Trans-isthmic pars interarticularis screwing under double CT and fluorcopic guidance : procedure accuracy and one year follow-up in patients with symptomatic low-grade lumbar isthmic lysis

Background To assess the accuracy of percutaneous trans-isthmic screwing with combined CT and fluoroscopic guidance guidance in patients with symptomatic low-grade isthmic spondylolisthesis. Materials and methods Fifty patients (28 women and 22 men, average age 50 years-old [min 17–max 80 ; SD 18.9]) with symptomatic low-grade isthmic spondylolisthesis refractory to medical treatment were treated by means of trans isthmic percutaneous screwing. The procedure was carried out under local anaesthesia with combined CT and fluoroscopic guidance. Primary outcome was the technical success of the procedure which was assessed on post operative CT using the same success criteria as surgical screw placement (Fig 1). Secondary outcome was pain decrease assessed by VAS score improvement. Results Ninety-nine procedures were performed in 50 patients and 99 screws were inserted. Post operative CT assessment showed satisfactory screw placement in 96 cases, that is a technical success rate of 96.9 %. No complication were noted intra or post operatively. Pain assessment showed a pain decrase of VAS score from 7,8 (Min 5, Max 10 ; SD 1,6) to 2,9 (Min 0, Max 7 ; SD 2,1) with a mean follow-up of 22 months. Discussion The results show a technical success rate of the percutaneous procedure under combined CT and fluoroscopic guidance similar to the surgical approach, and a significant VAS improvement. This study confirms preliminary results obtained on smaller cohort of patients. Conclusion Percutaneous trans-isthmic screwing under combined CT and fluoroscopic guidance allow accurate trans isthmic screwing in patients with symptomatic low grade isthmic lysis, and a satisfying pain reduction following the procedure.