Clinical outcome of ISOBAR TTL dynamic stabilization with pars bone grafting for treatment of lumbar spondylolysis

Abstract

To evaluate the effectiveness of ISOBAR TTL dynamic stabilization with pars bone grafting for the treatment of lumbar spondylolysis. A retrospective analysis was made the clinical data of 26 patients with lumbar spondylolysis who received ISOBAR TTL dynamic stabilization with pars bone grafting between September 2009 and March 2014. There were 14 males and 12 females, with a mean age of 31 years (range, 19-47 years). The disease duration ranged from 9 to 60 months (mean, 16 months). Preoperative lumbar anteroposterior and lateral X-ray films, CT three-dimensional reconstruction, and MRI scans were performed to identify the location of pars defect. The involved levels were L 4 in 9 cases and L 5 in 17 cases. There were 10 cases of pure spondylolysis and 16 cases of spondylolysis accompanied with I degree slipping. The clinical outcome was assessed by visual analogue scale (VAS) and Oswestry disability index (ODI) scores at preoperation and 1 week, 3 months, 6 months after operation, and at last follow-up. The lumbar CT three-dimensional reconstruction was obtained at 6 months after operation to evaluate bone fusion of the pars. The adjacent segment degeneration was assessed by the University of California at Los Angeles (UCLA) grading scale at preoperation and last follow-up. All incisions healed by first intention; no infection, cerebrospinal fluid leakage, or pain at iliac crest donor site occurred. Twenty-six patients were followed up 2-5 years (mean, 36.5 months). No secondary spondylolisthesis, internal fixation loosening and breakage were found during follow-up. The postoperative VAS and ODI scores showed significant differences ( P<0.05) when compared with preoperative scores, and the scores at 3 months, 6 months, and last follow-up were significantly better than that at 1 week ( P<0.05), but no significant difference was shown between the other time points after operation ( P>0.05). The CT three-dimensional reconstruction indicated satisfactory union at the pars in 23 cases (88.5%) at 6 months after operation. Of the 3 nonunion patients, good union was obtained in 1 patient at 1 year after operation; nonunion was observed in 2 patients at last follow-up, but low back pain was obviously alleviated. According to the UCLA grading scale, 20 cases were rated as grade I and 6 cases as grade II at last follow-up, which was the same as preoperative grade and indicated no adjacent segment degeneration. It is safe and effective to use the ISOBAR TTL dynamic stabilization with pars bone grafting technique to treat lumbar spondylolysis with or without degree I slipping. The fusion rate is satisfactory, and adjacent segment degeneration can be slowed down after lumbar fusion surgery.