Adjacent-segment morbidity after Graf ligamentoplasty compared with posterolateral lumbar fusion.

OBJECT: Of concern to spine surgeons are accelerated degenerative changes of motion segments located above and below where spinal fusion has been performed. Graf artificial ligament stabilization has been developed to avoid the adverse effect of spinal fusion. The object of this study was to assess the adjacent-segment morbidity of Graf ligamentoplasty compared with posterolateral fusion (PF) in which instrumentation was used. METHODS: Data obtained in 45 patients who underwent L4-5 Graf ligamentoplasty (18 patients) or PF with instrumentation (27 patients) were reviewed retrospectively. The minimum follow-up period was 5 years. In the PF group a solid fusion rate of 92.6% was achieved. Radiographic evaluation included assessment of lumbar sagittal alignment, range of motion (ROM), and adjacent-disc degeneration. Adjacent-segment morbidity was clinically assessed by determining the reoperation rate. Graf ligamentoplasty maintained regional lordosis and flexibility (13 degrees in L4-5 lordosis; 4.4 degrees in L4-5 ROM). Although there was no difference in preoperative adjacent-disc condition between the two groups, radiographic evidence of adjacent-disc deterioration was observed more frequently in patients in the PF group than the Graf group (25% and 6% at L1-2; 38% and 6% at L2-3; 38% and 18% at L3-4; and 43% and 18% at L5-sacrum, respectively). One case in the Graf group (5.6%) and five cases in the PF group (18.5%) required additional surgeries for adjacent-segment lesions. CONCLUSIONS: Graf ligamentoplasty cannot completely replace spinal fusion. In a well-selected group of patients, however, it was shown to maintain lumbar mobility and sagittal alignment, and it decreased the risk of adjacent-segment deterioration compared with PF with instrumentation.

Mid-term clinical results of Graf stabilization for lumbar degenerative pathologies. a minimum 2-year follow-up.

BACKGROUND CONTEXT: Spinal fusion has some adverse effects, such as nonunion and pain at the site of grafted bone, and fusion with rigid spinal instrumentation especially may have the possibility of increasing mechanical stress on the segments adjacent to the site of fusion. The theory of the Graf system is that it will decrease adjacent disc deterioration because of maintenance of regional lordosis with flexibility and restriction of the motion of unstable segments without rigid spinal fusion. PURPOSE: To assess the clinical and radiologic results of Graf stabilization for lumbar degenerative disorders with minimal or mild instability. STUDY DESIGN: This is a retrospective study examining the mid-term results of Graf stabilization. PATIENT SAMPLE: In total, 59 patients underwent Graf ligamentoplasty and adequate decompression from April 1993 to September 1997. The subjects were 30 men and 29 women, and the mean age at the time of surgery was 60.6 years, ranging from 23 to 82 years. The average follow-up period was 3 years and 5 months, ranging from 2 years to 5 years and 10 months. OUTCOME MEASURES: We evaluated the surgical results using a scoring system, a visual analog scale, and radiological measurements. METHODS: The results were assessed according to a clinical scoring system established by the Japanese Orthopaedic Association (JOA score) and ratings based on a visual analog scale. Through analysis of x-ray images, the sagittal alignment (regional lordosis) and the range of motion (ROM) of the stabilized segments were measured in all cases, and the percentage of segments slipping and posterior disc height were determined for 29 patients with degenerative spondylolisthesis. RESULTS: Clinical scores and low back pain ratings based on a visual analog scale were significantly improved at the time of final follow-up compared with the preoperative values. Regional alignment of the operative segments was maintained in lordosis at the time of final follow-up. Preoperative ROM was significantly reduced at the time of final follow-up. There were no statistical differences in percentage of slippage or percentage of posterior disc height between the final follow-up values and the preoperative values. CONCLUSIONS: Our clinical results indicate that the Graf system is a suitable treatment option for mild and early lumbar degenerative diseases with minimum flexion instability of less than 10 degrees.