X-rays or rotatory subluxation. For the remaining cases only one criteria of instability was found (hypermobility or olisthesis on flexion X-rays).

CONCLUSIONS

Concerning the postoperative low back pain using of a flexible system associated with a neural decompression did not improve the results. Concerning the prevention of postoperative instability the Graf system did not avoid the slipping of the most instable levels.