Zdeblick's 1993 RCT randomized 124 patients undergoing lumbar fusion for degenerative conditions to one of three groups. The study asks whether adding instrumentation — and its degree of rigidity — improves fusion rates and clinical outcomes. This was the first prospective randomized comparison of instrumented versus non-instrumented posterolateral lumbar fusion.
When a patient comes back with a failed lumbar fusion, this paper defines the decision rule: non-instrumented pseudarthrosis repair fails 80% of the time, so re-operation without rigid fixation is not an option.
For primary fusion, the diagnosis drives the instrumentation decision. Degenerative disc disease and degenerative spondylolisthesis have the lowest non-instrumented rates (45% and 65%) and gain the most from rigid fixation. Isthmic spondylolisthesis and stenosis with scoliosis fuse reasonably well without hardware.
Before operating, assess bone quality. Nine patients in this series could not receive screws due to severe intraoperative osteopenia. Have a plan to convert — and counsel smokers that their fusion rates are meaningfully lower regardless of fixation strategy.
This is the first RCT to compare instrumented and non-instrumented posterolateral lumbar fusion, and its core finding. That rigid fixation outperforms semi-rigid, which outperforms none. Remains the mechanistic basis for modern pedicle screw constructs.
Zdeblick's 1993 RCT randomized 124 patients undergoing lumbar fusion for degenerative conditions to one of three groups. The study asks whether adding instrumentation — and its degree of rigidity — improves fusion rates and clinical outcomes. This was the first prospective randomized comparison of instrumented versus non-instrumented posterolateral lumbar fusion.
When a patient comes back with a failed lumbar fusion, this paper defines the decision rule: non-instrumented pseudarthrosis repair fails 80% of the time, so re-operation without rigid fixation is not an option.
For primary fusion, the diagnosis drives the instrumentation decision. Degenerative disc disease and degenerative spondylolisthesis have the lowest non-instrumented rates (45% and 65%) and gain the most from rigid fixation. Isthmic spondylolisthesis and stenosis with scoliosis fuse reasonably well without hardware.
Before operating, assess bone quality. Nine patients in this series could not receive screws due to severe intraoperative osteopenia. Have a plan to convert — and counsel smokers that their fusion rates are meaningfully lower regardless of fixation strategy.
This is the first RCT to compare instrumented and non-instrumented posterolateral lumbar fusion, and its core finding. That rigid fixation outperforms semi-rigid, which outperforms none. Remains the mechanistic basis for modern pedicle screw constructs.