[CLINICAL APPLICATION OF INDIVIDUALIZED REFERENCE MODEL OF SAGITTAL CURVES BY THREE-DIMENSIONAL PRINTING TECHNIQUE AND COMPUTER-AIDED NAVIGATION SYSTEM FOR LUMBAR SPONDYLOLISTHESIS].

OBJECTIVE: To evaluate the clinical significance of individualized reference model of sagittal curves by three-dimensional (3D) printing technique and computer-aided navigation system for lumbar spondylolisthesis. METHODS Between February 2011 and October 2012, 66 patients with lumbar spondylolisthesis underwent posterior lumbar interbody fusion (PLIF) by traditional operation in 36 cases (control group) and by individualized reference model of sagittal curves by 3D printing technique and computer-aided navigation system in 30 cases (trial group). There was no significant difference in gender, age, disease duration, segment, type of disease, degree of spondylolisthesis, and preoperative the visual analogue scale (VAS) of low back pain and leg pain between 2 groups (P>0.05). The operation time, blood loss, fluoroscopy times, VAS score of low back pain and leg pain were compared between 2 groups; the sagittal screw angle (SSA), accuracy rate of pedicle screw, Taillard index, disc height recovery rate, and sagittal angle recovery rate were compared between 2 groups.

RESULTS: There was no significant difference in operation time and blood loss between 2 groups (P > 0.05). But fluoroscopy times of control group were significantly higher than those of trial group (P < 0.05). One case had radicular symptoms after operation in control group. The patients of 2 groups were followed up 24-36 months (mean, 26 months). The VAS scores of low back pain and leg pain at last follow-up were significantly better than pre-operative scores in 2 groups (P < 0.05); VAS score of low back pain in trial group at last follow-up was significantly lower than that in control group (P < 0.05). The accuracy rate of pedicle screw was 81.9% (118/144) in control group and 91.7% (110/120) in trial group, showing significant difference (χ2 = 5.25, P = 0.03). There was significant difference in SSA between 2 groups at immediate after operation (t = -6.21, P = 0.00). At immediate after operation and last follow-up, Taillard index, disc height recovery rate, and sagittal angle recovery rate in trial group were significantly better than those in control group (P < 0.05).

CONCLUSION: PLIF by individualized reference model of sagittal curves by 3D printing technique and computer-aided navigation system can effectively correct spondylolisthesis, recover the lumbar sagittal angle and improve the VAS score of low back pain though it has similar operation time and blood loss to traditional PLIF.