Sagittal Pelvic Radius in Low-Grade Isthmic Lumbar Spondylolisthesis of Chinese Population

OBJECTIVE: To investigate the variation of pelvic radius and related parameters in low-grade isthmic lumbar spondylolisthesis. METHODS: Seventy-four patients with isthmic lumbar spondylolisthesis and 47 controls were included in this study. There were 17 males and 57 females between 30 and 66 years of age, including 30 with grade I slippages and 44 grade II slippages; diseased levels included 34 cases on L4 and 40 cases on L5. Thoracic kyphosis (TK), the pelvic radius (PR), the pelvic angle (PA), pelvic morphology (PR-S1), and total lumbopelvic lordosis (PR-T12) were assessed from radiographs. RESULTS: Statistically significant differences were found for the PA, PR-T12, and PR-S1 (24.5±6.6°, 83.7±9.8°, and 25.4±11.2°, respectively) of the patients with spondylolisthesis and the healthy volunteers (13.7±7.8°, 92.9±9.2°, and 40.7±8.9°, respectively). The TK/PR-T12 ratios were between 0.15 and 0.75. However, there were no differences in all the parameters between the L4 and L5 spondylolysis subgroups (p>0.05). The TK and PR-S1 of grade II were less than grade I, but the PA was greater. The PR-T12 of female patients were less than male patients, but the PA was greater (p<0.05). CONCLUSION: Pelvic morphology differed in patients with low-grade isthmic lumbar spondylolisthesis compared to controls. Gender and the grade of slippage impacted the sagittal configuration of the pelvis, but the segment of the vertebral slip did not. Overall, the spine of those with spondylolisthesis remains able to maintain sagittal balance despite abnormal pelvic morphology.

Posterior Lumbar Interbody Fusion and Graf Band Fixation for Lumbar Isthmic Spondylolisthesis

With current developments in surgical instrumentation, the surgical management of symptomatic isthmic lumbar spondylolisthesis is diversifying. Many authors agree, the basic elements for this condition, are decompression of compressed neural structure, bone fusion, and internal fixation with or without reduction. In eleven isthmic lumbar spondylolisthesis patients treated between Jannuary and December 1994, we applied band fixation instead of the usual metalic rigid fixation after decompression and posterior interbody fusion using carbon fusion cages. Serial lumbar X-rays were taken, and we studied the changes in displacement, disc height and bone fusion, as well as evaluating surgical outcome and complications. Preoperative percent-slip was 18.5+/-5.5, and this fell to 12.7+/-6.3 and 12.4+/-6.1 at postoperative 6 and 18 months respectively. Percent-disc height was higher than its preoperative value, and the increase was maintained(21.2+/-6.2 preoperatively; 30.0+/-6.0 and 29.7+/-5.1 at postoperative 6 and 18 months respectively). In all patients, fusion was good, and there were no surgical complications. Over 18 months, the outcome in nine patients was good or excellent, but in 2 patients, it was not good. The poor results may be because the tension band was too tight and possible neural damage or incomplete decompression. On the basis of these observations, we concluded that posterior lumbar interbody fusion with Graf band fixation is good for fusion and for the maintenance of displacement and disc height, and that if performed with care, this is a possible surgical option in cases of isthmic lumbar spondylolisthesis.