Introduction: The elimination of motion produced by spinal fusion may have consequences, overloading the juxtaposed motion segments and leading to adjacent degenerative changes. In order to prevent changes at adjacent segments to fused levels, several techniques have been developed, one of them is pedicle screw fixation with flexible bars (semi-rigid dynamic rods).
Methods: Twenty consecutive patients with degenerative lumbar disease received posterior lumbar fusion with flexible bars. Preoperatively, 10 patients had low back pain for segmental instability, 6 severe stenosis with degenerative listhesis, 2 stenosis with instability, one mild unsteable listesis, and one L1 traumatic fracture.
In 6 cases severe osteoporosis was also detected, with pre-operative mean T-score of -3.1 on DEXA BMD examination. In 14 cases the fixation was performed using pedicle screws and flexible bars of three different brands (Scient’x-Alphatec; Spinevision; Blackstone). In osteoporotic patients, titanium expandable screws (Osseoscrew, Scient’x-Alphatec) with semi-rigid dynamic rods were used. Patients were observed for a follow up ranging from 9 to 51 months. Outcome measures included Visual Analogue Scale, Oswestry Disability Index, and complications.
Results: At 18-month median follow up, the VAS and ODI were improved in 18 cases. Two osteoporotic patients with stenosis and lysthesis have recurrent low back pain and 3 patients with severe stenosis and lysthesis had CSF leakage not related to the device and healed after treatment. There were no instances of screw loosening or pull-out of the expandable screws, and the screw-bone interface was good in all cases. All patients did not present until now degenerative lesions adjacent to the fixed segments. On plain radiographs and CT, there were no signs of radiolucency around the pedicle screws. Screw breakage and implant failure did not occur in any patient.
Conclusions: The raise of intradiscal pressure at segments adjacent to rigid instrumented arthodesis can be reduced by using semi-rigid dynamic rods. In our series, posterior flexible fixation allowed good clinical outcomes in the treatment of different lumbar diseases. Flexible constructs might have a possible protecting role in preventing the occurrence of adjacent degenerative disease. Augmentation with titanium expandable screws may represent an advisable option in patients with documented severe osteoporosis.
Patient Care: Reducing early and late pain for adjacent lumbar degeneration
Learning Objectives: Try to reduce the lumbar degenerative adjacent disease