[Lumbar spondylolisthesis management using expandable pedicle screw and interbody fusion cage].

Objective: To evaluate the therapeutic effects of expandable pedicle screw (EPS) combined with interbody fusion cage on lumbar spondylolisthesis.

Methods: From June 2004 to March 2008, 23 patients with lumbar spondylolisthesis were treated, including 9 males and 14 females aged 24-72 years old (average 48.7 years old). The course of the disease varied from 6 months to 6 years (average 30.4 months). There were 18 cases of degenerative spondylolisthesis and 5 of isthmic spondylolisthesis, including 1 case at L3,4 level, 14 at L4,5 level, and 8 at L5 and S1 levels. There were 17 cases of grade I, 4 of grade II, and 2 of grade III (including 1 case of recurrent L5 spondylolysis) according to Meyerding classification system. Posterior lumbar interbody fusion was performed using 48 PLIVIOS interbody fusion cages, and spondylolisthesis reduction and internal fixation were conducted using 84 pieces of EPS. The indications for use of EPS were initial operation with bone mass reduction or osteoporosis, reoperation of previous pedicle instrumentation, intraoperative screw relocation, sacral anchoring, and construct reinforcement. Clinical outcomes, radiographic reduction of spondylolisthesis and bone fusion of lumbar interbody were evaluated based on JOA score, Boxall index, and Cook criteria.

Results: The incision healed by first intension in all cases except for one revision case that suffered from postoperative cerebrospinal fluid leakage and obtained delayed-healing without infection 23 days after operation using conservative treatment. No operative complications such as nerve and organ injuries were found. All cases were followed up for 12-39 months (average 17.8 months). X-ray exams of spine AP, lateral, fully extended position and fully flexed position view showed all 84 EPS were fully expanded within vertebral body. The improvement rate of JOA at the final follow-up visit was markedly effective in 14 cases, and effective in 5 cases, and noneffective in 4 cases, with a total effective rate of 82.61%. Anatomic reduction was achieved in 14 cases, improvement was obtained in 6 cases, no improvement was observed in 3 cases, and the reduction rate was 86.69%. Lumber interbody fusion was achieved in 20 cases, fixation was achieved in 2 cases, failure was observed in 1 cases, and the fusion rate was 86.69%.

Conclusion: EPS in complex with interbody fusion cage provides effective reduction, internal fixation and interbody fusion for the reconstruction of lumbar spondylolisthesis.