Influence of iliac crest height on percutaneous transforaminal endoscopic discectomy in treatment of L5/S1 disc herniation

Objective To investigate the influencet of iliac crest height on the treatment of L5/S1 disc herniation by percutaneous transforaminal endoscopic discectomy (PTED). Methods Clinical data about 172 patients who underwent PTED for L5/S1 disc herniation in our hospital from October 2014 to October 2015 were retrospectively analyzed. According to the relationship between the highest point of the iliac crest and the L4/L5 pedicle of the lumbar in lateral radiograph, the patients were divided into 3 groups:in group I the highest point of the iliac crest was below the upper margin of the L5 pedicle. In groupⅡ the point was between the lower margin of the L4 pedicle and the upper margin of the L5 pedicle. In group Ⅲ the point was above the lower margin of the L4 pedicle. Operative time, fluoroscopy time, and complication between the three groups were compared. Clinical outcomes were assessed by the visual analogue scale (VAS), the oswestry disability index (ODI), and the modified MacNab criteria. Results The operations were completed in all the patients. The operative time prolonged from groupⅠto group Ⅲwith 50.6±7.0 min, 61.9±9.6 min, and 73.1±8.0 min (P< 0.05, respectively); The fluoroscopy time prolonged from group Ⅰto group Ⅲ with 4.7±2.2 s, 7.4±3.1 s, and 10.3±2.5 (P< 0.05, respectively); The VAS and ODI scores of each group were statistically different from those before operation (P< 0.05). There was no significant difference in VAS score and ODI score between groups at the same time point (P> 0.05). According to the improved MacNab scoring system, the excellent and good rate at three months after operation were 89.7%, 89.6% and 87.5% respectively. Conclusion In the treatment of L5/S1 disc herniation with PTED, when the iliac crest is below the upper margin of the L5 pedicle, the operation can be easily performed; when the iliac crest is between the lower margin of the L4 pedicle and the upper margin of the L5 pedicle, the surgery should be performed by a experienced surgeon; when the iliac crest is above the lower margin of the L4 pedicle, other surgical approach is recommended.